Microwave-assisted Synthesis, Characterization and Biological Study of Metal (Ii) Complex Derived From 2-aminophenol and P- Chlorobenzaldehyde Schiff Base

Microwave-assisted Synthesis, Characterization and Biological Study of Metal (Ii) Complex Derived From 2-aminophenol and P- Chlorobenzaldehyde Schiff Base | 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 Microwave-assisted Synthesis, Characterization and Biological Study of Metal (Ii) Complex Derived From 2-aminophenol and P- Chlorobenzaldehyde Schiff Base K.E Ajibulu, B.T Pii, V.I Adebiyi, R.A Nasiru This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8745555/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 13 You are reading this latest preprint version Abstract The growing resistance of microorganisms to existing antibiotics has increased the need for new and more effective antimicrobial agents. In this study, Schiff base ligand was synthesized from 2-aminophenol and p -chlorobenzaldehyde, and its cobalt(II) and lead(II) complexes. The compounds were characterized using melting point determination, solubility tests, UV–visible, FTIR spectroscopy, elemental analysis, and magnetic susceptibility measurements.The FTIR spectrum of the ligand showed a characteristic band at 1625cm⁻¹ due to the formation of azomethine (C = N) group, confirming Schiff base formation. In the metal(II) complexes, this band shifted to lower frequencies,1580 cm − 1 indicating coordination of the azomethine nitrogen to the metal ions. The O–H stretching band at 3406 cm − 1 upon complexation, suggesting involvement of the phenolic oxygen atom. UV–visible and magnetic data supported an octahedral geometry around the metal centers, while elemental analysis confirmed the expected molecular compositions of the prepared Schiff base ligand. Antimicrobial studies showed that the metal complexes displayed higher inhibitory activity against the tested bacterial strains compared with the free ligand. This enhancement suggests that coordination with metal ions increases the biological effectiveness of the Schiff base. Overall, the results confirm successful synthesis and characterization of the Schiff base ligand and its cobalt(II) and lead(II) complexes, demonstrating their potential as promising antimicrobial agents. Schiff base Complex 2-aminophenol Synthesis Characterization Figures Figure 1 Figure 2 Figure 3 1. Introduction Schiff base ligands and their metal complexes have become important in coordination chemistry due to their ease of synthesis, structural diversity, and wide range of applications(Desalegn, 2023 ; Prakash, 2010). The presence of the azomethine (–C = N–) linkage allows Schiff bases to act as good donors to metal ions, forming stable chelate rings (Ajibulu et al., 2023 ; Ravinderpal & Sataya, 2019; Anital et al ., 2015 and Wara, 2011 ). The importance of coordination compounds has significantly increased in recent years. Metal complexes play crucial roles in homogeneous and heterogeneous catalysis (Alshaheri et al., 2017 ), materials chemistry (including metal–organic frameworks and coordination polymers) (Biplab, 2022 ), photochemistry and optoelectronics(Yang et al., 2015 ), as well as biomedicine (such as diagnostics and metal-based nanomedicines used in anticancer and antimicrobial therapies) (Fahmi et al., 2013 ; Mahmoud et al., 2020 ; Desai and Parekh, 2021 ). The significance of Schiff base metal complexes stems from their diverse applications across biological, industrial, and environmental sectors. Schiff bases possess a strong metal-binding capacity, stability, and versatile donor characteristics due to the presence of the azomethine (–C = N–) group, making them highly effective ligands in coordination chemistry (Kargar et al., 2021 ; Mohamed et al., 2022 ). Schiff bases containing oxygen and nitrogen donor atoms are especially attractive for forming stable metal complexes that exhibit significant, biological activities such as antimicrobial, anticancer, anti fungal, anti oxidant and anti inflammatory properties ( Racheal et al., 2023 ; Ejidike et al., 2019 ; Sigh et al ., 2007; Chohan et al ., 2006; ). In this study, we presented the synthesis of Schiff base metal complexes using, (E)-2-[(4-chlorobenzylidene)amino]phenol Schiff base ligand, Co(II), and Pb(II). The synthesized compounds were characterized using spectroscopic techniques and their antimicrobial properties were examined. 2. Material and Methods All chemicals and reagents utilized in this research were of analytical quality and were employed without additional purification processes. Chemicals used for the preparation of Schiff base Ligands include: 2-aminophenol, p -chlorobenzaldehyde, sulphuric acid; cobalt(II) and lead (II) salts. FTIR spectra (4000-400cm -1 ) using KBr discs were recorded with Cary 630 FTIR. Magnetic susceptibility measurements were carried out at room temperature on a Gouy balance using Swissmake-H-1640 with maximum capacity of 80g. Electronic spectra were recorded using SpectraLab 7525 spectrophotometer in the range of 0-400, 400-900 for ligand and complxes. Elemental analysis was determined using Perkin Elmer, USA 2400 series II. 2.1. Synthesis of Schiff Base Ligand The Schiff base ligand was prepared by reacting, 2-aminophenol (1.50g, 0.0137 mol.) with p -chlorobenzaldehyde (1.93g, 0.0124 mol) in ethanol (20ml) under constant stirring at room temperature, little drops of sulphuric acid was introduced to aid the condensation process. This reaction in ethanol was stirred for 20 minutes, the mixture was then subjected to microwave irradiation for 6 minutes as shown in scheme 1. The resulting gold coloured precipitate formed was filtered, washed with ethanol and dried in an oven. 2.2. Synthesis of cobalt (II) and lead (II) complexes Equimolar ratio of Schiff base ligand (0.80g, 0.00345 mol.) was dissolved in ethanol, mixed with an ethanolic solution of (0.49g, 0.00198 mol.)Co(NO₃)₂·6H₂O; (0.64g, 0.00169 mol) (CH₃.COO)₂Pb. 3H₂O at 2:1 molar ratio of ligand to metal. The reaction mixture was stirred for 20 minutes, then subjected to