{"paper_id":"07f3c713-e1e6-43f0-91a8-74bb3d9aa686","body_text":"Dual-Action Innovation: Schiff Base for Trace Cu 2+ ions Detection and Powerful Antibacterial Potential | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Dual-Action Innovation: Schiff Base for Trace Cu 2+ ions Detection and Powerful Antibacterial Potential Prof Alaa Shafie, Mohammed Fareed Felemban, Faris J. Tayeb, Amal Adnan Ashour This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6796500/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 18 Feb, 2026 Read the published version in Transition Metal Chemistry → Version 1 posted 16 You are reading this latest preprint version Abstract A novel Schiff base SBA1 , was successfully synthesized and structurally characterized using UV-Vis, FTIR, and 1 H NMR spectroscopy. Its sensing capabilities were systematically investigated against a broad range of metal ions, including Cu 2+ , Co 2+ , Zn 2+ , Pb 2+ , Ag + , Cd 2+ , Mg 2+ , Ni 2+ , Ca 2+ , Fe 3+ , Mn 2+ , Hg 2+ , K + , and Na + . Among these, SBA1 exhibited a highly selective and distinct colorimetric response toward Cu 2+ ions, marked by a visible color change from yellow to colorless. Fluorescence studies further revealed a substantial enhancement in emission intensity upon Cu 2+ binding, indicating strong interaction and excellent sensing performance. The sensor demonstrated impressive sensitivity, achieving a limit of detection (LOD) of 0.0031 ppm and a limit of quantification (LOQ) of 0.0096 ppm, enabling trace-level detection of Cu²⁺ ions in aqueous media. To evaluate its practical utility, the SBA1 was tested in real environmental samples, including soil-extracted water, drinking water, lake water, river water, and pond water. Fluorescence titration with Cu²⁺-spiked samples showed outstanding recovery rates ranging from 91.0–102.0%, confirming the sensor reliability and accuracy in complex matrices. In addition to its sensing capabilities, the antibacterial potential of SBA1 was also assessed against selected bacterial strains. The compound exhibited notable antibacterial activity, indicating its dual functionality as both a highly sensitive Cu 2+ sensor and an effective antimicrobial agent. These findings position SBA1 as a promising multifunctional material for environmental monitoring and biomedical applications. 1H NMR spectroscopy Metal ions Colorimetric River water Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Introduction Heavy metal pollution, driven by both natural processes and human activities, poses significant environmental and health risks. These metals are persistent in the environment and bioaccumulate in ecosystems, particularly through industrial activities like mining, agriculture, and manufacturing. Their toxicity varies based on factors like oxidation state and concentration, leading to harmful effects on organisms, including mutations, carcinogenic effects, and immune system disruption. In aquatic environments, heavy metals accumulate in species and enter the food chain, posing risks to human health. [ 1 – 7 ] Among heavy metals, copper is a vital micronutrient required for various biological and physiological functions in both plants and animals. Copper plays a crucial role in enzymatic reactions, particularly as an electron donor in oxygen-utilizing processes like the respiratory chain in mitochondria, where cytochrome c oxidase acts as an electron transporter. This enzyme contains three copper centers per monomeric complex. Copper is also essential for connective tissue formation, such as collagen and keratin. Copper ions are transported into cells by specific copper transporters and reduced to Cu + , with metallochaperones guiding them to target enzymes. To avoid oxidative damage, free copper ions are maintained at low concentrations in living organisms, preventing harmful free radical production through the Fenton reaction.[ 8 , 9 ] Although copper is essential, excessive accumulation in the environment and biological systems can lead to severe toxicity and health issues. Excessive copper accumulation, as seen in conditions like Wilson disease, can lead to severe health issues, including liver damage, nervous system dysfunction, and reproductive problems. Copper toxicity can also result from long-term exposure to small amounts through food contaminated by corroded copper cookware, causing symptoms like abdominal pain, vomiting, and, in extreme cases, paralysis or death. In aquatic ecosystems, elevated copper levels are toxic to fish and other aquatic organisms, impairing gill function, disrupting ion regulation, and causing developmental abnormalities. Similarly, in plants, excessive copper uptake affects root elongation, chlorophyll synthesis, and overall growth, leading to reduced crop yields and soil degradation. The persistence of copper in the environment highlights the need for effective monitoring and detection methods to regulate its levels and prevent toxic accumulation.[ 10 – 14 ] Various analytical techniques, such as flame atomic absorption spectrometry, potentiometry, anodic stripping voltammetry, capillary electrophoresis (CE) and many others, have been widely employed for Cu 2+ detection. [ 15 – 18 ] However, these methods are often expensive, time-consuming, and require sophisticated instrumentation, making them less suitable for rapid or on-site analysis. Therefore, the development of new, cost-effective, and user-friendly detection techniques is crucial for efficient Cu 2+ monitoring in environmental, biological, and industrial applications. Colorimetric and fluorimetric chemosensors have gained significant attention for the detection of metal ions due to their simplicity, high sensitivity, and rapid response. [ 19 – 22 ] These sensors rely on changes in color or fluorescence intensity upon interaction with target metal ions, enabling easy visual or instrumental detection. Colorimetric sensors typically involve chromogenic dyes that exhibit distinct color changes upon metal binding, while fluorimetric sensors utilize fluorophores whose emission properties are altered by metal coordination. [ 23 – 25 ] Organic chemosensors, particularly those based on Schiff bases, have emerged as promising candidates for Cu 2+ detection due to their versatile coordination chemistry, ease of synthesis, and tunable optical properties. Schiff base ligands possess imine (-C = N-) functional groups that can strongly bind to metal ions, leading to significant colorimetric or fluorimetric changes. Their structural flexibility allows for the design of selective and sensitive probes for Cu 2+ ions. Schiff base-based chemosensors have been widely explored for Cu 2+ sensing in aqueous and biological media, providing valuable insights into metal ion interactions and potential applications in environmental monitoring and medical diagnose. [ 26 – 29 ] In addition to their well-established role in metal ion sensing, Schiff base compounds have demonstrated significant antimicrobial activity, making them attractive as standalone bioactive agents. The inherent structural features of Schiff bases, particularly the presence of the imine (-C = N-) group, play a crucial role in their biological activity. This functional group can interfere with vital microbial processes by interacting with cellular components such as proteins and nucleic acids, leading to inhibition of microbial growth. The ease of structural modification allows for the incorporation of various aromatic, aliphatic, or heterocyclic moieties into Schiff base frameworks, enhancing their ability to target specific pathogens and improving their lipophilicity for better cell membrane penetration. Studies have shown that Schiff bases can effectively inhibit a range of bacterial and fungal strains, often through various mechanisms. [ 30 – 33 ] In this work, a Schiff base sensor ( SBA1 ) was successfully synthesized and characterized by 1 H NMR, FT-IR, UV-Vis, and fluorescence spectroscopy. The sensing ability of SBA1 was evaluated with various metal ions and showing significant enhancement upon the addition of Cu 2+ . Optimization studies were conducted to achieve the best fluorescence response. In addition to its sensing capabilities, the antibacterial potential of SBA1 was also assessed against selected bacterial strains. The compound exhibited notable antibacterial activity, indicating its dual functionality as both a highly sensitive Cu 2+ sensor and an effective antimicrobial agent. Experimental Materials and methods The Schiff base sensor was synthesized using commercially available precursors. Solvents such as methanol, ethanol, chloroform, n-hexane, and ethyl acetate, along with various metal salts (Cu(acetate) 2 , (Co(acetate) 2 , ZnCl 2 , PbCl 2 , AgNO 3 , CdCl 2 , MgCl 2 , NiCl 2 , CaCl 2 , FeCl 3 , MnCl 2 , HgCl 2 , KCl, and NaCl), were obtained from Sigma-Aldrich. To maintain high purity and prevent contamination, all experiments were performed using double-distilled water. The fluorescencespectra were measured usingan LS 55 fluorescence spectrophotometer manufactured by Perkin-Elmer, USA. The pH of solutions was measured using a PHS-25C Precision pH/mV Meter (Aolilong, Hangzhou, China) to ensure accuracy across experimental conditions. UV–Vis absorption spectra were recorded on a Shimadzu UV-2450 spectrophotometer (Japan) to investigate the optical properties of SBA1 . Synthesis of SBA1 The Schiff base was synthesized through a condensation reaction between 2-hydroxy-1-naphthaldehyde (0.5 g, 2.9 mmol) and 4-chloroaniline (0.36 g, 2.9 mmol) in 20 mL of methanol ( Scheme. 1 ). The mixture was refluxed for 15 hr to facilitate the formation of the imine bond, with the progress being monitored by thin-layer chromatography (TLC). The successful completion of the reaction was confirmed by the disappearance of the reactants spots and the appearance of a new spot corresponding to the Schiff base product. The solid product was separated by filtration and purified through successive methanol washings to obtain the pure compound. Yield: 92%: IR(KBr) ν /cm − 1 O-H, 3454; Ar-H, 3026; C = N, 1618; C = C aromatic,1485; C-Cl, 750. 1 H NMR (300.00 MHz, CDCl 3 , 25°C): δ (ppm):7.129(d, 1H, J = 8.86 Hz), 7.312 (d,2H, J = 7.89 Hz), 7.377 (t, 1H, J = 7.49 Hz),7.432 (d, 2H, J = 8.28Hz), 7.553 (t, 1H, J = 7.78Hz), 7.744 (d,1H, J = 8.11Hz), 7.834(d, 1H,J = 9.07Hz ), 8.122(d, 1H,J = 8.61Hz), 9.382(s, 1H), 15.296(bs,1H,OH). Fluorescence study The fluorescence properties of SBA1 were evaluated by testing its response to a variety of metal ions, including Cu 2+ , Co 2+ , Zn 2+ , Pb 2+ , Ag + , Cd 2+ , Mg 2+ , Ni 2+ , Ca 2+ , Fe 3+ , Mn 2+ , Hg 2+ , K + , and Na + . Stock solutions of SBA1 (100 ppm) and various metal salts (100 ppm) were prepared. A measured volume of 3.0 mL of SBA1 stock solution was mixed with 2.0 mL of the respective metal ion solution in a 10 mL volumetric flask. After thorough shaking, the mixture was incubated at room temperature for 5 minutes to allow equilibrium. Following incubation, 3.0 mL of each solution was transferred into a quartz cuvette, and fluorescence spectra were recorded to assess the interaction between SBA1 and the metal ions. Antibacterial activity The antimicrobial activity of the newly synthesized compounds, SBA1 was investigated against both Gram-positive and Gram-negative bacterial strains. These included Salmonella typhimurium, Enterobacter aerogenes , Klebsiella pneumoniae , Pseudomonas aeruginosa, Bacillus megaterium, Salmonella enterica , Bacillus cereus, Escherichia coli , Bacillus subtilis , Staphylococcus aureus, Proteus vulgaris , Pseudomonas fluorescens , and Brevibacillus brevis . The antimicrobial activity of the synthesized Schiff base compound SBA1 was evaluated using the disc diffusion technique. [ 34 ]. For this assay, SBA1 was dissolved in dimethyl sulfoxide (DMSO) to prepare a stock solution with a concentration of 12.0 mg/L. Sterile paper discs with a diameter of 6 mm were each loaded with 10 µL of the prepared solution and then carefully placed on Mueller-Hinton Agar plates previously inoculated with bacterial suspensions standardized to 10⁶ CFU/mL. To serve as a negative control, a separate disc containing only 10 µL of DMSO was included on each plate to rule out any antimicrobial effects from the solvent. To facilitate even diffusion of the compound into the agar medium, the plates were pre-incubated at 4°C for 2 hours before being transferred to an incubator set at 37°C for 24 hours. Following incubation, the diameters of the clear zones surrounding each disc, indicative of bacterial growth inhibition, were measured in millimeters. All tests were conducted in triplicate to ensure accuracy, reproducibility, and statistical significance of the results. Results and discussion Characterization The structure of SBA1 was characterized using UV-Vis, FTIR, and 1 H NMR spectroscopy to confirm its structure. The UV-Vis absorption spectrum of SBA1 exhibited two characteristic absorption peaks. The peak at 334 nm is a relatively small peak, which can be attributed to the π–π* transition of the aromatic system, primarily arising from the benzene and naphthalene rings. This transition indicates the