DNA binding and Antibacterial study of a new highly planar Cu(II) Network

DNA binding and Antibacterial study of a new highly planar Cu(II) Network | 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 DNA binding and Antibacterial study of a new highly planar Cu(II) Network Xuan Li, Juan Li, Miao Jiang, Xue-Qin Song, Pei Zhang, Nana Zhao, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2838938/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The DNA binding and the antibacterial activities of metal organic compounds have great significance for the development of anticancer drugs. In this study, a copper coordination network, [Cu 2 L(H 2 O) 2 ] n ( CuNet ), based on H 4 L where 2,6-pyridine-dicarboxylic acid moieties are spaced by p -benzyloxy, is prepared hydrothermally. Single crystal X-ray analysis demonstrates that the fully deprotonated ligand L 4– with high planarity in CuNet adopts a bis-µ 2 -η 1 : η 1 : η 2 coordination mode to bind four Cu(II) to render a graphene-like network, which is further propped up to a 3D supramolecular framework through the hydrogen bonds between coordinated water and uncoordinated carboxyl oxygen. Considering its highly planar structural feature and excellent antibacterial properties of Cu(II), the DNA binding and antibacterial performance were explored. The UV-Visible absorption titration and EB-DNA competition determination exhibited that CuNet bound DNA in an intercalation mode with the higher binding constant K b of 2.42 × 10 5 M − 1 , and the comparable quenching constant K sv of 1.62 × 10 4 M − 1 upon compared with the documented DNA linkers. In addition, the antibacterial activity test demonstrates that CuNet exhibits comparable inhibitory effect on Escherichia coli with that of cefradine at the concertation of 0.70 mg/mL. This work has certain significance for the development of metal drugs. Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Cancer is a disease that does great harm to human body. It is understood that many cancers, such as breast cancer, lung cancer, thyroid cancer, rectal cancer, gastric cancer, etc., have different symptoms and causes, but they are basically caused by abnormal DNA sequence. [1 ~ 5] At the same time, a large number of biological studies have proved that DNA is the main target of anti-cancer drugs, and DNA plays a crucial role in the process of cell replication and cell differentiation. [ 6 ] Therefore, DNA binding agents have received extensive attention. In the past decades, cisplatin has been used as the main binding agent for clinical treatment of cancer. However, due to its systemic toxicity, acquired resistance, and limited activity range, it is necessary to explore binders with different metal centers. [7 ~ 10] In general, Metal ions show a wide range of coordination numbers, allowing them to combine with many organic ligands and interact with the redox state of cells, thus changing cell vitality. [ 11 ] Cu(II) ion is a Lewis acid, which shows affinity for nitrogen and oxygen donor atoms and forms complexes with coordination numbers of 4, 5 and 6. [ 12 , 13 ] As one of the essential trace elements for human body, copper have played very important roles in human metabolic process including erythrocyte formation, iron absorption and transportation as well as the respiration. [ 14 ] It has been proved that it has special biological activity and catalysis to life system. [ 15 ] Copper complexes exhibit a wide range of binding behaviors with DNA, including non-covalent and intercalation interactions. At the same time, it has been found that the antibacterial activity of copper complexes with nitrogen azocyclic carboxylic acids is higher than those free of nitrogen donor. [ 16 , 17 ] In addition, Cu(II) coordination polymers have stronger binding affinity and better cytotoxicity as the result of the larger plane area compared with their mononuclear analogues. [ 18 , 19 ] Therefore, the studying for DNA binding and antibacterial activity of copper coordination polymers has become one of the research focuses in recent years. [ 20 ] With these in mind, compounds containing pyridine carboxylic acids represent a very attractive class of ligands for the synthesis of copper complexes as potential antibacterial agents and DNA binding agents. Therefore, based on the advantages of 2D planar network structure in combination with DNA, a new Cu(II) coordination network with high planarity based on a new nitrogen hetercarboxylic acid ligands with pyridine-2,6-dicarboxylic acid as the terminal group, p -benzyloxy as the central skeleton was obtained by hydrothermal method. The compoune was well characterized by X-ray diffraction, IR spectrum, TGA and PXRD. In addition, the DNA binding effect of H 4 L and Cu (II) complexes was studied by UV-Vis and fluorescence spectra. And the antibacterial activity of the ligand and CuNet was tested by hole drilling method. 