microwave irradiation for 8 minutes.The resulting pink coloured precipitate of Co complex and cream colured precipitate of Pb complex was formed. The compounds were filtered, rinsed with ethanol and dried overnight in air. 3. Results and Discussion As shown in Table1, the Schiff base ligand dissolved readily in ethanol, and dimethyl sulfoxide (DMSO); in contrast, the metal(II) complexes were soluble only in DMSO. The difference in solubility behavior between the ligand and its metal complexes may be attributed to coordination and increased molecular weight after complexation, which reduces their ability to dissolve in most organic solvents. Elemental analysis of prepared ligand was carried out to determine the mass fraction of the elements present in the compounds. The observed values are in agreement with those calculated based on the proposed molecular formula. Table 1: Analytical data and Physical properties of Schiff base ligand and its complexes Compound Empirical formula / Colour Yield (%) M.P (°C) M.wt. (g) Solubility Elemental analysis(found/calc) C H N O Ligand C₁₃H₁₀NClO Gold 72 200 231 DMSO /Ethanol 67.31 (67.40) 4.38 (4.35) 5.84 (5.89) 6.70 (6.75) [Co(L) 2 ] Co[C₂₆H₂₀Cl₂N₂O₂] nH 2 O Pink 64 218 522 DMSO _ _ _ _ [Pb(L) 2 ] Pb[C 26 H 20 Cl 2 N 2 O 2 ]nH 2 O Cream 57 222 670 DMSO _ _ _ _ 3.1. Infrared spectra analysis of the compound The relevant FT-IR spectra band assignments of the ligand and the metal complexes of cobalt (II) and lead (II) are shown in Fig. 1-3. The spectrum of the free Schiff base ligand showed a band at 1625 cm⁻¹, corresponding to the azomethine (C=N) stretching vibration, confirming the formation of the Schiff base (Singh et al ., 2024; Ajibulu et al ., 2023). In the spectra of the Co(II) and Pb(II) complexes, this band shifted to 1580 cm⁻¹ respectively, indicating coordination of the azomethine nitrogen atom to the metal ions (Al-Shujaa et al., 2024; Adebayo et al., 2023; Ajibulu et al ., 2021; Ommenya et al ., 2020). A broad absorption band observed at 3406cm⁻¹ in Co(II) and Pb(II) complexes, assignable to O–H stretching vibration. This suggests participation of the phenolic oxygen in coordination with the metal center via O-H group (Ekennia et al ., 2019). The FTIR spectrum of the free Schiff base ligand showed no δ(H₂O) stretching vibration, indicating that the ligand was anhydrous and contained no coordinated water molecules. Whereas, the spectra of the metal(II) complexes displayed distinct absorptions at 752 cm⁻¹ for both cobalt(II) and Pb(II) complexes. These bands are assigned to the bending vibrations of water molecules (δH₂O), (M–O) or (M-N) stretching vibration modes in hydrated complexes (Kumari et al ., 2021; Ali & Mohammed, 2023). 3.2. Electronic spectroscopy The UV–visible spectral analysis also provided strong evidence for the coordination and geometry of the complexes. The free ligand exhibited an intense band around 273 nm, corresponding to π→π* within the aromatic and azomethine systems. Upon complexation, new bands appeared at higher wavelengths for both Co(II) and Pb(II) complexes, which are characteristic of d–d transitions and charge transfer processes. For the cobalt complex, absorption bands at 301, 412 and 560 nm, indicating n→ ℼ *, 4 A 2 g(F) → 4 T 2 g, 4 A 2 g(F) → 4 T 1 g(F) transitions suggesting a high-spin octahedral geometry, coupled with the magnetic moment value of 4.21 B.M. (Lever, 2001; Ali et al ., 2020 and Ajibulu et al ., 2025). Similarly, Pb(II) complex displayed bands at 287, 540, and 701 nm, and magnetic moment of 0B.M., indicating ℼ → ℼ *, 2 B 1 g→ 2 B 2 g and 2 B 1 g→ 2 Eg transitions for distorted octahedral geometry (Jingdong et al ., 2023; Osowole & Festus, 2015). These findings agree with previous studies that describe Co(II) and Pb(II) Schiff base complexes as exhibiting octahedral or pseudo-octahedral coordination environments (Raman et al., 2013; Shadia et al ., 2024). Table 2: Electronic data of the ligand and (L) and its complexes Compound Wavelength ƛmax (nm) Absorption band (cm⁻¹) μeff (B.M) Transition (s)band assignment Geometry Ligand (L) 273,318 36630, 31446 — π→π*, n→π* — Pb(L) 2 287,540, 701 34843,18518,14265 0 B.M π→π*, d→d Distorted Octahedral Co(L) 2 301,412, 560 33222,24271,17857 4.21B.M n→π*, d→d Octahedral 3.3 Antimicrobial The Schiff base ligand and its metal (II) complexes were screened against selected microorganisms, the zones of inhibition are tabulated in Table 3. The Schiff base is moderately active and its activity arises from the presence of an imine and chloro groups in its structure ( Ajibulu et a l., 2025; Sunjuk et al ., 2023 and Prakash et al ., 2010). The activity of cobalt(II) was found to be almost the same with the standard drug Ciprofloxacin for Staphylococcus aureus . From the biological study, the antimicrobial screening revealed that both metal complexes exhibited higher inhibitory activity against the tested microorganisms compared to the free ligand. This enhancement can be explained by the chelation theory, which postulates that coordination reduces the polarity of the metal ion through partial sharing of its positive charge with donor atoms and increases the lipophilic character of the complex (Chandra & Kumar, 2018). Cobalt(II) complex demonstrated the most significant antimicrobial activity, which may be linked to its higher stability and effective coordination geometry. These findings agree with reports that Co(II) Schiff base complexes often exhibit superior biological performance compared with their corresponding ligands and other metal analogues (Mahmoud et al ., 2020; Desalegn, 2023 and Patel et al. , 2012). Table 3: Antimicrobial activity of ligand and its metal complexes at (10µg) Zone of inhibition (mm) Gram - positive. Gram - negative Compound Staphylococcus aureus Escherichia coli Ligand (L) 12 10 Co(L) 24 15 Pb(L) 18 19 Ciprofloxacin 30 28 4. Conclusion The study successfully synthesized and characterized Schiff base ligand derived from 2-aminophenol and p -chlorobenzaldehyde and its corresponding cobalt(II) and lead(II) complexes. Spectroscopic results