presence of conjugated π-electron systems within the molecular framework. The strong absorption peak at 436 nm corresponds to the n–π* transition, which is associated with the azomethine (-C = N) group present in the Schiff base (Fig. 1 ). This transition is influenced bythe lone pair of electrons on the N- atom of imine, which facilitates charge transfer across the molecule, leading to an intense absorption band. The presence of this peak confirms the successful formation of SBA1 . The FTIR spectrum of the synthesized Schiff base SBA1 provides crucial insights into its functional groups. A broad absorption band observed at 3408.54 cm − 1 corresponds to the O–H stretching vibration, confirming the presence of a hydroxyl group. The characteristic C–H stretching vibrations of the aromatic rings appear at 3026.92 cm − 1 , indicating the presence of aromatic moieties within the molecular framework. A sharp and intense absorption peak at 1618.25 cm − 1 is attributed to the C = N stretching vibration of the azomethine group, a key functional feature of Schiff bases. Additionally, the C = C stretching vibrations of the aromatic system are observed at 1485.79 cm − 1 , further supporting the presence of conjugated aromatic rings. Lastly, the absorption band at 750.88 cm − 1 is assigned to C–Cl stretching, confirming the incorporation of the chloro substituent in the molecular structure (Fig. 2 ). These spectral features collectively validate the successful formation of the Schiff base and its characteristic functional groups. The 1 H NMR spectrum of the synthesized Schiff base, recorded in CDCl 3 , exhibited characteristic signals confirming its successful formation. A distinct singlet at δ9.382 ppm (1H) was assigned to the imine proton (-CH = N), verifying the presence of the C = N azomethine bond, which is a key structural feature of Schiff bases. Furthermore, a broad singlet atδ 15.296 ppm is attributed to OH proton, indicating strong intramolecular hydrogen bonding with the imine nitrogen, which stabilizes the Schiff base structure. The aromatic region of the spectrum further supports the expected structure. Signals appearing in the range of δ 7.129–8.184 ppm, showing multiple doublets and triplets, corresponding to the naphthalene and para-substituted benzene rings (Fig. 3 ). Colorimetric, UV-Vis and fluorescence analysis of Cu detection in solution Upon the addition of Cu 2+ , the color of SBA1 changes from yellow to colorless (Fig. 4 ), accompanied by distinct changes in its UV-Vis spectrum. The absorption peak at 436 nm, corresponding to the n–π* transition of the azomethine (-C = N) group, undergoes a blue shift to 420 nm. This shift is attributed to the hydrolysis process, which alters the electronic structure of the azomethine group and likely weakens the conjugation between the nitrogen and the aromatic system. As a result, the absorption occurs at a shorter wavelength. In addition to the blue shift, the intensity of the 436 nm peak decreases, suggesting that the hydrolysis reaction disrupts the electronic properties of the Schiff base. On the other hand, the peak at 334 nm, associated with the π–π* transition of the aromatic system (benzene and naphthalene rings), shows an increase in intensity (Fig. 5 ). This suggests that hydrolysis enhances the electronic interactions within the aromatic system. Overall, these UV-Vis spectral changes indicate that the hydrolysis of the Schiff base upon Cu 2+ addition leads to significant modifications in the electronic structure of SBA1 . The fluorescence study demonstrated that SBA1 exhibits weak emission at 554 nm upon excitation at 275 nm. This low fluorescence intensity is mainly due to the photoinduced electron transfer (PET) effect, which effectively quenches the emission, limiting its fluorescence response. PET occurs when an electron is transferred from the donor moiety to the acceptor, reducing the fluorescence efficiency of the molecule. When SBA1 is exposed to various metal ions such as Cu 2+ , Co 2+ , Zn 2+ , Pb 2+ , Ag + , Cd 2+ , Mg 2+ , Ni 2+ , Ca 2+ , Fe 3+ , Mn 2+ , Hg 2+ , K + , and Na + , no significant fluorescence changes are observed, indicating that the PET effect remains dominant and the structural integrity of SBA1 is not significantly altered. However, in the presence of Cu 2+ ions, a notable fluorescence enhancement is observed, suggesting a specific interaction between SBA1 and Cu 2+ that modifies its electronic properties (Fig. 6 ). The fluorescence enhancement observed with Cu 2+ is due to the hydrolysis of SBA1 facilitated by Cu 2+ ions. This hydrolysis process leads to the cleavage of the Schiff base linkage, releasing the naphthalene moiety. In its original form, SBA1 experiences fluorescence quenching due to PET. However, upon hydrolysis, the free naphthalene unit is no longer subjected to this quenching effect, allowing it to exhibit strong fluorescence. This transformation highlights the crucial role of Cu 2+ in breaking the Schiff base structure and freeing the fluorescent moiety. The hydrolysis-induced fluorescence enhancement provides a clear and measurable signal, making SBA1 a promising candidate for analytical applications. The ability to distinguish Cu 2+ from other metal ions based on fluorescence intensity changes further enhances its utility in metal ion sensing. This characteristic can be explored for designing selective and sensitive chemosensors, particularly for environmental and biological monitoring of Cu 2+ levels. To analyze the quantitative nature of Cu 2+ sensing and determine the selectivity range of the chemosensor SBA1 , a fluorescence titration experiment was performed with varying Cu 2+ concentrations ranging from 0.01 to 1.5 ppm. The results, as depicted in Fig. 7 , show a steady increase in fluorescence intensity with the gradual addition of Cu 2+ ions. This enhancement suggests a direct correlation between Cu 2+ concentration and fluorescence response, further supporting the hydrolysis-induced fluorescence mechanism. The observed linear increase in fluorescence intensity with rising Cu 2+ concentration shows the potential of SBA1 as a reliable and sensitive probe for Cu 2+ detection, demonstrating its suitability for quantitative sensing applications. Detection limit In analytical chemistry, evaluating the detection limit of a chemosensor is essential for determining its sensitivity and effectiveness in identifying low concentrations of target analytes. The sensing capability of SBA1 toward Cu 2+ was assessed through fluorescence titration experiments, where increasing concentrations of Cu 2+ (0.01 to 1.5 ppm) were introduced into SBA1 solutions. A progressive enhancement in fluorescence intensity was observed with each incremental addition, confirming a selective turn-on response to Cu 2+ (Fig. 8 ). To further quantify the sensitivity of SBA1 , calibration curves were constructed by plotting fluorescence intensity against Cu 2+ concentration. These curves displayed a linear trend within the tested range, allowing for precise calculations of detection limit, which was determined using the standard formula LOD = 3.3 × σ/S, where σ denotes the standard deviation and S represents the slope of the linear portion of the calibration curve. Based on these calculations, the detection limit for Cu 2+ was found to be 0.0031 ppm, while the LOQ was 0.0096 ppm. Interference of other metal ions The interference study was conducted to assess the selectivity of the sensor in the presence of other metal ions. To evaluate potential interferences, fluorescence measurements were performed with SBA1 in solutions containing Cu 2+ along with various competing metal ions, including Co 2+ , Zn 2+ , Pb 2+ , Ag + , Cd 2+ , Mg 2+ , Ni 2+ , Ca 2+ , Fe 3+ , Mn 2+ , Hg 2+ , K + , and Na + . The results demonstrated that the presence of these metal ions did not significantly alter the fluorescence response of SBA1 toward Cu 2+ (Fig. 9 ). The fluorescence enhancement observed upon Cu 2+ addition remained mostly unaffected, indicating that SBA1 exhibits a highly selective response to Cu 2+ without interference from other metal ions. These finding confirms its potential for accurate and reliable Cu 2+ detection in complex environments. Unlike other metal ions, Cu 2+ facilitates the cleavage of the Schiff base linkage in SBA1 , releasing the naphthalene moiety and leading to a pronounced fluorescence enhancement. Since none of the other tested metal ions triggered a similar hydrolysis process, their presence did not affect the fluorescence response. This exceptional selectivity ensures that SBA1 can be used effectively for Cu 2+ detection even in real-world samples containing diverse metal ions. Mechanism The mechanism by which SBA1 detects Cu 2+ is predominantly driven by hydrolysis, which results in distinct colorimetric, UV-Vis, and fluorescence changes. Schiff bases typically form colored complexes with Cu 2+ , and in this case, the addition of Cu 2+ induces a noticeable color change from yellow to colorless. This visual transition suggests the breakdown of the imine (-C = N) bond due to hydrolysis. UV-Vis spectral analysis further supports this structural transformation. The absorption peak at 436 nm, corresponding to the n–π* transition of the azomethine group, undergoes a blue shift to 420 nm. This shift occurs because the hydrolysis reaction alters the electronic structure of the azomethine group, weakening its conjugation with the aromatic system and reducing electron delocalization. Additionally, the intensity of the 436 nm peak diminishes, indicating the disruption of the Schiff base electronic properties. Simultaneously, the absorption peak at 334 nm, associated with the π–π* transition of the benzene and naphthalene rings, shows an increase in intensity. The fluorescence studies provide further insight into the hydrolysis mechanism. SBA1 initially exhibits weak fluorescence due to the PET effect. In the presence of Cu 2+ , a significant fluorescence enhancement is recorded. This enhancement is attributed to the hydrolysis of SBA1 by Cu 2+ , which cleaves the Schiff base linkage and releases the fluorescent naphthalene moiety. In its original form, SBA1 experiences PET quenching due to electron transfer from the azomethine nitrogen to naphthalene, suppressing fluorescence. However, hydrolysis disrupts this process, preventing PET quenching and allowing the fluorescence to be restored. This combined colorimetric, UV-Vis, and fluorescence response demonstrates that the Cu 2+ -induced hydrolysis of SBA1 serves as the key sensing mechanism, making it a highly selective and effective chemosensor for Cu 2+ detection. Application of the chemosensor for Cu 2+ detection in water samples The practical applicability of the chemosensor for detecting Cu 2+ ions was evaluated through a fluorescence-based analysis of real water samples. Various water sources (soil sample, drinking, lake, river and pond water) were collected, and Cu 2+ ions were introduced at different concentrations (0.1, 0.3, and 0.5 ppm) using a spiking method. The fluorescence response of the chemosensor was measured after titration with the spiked samples, revealing a high recovery rate of up to 91.0 to 102.0%. This excellent recovery rate indicates the reliability and efficiency of the sensor in accurately quantifying Cu 2+ ions in complex water matrices. The results were systematically analyzed and compiled in Table 1 , demonstrating the sensor performance under realistic conditions. Furthermore, the high recovery values suggest that the developed chemosensor effectively detects Cu 2+ ions without significant interference from other metal ions commonly present in water samples. This selectivity is crucial for real-world applications, as environmental and industrial water sources often contain multiple competing ions. These findings confirm that the chemosensor is a promising tool for rapid and reliable Cu 2+ detection, paving the way for its application in practical water analysis scenarios. Antibacterial activity Schiff bases have gained considerable attention in the fields of chemistry, biology, and materials science due to their ease of synthesis, structural diversity, and remarkable range of applications. [ 35 – 38 ] Schiff bases possess a characteristic azomethine group (-C = N-) that is central to their chemical reactivity and biological interactions. The presence of lone-pair electrons on the nitrogen atom within the imine group allows Schiff bases to coordinate easily with metal ions, making them excellent ligands in coordination chemistry.