2. Experimental Section 2.1. Materials and Methods. All solvents and chemicals were obtained from commercial sources and used without further purification. The crystallographic data collection and refinement, the important bond lengths of CuNet were described in Table 1 and Table 2 . The details of instrumentation are described in supporting information. Table 1 Crystal data and structure refinement parameters for CuNet . Chemical formula C 11 H 8 CuNO 6 Formula weight 313.72 T (K) 173(2) Wavelength (Å) 0.71073 Crystal system, Space group Monoclinic, C2/c Unit cell dimensions a = 22.5814(16) Å b = 10.2577(5) Å, β = 97.295(6) º c = 9.6152(5) Å V (Å 3 ), Z 2209.2(2), 8 D calc (Mg /m 3 ) 1.887 Absorption coefficient (mm – 1 ) 3.064 F (000) 1264 Crystal size (mm 3 ) 0.16 × 0.16 × 0.18 θ ranges (°) 3.91 ~ 69.8 Index ranges –27 ≤ h ≤ 21; − 11 ≤ k ≤ 12; − 11 ≤ l ≤ 11 Reflections collected 7154 Independent reflections 2062 [ R (int) = 0.028] θ Range for data collection (°) 99.62 Data/restraints/parameters 1830/0/427 Goodness-of-fit on F 2 1.542 Final R indices [ I > 2 σ(I) ] R 1 = 0.0376, wR 2 = 0.1525 R indices (all data) R 1 = 0.0692, wR 2 = 0.1637 Largest difference peak and hole(e Å –3 ) 1.79 and − 0.62 a w = 1/[ σ 2 ( F o 2 )+(0.0295 P ) 2 ], b w = 1/[ σ 2 ( F o 2 )+(0.0151 P ) 2 ],Where P = ( F o 2 + 2 F c 2 ) /3. Table 2. Selected bond lengths (Å) and angles (˚) for CuCP . 2.2. The synthesis of H 4 L The synthetic of the ligand H 4 L is by four steps with chelidamic acid as starting material. (Scheme 1 ) The intermediate dimethyl 4-hydroxypyridine-2,6-dicarboxylate ( 2 ) was prepared as referenced. [ 21 ] To a 175 mL anhydrous acetonitrile solution of dimethyl 4-hydroxypyridine-2,6-dicarboxylate ( 2 ) (2.64 g, 12.5 mmol), 2.48 g (18 mmol) anhydrous potassium carbonate and 1.32 g (5 mmol) 1,4-bis(bromomethyl)benzene ( 3 ) were added as a solid under stirring. The mixture was refluxed for 10 hours at 70 ~ 80 ℃ and milky suspension was observed. After refluxing 50 h, the mixture was cooled to room temperature and filtered. Acetonitrile is removed by rotary evaporator and the residue was partitioned between dichloromethane (200 mL) and water (50 mL). The organic layer was washed with 1% aqueous acetic acid, water and dried (sodium sulfate). White residue obtained by removing dichloromethane solvent through rotary evaporator, the white residue was recrystallized from ethanol to get a white crystalline sample 1,4-Bis-2,6-pyridine-dicarboxylic acid dimethyl benzene ( 4 ) which was washed with cold ethanol for three times and dried in air. 2.35 g, Yield 89.69%. Anal. calcd for C 26 H 24 N 2 O 10 : C, 59.54; H, 4.61; N, 5.34. Found: C 58.86; H, 4.75; N, 5.29. 1 H NMR (CDCl 3 , 400MHz), δ (ppm): 4.02 (s, 12H, CH 3 ); 5.26 (s, 4H, CH 2 ); 7.50 (s, 4H, CH); 7.90 (s, 4H, CH). (Figure S1 ) To a 50 mL (1 mol·L ‒1 ) lithium hydroxide aqueous solution of 8.0 g (15.27 mmol) of 1,4-Bis-2,6-pyridine-dicarboxylic acid dimethyl benzene ( 4 ) was added as a solid under stirring. The mixture was refluxed for 10 h until the solution changes from white suspension to clear solution to stop the reaction, the mixture was cooled to room temperature and filtered. The filtrate was adjusted to the pH value of 1 with 3 M hydrochloric acid and white solids will be obtained by suction filtration. The solids was washed three times with deionized water and ethanol respectively, and dried under vacuum to obtain 6.45 g of ligand H 4 L , with a yield of 90.26%. Anal. calcd for C 22 H 16 N 2 O 10 : C, 56.42; H, 3.44; N, 5.98. Found: C, 56.61; H, 3.47; N, 5.72. 1 H NMR (CDCl 3 , 400MHz), δ (ppm): 5.40 (s, 4H, CH 2 ); 7.54 (s, 4H, CH); 7.81 (s, 4H, CH). (Figure S2 ) IR (KBr, cm-1):3079 (w), 1656(s), 1569(s), 1407(s), 1369(m), 1337(s), 1289(w), 1116(m), 1073(s), 900(m), 808(s), 665(m). 2.3. The synthesis of [Cu 2 L(H 2 O) 2 ] n (CuNet) To a 10 mL Teflon-lined glass vial containing Cu(NO 3 ) 2 ·3H 2 O (4.8 mg, 0.02 mmol) and H 4 L (4.6 mg, 0.01 mmol), 6 mL H 2 O and 40 µL HNO 3 were added. The resulted suspension was ultrasound-dispersed over 30 min and placed in a tightly capped 10 mL Teflon-lined glass vial and heated under autogenous pressure at 160 ℃ for 3 days. After it was cooled to room temperature at the rate of 5 ℃·h − 1 , transparent and blue flake crystals which was washed by methanol were obtained and air-dried (yield of 52.86% base on Cu(NO 3 ) 2 ·3H 2 O). Anal. Calcd for C 11 H 8 CuNO 6 : C, 42.11; H, 2.57; N, 4.66. Found: C, 42.16; H, 2.53; N, 4.58. IR (KBr, cm − 1 ):3321 (w), 3094 (w), 1730 (s), 1595 (m), 1462 (m), 1421 (m), 1371 (m), 1309 (m), 896 (m), 681 (m). 