confirmed coordination through both the azomethine nitrogen and phenolic oxygen donor atoms, while magnetic and UV–visible data suggested an octahedral geometry for cobalt(II) complex. The lead(II) complex was found to be diamagnetic, consistent with its 6s² electronic configuration and closed-shell structure. The elemental and spectroscopic data confirmed the proposed formulations of the prepared compounds. Biological studies revealed that the metal complexes displayed higher antimicrobial activity compared with the free ligand, demonstrating, chelation enhances the lipophilic character and biological effectiveness of Schiff base compounds. The prepared complexes could serve as good candidates for pharmaceutical applications. Declarations Acknowledgements The authors are grateful to the Department of Chemical and Biological Sciences, Bamidele Olumilua University of Education Science and Technology, for providing facilities to carry out this research work. Author contributions Conceptualization, K. E. Ajibulu; K. E. Ajibulu and R. A. Nasiru, performed the practical work; K. E. Ajibulu and B. T. Pii supervised the overall work; V. I. Adebiyi, K. E. Ajibulu and R. A. Nasiru analysed and interpreted the data. K. E. Ajibulu and R. A. Nasiru wrote the original draft. All authors reviewed and edited the manuscript. Conflict of interest : The authors declared no conflict of interest. Data availability Statement: The data presented in this study are available on request from the corresponding author Funding : This research received no external funding. Ethics, Consent to Participate, and Consent to Publish declarations : Not applicable. References Adebayo, T. M., Oladipo, A. A., & Ogunyemi, A. O. (2023). Spectroscopic and biological evaluation of transition-metal Schiff base complexes derived from substituted salicylaldehydes. Journal of Molecular Structure , 1298, 136222. Ajibulu1, K. E., Okoronkwo, A. E., Owolabi, J. B., Oyetayo,V. O., Adeyemi, E. O and B. T. Pii, B. T. (2025). Metal Complexes of Schiff Base Derived from Ethylenediamine, Nitro and Chlorobenzaldehyde; Synthesis, Characterization, Biological and Toxicological Study. 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FTIR and UV–Visible spectral characterization of cobalt(II) and nickel(II) Schiff base complexes derived from o-aminophenol derivatives. Inorganic Chemistry Communications , 158, 111689. Wara, A. A.(2011). Transition Metal Complexes and their application in drugs and cosmetic – A Review, J Chem Pharm Res, 3(4): 951-95. Yang, X., Zhuang, X., Huang, Y., Jiang, J., Tian, H., Wu D. (2015). Nitrogen enriched hierarchically porous carbon materials fabricated by graphene aerogel templated Schiff-base chemistry for high performance electrochemical capacitors. Polymer Chemistry . 6(7):1088 1095. Scheme Scheme 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files scheme.png Scheme1: Synthesis of Schiff base ligand and its metal complexes Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 09 Mar, 2026 Reviews received at journal 07 Mar, 2026 Reviews received at journal 05 Mar, 2026 Reviews received at journal 03 Mar, 2026 Reviewers agreed at journal 27 Feb, 2026 Reviewers agreed at journal 26 Feb, 2026 Reviewers agreed at journal 25 Feb, 2026 Reviewers agreed at journal 25 Feb, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers invited by journal 23 Feb, 2026 Editor assigned by journal 23 Feb, 2026 Submission checks completed at journal 20 Feb, 2026 First submitted to journal 20 Feb, 2026 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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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8745555","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":596525658,"identity":"2621d262-8379-4b9a-a1f7-cbfb412c67a1","order_by":0,"name":"K.E 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01:08:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8745555/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8745555/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103408013,"identity":"5076329f-0396-436c-8ffb-049780dc4038","added_by":"auto","created_at":"2026-02-25 10:29:10","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":100839,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectrum of the ligand\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8745555/v1/89fac67c5ac3e088cb6b1f85.png"},{"id":103408014,"identity":"4a4ca0e8-d881-4b4a-851a-ada5088ad95c","added_by":"auto","created_at":"2026-02-25 10:29:10","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":98082,"visible":true,"origin":"","legend":"\u003cp\u003eFTR spectrum of Co(L)\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8745555/v1/0dbc0bdf98cb66767ac0845d.png"},{"id":103408017,"identity":"c40cf199-4920-49bb-9b49-438cd3c60aa6","added_by":"auto","created_at":"2026-02-25 10:29:10","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":103858,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectrum of Pb(L)\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8745555/v1/10582454434050c0cd2ceb28.png"},{"id":103509985,"identity":"ab726d21-a788-4e29-ad87-dfa824289547","added_by":"auto","created_at":"2026-02-26 14:02:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":893298,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8745555/v1/6e298f00-c8a3-4078-9380-9538b6680e6e.pdf"},{"id":103507145,"identity":"f87141bb-4230-4ab3-8860-482dd899fed3","added_by":"auto","created_at":"2026-02-26 13:40:34","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":40933,"visible":true,"origin":"","legend":"\u003cp\u003eScheme1: Synthesis of Schiff base ligand and its metal complexes\u003c/p\u003e","description":"","filename":"scheme.png","url":"https://assets-eu.researchsquare.com/files/rs-8745555/v1/fabed806cab39bb070f5be06.