[ 39 , 40 ] Table 1 % recovery of Cu2+ in water and soil samples at different spiked concentrations Samples Cu 2+ concentration(µg mL − 1 ) % Recovery Added Found Soil 0.1 0.3 0.5 0.092 0.281 0.462 92.0 93.6 92.4 Drinking water 0.1 0.3 0.5 0.096 0.297 0.510 96.0 99.0 102.0 Lake water 0.1 0.3 0.5 0.094 0.287 0.498 94.0 95.6 99.6 River water 0.1 0.3 0.5 0.091 0.281 0.472 91.0 93.6 94.4 Pond water 0.1 0.3 0.5 0.095 0.296 0.508 95.0 98.6 101.6 Schiff bases exhibit a broad spectrum of biological activities. These characteristics position Schiff bases as versatile candidates in the design of therapeutic agents and functional materials. One of the most significant advantages of Schiff base compounds is the ability to tailor their structure by varying the nature of the aldehyde or amine precursors. This tunability allows chemists to fine-tune the physicochemical and biological properties of the resulting compounds, creating molecules with high selectivity and potency against specific biological targets. Over the years, Schiff base derivatives have been extensively studied for their therapeutic potential. [ 41 – 45 ] In the wake of increasing global concerns regarding antimicrobial resistance, the search for new classes of antimicrobial agents has intensified. Schiff bases have emerged as promising alternatives owing to their diverse mechanisms of action and adaptability to structural modification. The antimicrobial potential of Schiff bases can be attributed to their unique mode of action. Moreover, Schiff bases are known to penetrate microbial cell membranes more effectively due to their lipophilic nature, which enhances their interaction with intracellular targets. Structural modifications such as the introduction of aromatic rings, heterocycles, halogens, or other functional groups can further enhance the biological efficacy of Schiff base compounds, making them potent candidates against a variety of bacterial and fungal pathogens. These characteristics have led to growing interest in Schiff base compounds not only as standalone antimicrobial agents but also as synergistic agents that can enhance the efficacy of existing antibiotics. [ 30 – 32 , 46 ] The Schiff base SBA1 , synthesized and investigated in the current study, was evaluated for its antimicrobial properties against a diverse panel of Gram-positive and Gram-negative bacterial strains such as Salmonella typhimurium, Enterobacter aerogenes , Klebsiella pneumoniae , Pseudomonas aeruginosa, Bacillus megaterium, Salmonella enterica , Bacillus cereus, Escherichia coli , Bacillus subtilis , Staphylococcus aureus, Proteus vulgaris , Pseudomonas fluorescens , and Brevibacillus brevis . The disc diffusion method, a widely accepted and reliable technique for initial screening of antibacterial agents, was employed to assess the efficacy of SBA1 . In this assay, sterile paper discs impregnated with a fixed amount of the compound were placed on agar plates inoculated with bacterial cultures. After incubation, the diameter of the inhibition zone around each disc was measured, with larger zones indicating stronger antibacterial activity. Table 2 presents the antibacterial activity of SBA1 against 13 different bacterial strains. The results indicate that SBA1 exhibits broad-spectrum antibacterial activity, demonstrating effectiveness against both Gram-positive and Gram-negative bacteria. Among the tested strains, Staphylococcus aureus showed the highest sensitivity to SBA1 , with a zone of inhibition measuring 17.20 ± 0.75 mm. Similarly, Bacillus subtilis and Bacillus cereus exhibited substantial susceptibility to SBA1 , with inhibition zones of 16.35 ± 0.88 mm and 16.24 ± 0.76 mm, respectively. The activity of SBA1 against these bacteria suggests that the compound may be effective in environmental or food safety applications, where control of such pathogens is essential. Proteus vulgaris and Salmonella typhimurium , both Gram-negative bacteria associated with urinary tract infections and gastrointestinal diseases, also responded well to SBA1 , with inhibition zones of 15.71 ± 0.52 mm and 15.44 ± 0.67 mm, respectively. Other strains, including Salmonella enterica , Escherichia coli , Enterobacter aerogenes , and Klebsiella pneumoniae , exhibited moderate sensitivity to SBA1 , with inhibition zones ranging from 10.88 mm to 13.42 mm. Notably, Pseudomonas aeruginosa and Pseudomonas fluorescens , which are often more resistant to antibiotics due to their robust efflux systems and biofilm-forming capabilities, showed smaller inhibition zones of 10.65 ± 0.61 mm and 10.27 ± 0.34 mm, respectively. Despite the lower activity against these strains, the results are still promising, especially considering that many synthetic compounds fail to show any effect on Pseudomonas species without specific structural optimization. The variability in the antibacterial activity of SBA1 across different strains may be attributed to differences in cell wall composition, membrane permeability, and intrinsic resistance mechanisms. Table 2 Antibacterial activity of Schiff base SBA1. Bacterial Strains SBPY-1 Zone of inhibition (mm) Salmonella typhimurium 15.44 ± 0.67 Enterobacter aerogenes 10.88 ± 0.39 Klebsiella pneumoniae 11.84 ± 0.83 Pseudomonas aeruginosa 10.65 ± 0.61 Bacillus megaterium 12.48 ± 0.58 Salmonella enterica 13.42 ± 0.25 Bacillus cereus 16.24 ± 0.76 Escherichia coli 11.33 ± 0.69 Bacillus subtilis 16.35 ± 0.88 Staphylococcus aureus 17.20 ± 0.75 Proteus vulgaris 15.71 ± 0.52 Pseudomonas fluorescens 10.27 ± 0.34 Brevibacillus brevis 12.16 ± 0.94 Conclusion The successful synthesis and characterization of the novel Schiff base SBA1 have unveiled its remarkable multifunctional capabilities, making it a promising candidate for both environmental and biomedical applications. Through detailed spectroscopic analysis using UV-Vis, FTIR, and 1 H NMR, the structural integrity and functional groups of SBA1 were confirmed, laying the foundation for its application in sensing and bioactivity studies. Its highly selective colorimetric and fluorescence responses toward Cu 2+ ions, marked by a pronounced color change and significant fluorescence enhancement, highlight its potential as an efficient chemosensor. The extremely low detection (LOD = 0.0031 ppm) and quantification limits (LOQ = 0.0096 ppm), coupled with high recovery rates (91.0–102.0%) in real environmental samples such as drinking water, river water, and soil-extracted water, affirm SBA1 reliability and effectiveness in trace-level Cu 2+ detection under complex conditions. Furthermore, the additional demonstration of broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacterial strains highlights the therapeutic potential of SBA1 , presenting it not only as a sensor but also as a bioactive compound. The dual role of SBA1 as a selective Cu 2+ sensor and potent antimicrobial agent emphasizes its multifunctionality, offering a valuable tool for integrated applications in environmental safety monitoring and infectious disease control. Declarations Acknowledgement The authors extend their appreciation to Taif University, Saudi Arabia for supporting this work through project number (TU-DSPP-2024-58)”. Funding The research was funded by Taif University, Saudi Arabia, Project Number (TU-DSPP-2024-58) Data Availability : All data generated or analyzed during this study are included in this published article Code Availability: ChemDraw Ethical Approval : This article does not contain any studies with human participants or animals, clinical trial registration, or plant reproducibility performed by any authors. Consent to Publish: The authors have approved the paper and agree with its publication. Consent to participate : No applicable. Conflict of Interest: The authors declare that they have no conflicts of interest. Author Contribution Prof. Alaa Shafie: Conceptualized and supervised the study, provided critical revisions, and contributed to the final manuscript editing.Dr. Mohammed Fareed Felemban: Responsible for methodology development, data analysis, and manuscript writing.Dr. Faris J. Tayeb: Experimental validation, and review of the manuscript.Dr. Amal Adnan Ashour: Assisted in literature review, visualization, and manuscript formatting and proofreading. References Ali H, Khan E, Ilahi I (2019) Environmental Chemistry and Ecotoxicology of Hazardous Heavy Metals: Environmental Persistence, Toxicity, and Bioaccumulation, J. Chem. (2019) 6730305. https://doi.org/10.1155/2019/6730305 Edo GI, Samuel PO, Oloni GO, Ezekiel GO, Ikpekoro VO, Obasohan P, Ongulu J, Otunuya CF, Opiti AR, Ajakaye RS, Essaghah AEA, Agbo JJ (2024) Environmental persistence, bioaccumulation, and ecotoxicology of heavy metals. 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Vol. 10, Page 1126 10 (2020) 1126. https://doi.org/10.3390/NANO10061126 Gaetke LM, Chow-Johnson HS, Chow CK (2014) Copper: toxicological relevance and mechanisms. Arch Toxicol 88:1929–1938. https://doi.org/10.1007/S00204-014-1355-Y/METRICS Fu Z, Wu F, Chen L, Xu B, Feng C, Bai Y, Liao H, Sun S, Giesy JP, Guo W (2016) Copper and zinc, but not other priority toxic metals, pose risks to native aquatic species in a large urban lake in Eastern China. Environ Pollut 219:1069–1076. https://doi.org/10.1016/J.ENVPOL.2016.09.007 Mir AR, Pichtel J, Hayat S (2021) Copper: uptake, toxicity and tolerance in plants and management of Cu-contaminated soil, BioMetals 2021 344 34 737–759. https://doi.org/10.1007/S10534-021-00306-Z Sailer J, Nagel J, Akdogan B, Jauch AT, Engler J, Knolle PA, Zischka H (2024) Deadly excess copper. Redox Biol 75:103256. https://doi.org/10.1016/J.REDOX.2024.103256 Hanf L, Brüning K, Winter M, Nowak S (2023) Method development for the investigation of Mn2+/3+, Cu2+, Co2+, and Ni2 + with capillary electrophoresis hyphenated to inductively coupled plasma–mass spectrometry, Electrophoresis 44 89–95. https://doi.org/10.1002/ELPS.202200139 Ferreira R, Chaar J, Baldan M, Braga N (2021) Simultaneous voltammetric detection of Fe3+, Cu2+, Zn2+, Pb2 + e Cd2 + in fuel ethanol using anodic stripping voltammetry and boron-doped diamond electrodes. Fuel 291:120104. https://doi.org/10.1016/J.FUEL.2020.120104 Islamnezhad A, Mahmoodi N (2011) Potentiometric Cu2+-selective electrode with subnanomolar detection limit. Desalination 271:157–162. https://doi.org/10.1016/J.DESAL.2010.12.020 Ghaedi M, Ahmadi F, Shokrollahi A (2007) Simultaneous preconcentration and determination of copper, nickel, cobalt and lead ions content by flame atomic absorption spectrometry. J Hazard Mater 142:272–278. https://doi.org/10.1016/J.JHAZMAT.2006.08.012 Alshareef FM, Algethami JS, Alhamami MAM, Alosaimi EH, Al-Saidi HM, Khan S (2024) Recent advancement in organic fluorescent and colorimetric chemosensors for the detection of Al3 + ions: A review (2019–2024). J Environ Chem Eng 12:114110. https://doi.org/10.1016/J.JECE.2024.114110 Algethami JS, Al-Saidi HM, Alosaimi EH, Alnaam YA, Al-Ahmary KM, Khan S (2024) Recent Advancements in Fluorometric and Colorimetric Detection of Cd2 + Using Organic Chemosensors: A Review (2019–2024). Crit Rev Anal Chem. https://doi.org/10.1080/10408347.2024.2339968 Alhamami MAM, Algethami JS, Khan S (2024) A Review on Thiazole Based Colorimetric and Fluorimetric Chemosensors for the Detection of Heavy Metal Ions. Crit Rev Anal Chem. https://doi.org/10.1080/10408347.2023.2197073 Abu-Taweel GM, Alharthi SS, Al-Saidi HM, Babalghith AO, Ibrahim MM, Khan S (2023) Heterocyclic Organic Compounds as a Fluorescent Chemosensor for Cell Imaging Applications: A Review, Crit. Rev Anal Chem 1–16. https://doi.org/10.1080/10408347.2023.2186695 Al-Saidi HM, Khan S (2022) A Review on Organic Fluorimetric and Colorimetric Chemosensors for the Detection of Ag(I) Ions, Crit. Rev Anal Chem. https://doi.org/10.1080/10408347.2022.2133561 Abu-Taweel GM, Ibrahim MM, Khan S, Al-Saidi HM, Alshamrani M, Alhumaydhi FA, Alharthi SS (2022) Medicinal Importance and Chemosensing Applications of Pyridine Derivatives: A Review, Crit. Rev Anal Chem. https://doi.org/10.1080/10408347.2022.2089839 Al-Saidi HM, Khan S (2024) Recent Advances in Thiourea Based Colorimetric and Fluorescent Chemosensors for Detection of Anions and Neutral Analytes: A Review, Crit. Rev Anal Chem 54:93–109. https://doi.org/10.1080/10408347.2022.2063017 Alam MZ, Alimuddin SA, Khan (2023) A Review on Schiff Base as a Versatile Fluorescent Chemo-sensors Tool for Detection of Cu2 + and Fe3 + Metal Ion. J Fluoresc 33:1241–1272. https://doi.org/10.1007/S10895-022-03102-1/METRICS Kumar R, Singh B, Gahlyan P, Verma A, Bhandari M, Kakkar R, Pani B (2024) An innovative Schiff-base colorimetric chemosensor for the selective detection of Cu 2 + ions and its applications. RSC Adv 14:23083–23094. https://doi.org/10.1039/D4RA03097D Alam MZ, Khan SA (2023) A review on Rhodamine-based Schiff base derivatives: synthesis and fluorescent chemo-sensors behaviour for detection of Fe3 + and Cu2 + ions. J Coord Chem 76:371–402. https://doi.org/10.1080/00958972.2023.2183852 Khan S, Chen X, Almahri A, Allehyani ES, Alhumaydhi FA, Ibrahim MM, Ali S (2021) Recent developments in fluorescent and colorimetric chemosensors based on schiff bases for metallic cations detection: A review. J Environ Chem Eng 9:106381. https://doi.org/10.1016/J.JECE.2021.106381 Ceramella J, Iacopetta D, Catalano A, Cirillo F, Lappano R, Sinicropi MS (2022) A Review on the Antimicrobial Activity of Schiff Bases: Data Collection and Recent Studies, Antibiot. Vol. 11, Page 191 11 (2022) 191. https://doi.org/10.3390/ANTIBIOTICS11020191 Da Silva CM, Da Silva DL, Modolo LV, Alves RB, De Resende MA, Martins CVB (2011) De Fátima, Schiff bases: A short review of their antimicrobial activities. J Adv Res 2:1–8. https://doi.org/10.1016/J.JARE.2010.05.004 Dhedan RM, Alsahib SA, Ali RA (2023) A Brief Review