2.4. DNA binding experiment In general, the binding mode and affinity between the complex and DNA were deduced by absorption spectrum titration. [ 22 , 23 ] All spectrophotometric measurements were carried out in a constant temperature quartz sample cell at 25 ℃. The electronic absorption titration was carried out by increasing the concentration of CT-DNA, while the concentration of the substance to be measured was kept constant. [ 24 ] In order to obtain the absorption spectrum, the required CT-DNA needs to be added to the test solution and reference solution to eliminate the absorption of CT-DNA itself. Based on the absorption titration data, the binding constant is obtained using the following formula: $$\frac{\left[\text{D}\text{N}\text{A}\right]}{{{\epsilon }}_{\text{a}}–{{\epsilon }}_{\text{f}}} = \frac{\left[\text{D}\text{N}\text{A}\right]}{{{\epsilon }}_{\text{b}}–{{\epsilon }}_{\text{f}}}+ \frac{1}{{\text{K}}_{\text{b}}}({{\epsilon }}_{\text{b}}–{{\epsilon }}_{\text{f}})$$ where [DNA] is the concentration of DNA in the base pair; ε a is the extinction coefficient observed at different DNA concentrations (A obsd /[M]); ε f corresponds to the extinction coefficient of the free compound; ε b is the extinction coefficient of the compound after fully binding to DNA; K b is the binding constant through [DNA]/(ε a – ε f ) for [DNA], the ratio of slope to intercept is K b . In this experiment, the concentration of ligand H 4 L and CuNet in DMF solution are 3×10 ‒3 M. The concentration of CT-DNA in Tris-HCl/NaCl buffer solution of pH = 7.2 were 2.5×10 ‒3 M. In a quartz cuvette of 3 mL, the above H 4 L or CuNet solution of 25 µL was added to 2.5 mL of Tris-HCl/NaCl buffer solution (pH = 7.2), the CT-DNA above was gradually added (0 ~ 240 µL), and the changes were observed in the UV spectrum. 2.5. EB-DNA fluorescence competition experiment In order to further study the binding characteristics of H 4 L and CuNet with DNA, EB-DNA fluorescence competition experiment was carried out, because EB is an aromatic fluorescent compound that can be embedded in nuclear base molecules to detect DNA. It is reported that ethidium bromide (EB) does not show any obvious emission in Tris HCl/NaCl buffer solution with pH = 7.2. When adding ligands or complexes to the solution containing EB, no change of fluorescence spectrum was observed. However, when CT-DNA was added to EB solution, the fluorescence intensity was greatly enhanced, which was caused by EB's strong insertion of DNA base pairs. Generally, the fluorescence emitted by EB binding with DNA can compete with EB for DNA by adding other molecules, thus leading to fluorescence quenching. [ 25 ] Therefore, the degree of fluorescence quenching can determine the binding degree of other molecules with CT-DNA, and the fluorescence quenching constant was calculated according to Stern-Volmer equation: I 0 / I = 1 + K SV [Q] I 0 and I are fluorescence intensities at 598 nm in the absence and presence of other molecules respectively, K SV is the quenching constant of linear Stern Volmer, and [Q] is the concentration of other molecules. The CT-DNA solution used in this experiment was the same as that of the electron absorption titration experiment. The concentration of EB in Tris-HCl/NaCl buffer solution of pH = 7.2 was 2.5×10 ‒3 M. 10 µL of H 4 L or CuNet solution was added to a 3 mL quartz cuvette with 2.5 mL of Tris-HCl/NaCl buffer respectively, and then dropped the sample solution to observe the changes in the fluorescence spectrum. 2.6. Antibacterial experiment In this study, the antibacterial activity against Escherichia coli was studied by measuring the growth inhibition under different concentrations of CuNet in the culture medium (containing 5 g·L –1 yeast extract, 10 g·L –1 sodium chloride and 10 g·L –1 tryptone). All experiments were conducted under dark conditions. Firstly, yeast extract, NaCl and trypsin were added to warm distilled water to obtain a solution, which was further sterilized in a pressure cooker for 22 minutes. The sterilized seed solution was then inoculated with bacteria, placed in a gas bath thermostatic oscillator, and incubated at 37 ℃ for 12 hours. The activated bacterial solution with the culture medium was mixed and poured it into the culture dish. Perforated and sucked the test solution into the hole (conduct three control experiments). Finally, the culture dish was putted into a constant temperature incubator at 30 ℃, and observe the size of the zone of inhibition after 10 hours. 