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eMicrowave-assisted Synthesis, Characterization and Biological Study of Metal (Ii) Complex Derived From 2-aminophenol and P- Chlorobenzaldehyde Schiff Base\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eSchiff base ligands and their metal complexes have become important in coordination chemistry due to their ease of synthesis, structural diversity, and wide range of applications(Desalegn, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Prakash, 2010). The presence of the azomethine (\u0026ndash;C\u0026thinsp;=\u0026thinsp;N\u0026ndash;) linkage allows Schiff bases to act as good donors to metal ions, forming stable chelate rings (Ajibulu et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Ravinderpal \u0026amp; Sataya, 2019; Anital \u003cem\u003eet al\u003c/em\u003e., 2015 and Wara, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The importance of coordination compounds has significantly increased in recent years. Metal complexes play crucial roles in homogeneous and heterogeneous catalysis (Alshaheri et al., \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), materials chemistry (including metal\u0026ndash;organic frameworks and coordination polymers) (Biplab, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2022\u003c/span\u003e), photochemistry and optoelectronics(Yang et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), as well as biomedicine (such as diagnostics and metal-based nanomedicines used in anticancer and antimicrobial therapies) (Fahmi et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Mahmoud et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Desai and Parekh, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The significance of Schiff base metal complexes stems from their diverse applications across biological, industrial, and environmental sectors. Schiff bases possess a strong metal-binding capacity, stability, and versatile donor characteristics due to the presence of the azomethine (\u0026ndash;C\u0026thinsp;=\u0026thinsp;N\u0026ndash;) group, making them highly effective ligands in coordination chemistry (Kargar et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Mohamed et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Schiff bases containing oxygen and nitrogen donor atoms are especially attractive for forming stable metal complexes that exhibit significant, biological activities such as antimicrobial, anticancer, anti fungal, anti oxidant and anti inflammatory properties ( Racheal et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Ejidike et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Sigh \u003cem\u003eet al\u003c/em\u003e., 2007; Chohan \u003cem\u003eet al\u003c/em\u003e., 2006; ). In this study, we presented the synthesis of Schiff base metal complexes using, (E)-2-[(4-chlorobenzylidene)amino]phenol Schiff base ligand, Co(II), and Pb(II). The synthesized compounds were characterized using spectroscopic techniques and their antimicrobial properties were examined.\u003c/p\u003e"},{"header":"2. Material and Methods","content":"\u003cp\u003eAll chemicals and reagents utilized in this research were of analytical quality and were employed without additional purification processes. Chemicals used for the preparation of Schiff base Ligands include: 2-aminophenol,\u003cem\u003e\u0026nbsp;p\u003c/em\u003e-chlorobenzaldehyde, sulphuric acid; cobalt(II) and lead (II) salts. FTIR spectra (4000-400cm\u003csup\u003e-1\u003c/sup\u003e) using KBr discs were recorded with Cary 630 FTIR. Magnetic susceptibility measurements were carried out at room temperature on a Gouy balance using Swissmake-H-1640 with maximum capacity of 80g. Electronic spectra were recorded using SpectraLab 7525 spectrophotometer in the range of 0-400, 400-900 for ligand and complxes. Elemental analysis was determined using Perkin Elmer, USA 2400 series II.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.1. Synthesis of Schiff Base Ligand\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Schiff base ligand was prepared by reacting, 2-aminophenol (1.50g, 0.0137 mol.) with \u003cem\u003ep\u003c/em\u003e-chlorobenzaldehyde (1.93g, 0.0124 mol) in ethanol (20ml) under constant stirring at room temperature, little drops of sulphuric acid was introduced to aid the condensation process. This reaction in ethanol was stirred for 20 minutes, the mixture was then subjected to microwave irradiation for 6 minutes as shown in scheme 1. The resulting gold coloured precipitate formed was filtered, washed with ethanol and dried in an oven.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2. \u0026nbsp;Synthesis of cobalt (II) and lead (II) complexes\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEquimolar ratio of Schiff base ligand (0.80g, 0.00345 mol.) was dissolved in ethanol, mixed with an ethanolic solution of (0.49g, 0.00198 mol.)Co(NO₃)₂\u0026middot;6H₂O; (0.64g, 0.00169 mol) (CH₃.COO)₂Pb. 3H₂O at 2:1 molar ratio of ligand to metal. The reaction mixture was stirred for 20 minutes, then subjected to microwave irradiation for 8 minutes.The resulting pink coloured precipitate of Co complex and cream colured precipitate of Pb complex was formed. The compounds were filtered, rinsed with ethanol and dried overnight in air.\u0026nbsp;\u003c/p\u003e"},{"header":"3. Results and Discussion","content":"\u003cp\u003eAs shown in Table1, the Schiff base ligand dissolved readily in ethanol, and dimethyl sulfoxide (DMSO); in contrast, the metal(II) complexes were soluble only in DMSO. The difference in solubility behavior between the ligand and its metal complexes may be attributed to coordination and increased molecular weight after complexation, which reduces their ability to dissolve in most organic solvents. Elemental analysis of prepared ligand was carried out to determine the mass fraction of the elements present in the compounds. The observed values are in agreement with those calculated based on the proposed molecular formula.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1: \u0026nbsp;Analytical data and Physical properties of Schiff base ligand and its complexes\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"638\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003eCompound\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003eEmpirical formula / Colour\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003eYield (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 44px;\"\u003e\n \u003cp\u003eM.P \u0026nbsp;(\u0026deg;C)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003eM.wt.