on Schiff Base, Synthesis, and Their Antimicrobial Activities, Russ. J. Bioorganic Chem. 491 49 (2024) S31–S52. https://doi.org/10.1134/S1068162023080046 Salihović M, Pazalja M, Špirtović Halilović S, Veljović E, Mahmutović-Dizdarević I, Roca S, Novaković I, Trifunović S (2021) Synthesis, characterization, antimicrobial activity and DFT study of some novel Schiff bases. J Mol Struct 1241:130670. https://doi.org/10.1016/J.MOLSTRUC.2021.130670 Alelwani W, Alnajeebi AM, Shafie A, Adnan Ashour A, Felemban MF, Tayeb FJ (2024) Design, synthesis, and antibacterial evaluation of a thiazole-based schiff base with fluorescence sensing for Cu2 + ions. Int J Environ Anal Chem. https://doi.org/10.1080/03067319.2024.2436603 More MS, Joshi PG, Mishra YK, Khanna PK (2019) Metal complexes driven from Schiff bases and semicarbazones for biomedical and allied applications: a review. Mater Today Chem 14:100195. https://doi.org/10.1016/J.MTCHEM.2019.100195 Wesley Jeevadason A, Kalidasa Murugavel K, Neelakantan MA (2014) Review on Schiff bases and their metal complexes as organic photovoltaic materials. Renew Sustain Energy Rev 36:220–227. https://doi.org/10.1016/j.rser.2014.04.060 Pawariya V, De S, Dutta J (2024) Chitosan-based Schiff bases: Promising materials for biomedical and industrial applications. Carbohydr Polym 323:121395. https://doi.org/10.1016/J.CARBPOL.2023.121395 Khan S, Alhumaydhi FA, Ibrahim MM, Alqahtani A, Alshamrani M, Alruwaili AS, Hassanian AA, Khan S (2022) Recent Advances and Therapeutic Journey of Schiff Base Complexes with Selected Metals (Pt, Pd, Ag, Au) as Potent Anticancer Agents: A Review, Anticancer. Agents Med Chem 22:3086–3096. https://doi.org/10.2174/1871520622666220511125600 Qin W, Long S, Panunzio M, Biondi S, - Molecules SB (2013) undefined Schiff bases: A short survey on an evergreen chemistry tool, Mdpi.Com 18 (2013) 12264–12289. https://doi.org/10.3390/molecules181012264 Abu-Dief AM, Mohamed IMA (2015) A review on versatile applications of transition metal complexes incorporating Schiff bases, Beni-Suef Univ. J Basic Appl Sci 4:119–133. https://doi.org/10.1016/J.BJBAS.2015.05.004 Uddin MN, Ahmed SS, Alam SMR (2020) Biomedical applications of Schiff base metal complexes. J Coord Chem 73:3109–3149. https://doi.org/10.1080/00958972.2020.1854745;WGROUP:STRING:PUBLICATION Biswas T, Mittal RK, Sharma V, Kanupriya I, Mishra (2024) Schiff Bases: Versatile Mediators of Medicinal and Multifunctional Advancements. Lett Org Chem 21:505–519. https://doi.org/10.2174/0115701786278580231126034039/CITE/REFWORKS Kaushik S, Paliwal SK, Iyer MR, Patil VM (2023) Promising Schiff bases in antiviral drug design and discovery. Med Chem Res 2023 326 32:1063–1076. https://doi.org/10.1007/S00044-023-03068-0 Emam SM, El Sayed IET, Ayad MI, Hathout HMR (2017) Synthesis, characterization and anticancer activity of new Schiff bases bearing neocryptolepine. J Mol Struct 1146:600–619. https://doi.org/10.1016/J.MOLSTRUC.2017.06.006 Ceyhan G, Köse M, Tümer M, Demirtaş I, Şahin Yaǧlioǧlu A, McKee V (2013) Structural characterization of some Schiff base compounds: Investigation of their electrochemical, photoluminescence, thermal and anticancer activity properties. J Lumin 143:623–634. https://doi.org/10.1016/J.JLUMIN.2013.06.002 Jorge J, Del Pino Santos KF, Timóteo F, Piva Vasconcelos RR, Ignacio Ayala O, Cáceres I, Juliane Arantes Granja DM, de Souza TE, Allievi Frizon G, Di Vaccari Botteselle A, Luiz Braga S, Saba H, ur Rashid J, Rafique (2023) Recent Advances on the Antimicrobial Activities of Schiff Bases and their Metal Complexes: An Updated Overview. Curr Med Chem 31:2330–2344. https://doi.org/10.2174/0929867330666230224092830/CITE/REFWORKS Schemes Scheme 1 is available in the Supplementary Files section Additional Declarations No competing interests reported. Supplementary Files Schemes.docx Cite Share Download PDF Status: Published Journal Publication published 18 Feb, 2026 Read the published version in Transition Metal Chemistry → Version 1 posted Editorial decision: Revision requested 29 Jun, 2025 Reviews received at journal 20 Jun, 2025 Reviews received at journal 16 Jun, 2025 Reviews received at journal 11 Jun, 2025 Reviews received at journal 10 Jun, 2025 Reviewers agreed at journal 04 Jun, 2025 Reviewers agreed at journal 04 Jun, 2025 Reviews received at journal 03 Jun, 2025 Reviewers agreed at journal 03 Jun, 2025 Reviewers agreed at journal 02 Jun, 2025 Reviewers agreed at journal 02 Jun, 2025 Reviewers agreed at journal 02 Jun, 2025 Reviewers invited by journal 02 Jun, 2025 Editor assigned by journal 02 Jun, 2025 Submission checks completed at journal 02 Jun, 2025 First submitted to journal 01 Jun, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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in MeOH:Water (5:95,\\u0026nbsp; v/v) system.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"image9.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6796500/v1/178fd6080c7f3cdea8074d71.png\"},{\"id\":83893538,\"identity\":\"0dd3c14f-c05b-49f4-9e94-cb887ec91e78\",\"added_by\":\"auto\",\"created_at\":\"2025-06-04 08:26:28\",\"extension\":\"png\",\"order_by\":8,\"title\":\"Figure 8\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":42543,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eCalibration curve of \\u003cstrong\\u003eSBA1\\u003c/strong\\u003e with different concentration of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e (0.01-1.5 ppm)\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"image10.png\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6796500/v1/4b789ae8bee8009f52fdff2a.png\"},{\"id\":83893545,\"identity\":\"64418c47-bce0-4930-afe1-35fc91a513ec\",\"added_by\":\"auto\",\"created_at\":\"2025-06-04 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16:03:47\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":2254422,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6796500/v1/f813fe35-cd81-4915-b0db-c75cab4fc6b1.pdf\"},{\"id\":83893527,\"identity\":\"4c9997a3-40dc-4e21-afea-ecab34623c04\",\"added_by\":\"auto\",\"created_at\":\"2025-06-04 08:26:28\",\"extension\":\"docx\",\"order_by\":1,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"supplement\",\"size\":20883,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"Schemes.docx\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6796500/v1/843057457dac0952d768d954.docx\"}],\"financialInterests\":\"No competing interests reported.\",\"formattedTitle\":\"Dual-Action Innovation: Schiff Base for Trace Cu 2+ ions Detection and Powerful Antibacterial Potential\",\"fulltext\":[{\"header\":\"Introduction\",\"content\":\"\\u003cp\\u003eHeavy metal pollution, driven by both natural processes and human activities, poses significant environmental and health risks. These metals are persistent in the environment and bioaccumulate in ecosystems, particularly through industrial activities like mining, agriculture, and manufacturing. Their toxicity varies based on factors like oxidation state and concentration, leading to harmful effects on organisms, including mutations, carcinogenic effects, and immune system disruption. In aquatic environments, heavy metals accumulate in species and enter the food chain, posing risks to human health. [\\u003cspan additionalcitationids=\\\"CR2 CR3 CR4 CR5 CR6\\\" citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e7\\u003c/span\\u003e] Among heavy metals, copper is a vital micronutrient required for various biological and physiological functions in both plants and animals. Copper plays a crucial role in enzymatic reactions, particularly as an electron donor in oxygen-utilizing processes like the respiratory chain in mitochondria, where cytochrome c oxidase acts as an electron transporter. This enzyme contains three copper centers per monomeric complex. Copper is also essential for connective tissue formation, such as collagen and keratin. Copper ions are transported into cells by specific copper transporters and reduced to Cu\\u003csup\\u003e+\\u003c/sup\\u003e, with metallochaperones guiding them to target enzymes. To avoid oxidative damage, free copper ions are maintained at low concentrations in living organisms, preventing harmful free radical production through the Fenton reaction.[\\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e8\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e9\\u003c/span\\u003e] Although copper is essential, excessive accumulation in the environment and biological systems can lead to severe toxicity and health issues. Excessive copper accumulation, as seen in conditions like Wilson disease, can lead to severe health issues, including liver damage, nervous system dysfunction, and reproductive problems. Copper toxicity can also result from long-term exposure to small amounts through food contaminated by corroded copper cookware, causing symptoms like abdominal pain, vomiting, and, in extreme cases, paralysis or death. In aquatic ecosystems, elevated copper levels are toxic to fish and other aquatic organisms, impairing gill function, disrupting ion regulation, and causing developmental abnormalities. Similarly, in plants, excessive copper uptake affects root elongation, chlorophyll synthesis, and overall growth, leading to reduced crop yields and soil degradation. The persistence of copper in the environment highlights the need for effective monitoring and detection methods to regulate its levels and prevent toxic accumulation.[\\u003cspan additionalcitationids=\\\"CR11 CR12 CR13\\\" citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e10\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e14\\u003c/span\\u003e]\\u003c/p\\u003e \\u003cp\\u003eVarious analytical techniques, such as flame atomic absorption spectrometry, potentiometry, anodic stripping voltammetry, capillary electrophoresis (CE) and many others, have been widely employed for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection. [\\u003cspan additionalcitationids=\\\"CR16 CR17\\\" citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e15\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e18\\u003c/span\\u003e] However, these methods are often expensive, time-consuming, and require sophisticated instrumentation, making them less suitable for rapid or on-site analysis. Therefore, the development of new, cost-effective, and user-friendly detection techniques is crucial for efficient Cu\\u003csup\\u003e2+\\u003c/sup\\u003e monitoring in environmental, biological, and industrial applications. Colorimetric and fluorimetric chemosensors have gained significant attention for the detection of metal ions due to their simplicity, high sensitivity, and rapid response. [\\u003cspan additionalcitationids=\\\"CR20 CR21\\\" citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e19\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e22\\u003c/span\\u003e] These sensors rely on changes in color or fluorescence intensity upon interaction with target metal ions, enabling easy visual or instrumental detection. Colorimetric sensors typically involve chromogenic dyes that exhibit distinct color changes upon metal binding, while fluorimetric sensors utilize fluorophores whose emission properties are altered by metal coordination. [\\u003cspan additionalcitationids=\\\"CR24\\\" citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e23\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e25\\u003c/span\\u003e] Organic chemosensors, particularly those based on Schiff bases, have emerged as promising candidates for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection due to their versatile coordination chemistry, ease of synthesis, and tunable optical properties. Schiff base ligands possess imine (-C\\u0026thinsp;=\\u0026thinsp;N-) functional groups that can strongly bind to metal ions, leading to significant colorimetric or fluorimetric changes. Their structural flexibility allows for the design of selective and sensitive probes for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions. Schiff base-based chemosensors have been widely explored for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e sensing in aqueous and biological media, providing valuable insights into metal ion interactions and potential applications in environmental monitoring and medical diagnose. [\\u003cspan additionalcitationids=\\\"CR27 CR28\\\" citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e26\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e29\\u003c/span\\u003e] In addition to their well-established role in metal ion sensing, Schiff base compounds have demonstrated significant antimicrobial activity, making them attractive as standalone bioactive agents. The inherent structural features of Schiff bases, particularly the presence of the imine (-C\\u0026thinsp;=\\u0026thinsp;N-) group, play a crucial role in their biological activity. This functional group can interfere with vital microbial processes by interacting with cellular components such as proteins and nucleic acids, leading to inhibition of microbial growth. The ease of structural modification allows for the incorporation of various aromatic, aliphatic, or heterocyclic moieties into Schiff base frameworks, enhancing their ability to target specific pathogens and improving their lipophilicity for better cell membrane penetration. Studies have shown that Schiff bases can effectively inhibit a range of bacterial and fungal strains, often through various mechanisms. [\\u003cspan additionalcitationids=\\\"CR31 CR32\\\" citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e30\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR33\\\" class=\\\"CitationRef\\\"\\u003e33\\u003c/span\\u003e]\\u003c/p\\u003e \\u003cp\\u003eIn this work, a Schiff base sensor (\\u003cb\\u003eSBA1\\u003c/b\\u003e) was successfully synthesized and characterized by \\u003csup\\u003e1\\u003c/sup\\u003eH NMR, FT-IR, UV-Vis, and fluorescence spectroscopy. The sensing ability of \\u003cb\\u003eSBA1\\u003c/b\\u003e was evaluated with various metal ions and showing significant enhancement upon the addition of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e. Optimization studies were conducted to achieve the best fluorescence response. In addition to its sensing capabilities, the antibacterial potential of \\u003cb\\u003eSBA1\\u003c/b\\u003e was also assessed against selected bacterial strains. The compound exhibited notable antibacterial activity, indicating its dual functionality as both a highly sensitive Cu\\u003csup\\u003e2+\\u003c/sup\\u003e sensor and an effective antimicrobial agent.