3. Results And Discussion 3.1. Characterization of CuNet The infrared spectra of H 4 L and CuNet are shown in Figure S3 . In the infrared spectrum of H 4 L , the hydroxyl group of the ligand carboxylate is assigned to the band at 3079 cm − 1 , the absorption band at 1730 cm –1 is attributed to the C = O stretching vibration of the carboxylate, the peak of 1309 cm –1 belong to the C-O stretching vibration of the carboxylate. Compared with the infrared spectrum of H 4 L , it can be clearly observed that a broad peak of moderate intensity centered at 3321 cm –1 ranging from 2976 to 3630 cm –1 , indicating the existence of water in the coordination sphere of Cu (II). The υ C=O and υ C−O of the carboxylate on the pyridine have moved 74 cm –1 and 20 cm –1 to lower wavenumbers, respectively, indicating that both the carbonyl oxygen and the hydroxyl oxygen on the carboxylate are involved in the coordination, forming an M–O bond. In addition, in the far infrared region, it is allocated to υ M−O and υ M−N at 665 cm –1 . [ 26 ] The framework of CuNet is stable before 170°C, and the loss of coordination H 2 O molecule is observed from 170 to 200°C with a weight loss of 10.79%. After further heating, the skeleton begins to collapse and the weight loss is completed at 450°C (Fig. S4). The solid sample of CuNet collected is characterized by PXRD (Fig. S5). The dry sample obtained from the synthesized complex CuNet crystal is very consistent with the PXRD diagram simulated by the single crystal X-ray data, indicating that the crystal sample is pure phase. 3.2 Crystal structure description Single-crystal X-ray diffraction analysis reveals that CuNet crystallized in C 2 /c space group of monoclinic crystal system and exhibit a two-dimensional (2D) structure with high planarity. As depicted in Fig. 1 a, the asymmetric unit of the CuNet is constituted by one Cu(II), one half ligand L 4– , and one water. The fully deprotonated ligand L 4– in CuNet adopts a much extended trans-configuration with µ 4 -bis (η 1 : η 1 : η 2 ) coordination mode and exhibited high planarity where all of the atoms in the ligand L 4– are in the same plane as the result of the incorporation of Cu(II). The penta-coordination sphere of CuNet in tetragonal pyramidal configuration is completed by one pyridine nitrogen and two carboxylic oxygen atoms of one 2,6-pyridine dicarboxylic acid moiety of one ligand L 4‒ , one carboxylic oxygen from one 2,6-pyridine dicarboxylic acid moiety of another ligand L 4‒ as well as one coordinated water molecule. The tetragonal pyramid is realized with the bottom completed by one pyridine nitrogen atom and three oxygen from two ligand L 4‒ as well as the oxygen of coordinating water molecule acting as the top (Fig. 1 a). Therefore, two Cu(II) ions are connected by two carboxylic oxygen atoms from two L 4‒ and form a Cu(II) dinuclear subunit. Each ligand L 4– is bound by two such Cu(II) dinuclear subunits, meanwhile each Cu(II) dinuclear subunits is connected by three ligands L 4– (Fig. 1 b and 1 c). Therefore, the whole structure of the planar CuNet can be regarded as a (2, 3)-connected network featuring a graphene topology (Fig. 1 d). The adjacent layers are connected by forficate hydrogen bonds between coordinated water and free carboxylic oxygen atom (O − H···O = 2.69 Å/2.69 Å), which may enhance the stability of CuNet (Figure S6). As shown in Table 2 , the Cu − N bond length is 1.902(2) Å and that for Cu − O bond lengths range from 1.907(2) to 2.224(2) Å, which are all comparable to those previously reported Cu(II) complexes. [ 27 ] Compared with the puckered Cu(II) analogue constructed by the similar ligand where 2,6-pyridine dicarboxylic acid is spaced by more rigid benzene backbone, we can safely conclude that the ligand characteristic of more flexible spacer contributes a lot to this planar two-dimensional network. [ 28 ] 3.3. DNA binding studies It is necessary to check the interaction between DNA and the newly synthesized compound before estimating the anti-tumor activity of any new compound. Studying this interaction by using electronic absorption spectroscopy is one of the most common methods. [ 29 , 30 ] In the presence and absence of CT-DNA, the changes in the absorption spectra of H 4 L and CuNet are shown in Figs. 2 a and 2 c. It can be seen that when the same concentration of CT-DNA is added to H 4 L and CuNet , the absorption band intensity at 360 and 368 nm (π→π*) decrease, and as the concentration of CT-DNA increases, the absorption bands of H 4 L and CuNet exhibit a color reduction phenomenon of about 22.29% and 34.67%, respectively. At the same time, the color reduction phenomenon is accompanied by a change of 1 to 2 nm in red shift. According to previous reports on DNA binding, it can be known that the UV spectrum of the complex is decolorized and red-shifted, which is evidence of binding to DNA through the intercalation mode. [ 31 , 32 ] The degree of decolorization of the absorption band can be used as a measure of the strength of intercalation and binding. Therefore, H 4 L and complex CuNet are most likely to bind to DNA in an intercalation mode. The binding constant ( K b ) of H 4 L and CuNet to CT-DNA was determined by monitoring the change in absorbance (Figs. 2 b and 2 d). The K b of H 4 L and CuNet are 2.26×10 4 M ‒1 (R 2 = 0.992) and 2.42×10 5 M ‒1 (R 2 = 0.997), respectively. These results indicate that the CuNet penetrates more deeply into and stacks more strongly with the base pairs of the DNA than the H 4 L . Based on the