\u003c/p\u003e\n \u003cp\u003e(g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 68px;\"\u003e\n \u003cp\u003eSolubility\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" valign=\"top\" style=\"width: 202px;\"\u003e\n \u003cp\u003eElemental analysis(found/calc)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003eC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003eH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003eLigand\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003eC₁₃H₁₀NClO\u003c/p\u003e\n \u003cp\u003eGold\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 44px;\"\u003e\n \u003cp\u003e200\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e231\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 68px;\"\u003e\n \u003cp\u003eDMSO\u003c/p\u003e\n \u003cp\u003e/Ethanol\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e67.31\u003c/p\u003e\n \u003cp\u003e(67.40)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e4.38\u003c/p\u003e\n \u003cp\u003e(4.35)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e5.84\u003c/p\u003e\n \u003cp\u003e(5.89)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e6.70\u003c/p\u003e\n \u003cp\u003e(6.75)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e[Co(L)\u003csub\u003e2\u003c/sub\u003e]\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003eCo[C₂₆H₂₀Cl₂N₂O₂] nH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Pink\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 44px;\"\u003e\n \u003cp\u003e218\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e522\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 68px;\"\u003e\n \u003cp\u003e\u0026nbsp;DMSO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e_\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e_\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e_\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e_\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 66px;\"\u003e\n \u003cp\u003e[Pb(L)\u003csub\u003e2\u003c/sub\u003e]\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 152px;\"\u003e\n \u003cp\u003ePb[C\u003csub\u003e26\u003c/sub\u003eH\u003csub\u003e20\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e]nH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Cream\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 44px;\"\u003e\n \u003cp\u003e222\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 57px;\"\u003e\n \u003cp\u003e670\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 68px;\"\u003e\n \u003cp\u003e\u0026nbsp;DMSO\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 55px;\"\u003e\n \u003cp\u003e_\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 47px;\"\u003e\n \u003cp\u003e_\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 50px;\"\u003e\n \u003cp\u003e_\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 49px;\"\u003e\n \u003cp\u003e_\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e3.1. \u003cstrong\u003e\u0026nbsp;Infrared spectra analysis of the compound\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe relevant FT-IR spectra band assignments of the ligand and the metal complexes of cobalt (II) and lead (II) are shown in Fig. 1-3. \u0026nbsp;The spectrum of the free Schiff base ligand showed a band at 1625 cm⁻\u0026sup1;, corresponding to the azomethine (C=N) stretching vibration, confirming the formation of the Schiff base (Singh\u003cem\u003e\u0026nbsp;et al\u003c/em\u003e., 2024; Ajibulu \u003cem\u003eet al\u003c/em\u003e., 2023). In the spectra of the Co(II) and Pb(II) complexes, this band shifted to 1580 cm⁻\u0026sup1; respectively, indicating coordination of the azomethine nitrogen atom to the metal ions (Al-Shujaa\u003cem\u003e\u0026nbsp;et al.,\u0026nbsp;\u003c/em\u003e2024; Adebayo\u003cem\u003e\u0026nbsp;et al.,\u0026nbsp;\u003c/em\u003e2023; Ajibulu \u003cem\u003eet al\u003c/em\u003e., 2021; Ommenya \u003cem\u003eet al\u003c/em\u003e., 2020). A broad absorption band observed at 3406cm⁻\u0026sup1; in Co(II) and Pb(II) complexes, assignable to O\u0026ndash;H stretching vibration. This suggests participation of the phenolic oxygen in coordination with the metal center via O-H group (Ekennia \u003cem\u003eet al\u003c/em\u003e., 2019). The FTIR spectrum of the free Schiff base ligand showed no \u0026delta;(H₂O) stretching vibration, indicating that the ligand was anhydrous and contained no coordinated water molecules. Whereas, the spectra of the metal(II) complexes displayed distinct absorptions at 752 cm⁻\u0026sup1; for both cobalt(II) and Pb(II) complexes. These bands are assigned to the bending vibrations of water molecules (\u0026delta;H₂O), (M\u0026ndash;O) or (M-N) stretching vibration modes in hydrated complexes (Kumari \u003cem\u003eet al\u003c/em\u003e., 2021; Ali \u0026amp; Mohammed, 2023).\u003c/p\u003e\n\u003cp\u003e3.2. \u003cstrong\u003eElectronic spectroscopy\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The UV\u0026ndash;visible spectral analysis also provided strong evidence for the coordination and geometry of the complexes. The free ligand exhibited an intense band around 273 nm, corresponding to \u0026pi;\u0026rarr;\u0026pi;* within the aromatic and azomethine systems. Upon complexation, new bands appeared at higher wavelengths for both Co(II) and Pb(II) complexes, which are characteristic of d\u0026ndash;d transitions and charge transfer processes. For the cobalt complex, absorption bands at 301, 412 and 560 nm, indicating n\u0026rarr;\u003cstrong\u003eℼ\u003c/strong\u003e*, \u003csup\u003e4\u003c/sup\u003eA\u003csub\u003e2\u003c/sub\u003eg(F) \u0026rarr; \u003csup\u003e4\u003c/sup\u003eT\u003csub\u003e2\u003c/sub\u003eg, \u003csup\u003e4\u003c/sup\u003eA\u003csub\u003e2\u003c/sub\u003eg(F) \u0026rarr; \u003csup\u003e4\u003c/sup\u003eT\u003csub\u003e1\u003c/sub\u003eg(F) transitions