\\u003c/p\\u003e\"},{\"header\":\"Experimental\",\"content\":\"\\n\\u003ch3\\u003eMaterials and methods\\u003c/h3\\u003e\\n\\u003cp\\u003eThe Schiff base sensor was synthesized using commercially available precursors. Solvents such as methanol, ethanol, chloroform, n-hexane, and ethyl acetate, along with various metal salts (Cu(acetate)\\u003csub\\u003e2\\u003c/sub\\u003e, (Co(acetate)\\u003csub\\u003e2\\u003c/sub\\u003e, ZnCl\\u003csub\\u003e2\\u003c/sub\\u003e, PbCl\\u003csub\\u003e2\\u003c/sub\\u003e, AgNO\\u003csub\\u003e3\\u003c/sub\\u003e, CdCl\\u003csub\\u003e2\\u003c/sub\\u003e, MgCl\\u003csub\\u003e2\\u003c/sub\\u003e, NiCl\\u003csub\\u003e2\\u003c/sub\\u003e, CaCl\\u003csub\\u003e2\\u003c/sub\\u003e, FeCl\\u003csub\\u003e3\\u003c/sub\\u003e, MnCl\\u003csub\\u003e2\\u003c/sub\\u003e, HgCl\\u003csub\\u003e2\\u003c/sub\\u003e, KCl, and NaCl), were obtained from Sigma-Aldrich. To maintain high purity and prevent contamination, all experiments were performed using double-distilled water. The fluorescencespectra were measured usingan LS 55 fluorescence spectrophotometer manufactured by Perkin-Elmer, USA. The pH of solutions was measured using a PHS-25C Precision pH/mV Meter (Aolilong, Hangzhou, China) to ensure accuracy across experimental conditions. UV\\u0026ndash;Vis absorption spectra were recorded on a Shimadzu UV-2450 spectrophotometer (Japan) to investigate the optical properties of \\u003cb\\u003eSBA1\\u003c/b\\u003e.\\u003c/p\\u003e\\n\\u003ch3\\u003eSynthesis of SBA1\\u003c/h3\\u003e\\n\\u003cp\\u003eThe Schiff base was synthesized through a condensation reaction between 2-hydroxy-1-naphthaldehyde (0.5 g, 2.9 mmol) and 4-chloroaniline (0.36 g, 2.9 mmol) in 20 mL of methanol (\\u003cb\\u003eScheme. 1\\u003c/b\\u003e). The mixture was refluxed for 15 hr to facilitate the formation of the imine bond, with the progress being monitored by thin-layer chromatography (TLC). The successful completion of the reaction was confirmed by the disappearance of the reactants spots and the appearance of a new spot corresponding to the Schiff base product. The solid product was separated by filtration and purified through successive methanol washings to obtain the pure compound. Yield: 92%: IR(KBr)\\u003cem\\u003eν\\u003c/em\\u003e/cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e O-H, 3454; Ar-H, 3026; C\\u0026thinsp;=\\u0026thinsp;N, 1618; C\\u0026thinsp;=\\u0026thinsp;C aromatic,1485; C-Cl, 750. \\u003csup\\u003e1\\u003c/sup\\u003eH NMR (300.00 MHz, CDCl\\u003csub\\u003e3\\u003c/sub\\u003e, 25\\u0026deg;C): δ (ppm):7.129(d, 1H, J\\u0026thinsp;=\\u0026thinsp;8.86 Hz), 7.312 (d,2H, J\\u0026thinsp;=\\u0026thinsp;7.89 Hz), 7.377 (t, 1H, J\\u0026thinsp;=\\u0026thinsp;7.49 Hz),7.432 (d, 2H, J\\u0026thinsp;=\\u0026thinsp;8.28Hz), 7.553 (t, 1H, J\\u0026thinsp;=\\u0026thinsp;7.78Hz), 7.744 (d,1H, J\\u0026thinsp;=\\u0026thinsp;8.11Hz), 7.834(d, 1H,J\\u0026thinsp;=\\u0026thinsp;9.07Hz ), 8.122(d, 1H,J\\u0026thinsp;=\\u0026thinsp;8.61Hz), 9.382(s, 1H), 15.296(bs,1H,OH).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\\n\\u003ch3\\u003eFluorescence study\\u003c/h3\\u003e\\n\\u003cp\\u003eThe fluorescence properties of \\u003cb\\u003eSBA1\\u003c/b\\u003e were evaluated by testing its response to a variety of metal ions, including Cu\\u003csup\\u003e2+\\u003c/sup\\u003e, Co\\u003csup\\u003e2+\\u003c/sup\\u003e, Zn\\u003csup\\u003e2+\\u003c/sup\\u003e, Pb\\u003csup\\u003e2+\\u003c/sup\\u003e, Ag\\u003csup\\u003e+\\u003c/sup\\u003e, Cd\\u003csup\\u003e2+\\u003c/sup\\u003e, Mg\\u003csup\\u003e2+\\u003c/sup\\u003e, Ni\\u003csup\\u003e2+\\u003c/sup\\u003e, Ca\\u003csup\\u003e2+\\u003c/sup\\u003e, Fe\\u003csup\\u003e3+\\u003c/sup\\u003e, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, Hg\\u003csup\\u003e2+\\u003c/sup\\u003e, K\\u003csup\\u003e+\\u003c/sup\\u003e, and Na\\u003csup\\u003e+\\u003c/sup\\u003e. Stock solutions of \\u003cb\\u003eSBA1\\u003c/b\\u003e (100 ppm) and various metal salts (100 ppm) were prepared. A measured volume of 3.0 mL of \\u003cb\\u003eSBA1\\u003c/b\\u003e stock solution was mixed with 2.0 mL of the respective metal ion solution in a 10 mL volumetric flask. After thorough shaking, the mixture was incubated at room temperature for 5 minutes to allow equilibrium. Following incubation, 3.0 mL of each solution was transferred into a quartz cuvette, and fluorescence spectra were recorded to assess the interaction between \\u003cb\\u003eSBA1\\u003c/b\\u003e and the metal ions.\\u003c/p\\u003e\\n\\u003ch3\\u003eAntibacterial activity\\u003c/h3\\u003e\\n\\u003cp\\u003eThe antimicrobial activity of the newly synthesized compounds, \\u003cb\\u003eSBA1\\u003c/b\\u003e was investigated against both Gram-positive and Gram-negative bacterial strains. These included \\u003cem\\u003eSalmonella typhimurium, Enterobacter aerogenes\\u003c/em\\u003e, \\u003cem\\u003eKlebsiella pneumoniae\\u003c/em\\u003e, \\u003cem\\u003ePseudomonas aeruginosa, Bacillus megaterium, Salmonella enterica\\u003c/em\\u003e, \\u003cem\\u003eBacillus cereus, Escherichia coli\\u003c/em\\u003e, \\u003cem\\u003eBacillus subtilis\\u003c/em\\u003e, \\u003cem\\u003eStaphylococcus aureus, Proteus vulgaris\\u003c/em\\u003e, \\u003cem\\u003ePseudomonas fluorescens\\u003c/em\\u003e, and \\u003cem\\u003eBrevibacillus brevis\\u003c/em\\u003e. The antimicrobial activity of the synthesized Schiff base compound \\u003cb\\u003eSBA1\\u003c/b\\u003e was evaluated using the disc diffusion technique. [\\u003cspan citationid=\\\"CR34\\\" class=\\\"CitationRef\\\"\\u003e34\\u003c/span\\u003e]. For this assay, \\u003cb\\u003eSBA1\\u003c/b\\u003e was dissolved in dimethyl sulfoxide (DMSO) to prepare a stock solution with a concentration of 12.0 mg/L. Sterile paper discs with a diameter of 6 mm were each loaded with 10 \\u0026micro;L of the prepared solution and then carefully placed on Mueller-Hinton Agar plates previously inoculated with bacterial suspensions standardized to 10⁶ CFU/mL. To serve as a negative control, a separate disc containing only 10 \\u0026micro;L of DMSO was included on each plate to rule out any antimicrobial effects from the solvent. To facilitate even diffusion of the compound into the agar medium, the plates were pre-incubated at 4\\u0026deg;C for 2 hours before being transferred to an incubator set at 37\\u0026deg;C for 24 hours. Following incubation, the diameters of the clear zones surrounding each disc, indicative of bacterial growth inhibition, were measured in millimeters. All tests were conducted in triplicate to ensure accuracy, reproducibility, and statistical significance of the results.\\u003c/p\\u003e\"},{\"header\":\"Results and discussion\",\"content\":\"\\u003cdiv id=\\\"Sec8\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eCharacterization\\u003c/h2\\u003e \\u003cp\\u003eThe structure of \\u003cb\\u003eSBA1\\u003c/b\\u003e was characterized using UV-Vis, FTIR, and \\u003csup\\u003e1\\u003c/sup\\u003eH NMR spectroscopy to confirm its structure. The UV-Vis absorption spectrum of \\u003cb\\u003eSBA1\\u003c/b\\u003e exhibited two characteristic absorption peaks. The peak at 334 nm is a relatively small peak, which can be attributed to the π\\u0026ndash;π* transition of the aromatic system, primarily arising from the benzene and naphthalene rings. This transition indicates the presence of conjugated π-electron systems within the molecular framework. The strong absorption peak at 436 nm corresponds to the n\\u0026ndash;π* transition, which is associated with the azomethine (-C\\u0026thinsp;=\\u0026thinsp;N) group present in the Schiff base (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). This transition is influenced bythe lone pair of electrons on the N- atom of imine, which facilitates charge transfer across the molecule, leading to an intense absorption band. The presence of this peak confirms the successful formation of \\u003cb\\u003eSBA1\\u003c/b\\u003e.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe FTIR spectrum of the synthesized Schiff base \\u003cb\\u003eSBA1\\u003c/b\\u003e provides crucial insights into its functional groups. A broad absorption band observed at 3408.54 cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e corresponds to the O\\u0026ndash;H stretching vibration, confirming the presence of a hydroxyl group. The characteristic C\\u0026ndash;H stretching vibrations of the aromatic rings appear at 3026.92 cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e, indicating the presence of aromatic moieties within the molecular framework. A sharp and intense absorption peak at 1618.25 cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e is attributed to the C\\u0026thinsp;=\\u0026thinsp;N stretching vibration of the azomethine group, a key functional feature of Schiff bases. Additionally, the C\\u0026thinsp;=\\u0026thinsp;C stretching vibrations of the aromatic system are observed at 1485.79 cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e, further supporting the presence of conjugated aromatic rings. Lastly, the absorption band at 750.88 cm\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e is assigned to C\\u0026ndash;Cl stretching, confirming the incorporation of the chloro substituent in the molecular structure (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). These spectral features collectively validate the successful formation of the Schiff base and its characteristic functional groups.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe \\u003csup\\u003e1\\u003c/sup\\u003eH NMR spectrum of the synthesized Schiff base, recorded in CDCl\\u003csub\\u003e3\\u003c/sub\\u003e, exhibited characteristic signals confirming its successful formation. A distinct singlet at δ9.382 ppm (1H) was assigned to the imine proton (-CH\\u0026thinsp;=\\u0026thinsp;N), verifying the presence of the C\\u0026thinsp;=\\u0026thinsp;N azomethine bond, which is a key structural feature of Schiff bases. Furthermore, a broad singlet atδ 15.296 ppm is attributed to OH proton, indicating strong intramolecular hydrogen bonding with the imine nitrogen, which stabilizes the Schiff base structure. The aromatic region of the spectrum further supports the expected structure. Signals appearing in the range of δ 7.129\\u0026ndash;8.184 ppm, showing multiple doublets and triplets, corresponding to the naphthalene and para-substituted benzene rings (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e\\n\\u003ch3\\u003eColorimetric, UV-Vis and fluorescence analysis of Cu detection in solution\\u003c/h3\\u003e\\n\\u003cp\\u003eUpon the addition of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e, the color of \\u003cb\\u003eSBA1\\u003c/b\\u003e changes from yellow to colorless (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e), accompanied by distinct changes in its UV-Vis spectrum. The absorption peak at 436 nm, corresponding to the n\\u0026ndash;π* transition of the azomethine (-C\\u0026thinsp;=\\u0026thinsp;N) group, undergoes a blue shift to 420 nm. This shift is attributed to the hydrolysis process, which alters the electronic structure of the azomethine group and likely weakens the conjugation between the nitrogen and the aromatic system. As a result, the absorption occurs at a shorter wavelength.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eIn addition to the blue shift, the intensity of the 436 nm peak decreases, suggesting that the hydrolysis reaction disrupts the electronic properties of the Schiff base. On the other hand, the peak at 334 nm, associated with the π\\u0026ndash;π* transition of the aromatic system (benzene and naphthalene rings), shows an increase in intensity (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). This suggests that hydrolysis enhances the electronic interactions within the aromatic system. Overall, these UV-Vis spectral changes indicate that the hydrolysis of the Schiff base upon Cu\\u003csup\\u003e2+\\u003c/sup\\u003e addition leads to significant modifications in the electronic structure of \\u003cb\\u003eSBA1\\u003c/b\\u003e.