above results, two reasons are inferred: one is that the increased coordination effect of coplanar aromatic rings may lead to high affinity to DNA. [33 ~ 35] The second is the ligand charge transfer caused by the coordination of the central Cu(II) atom, which reduce the electron density on the ligand, thereby reducing the charge density of the planar conjugate system, which is conducive to the insertion of DNA base pairs. Compared with the related decumented reports, CuNet showed a better affinity to the classical copper coordination polymer intercalators as summaried in Table 3 . [36 ~ 41]. Table 3 The comparison of the binding constants, K b , of some copper coordination polymers with DNA. coordination polymer K b ( M –1 ) References [Cu 2 (H 2 O) 2 (dmapox)(ipa) 2 ] n [Cu 2 (H 2 O) 2 (dmapox)(tpa) 2 ] n 1.22×10 4 1.45×10 4 36 36 {(Cu(phen)(trp))ClO 4 ·3H 2 O} n 8.24×10 2 37 {[Cu(4-mphen)(trp)]ClO 4 ·3H 2 O} n 1.77×10 3 37 [{Cu(BIG)(H 2 O)} 2 ] n (ClO 4 ) 2n ·3nH 2 O 1.25×10 4 38 {[Cu 4 L 1 (4,4′-bipy) 2 ](ClO 4 ) 4 ·H 2 O} ∞ 7.2×10 4 39 {[Cu 4 L 2 (4,4′-bipy)4](ClO 4 ) 4 ·2CH 3 CN·2H 2 O} ∞ 2.1×10 5 39 [Cu 2 L 2 (H 2 O)] ∞ 4.91×10 3 40 {[Cu 2 L 2 (H 2 O)]·H 2 O} ∞ 8.75×10 3 40 [Cu(bpmt)Cl 2 ·2DMF] n 1.42×10 4 41 [Cu(bpmt)(µ-Cl)·DMSO] n 1.41×10 4 41 CuNet 2.42×10 5 This work 3.4. EB-DNA fluorescence competition study After the discovery of the binding ability of the compound to DNA, some other studies were needed to confirm the binding mode and binding affinity, which was usually completed through the study of EB replacement investigations. The changes in the EB-DNA fluorescence spectrum upon addition of the sample solution dropwise to the EB-DNA solution was observed. (Fig. 3 a and 3 c). It can be seen that when H 4 L and CuNet solutions are added, the fluorescence intensity was obviously quenched. In addition, the fluorescence quenching data were further analyzed by Stern-Volmer relationship. As shown in Fig. 3 b and 3 d, Ksv values of H 4 L and CuNet were 1.4 × 10 4 M − 1 (R 2 = 0.987) and 1.62 × 10 4 M ‒1 (R 2 = 0.997) respectively. This shows that the copper coordination polymer had a higher quenching efficiency and stronger DNA binding force than H 4 L and CuNet . [ 42 ] This trend was consistent with the above absorption spectrum results and it shows that the interaction of CuNet with DNA was likely to be through intercalation. [ 43 ] In addition, the Ksv value of CuNet is comparable when compared with other copper coordination polymer as shown in Table 4 . [ 36 , 37 , 41 , 44 ] Table 4 The comparison of Ksv between copper coordination polymers and DNA. coordination polymer K SV (M − 1 ) Ref. [Cu 2 (H 2 O) 2 (dmapox)(ipa) 2 ] n 1.02 × 10 4 36 [Cu 2 (H 2 O) 2 (dmapox)(tpa) 2 ] n 3.40 × 10 4 36 {(Cu(phen)(trp))ClO 4 ·3H 2 O} n 1.51 × 10 3 37 {[Cu(4-mphen)(trp)]ClO 4 ·3H 2 O} n 3.79 × 10 3 37 [Cu(bpmt)Cl 2 ·2DMF] n 2.3× 10 4 41 [Cu(bpmt)(µ-Cl)·DMSO] n 2.2× 10 4 41 [Cu 2 (dmeo)(N 3 ) 2 ] n 1.85 × 10 3 44 CuNet 1.62 × 10 4 This work 3.5. Antimicrobial activity studies In recent years, the transition metal complexes obtained through pyridine carboxylic acid complexes have greatly promoted the research of antibacterial drugs. [ 45 ] Therefore, DMF test solutions with different concentrations have been prepared here, and the antibacterial activities of the synthesized H 4 L and CuNet against Escherichia coli (Gram negative bacteria) have been tested by hole drilling method. As shown in Fig. 4 a, the concentration of the test solution is 0.70 mg/mL, the antibiotic is cefradine, and DMF is used as the blank control. The size of the bacteriostatic circle of various test solutions records by the camera. It can be clearly seen that the bacteriostatic circles of DMF, copper nitrate, and H 4 L are relatively small, less than 10 mm. However, the bacteriostatic circles of CuNet and cefradine are relatively larger, and the size of the bacteriostatic circles is 17.5 mm and 18.2 mm, respectively. These results indicate that the antibacterial activity of H 4 L is basically low, while the antibacterial activity of CuNet and Cefradine are comparable. This may be because when Cu(II) atoms coordinate with H 4 L , partial charge sharing occurs, leading to electron delocalization in the system, which makes the antibacterial activity of complex CuNet much higher than that of H 4 L . [ 46 ] To further evaluate the antibacterial performance of the CuNet against Escherichia coli, the inhibition zones of three different concentrations (0.35, 0.70 and 1.40 mg/mL) were measured (Fig. 4 b). At the above concentrations, the zone of inhibition for CuNet are 11.5, 17.5, and 18 mm, respectively, which indicates that its antibacterial zone increases with the increase of CuNet concentration. But when the concentration increases of CuNet from 0.7 to 1.4 mg/mL, the inhibitory effect of CuNet did not significantly increase, and its antibacterial