suggesting a high-spin octahedral geometry, coupled with the magnetic moment value of 4.21 B.M. (Lever, 2001; Ali \u003cem\u003eet al\u003c/em\u003e., 2020 and Ajibulu \u003cem\u003eet al\u003c/em\u003e., 2025). Similarly, Pb(II) complex displayed bands at 287, 540, and \u0026nbsp;701 nm, and magnetic moment of 0B.M., indicating \u003cstrong\u003eℼ\u003c/strong\u003e\u003cstrong\u003e\u0026rarr;\u003c/strong\u003e\u003cstrong\u003eℼ\u003c/strong\u003e*, \u003csup\u003e2\u003c/sup\u003eB\u003csub\u003e1\u003c/sub\u003eg\u0026rarr;\u003csup\u003e2\u003c/sup\u003eB\u003csub\u003e2\u003c/sub\u003eg and \u003csup\u003e2\u003c/sup\u003eB\u003csub\u003e1\u003c/sub\u003eg\u0026rarr;\u003csup\u003e2\u003c/sup\u003eEg transitions for distorted octahedral geometry (Jingdong \u003cem\u003eet al\u003c/em\u003e., 2023; Osowole \u0026amp; Festus, 2015). These findings agree with previous studies that describe Co(II) and Pb(II) Schiff base complexes as exhibiting octahedral or pseudo-octahedral coordination environments (Raman \u003cem\u003eet al.,\u0026nbsp;\u003c/em\u003e2013; Shadia \u003cem\u003eet al\u003c/em\u003e., 2024).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2: Electronic data of the ligand and (L) and its complexes\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eCompound\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003eWavelength\u0026nbsp;ƛmax (nm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 103px;\"\u003e\n \u003cp\u003eAbsorption band (cm⁻\u0026sup1;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026mu;eff\u003c/p\u003e\n \u003cp\u003e(B.M)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003eTransition (s)band assignment\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eGeometry\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eLigand (L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e273,318\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 103px;\"\u003e\n \u003cp\u003e36630,\u003c/p\u003e\n \u003cp\u003e31446\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u0026pi;\u0026rarr;\u0026pi;*, n\u0026rarr;\u0026pi;*\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026mdash;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003ePb(L)\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e287,540,\u003c/p\u003e\n \u003cp\u003e701\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 103px;\"\u003e\n \u003cp\u003e34843,18518,14265\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e0 \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; B.M\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u0026pi;\u0026rarr;\u0026pi;*, d\u0026rarr;d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eDistorted\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;Octahedral\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 85px;\"\u003e\n \u003cp\u003eCo(L)\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 93px;\"\u003e\n \u003cp\u003e301,412,\u003c/p\u003e\n \u003cp\u003e560\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 103px;\"\u003e\n \u003cp\u003e33222,24271,17857\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 83px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e4.21B.M\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 110px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003en\u0026rarr;\u0026pi;*, d\u0026rarr;d\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 95px;\"\u003e\n \u003cp\u003eOctahedral\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e3.3 Antimicrobial\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe Schiff base ligand and its metal (II) complexes were screened against selected microorganisms, the zones of inhibition are tabulated in Table 3. The Schiff base is moderately active and its activity arises from the presence of an imine and chloro groups in its structure ( Ajibulu \u003cem\u003eet a\u003c/em\u003el., 2025; Sunjuk \u003cem\u003eet al\u003c/em\u003e., 2023 and Prakash \u003cem\u003eet al\u003c/em\u003e., 2010). The activity of cobalt(II) was \u0026nbsp; found to be almost the same with the standard drug \u003cem\u003eCiprofloxacin\u003c/em\u003e for \u003cem\u003eStaphylococcus\u003c/em\u003e \u003cem\u003eaureus\u003c/em\u003e. From the biological study, the antimicrobial screening revealed that both metal complexes exhibited higher inhibitory activity against the tested microorganisms compared to the free ligand. This enhancement can be explained by the chelation theory, which postulates that coordination reduces the polarity of the metal ion through partial sharing of its positive charge with donor atoms and increases the lipophilic character of the complex (Chandra \u0026amp; Kumar, 2018). Cobalt(II) complex demonstrated the most significant antimicrobial activity, which may be linked to its higher stability and effective coordination geometry. These findings agree with reports that Co(II) Schiff base complexes often exhibit superior biological performance compared with their corresponding ligands and other metal analogues (Mahmoud \u003cem\u003eet al\u003c/em\u003e., 2020; Desalegn, 2023 and Patel\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e, 2012).