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe fluorescence study demonstrated that \\u003cb\\u003eSBA1\\u003c/b\\u003e exhibits weak emission at 554 nm upon excitation at 275 nm. This low fluorescence intensity is mainly due to the photoinduced electron transfer (PET) effect, which effectively quenches the emission, limiting its fluorescence response. PET occurs when an electron is transferred from the donor moiety to the acceptor, reducing the fluorescence efficiency of the molecule. When \\u003cb\\u003eSBA1\\u003c/b\\u003e is exposed to various metal ions such as Cu\\u003csup\\u003e2+\\u003c/sup\\u003e, Co\\u003csup\\u003e2+\\u003c/sup\\u003e, Zn\\u003csup\\u003e2+\\u003c/sup\\u003e, Pb\\u003csup\\u003e2+\\u003c/sup\\u003e, Ag\\u003csup\\u003e+\\u003c/sup\\u003e, Cd\\u003csup\\u003e2+\\u003c/sup\\u003e, Mg\\u003csup\\u003e2+\\u003c/sup\\u003e, Ni\\u003csup\\u003e2+\\u003c/sup\\u003e, Ca\\u003csup\\u003e2+\\u003c/sup\\u003e, Fe\\u003csup\\u003e3+\\u003c/sup\\u003e, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, Hg\\u003csup\\u003e2+\\u003c/sup\\u003e, K\\u003csup\\u003e+\\u003c/sup\\u003e, and Na\\u003csup\\u003e+\\u003c/sup\\u003e, no significant fluorescence changes are observed, indicating that the PET effect remains dominant and the structural integrity of \\u003cb\\u003eSBA1\\u003c/b\\u003e is not significantly altered. However, in the presence of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions, a notable fluorescence enhancement is observed, suggesting a specific interaction between \\u003cb\\u003eSBA1\\u003c/b\\u003e and Cu\\u003csup\\u003e2+\\u003c/sup\\u003e that modifies its electronic properties (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig6\\\" class=\\\"InternalRef\\\"\\u003e6\\u003c/span\\u003e). The fluorescence enhancement observed with Cu\\u003csup\\u003e2+\\u003c/sup\\u003e is due to the hydrolysis of \\u003cb\\u003eSBA1\\u003c/b\\u003e facilitated by Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions. This hydrolysis process leads to the cleavage of the Schiff base linkage, releasing the naphthalene moiety. In its original form, \\u003cb\\u003eSBA1\\u003c/b\\u003e experiences fluorescence quenching due to PET. However, upon hydrolysis, the free naphthalene unit is no longer subjected to this quenching effect, allowing it to exhibit strong fluorescence. This transformation highlights the crucial role of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e in breaking the Schiff base structure and freeing the fluorescent moiety.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003eThe hydrolysis-induced fluorescence enhancement provides a clear and measurable signal, making \\u003cb\\u003eSBA1\\u003c/b\\u003e a promising candidate for analytical applications. The ability to distinguish Cu\\u003csup\\u003e2+\\u003c/sup\\u003e from other metal ions based on fluorescence intensity changes further enhances its utility in metal ion sensing. This characteristic can be explored for designing selective and sensitive chemosensors, particularly for environmental and biological monitoring of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e levels. To analyze the quantitative nature of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e sensing and determine the selectivity range of the chemosensor \\u003cb\\u003eSBA1\\u003c/b\\u003e, a fluorescence titration experiment was performed with varying Cu\\u003csup\\u003e2+\\u003c/sup\\u003e concentrations ranging from 0.01 to 1.5 ppm. The results, as depicted in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig7\\\" class=\\\"InternalRef\\\"\\u003e7\\u003c/span\\u003e, show a steady increase in fluorescence intensity with the gradual addition of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions. This enhancement suggests a direct correlation between Cu\\u003csup\\u003e2+\\u003c/sup\\u003e concentration and fluorescence response, further supporting the hydrolysis-induced fluorescence mechanism. The observed linear increase in fluorescence intensity with rising Cu\\u003csup\\u003e2+\\u003c/sup\\u003e concentration shows the potential of \\u003cb\\u003eSBA1\\u003c/b\\u003e as a reliable and sensitive probe for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection, demonstrating its suitability for quantitative sensing applications.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\\n\\u003ch3\\u003eDetection limit\\u003c/h3\\u003e\\n\\u003cp\\u003eIn analytical chemistry, evaluating the detection limit of a chemosensor is essential for determining its sensitivity and effectiveness in identifying low concentrations of target analytes. The sensing capability of \\u003cb\\u003eSBA1\\u003c/b\\u003e toward Cu\\u003csup\\u003e2+\\u003c/sup\\u003e was assessed through fluorescence titration experiments, where increasing concentrations of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e (0.01 to 1.5 ppm) were introduced into \\u003cb\\u003eSBA1\\u003c/b\\u003e solutions. A progressive enhancement in fluorescence intensity was observed with each incremental addition, confirming a selective turn-on response to Cu\\u003csup\\u003e2+\\u003c/sup\\u003e (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig8\\\" class=\\\"InternalRef\\\"\\u003e8\\u003c/span\\u003e). To further quantify the sensitivity of \\u003cb\\u003eSBA1\\u003c/b\\u003e, calibration curves were constructed by plotting fluorescence intensity against Cu\\u003csup\\u003e2+\\u003c/sup\\u003e concentration. These curves displayed a linear trend within the tested range, allowing for precise calculations of detection limit, which was determined using the standard formula LOD\\u0026thinsp;=\\u0026thinsp;3.3\\u0026thinsp;\\u0026times;\\u0026thinsp;σ/S, where σ denotes the standard deviation and S represents the slope of the linear portion of the calibration curve. Based on these calculations, the detection limit for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e was found to be 0.0031 ppm, while the LOQ was 0.0096 ppm.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cdiv id=\\\"Sec11\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eInterference of other metal ions\\u003c/h2\\u003e \\u003cp\\u003eThe interference study was conducted to assess the selectivity of the sensor in the presence of other metal ions. To evaluate potential interferences, fluorescence measurements were performed with \\u003cb\\u003eSBA1\\u003c/b\\u003e in solutions containing Cu\\u003csup\\u003e2+\\u003c/sup\\u003e along with various competing metal ions, including Co\\u003csup\\u003e2+\\u003c/sup\\u003e, Zn\\u003csup\\u003e2+\\u003c/sup\\u003e, Pb\\u003csup\\u003e2+\\u003c/sup\\u003e, Ag\\u003csup\\u003e+\\u003c/sup\\u003e, Cd\\u003csup\\u003e2+\\u003c/sup\\u003e, Mg\\u003csup\\u003e2+\\u003c/sup\\u003e, Ni\\u003csup\\u003e2+\\u003c/sup\\u003e, Ca\\u003csup\\u003e2+\\u003c/sup\\u003e, Fe\\u003csup\\u003e3+\\u003c/sup\\u003e, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, Hg\\u003csup\\u003e2+\\u003c/sup\\u003e, K\\u003csup\\u003e+\\u003c/sup\\u003e, and Na\\u003csup\\u003e+\\u003c/sup\\u003e. The results demonstrated that the presence of these metal ions did not significantly alter the fluorescence response of \\u003cb\\u003eSBA1\\u003c/b\\u003e toward Cu\\u003csup\\u003e2+\\u003c/sup\\u003e (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e9\\u003c/span\\u003e). The fluorescence enhancement observed upon Cu\\u003csup\\u003e2+\\u003c/sup\\u003e addition remained mostly unaffected, indicating that \\u003cb\\u003eSBA1\\u003c/b\\u003e exhibits a highly selective response to Cu\\u003csup\\u003e2+\\u003c/sup\\u003e without interference from other metal ions. These finding confirms its potential for accurate and reliable Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection in complex environments. Unlike other metal ions, Cu\\u003csup\\u003e2+\\u003c/sup\\u003e facilitates the cleavage of the Schiff base linkage in \\u003cb\\u003eSBA1\\u003c/b\\u003e, releasing the naphthalene moiety and leading to a pronounced fluorescence enhancement. Since none of the other tested metal ions triggered a similar hydrolysis process, their presence did not affect the fluorescence response. This exceptional selectivity ensures that \\u003cb\\u003eSBA1\\u003c/b\\u003e can be used effectively for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection even in real-world samples containing diverse metal ions.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec12\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eMechanism\\u003c/h2\\u003e \\u003cp\\u003eThe mechanism by which \\u003cb\\u003eSBA1\\u003c/b\\u003e detects Cu\\u003csup\\u003e2+\\u003c/sup\\u003e is predominantly driven by hydrolysis, which results in distinct colorimetric, UV-Vis, and fluorescence changes. Schiff bases typically form colored complexes with Cu\\u003csup\\u003e2+\\u003c/sup\\u003e, and in this case, the addition of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e induces a noticeable color change from yellow to colorless. This visual transition suggests the breakdown of the imine (-C\\u0026thinsp;=\\u0026thinsp;N) bond due to hydrolysis. UV-Vis spectral analysis further supports this structural transformation. The absorption peak at 436 nm, corresponding to the n\\u0026ndash;π* transition of the azomethine group, undergoes a blue shift to 420 nm. This shift occurs because the hydrolysis reaction alters the electronic structure of the azomethine group, weakening its conjugation with the aromatic system and reducing electron delocalization. Additionally, the intensity of the 436 nm peak diminishes, indicating the disruption of the Schiff base electronic properties. Simultaneously, the absorption peak at 334 nm, associated with the π\\u0026ndash;π* transition of the benzene and naphthalene rings, shows an increase in intensity. The fluorescence studies provide further insight into the hydrolysis mechanism. \\u003cb\\u003eSBA1\\u003c/b\\u003e initially exhibits weak fluorescence due to the PET effect. In the presence of Cu\\u003csup\\u003e2+\\u003c/sup\\u003e, a significant fluorescence enhancement is recorded. This enhancement is attributed to the hydrolysis of \\u003cb\\u003eSBA1\\u003c/b\\u003e by Cu\\u003csup\\u003e2+\\u003c/sup\\u003e, which cleaves the Schiff base linkage and releases the fluorescent naphthalene moiety. In its original form, \\u003cb\\u003eSBA1\\u003c/b\\u003e experiences PET quenching due to electron transfer from the azomethine nitrogen to naphthalene, suppressing fluorescence. However, hydrolysis disrupts this process, preventing PET quenching and allowing the fluorescence to be restored. This combined colorimetric, UV-Vis, and fluorescence response demonstrates that the Cu\\u003csup\\u003e2+\\u003c/sup\\u003e-induced hydrolysis of \\u003cb\\u003eSBA1\\u003c/b\\u003e serves as the key sensing mechanism, making it a highly selective and effective chemosensor for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec13\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eApplication of the chemosensor for Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection in water samples\\u003c/h2\\u003e \\u003cp\\u003eThe practical applicability of the chemosensor for detecting Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions was evaluated through a fluorescence-based analysis of real water samples. Various water sources (soil sample, drinking, lake, river and pond water) were collected, and Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions were introduced at different concentrations (0.1, 0.3, and 0.5 ppm) using a spiking method. The fluorescence response of the chemosensor was measured after titration with the spiked samples, revealing a high recovery rate of up to 91.0 to 102.0%. This excellent recovery rate indicates the reliability and efficiency of the sensor in accurately quantifying Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions in complex water matrices. The results were systematically analyzed and compiled in Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e, demonstrating the sensor performance under realistic conditions. Furthermore, the high recovery values suggest that the developed chemosensor effectively detects Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions without significant interference from other metal ions commonly present in water samples. This selectivity is crucial for real-world applications, as environmental and industrial water sources often contain multiple competing ions. These findings confirm that the chemosensor is a promising tool for rapid and reliable Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection, paving the way for its application in practical water analysis scenarios.