effect was almost equivalent to that of cefradine, indicating that it has relatively good antibacterial activity when the concentration of CuNet is 0.70 mg/mL. For DMF, copper nitrate and H 4 L , the antibacterial activity is relatively small, and its zone of inhibition hardly changes as the concentration increases. The biological study in the case of the antibacterial assay discloses that the coordination polymer has higher antibacterial activity than ligands. Such improved activity can be explained on the basis of the theory of chelation. [ 47 ] In addition, a comparison between the antibacterial activity of CuNet and some other copper coordination polymers has been provided as compiled in Table 5 , and it shows that CuNet has better antibacterial activity than other copper coordination polymer. [48 ~ 53] Table 5 A comparison of the antibacterial activity of copper coordination polymers. Coordination polymer Against E. coli (mm) Ref. [NaCu 2 (pdc) 2 (H 2 O) 4 (OH)] n (1) No effect 48 [NaCu 2 (pdc) 2 (H 2 O) 4 (OH)] n (1-sono) 10 48 CP-1(Cu) 15 49 SLys-Cu(II) 14 50 [Cu(pdc) 2 (DMA) 2 ] n (BCP-1) No effect 51 [Cu(pdc) 2 (DMA) 2 ] n (BCP-2) 12 51 [Cu 2 (bdc) 2 (dabco)] (CB) No effect 52 [Cu 2 (bdc) 2 (dabco)] (CS) 17 52 [Cu(dipic)(4-picoline)] n 28 53 [Cu(H-dipic)(4-picoline)] n 27 53 CuNet 17.5 This work 4. Conclusion Herein, a new copper coordination net ( CuNet ) based on a multidentate pyridine carboxylic ligand where two 2,6-pyridine dicarboxylic cavities are spaced by p -benzyloxy is prepared hydrothermally and well characterized. Crystal structure analysis demonstrates that CuNet is a highly planar network which is similar to graphene. Electron absorption titration and EB-DNA competition experiments showed that CuNet had higher ability to bind DNA through intercalation than other copper coordination polymers. In addition, the bacteriostatic exploration based on Escherichia coli exhibited that CuNet had excellent antibacterial performance and is comparable to cefradine and other copper coordination polymers. This study enriched the DNA binding and antibacterial performance of copper coordination polymers. Declarations ASSOCIATED CONTENT Crystallographic files in CIF format have been deposited with the Cambridge Crystallographic Data Center with deposition numbers CCDC 2257062. Corresponding Author *E-mail: [email protected] . Author contributions This manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China (grants 22161025). References Albogami S (2022) Comprehensive analysis of gene expression profiles to identify differential prognostic factors of primary and metastatic breast cancer. 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Synthesis, DNA-binding and photocleavage studies of cobalt(III) mixed-polypyridyl complexes: [Co(phen)(2)(dpta)](3+) and [Co(phen)(2)(amtp)](3+). Journal of Inorganic Biochemistry, 101(3): 404-411. Hu YJ, Yu OY, Dai CM, Liu Y, Xiao XH (2010) Site-Selective Binding of Human Serum Albumin by Palmatine: Spectroscopic Approach. Biomacromolecules, 11(1): 106-112. Jiang M, Li YT, Wu ZY (2012) Synthesis, structure, cytotoxic activities, and DNA-binding of 1-D copper(II) and zinc(II) coordination polymers. Journal of Coordination Chemistry, 65(11): 1858-1871. Khan MS, Hayat MU, Khanam M, Saeed H, Owais M, Khalid M, Shahid M, Ahmad M (2021) Role of biologically important imidazole moiety on the antimicrobial and anticancer activity of Fe(III) and Mn(II) complexes. Journal of Biomolecular Structure and Dynamics, 39(11): 4037-4050. Mohamed TA, Shaaban IA, Farag RS, Zoghaib WM, Afifi MS (2015) Synthesis, antimicrobial activity, structural and spectral characterization and DFT calculations of Co(II), Ni(II), Cu(II) and Pd(II) complexes of 4-amino-5-pyrimidinecarbonitrile. Spectrochimica acta, Part A. Molecular and biomolecular spectroscopy, 135: 417-427. Azam M, Al-Resayes SI, Wabaidur SM, Altaf M, Chaurasia B, Alam M, Shukla SN, Gaur P, Albaqami NTM, Islam MS, Park S (2018) Synthesis, Structural Characterization and Antimicrobial Activity of Cu(II) and Fe(III) Complexes Incorporating Azo-Azomethine Ligand. Molecules, 23(4): 813. Soltani S, Akhbari K, White J (2021) Sonochemical Synthesis, Crystal Structure and Antimicrobial Property of One-dimensional Dinuclear Coordination Polymer. Z. Anorg. Allg. Chem. 647(5): 442-447. Jayendran M, Begum PMS, Kurup MPP (2020) Structural, spectral and biological investigations on Cu(II) and Zn(II) complexes derived from NNO donor tridentate Schiff base: Crystal structure of a 1D Cu(II) coordination polymer. Journal of Molecular Structure, 1206: 127682. Nishat N, Malik A (2013) Antimicrobial Bioplastics, Synthesis and Characterization of Thermally Stable Starch and Lysine-Based Polymeric Ligand and Its Transition Metals Incorporated Coordination Polymer. Isrn Inorganic Chemistry, 2013:1-10. Salimi S, Akhbari K, Farniaa SMF, White JM (2022) Sonochemical