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3: Antimicrobial activity of ligand and its metal complexes at (10\u0026micro;g)\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"554\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 185px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 66.6065%; text-align: center;\" colspan=\"2\"\u003eZone of inhibition (mm)\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 185px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 185px;\"\u003eGram - positive. \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 185px;\"\u003eGram - negative\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eCompound\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u003cem\u003eStaphylococcus aureus\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u003cem\u003eEscherichia coli\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eLigand (L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eCo(L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003ePb(L)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; 19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003eCiprofloxacin\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 185px;\"\u003e\n \u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;28\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThe study successfully synthesized and characterized Schiff base ligand derived from 2-aminophenol and \u003cem\u003ep\u003c/em\u003e-chlorobenzaldehyde and its corresponding cobalt(II) and lead(II) complexes. Spectroscopic results confirmed coordination through both the azomethine nitrogen and phenolic oxygen donor atoms, while magnetic and UV\u0026ndash;visible data suggested an octahedral geometry for cobalt(II) complex. The lead(II) complex was found to be diamagnetic, consistent with its 6s\u0026sup2; electronic configuration and closed-shell structure. The elemental and spectroscopic data confirmed the proposed formulations of the prepared compounds. Biological studies revealed that the metal complexes displayed higher antimicrobial activity compared with the free ligand, demonstrating, chelation enhances the lipophilic character and biological effectiveness of Schiff base compounds. The prepared complexes could serve as good candidates for pharmaceutical applications.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors are grateful to the Department of Chemical \u0026nbsp; and Biological Sciences, Bamidele Olumilua University of Education Science and Technology, for providing facilities to carry out this research work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization, K. E. Ajibulu; K. E. Ajibulu and R. A. Nasiru, performed the practical work; K. E. Ajibulu and B. T. Pii supervised the overall work; V. I. Adebiyi, K. E. Ajibulu and R. A. Nasiru analysed and interpreted the data. K. E. Ajibulu and R. A. Nasiru wrote the original draft. All authors reviewed and edited the manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e: The authors declared no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability Statement:\u0026nbsp;\u003c/strong\u003eThe data presented in this study are available on request from the corresponding author\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e: This research received no external funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics, Consent to Participate, and Consent to Publish declarations\u003c/strong\u003e: Not applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAdebayo, T. M., Oladipo, A. A., \u0026amp; Ogunyemi, A. O. (2023). 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Inorganic electronic spectroscopy (2nd ed.). \u003cem\u003eElsevier\u003c/em\u003e.\u003c/li\u003e\n\u003cli\u003eMohamed, G. G., Omar, M. M., Moustafa, B. S., AbdEl-Halim, H. F., Farag, N. A. (2022). Spectroscopic investigation, thermal, molecular structure, antimicrobial and anticancer activity with modelling studies of some metal complexes derived from isatin Schiff base ligand. \u003cem\u003eInorganic Chemistry Communications\u003c/em\u003e. 141:109606.\u003c/li\u003e\n\u003cli\u003eMahmoud, W. H., Omar, M. M., Ahmed, Y. M., \u0026amp; Mohamed, G. G. (2020). Transition metal complexes of Schiff base ligand based on 4,6-diacetyl resorcinol. \u003cem\u003eApplied Organometallic Chemistry,\u003c/em\u003e 34 (4), 1\u0026ndash;20.\u003c/li\u003e\n\u003cli\u003eOmmenya, F. K. Nyawade, E. A. Andala, D. M. and Kinyua, J.(2020). Synthesis, Characterization and Antibacterial Activity of Schiff Base, 4-Chloro-2-{(E)-[(4 Fluoro phenyl) imino]methyl}phenol Metal (II) Complexes. \u003cem\u003eJournal of Chemistry\u003c/em\u003e, Volume 2020, 8 pages.\u003c/li\u003e\n\u003cli\u003eOsowole, A. A. \u0026amp; Festus, C. (2015). Synthesis, Characterization, Antimicrobial and Antioxidant Activities of Some Heteroleptic Metal (II) Complexes of 3-{[(Pyrimidin-2- yl)Imino]Methyl}Napthalen-2-ol. \u003cem\u003eJournal of Chemical, Biological and Physical Sciences Section A\u003c/em\u003e, 6(1), 080-089.\u003c/li\u003e\n\u003cli\u003ePatel, R. N., Singh, A., \u0026amp; Pandeya, K. B. (2012). Antimicrobial activity of cobalt(II) Schiff base complexes. \u003cem\u003eApplied Organometallic Chemistry\u003c/em\u003e, 26(5), 238\u0026ndash;243.\u003c/li\u003e\n\u003cli\u003ePrakash, A. Singh, B. K. Bhojak, N and Adhikari, D.(2010). \u0026ldquo;Synthesis and characterization of bioactive zinc(II) and cadmium(II) complexes with new Schiff bases derived from 4- nitrobenzaldehyde and acetophenone with ethylenediamine,\u0026rdquo;\u003cem\u003e Spectrochim. Acta -Part A Mol. Biomol. Spectrosc\u003c/em\u003e., 2010.\u003c/li\u003e\n\u003cli\u003eRacheal, O. A., Ikechukwu, P. E., Hadley, S. C. (2023). Schiff base metal complexes as a dual antioxidant and antimicrobial agents. \u003cem\u003eJournal of Applied Pharmaceutical Science, \u003c/em\u003e13(03), 132-140.\u003c/li\u003e\n\u003cli\u003eRavinderpal, K. S., and Satya, P. (2019). Metal Complexes in Medicine: An Overview and Update from Drug Design Perspective. \u003cem\u003eCancer Therapy \u0026amp; Oncology International Journal\u003c/em\u003e, 2019; 14:1-8.\u003c/li\u003e\n\u003cli\u003eRaman, N., Sakthivel, A., \u0026amp; Thangaraja, C. (2013). DNA interaction and antimicrobial studies of Schiff base complexes. \u003cem\u003eJournal of Molecular Structure\u003c/em\u003e, 1035, 398\u0026ndash;405.\u003c/li\u003e\n\u003cli\u003eShadia, A., E., and Ahmed, M. El., Islam, M. E., Mohamed, M. A. (2024). Palladium(II), platinum(II), and silver(I) complexes with 3-acetylcoumarin benzoylhydrazone Schiff base: Synthesis, characterization, biomolecular interactions, cytotoxic activity, and computational studies. \u003cem\u003eRSC Adv\u003c/em\u003e., 2024, 14, 19512\u0026ndash;19527\u003c/li\u003e\n\u003cli\u003eSivasubramania, P., Nallamohamed, H., Rafik, R. S., Sathya, R., \u0026amp; Davoodbasha, M. a. (2023). Synthesis and Characterization of Novel Schiff bases Derived from 2-butyl-4-chloro imidazole for the enhancemed Antimicrobial Property.