\\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec14\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003eAntibacterial activity\\u003c/h2\\u003e \\u003cp\\u003eSchiff bases have gained considerable attention in the fields of chemistry, biology, and materials science due to their ease of synthesis, structural diversity, and remarkable range of applications. [\\u003cspan additionalcitationids=\\\"CR36 CR37\\\" citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e35\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR38\\\" class=\\\"CitationRef\\\"\\u003e38\\u003c/span\\u003e] Schiff bases possess a characteristic azomethine group (-C\\u0026thinsp;=\\u0026thinsp;N-) that is central to their chemical reactivity and biological interactions. The presence of lone-pair electrons on the nitrogen atom within the imine group allows Schiff bases to coordinate easily with metal ions, making them excellent ligands in coordination chemistry.[\\u003cspan citationid=\\\"CR39\\\" class=\\\"CitationRef\\\"\\u003e39\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR40\\\" class=\\\"CitationRef\\\"\\u003e40\\u003c/span\\u003e]\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab1\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 1\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003e% recovery of Cu2+ in water and soil samples at different spiked concentrations\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"4\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\" morerows=\\\"1\\\" rowspan=\\\"2\\\"\\u003e \\u003cp\\u003eSamples\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colspan=\\\"2\\\" nameend=\\\"c3\\\" namest=\\\"c2\\\"\\u003e \\u003cp\\u003eCu\\u003csup\\u003e2+\\u003c/sup\\u003e concentration(\\u0026micro;g mL\\u003csup\\u003e\\u0026minus;\\u0026thinsp;1\\u003c/sup\\u003e)\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\" morerows=\\\"1\\\" rowspan=\\\"2\\\"\\u003e \\u003cp\\u003e% Recovery\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eAdded\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eFound\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSoil\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.1\\u003c/p\\u003e \\u003cp\\u003e0.3\\u003c/p\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.092\\u003c/p\\u003e \\u003cp\\u003e0.281\\u003c/p\\u003e \\u003cp\\u003e0.462\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e92.0\\u003c/p\\u003e \\u003cp\\u003e93.6\\u003c/p\\u003e \\u003cp\\u003e92.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eDrinking water\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.1\\u003c/p\\u003e \\u003cp\\u003e0.3\\u003c/p\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.096\\u003c/p\\u003e \\u003cp\\u003e0.297\\u003c/p\\u003e \\u003cp\\u003e0.510\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e96.0\\u003c/p\\u003e \\u003cp\\u003e99.0\\u003c/p\\u003e \\u003cp\\u003e102.0\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eLake water\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.1\\u003c/p\\u003e \\u003cp\\u003e0.3\\u003c/p\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.094\\u003c/p\\u003e \\u003cp\\u003e0.287\\u003c/p\\u003e \\u003cp\\u003e0.498\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e94.0\\u003c/p\\u003e \\u003cp\\u003e95.6\\u003c/p\\u003e \\u003cp\\u003e99.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eRiver water\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.1\\u003c/p\\u003e \\u003cp\\u003e0.3\\u003c/p\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.091\\u003c/p\\u003e \\u003cp\\u003e0.281\\u003c/p\\u003e \\u003cp\\u003e0.472\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e91.0\\u003c/p\\u003e \\u003cp\\u003e93.6\\u003c/p\\u003e \\u003cp\\u003e94.4\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003ePond water\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e0.1\\u003c/p\\u003e \\u003cp\\u003e0.3\\u003c/p\\u003e \\u003cp\\u003e0.5\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003e0.095\\u003c/p\\u003e \\u003cp\\u003e0.296\\u003c/p\\u003e \\u003cp\\u003e0.508\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e95.0\\u003c/p\\u003e \\u003cp\\u003e98.6\\u003c/p\\u003e \\u003cp\\u003e101.6\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003cp\\u003eSchiff bases exhibit a broad spectrum of biological activities. These characteristics position Schiff bases as versatile candidates in the design of therapeutic agents and functional materials. One of the most significant advantages of Schiff base compounds is the ability to tailor their structure by varying the nature of the aldehyde or amine precursors. This tunability allows chemists to fine-tune the physicochemical and biological properties of the resulting compounds, creating molecules with high selectivity and potency against specific biological targets. Over the years, Schiff base derivatives have been extensively studied for their therapeutic potential. [\\u003cspan additionalcitationids=\\\"CR42 CR43 CR44\\\" citationid=\\\"CR41\\\" class=\\\"CitationRef\\\"\\u003e41\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR45\\\" class=\\\"CitationRef\\\"\\u003e45\\u003c/span\\u003e] In the wake of increasing global concerns regarding antimicrobial resistance, the search for new classes of antimicrobial agents has intensified. Schiff bases have emerged as promising alternatives owing to their diverse mechanisms of action and adaptability to structural modification. The antimicrobial potential of Schiff bases can be attributed to their unique mode of action. Moreover, Schiff bases are known to penetrate microbial cell membranes more effectively due to their lipophilic nature, which enhances their interaction with intracellular targets. Structural modifications such as the introduction of aromatic rings, heterocycles, halogens, or other functional groups can further enhance the biological efficacy of Schiff base compounds, making them potent candidates against a variety of bacterial and fungal pathogens. These characteristics have led to growing interest in Schiff base compounds not only as standalone antimicrobial agents but also as synergistic agents that can enhance the efficacy of existing antibiotics. [\\u003cspan additionalcitationids=\\\"CR31\\\" citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e30\\u003c/span\\u003e\\u0026ndash;\\u003cspan citationid=\\\"CR32\\\" class=\\\"CitationRef\\\"\\u003e32\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e46\\u003c/span\\u003e] The Schiff base \\u003cb\\u003eSBA1\\u003c/b\\u003e, synthesized and investigated in the current study, was evaluated for its antimicrobial properties against a diverse panel of Gram-positive and Gram-negative bacterial strains \\u003cem\\u003esuch as Salmonella typhimurium, Enterobacter aerogenes\\u003c/em\\u003e, \\u003cem\\u003eKlebsiella pneumoniae\\u003c/em\\u003e, \\u003cem\\u003ePseudomonas aeruginosa, Bacillus megaterium, Salmonella enterica\\u003c/em\\u003e, \\u003cem\\u003eBacillus cereus, Escherichia coli\\u003c/em\\u003e, \\u003cem\\u003eBacillus subtilis\\u003c/em\\u003e, \\u003cem\\u003eStaphylococcus aureus, Proteus vulgaris\\u003c/em\\u003e, \\u003cem\\u003ePseudomonas fluorescens\\u003c/em\\u003e, and \\u003cem\\u003eBrevibacillus brevis\\u003c/em\\u003e. The disc diffusion method, a widely accepted and reliable technique for initial screening of antibacterial agents, was employed to assess the efficacy of \\u003cb\\u003eSBA1\\u003c/b\\u003e. In this assay, sterile paper discs impregnated with a fixed amount of the compound were placed on agar plates inoculated with bacterial cultures. After incubation, the diameter of the inhibition zone around each disc was measured, with larger zones indicating stronger antibacterial activity. Table\\u0026nbsp;\\u003cspan refid=\\\"Tab2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e presents the antibacterial activity of \\u003cb\\u003eSBA1\\u003c/b\\u003e against 13 different bacterial strains. The results indicate that \\u003cb\\u003eSBA1\\u003c/b\\u003e exhibits broad-spectrum antibacterial activity, demonstrating effectiveness against both Gram-positive and Gram-negative bacteria. Among the tested strains, \\u003cem\\u003eStaphylococcus aureus\\u003c/em\\u003e showed the highest sensitivity to \\u003cb\\u003eSBA1\\u003c/b\\u003e, with a zone of inhibition measuring 17.20\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.75 mm. Similarly, \\u003cem\\u003eBacillus subtilis\\u003c/em\\u003e and \\u003cem\\u003eBacillus cereus\\u003c/em\\u003e exhibited substantial susceptibility to \\u003cb\\u003eSBA1\\u003c/b\\u003e, with inhibition zones of 16.35\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.88 mm and 16.24\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.76 mm, respectively. The activity of SBA1 against these bacteria suggests that the compound may be effective in environmental or food safety applications, where control of such pathogens is essential. \\u003cem\\u003eProteus vulgaris\\u003c/em\\u003e and \\u003cem\\u003eSalmonella typhimurium\\u003c/em\\u003e, both Gram-negative bacteria associated with urinary tract infections and gastrointestinal diseases, also responded well to \\u003cb\\u003eSBA1\\u003c/b\\u003e, with inhibition zones of 15.71\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.52 mm and 15.44\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.67 mm, respectively. Other strains, including \\u003cem\\u003eSalmonella enterica\\u003c/em\\u003e, \\u003cem\\u003eEscherichia coli\\u003c/em\\u003e, \\u003cem\\u003eEnterobacter aerogenes\\u003c/em\\u003e, and \\u003cem\\u003eKlebsiella pneumoniae\\u003c/em\\u003e, exhibited moderate sensitivity to \\u003cb\\u003eSBA1\\u003c/b\\u003e, with inhibition zones ranging from 10.88 mm to 13.42 mm. Notably, \\u003cem\\u003ePseudomonas aeruginosa\\u003c/em\\u003e and \\u003cem\\u003ePseudomonas fluorescens\\u003c/em\\u003e, which are often more resistant to antibiotics due to their robust efflux systems and biofilm-forming capabilities, showed smaller inhibition zones of 10.65\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.61 mm and 10.27\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.34 mm, respectively. Despite the lower activity against these strains, the results are still promising, especially considering that many synthetic compounds fail to show any effect on \\u003cem\\u003ePseudomonas species\\u003c/em\\u003e without specific structural optimization. The variability in the antibacterial activity of \\u003cb\\u003eSBA1\\u003c/b\\u003e across different strains may be attributed to differences in cell wall composition, membrane permeability, and intrinsic resistance mechanisms.\\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab2\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 2\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eAntibacterial activity of Schiff base SBA1.\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"2\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eBacterial Strains\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eSBPY-1\\u003c/p\\u003e \\u003cp\\u003eZone of inhibition (mm)\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eSalmonella typhimurium\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e15.44\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.67\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eEnterobacter aerogenes\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e10.88\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.39\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eKlebsiella pneumoniae\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e11.84\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.83\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003ePseudomonas aeruginosa\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e10.65\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.61\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eBacillus megaterium\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e12.48\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.58\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eSalmonella enterica\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e13.42\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.25\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eBacillus cereus\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e16.24 \\u0026plusmn; 0.76\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eEscherichia coli\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e11.33\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.69\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eBacillus subtilis\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e16.35\\u0026thinsp;\\u0026plusmn;\\u0026thinsp;0.88\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eStaphylococcus aureus\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e17.20 \\u0026plusmn; 0.75\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eProteus vulgaris\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e15.71 \\u0026plusmn; 0.52\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003ePseudomonas fluorescens\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e10.27 \\u0026plusmn; 0.34\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eBrevibacillus brevis\\u003c/em\\u003e\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"char\\\" char=\\\"\\u0026plusmn;\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e12.16 \\u0026plusmn; 0.94\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"Conclusion\",\"content\":\"\\u003cp\\u003eThe successful synthesis and characterization of the novel Schiff base \\u003cb\\u003eSBA1\\u003c/b\\u003e have unveiled its remarkable multifunctional capabilities, making it a promising candidate for both environmental and biomedical applications. Through detailed spectroscopic analysis using UV-Vis, FTIR, and \\u003csup\\u003e1\\u003c/sup\\u003eH NMR, the structural integrity and functional groups of \\u003cb\\u003eSBA1\\u003c/b\\u003e were confirmed, laying the foundation for its application in sensing and bioactivity studies. Its highly selective colorimetric and fluorescence responses toward Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions, marked by a pronounced color change and significant fluorescence enhancement, highlight its potential as an efficient chemosensor. The extremely low detection (LOD\\u0026thinsp;=\\u0026thinsp;0.0031 ppm) and quantification limits (LOQ\\u0026thinsp;=\\u0026thinsp;0.0096 ppm), coupled with high recovery rates (91.0\\u0026ndash;102.0%) in real environmental samples such as drinking water, river water, and soil-extracted water, affirm \\u003cb\\u003eSBA1\\u003c/b\\u003e reliability and effectiveness in trace-level Cu\\u003csup\\u003e2+\\u003c/sup\\u003e detection under complex conditions. Furthermore, the additional demonstration of broad-spectrum antibacterial activity against both Gram-positive and Gram-negative bacterial strains highlights the therapeutic potential of \\u003cb\\u003eSBA1\\u003c/b\\u003e, presenting it not only as a sensor but also as a bioactive compound. The dual role of \\u003cb\\u003eSBA1\\u003c/b\\u003e as a selective Cu\\u003csup\\u003e2+\\u003c/sup\\u003e sensor and potent antimicrobial agent emphasizes its multifunctionality, offering a valuable tool for integrated applications in environmental safety monitoring and infectious disease control.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003e\\u003cstrong\\u003eAcknowledgement\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe authors extend their appreciation to Taif University, Saudi Arabia for supporting this work through project number (TU-DSPP-2024-58)\\u0026rdquo;.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eFunding\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe research was funded by Taif University, Saudi Arabia, Project Number (TU-DSPP-2024-58)\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eData Availability\\u003c/strong\\u003e: All data generated or analyzed during this study are included in this published article\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eCode Availability:\\u003c/strong\\u003e ChemDraw\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eEthical Approval\\u003c/strong\\u003e: This article does not contain any studies with human participants or animals, clinical trial registration, or plant reproducibility performed by any authors.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConsent to Publish:\\u003c/strong\\u003e The authors have approved the paper and agree with its publication.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConsent to participate\\u003c/strong\\u003e: \\u0026nbsp;No applicable.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eConflict of Interest:\\u0026nbsp;\\u003c/strong\\u003eThe authors declare that they have no conflicts of interest.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eAuthor Contribution\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eProf. Alaa Shafie: Conceptualized and supervised the study, provided critical revisions, and contributed to the final manuscript editing.Dr. Mohammed Fareed Felemban: Responsible for methodology development, data analysis, and manuscript writing.Dr. Faris J. Tayeb: Experimental validation, and review of the manuscript.Dr. Amal Adnan Ashour: Assisted in literature review, visualization, and manuscript formatting and proofreading.\\u003c/p\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\u003cli\\u003e\\u003cspan\\u003eAli H, Khan E, Ilahi I (2019) Environmental Chemistry and Ecotoxicology of Hazardous Heavy Metals: Environmental Persistence, Toxicity, and Bioaccumulation, J. Chem. 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J Mol Struct 1146:600\\u0026ndash;619. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1016/J.MOLSTRUC.2017.06.006\\u003c/span\\u003e\\u003cspan address=\\\"10.1016/J.MOLSTRUC.2017.06.006\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eCeyhan G, K\\u0026ouml;se M, T\\u0026uuml;mer M, Demirtaş I, Şahin Yaǧlioǧlu A, McKee V (2013) Structural characterization of some Schiff base compounds: Investigation of their electrochemical, photoluminescence, thermal and anticancer activity properties. J Lumin 143:623\\u0026ndash;634. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.1016/J.JLUMIN.2013.06.002\\u003c/span\\u003e\\u003cspan address=\\\"10.1016/J.JLUMIN.2013.06.002\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e \\u003cli\\u003e\\u003cspan\\u003eJorge J, Del Pino Santos KF, Tim\\u0026oacute;teo F, Piva Vasconcelos RR, Ignacio Ayala O, C\\u0026aacute;ceres I, Juliane Arantes Granja DM, de Souza TE, Allievi Frizon G, Di Vaccari Botteselle A, Luiz Braga S, Saba H, ur Rashid J, Rafique (2023) Recent Advances on the Antimicrobial Activities of Schiff Bases and their Metal Complexes: An Updated Overview. Curr Med Chem 31:2330\\u0026ndash;2344. \\u003cspan class=\\\"ExternalRef\\\"\\u003e\\u003cspan class=\\\"RefSource\\\"\\u003ehttps://doi.org/10.2174/0929867330666230224092830/CITE/REFWORKS\\u003c/span\\u003e\\u003cspan address=\\\"10.2174/0929867330666230224092830/CITE/REFWORKS\\\" targettype=\\\"DOI\\\" class=\\\"RefTarget\\\"\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/span\\u003e\\u003c/li\\u003e\\u003c/ol\\u003e\"},{\"header\":\"Schemes\",\"content\":\"\\u003cp\\u003eScheme 1 is available in the Supplementary Files section\\u003c/p\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":false,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":true,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"transition-metal-chemistry\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"tmch\",\"sideBox\":\"Learn more about [Transition Metal Chemistry](http://link.springer.com/journal/11243)\",\"snPcode\":\"11243\",\"submissionUrl\":\"https://submission.nature.com/new-submission/11243/3\",\"title\":\"Transition Metal Chemistry\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"em\",\"reportingPortfolio\":\"Springer Hybrid\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false},\"keywords\":\"1H NMR spectroscopy, Metal ions, Colorimetric, River water\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-6796500/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-6796500/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003eA novel Schiff base \\u003cb\\u003eSBA1\\u003c/b\\u003e, was successfully synthesized and structurally characterized using UV-Vis, FTIR, and \\u003csup\\u003e1\\u003c/sup\\u003eH NMR spectroscopy. Its sensing capabilities were systematically investigated against a broad range of metal ions, including Cu\\u003csup\\u003e2+\\u003c/sup\\u003e, Co\\u003csup\\u003e2+\\u003c/sup\\u003e, Zn\\u003csup\\u003e2+\\u003c/sup\\u003e, Pb\\u003csup\\u003e2+\\u003c/sup\\u003e, Ag\\u003csup\\u003e+\\u003c/sup\\u003e, Cd\\u003csup\\u003e2+\\u003c/sup\\u003e, Mg\\u003csup\\u003e2+\\u003c/sup\\u003e, Ni\\u003csup\\u003e2+\\u003c/sup\\u003e, Ca\\u003csup\\u003e2+\\u003c/sup\\u003e, Fe\\u003csup\\u003e3+\\u003c/sup\\u003e, Mn\\u003csup\\u003e2+\\u003c/sup\\u003e, Hg\\u003csup\\u003e2+\\u003c/sup\\u003e, K\\u003csup\\u003e+\\u003c/sup\\u003e, and Na\\u003csup\\u003e+\\u003c/sup\\u003e. Among these, \\u003cb\\u003eSBA1\\u003c/b\\u003e exhibited a highly selective and distinct colorimetric response toward Cu\\u003csup\\u003e2+\\u003c/sup\\u003e ions, marked by a visible color change from yellow to colorless. Fluorescence studies further revealed a substantial enhancement in emission intensity upon Cu\\u003csup\\u003e2+\\u003c/sup\\u003e binding, indicating strong interaction and excellent sensing performance. The sensor demonstrated impressive sensitivity, achieving a limit of detection (LOD) of 0.0031 ppm and a limit of quantification (LOQ) of 0.0096 ppm, enabling trace-level detection of Cu\\u0026sup2;⁺ ions in aqueous media. To evaluate its practical utility, the \\u003cb\\u003eSBA1\\u003c/b\\u003e was tested in real environmental samples, including soil-extracted water, drinking water, lake water, river water, and pond water. Fluorescence titration with Cu\\u0026sup2;⁺-spiked samples showed outstanding recovery rates ranging from 91.0\\u0026ndash;102.0%, confirming the sensor reliability and accuracy in complex matrices. In addition to its sensing capabilities, the antibacterial potential of \\u003cb\\u003eSBA1\\u003c/b\\u003e was also assessed against selected bacterial strains. The compound exhibited notable antibacterial activity, indicating its dual functionality as both a highly sensitive Cu\\u003csup\\u003e2+\\u003c/sup\\u003e sensor and an effective antimicrobial agent. These findings position \\u003cb\\u003eSBA1\\u003c/b\\u003e as a promising multifunctional material for environmental monitoring and biomedical applications.\\u003c/p\\u003e\",\"manuscriptTitle\":\"Dual-Action Innovation: Schiff Base for Trace Cu 2+ ions Detection and Powerful Antibacterial Potential\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2025-06-04 08:26:23\",\"doi\":\"10.21203/rs.3.rs-6796500/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0},{\"type\":\"decision\",\"content\":\"Revision requested\",\"date\":\"2025-06-29T17:32:37+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2025-06-20T07:39:50+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2025-06-16T08:31:21+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2025-06-11T14:45:10+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2025-06-10T06:11:00+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"257088909669704521752673930844633331165\",\"date\":\"2025-06-04T15:06:52+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"206307758461356993955431041582710386362\",\"date\":\"2025-06-04T06:03:23+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"editorInvitedReview\",\"content\":\"\",\"date\":\"2025-06-03T07:21:06+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"83110921630261392820489348672729351070\",\"date\":\"2025-06-03T06:54:21+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"120251281515822197903652997859382082278\",\"date\":\"2025-06-02T18:07:38+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"338519067810749372362509009631318944492\",\"date\":\"2025-06-02T16:41:25+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewerAgreed\",\"content\":\"218490869004616169589825596539235127824\",\"date\":\"2025-06-02T14:55:34+00:00\",\"index\":\"hide\",\"fulltext\":\"\"},{\"type\":\"reviewersInvited\",\"content\":\"\",\"date\":\"2025-06-02T14:28:46+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"editorAssigned\",\"content\":\"\",\"date\":\"2025-06-02T13:28:31+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"checksComplete\",\"content\":\"\",\"date\":\"2025-06-02T08:40:05+00:00\",\"index\":\"\",\"fulltext\":\"\"},{\"type\":\"submitted\",\"content\":\"Transition Metal Chemistry\",\"date\":\"2025-06-01T15:13:10+00:00\",\"index\":\"\",\"fulltext\":\"\"}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"transition-metal-chemistry\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":false,\"externalIdentity\":\"tmch\",\"sideBox\":\"Learn more about [Transition Metal Chemistry](http://link.springer.com/journal/11243)\",\"snPcode\":\"11243\",\"submissionUrl\":\"https://submission.nature.com/new-submission/11243/3\",\"title\":\"Transition Metal Chemistry\",\"twitterHandle\":\"\",\"acdcEnabled\":true,\"dfaEnabled\":true,\"editorialSystem\":\"em\",\"reportingPortfolio\":\"Springer Hybrid\",\"inReviewEnabled\":true,\"inReviewRevisionsEnabled\":false}}],\"origin\":\"\",\"ownerIdentity\":\"d6e6d06a-8c25-45e9-ac38-3570d6c5a7e1\",\"owner\":[],\"postedDate\":\"June 4th, 2025\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"published-in-journal\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2026-02-23T16:01:01+00:00\",\"versionOfRecord\":{\"articleIdentity\":\"rs-6796500\",\"link\":\"https://doi.org/10.1007/s11243-025-00698-8\",\"journal\":{\"identity\":\"transition-metal-chemistry\",\"isVorOnly\":false,\"title\":\"Transition Metal Chemistry\"},\"publishedOn\":\"2026-02-18 15:57:06\",\"publishedOnDateReadable\":\"February 18th, 2026\"},\"versionCreatedAt\":\"2025-06-04 08:26:23\",\"video\":\"\",\"vorDoi\":\"10.1007/s11243-025-00698-8\",\"vorDoiUrl\":\"https://doi.org/10.1007/s11243-025-00698-8\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-6796500\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-6796500\",\"identity\":\"rs-6796500\",\"version\":[\"v1\"]},\"buildId\":\"XKTyCvWXoU3ODBz1xrDgd\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}