synthesis and crystal structure of copper(II)-based biodegradable antibacterial scaffold. Journal of Molecular Structure, 1267: 133521. Batool SS, Gilani SR, Zainab SS, Tahir MN, Harrison WTA, Haider MS, Syed Q, Mazhar S, Shoaib M (2021) Synthesis, crystal structure, thermal studies and antimicrobial activity of a new chelate complex of copper(II) succinate with N,N,N′,N′-tetramethylethylenediamine. Journal of Coordination Chemistry, 1225: 129261. Siddiqi ZA, Khalid M, Kumar S, Shahid M, Noor S (2010) Antimicrobial and SOD activities of novel transition metal complexes of pyridine-2,6-dicarboxylic acid containing 4-picoline as auxiliary ligand. European journal of medicinal chemistry, 45(1): 264-269. Scheme 1 Scheme 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files CuNet.cif SupportingInformation.docx checkcif.pdf Scheme1.png Scheme 1 The synthetic route of the ligand H 4 L. Cite Share Download PDF Status: Posted Version 1 posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-2838938","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":193663582,"identity":"d2bcb4f7-bed1-4993-9936-a314de89e9aa","order_by":0,"name":"Xuan Li","email":"","orcid":"","institution":"Lanzhou Jiaotong University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Xuan","middleName":"","lastName":"Li","suffix":""},{"id":193663583,"identity":"9b08e404-0fec-446c-b74c-9d3c6e46ed46","order_by":1,"name":"Juan Li","email":"","orcid":"","institution":"Lanzhou Jiaotong University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Juan","middleName":"","lastName":"Li","suffix":""},{"id":193663584,"identity":"b935a9e9-0c82-428c-9f0c-8f2daaec41f5","order_by":2,"name":"Miao Jiang","email":"","orcid":"","institution":"Lanzhou Jiaotong University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Miao","middleName":"","lastName":"Jiang","suffix":""},{"id":193663585,"identity":"da6abc56-7b20-4adc-a647-ed0b9932d9f9","order_by":3,"name":"Xue-Qin Song","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA4klEQVRIiWNgGAWjYPACGwYGZuYGhgcMbERrSQNqYWxgSGBgkyBWy2EgBmthIKxFvr338GuesvPR/O0gLX/46gwOMD97gE+LwZlzaZYzzt3OnXEYpIWHTcLgAJu5AV4tEjlmBh/bbuc2gLVIgLTw4PeQ/AyglsS2c7nzwVoMiNDCcCPH+MHHtgO5G8BaEojQYnDmjBnjjHPJuRuBWg4kHGCTnHmYzQy/w9p7jD/zlNnlzjt/+OCDD3+O8fMdb35GKKSBzoDG+QEGhmPAOCWgHgiYPyAlkxrC6kfBKBgFo2DEAQCp7UjeCzXtwQAAAABJRU5ErkJggg==","orcid":"","institution":"Lanzhou Jiaotong University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Xue-Qin","middleName":"","lastName":"Song","suffix":""},{"id":193663586,"identity":"5e909127-00bd-4d66-9f0d-02f1b0faea7a","order_by":4,"name":"Pei Zhang","email":"","orcid":"","institution":"Lanzhou Jiaotong University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Pei","middleName":"","lastName":"Zhang","suffix":""},{"id":193663587,"identity":"313d53a3-9178-442f-85e1-ad219388ecaa","order_by":5,"name":"Nana Zhao","email":"","orcid":"","institution":"Lanzhou Jiaotong University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Nana","middleName":"","lastName":"Zhao","suffix":""},{"id":193663588,"identity":"d9757b99-0e32-40bb-af28-d9467cced3f6","order_by":6,"name":"Hao Cheng","email":"","orcid":"","institution":"Lanzhou Jiaotong University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Hao","middleName":"","lastName":"Cheng","suffix":""}],"badges":[],"createdAt":"2023-04-20 02:44:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2838938/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2838938/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":36223278,"identity":"6f17012d-11ff-4096-946e-d46afe84c09c","added_by":"auto","created_at":"2023-04-24 14:21:29","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":239397,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The asymmetric unit of \u003cstrong\u003eCuNet \u003c/strong\u003ewith hydrogen atoms omitted for clarity; (b) The coordination mode of ligand \u003cstrong\u003eL\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e4-\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e \u003c/strong\u003ein \u003cstrong\u003eCuNet\u003c/strong\u003e; (c) The connection mode of a dinuclear Cu(II) subunits in \u003cstrong\u003eCuNet\u003c/strong\u003e; (d) Two-dimensional planar structure of \u003cstrong\u003eCuNet\u003c/strong\u003e; (e) Irregular hexagonal pattern formed by ligand \u003cstrong\u003eL\u003c/strong\u003e\u003csup\u003e\u003cstrong\u003e4-\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003e \u003c/strong\u003eand copper cluster.