\u003cem\u003e Appl. Biochem Biotecnol\u003c/em\u003e, 195(1):253-263.\u003c/li\u003e\n\u003cli\u003eSunjuk, M., Al-Najjar, L., Shtaiwi, M., El-Eswed, B. I., Sweidan, K., Bernhardt, P.V., Zalloum, H., Al-Essa, L. (2023). Metal Complexes of Schiff Bases Prepared from Quinoline-3- Carbohydrazide with 2-Nitrobenzaldehyde, 2-Chlorobenzaldehyde and 2,4- Dihydroxybenzaldehyde: Structure and Biological Activity. \u003cem\u003eInorganics,\u003c/em\u003e 2023, 11, 412.\u003c/li\u003e\n\u003cli\u003eSingh, R., Kumar, D., \u0026amp; Verma, P. (2024). FTIR and UV\u0026ndash;Visible spectral characterization of cobalt(II) and nickel(II) Schiff base complexes derived from o-aminophenol derivatives. \u003cem\u003eInorganic Chemistry Communications\u003c/em\u003e, 158, 111689.\u003c/li\u003e\n\u003cli\u003eWara, A. A.(2011). Transition Metal Complexes and their application in drugs and cosmetic \u0026ndash; A Review, \u003cem\u003eJ Chem Pharm Res, \u003c/em\u003e3(4): 951-95.\u003c/li\u003e\n\u003cli\u003eYang, X., Zhuang, X., Huang, Y., Jiang, J., Tian, H., Wu D. (2015). Nitrogen enriched hierarchically porous carbon materials fabricated by graphene aerogel templated Schiff-base chemistry for high performance electrochemical capacitors. \u003cem\u003ePolymer Chemistry\u003c/em\u003e. 6(7):1088 1095.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme","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":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"discover-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Chemistry](https://link.springer.com/journal/44371)","snPcode":"44371","submissionUrl":"https://submission.nature.com/new-submission/44371/3","title":"Discover Chemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Schiff base, Complex, 2-aminophenol, Synthesis, Characterization","lastPublishedDoi":"10.21203/rs.3.rs-8745555/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8745555/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe growing resistance of microorganisms to existing antibiotics has increased the need for new and more effective antimicrobial agents. In this study, Schiff base ligand was synthesized from 2-aminophenol and \u003cem\u003ep\u003c/em\u003e-chlorobenzaldehyde, and its cobalt(II) and lead(II) complexes. The compounds were characterized using melting point determination, solubility tests, UV\u0026ndash;visible, FTIR spectroscopy, elemental analysis, and magnetic susceptibility measurements.The FTIR spectrum of the ligand showed a characteristic band at 1625cm⁻\u0026sup1; due to the formation of azomethine (C\u0026thinsp;=\u0026thinsp;N) group, confirming Schiff base formation. In the metal(II) complexes, this band shifted to lower frequencies,1580 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e indicating coordination of the azomethine nitrogen to the metal ions. The O\u0026ndash;H stretching band at 3406 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e upon complexation, suggesting involvement of the phenolic oxygen atom. UV\u0026ndash;visible and magnetic data supported an octahedral geometry around the metal centers, while elemental analysis confirmed the expected molecular compositions of the prepared Schiff base ligand. Antimicrobial studies showed that the metal complexes displayed higher inhibitory activity against the tested bacterial strains compared with the free ligand. This enhancement suggests that coordination with metal ions increases the biological effectiveness of the Schiff base. Overall, the results confirm successful synthesis and characterization of the Schiff base ligand and its cobalt(II) and lead(II) complexes, demonstrating their potential as promising antimicrobial agents.\u003c/p\u003e","manuscriptTitle":"Microwave-assisted Synthesis, Characterization and Biological Study of Metal (Ii) Complex Derived From 2-aminophenol and P- Chlorobenzaldehyde Schiff Base","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-25 10:29:00","doi":"10.21203/rs.3.rs-8745555/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-03-09T11:24:24+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-07T21:40:51+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-05T18:51:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-03-03T16:29:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"322527435956915057331637210529679146187","date":"2026-02-27T16:35:19+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"276677301932913387633357915958693310046","date":"2026-02-26T07:24:48+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"256152572616995045411371018388293598342","date":"2026-02-26T04:34:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"328725275396679453439671438642344154924","date":"2026-02-26T02:11:43+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"336467134989284999872744101220007550285","date":"2026-02-24T15:59:57+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-02-23T14:59:47+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-23T07:52:31+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-20T12:07:08+00:00","index":"","fulltext":""},{"type":"submitted","content":"Discover Chemistry","date":"2026-02-20T12:02:45+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"discover-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"Learn more about [Discover Chemistry](https://link.springer.com/journal/44371)","snPcode":"44371","submissionUrl":"https://submission.nature.com/new-submission/44371/3","title":"Discover Chemistry","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Discover Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"95063a1e-933f-4eb5-bbe7-d5765baf9556","owner":[],"postedDate":"February 25th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-12T21:53:18+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-25 10:29:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8745555","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8745555","identity":"rs-8745555","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}