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/52537466353ba896f7f006a3.png"},{"id":36224990,"identity":"9c1c2ae3-ed17-4635-85be-ab37ebbe79f9","added_by":"auto","created_at":"2023-04-24 14:37:29","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":259898,"visible":true,"origin":"","legend":"\u003cp\u003eElectronic spectra of (a) \u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eL\u003c/strong\u003e and\u003cstrong\u003e \u003c/strong\u003e(c) \u003cstrong\u003eCuNet\u003c/strong\u003e in Tris HCl/NaCl buffer solution (pH = 7.2) after adding CT-DNA (arrows indicate that the emission intensity decreases with the increase of DNA concentration); (b) \u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eL\u003c/strong\u003e and (d) \u003cstrong\u003eCuNet\u003c/strong\u003e [DNA] / (ε\u003csub\u003ea\u003c/sub\u003e–ε\u003csub\u003ef\u003c/sub\u003e) diagram with [DNA].\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/516c11b3df701b4575379c46.png"},{"id":36223276,"identity":"dba2fd49-aea5-407b-ba4c-1409a9a5e14c","added_by":"auto","created_at":"2023-04-24 14:21:28","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":299205,"visible":true,"origin":"","legend":"\u003cp\u003eEmission spectrum of EB-DNA in the presence of\u003cstrong\u003e \u003c/strong\u003e(a) \u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eL\u003c/strong\u003e and (c) \u003cstrong\u003eCuNet\u003c/strong\u003e, λ\u003csub\u003eex \u003c/sub\u003e= 520 nm. (The arrow shows that the intensity decreases with the increase of \u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eL\u003c/strong\u003e or \u003cstrong\u003eCuNet\u003c/strong\u003e concentration.) Fluorescence quenching curve of EB-DNA after adding (b) \u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eL\u003c/strong\u003e and (d) \u003cstrong\u003eCuNet\u003c/strong\u003e.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/a3dfc6d4494e0af6314d4beb.png"},{"id":36224991,"identity":"23835011-c9c8-46bf-b627-f85e7b6fb254","added_by":"auto","created_at":"2023-04-24 14:37:29","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":249048,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The inhibition effect of various test solutions on Escherichia coli is recorded by camera. (b)The inhibition circle diameter of each test solution against Escherichia coli at different concentrations (0.35, 0.70 and 1.40 mg/mL).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/0fae154bd94553c5ed24b9bb.png"},{"id":43041156,"identity":"eded5401-efb9-408e-91eb-ed96a0db7fcc","added_by":"auto","created_at":"2023-09-13 04:52:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1352779,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/8de4c291-267f-44f6-824b-6fc2537ff9b0.pdf"},{"id":36223282,"identity":"eae7f963-9017-440b-b1f0-fec424f423ca","added_by":"auto","created_at":"2023-04-24 14:21:29","extension":"cif","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":243372,"visible":true,"origin":"","legend":"","description":"","filename":"CuNet.cif","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/5c4a362aed554c301a53d838.cif"},{"id":36223283,"identity":"d0736583-7bcc-41e2-9d1f-b140f86f4936","added_by":"auto","created_at":"2023-04-24 14:21:29","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":710308,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/27ddfa338814d991b90b7a78.docx"},{"id":36224397,"identity":"b5f09456-590c-4451-ac0f-f6fc09e899f9","added_by":"auto","created_at":"2023-04-24 14:29:29","extension":"pdf","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":143635,"visible":true,"origin":"","legend":"","description":"","filename":"checkcif.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/b8bae179dda8cb38ffcefd76.pdf"},{"id":36224396,"identity":"462dc5e3-0ba0-4b7d-aaa3-46e97718d093","added_by":"auto","created_at":"2023-04-24 14:29:29","extension":"png","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":103867,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1\u003c/strong\u003e The synthetic route of the ligand \u003cstrong\u003eH\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e4\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003eL\u003c/strong\u003e.\u003c/p\u003e","description":"","filename":"Scheme1.png","url":"https://assets-eu.researchsquare.com/files/rs-2838938/v1/e3f96344a8d21b93f5fe00df.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"DNA binding and Antibacterial study of a new highly planar Cu(II) Network","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eCancer is a disease that does great harm to human body. It is understood that many cancers, such as breast cancer, lung cancer, thyroid cancer, rectal cancer, gastric cancer, etc., have different symptoms and causes, but they are basically caused by abnormal DNA sequence. [1 ~ 5] At the same time, a large number of biological studies have proved that DNA is the main target of anti-cancer drugs, and DNA plays a crucial role in the process of cell replication and cell differentiation. [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] Therefore, DNA binding agents have received extensive attention. In the past decades, cisplatin has been used as the main binding agent for clinical treatment of cancer. However, due to its systemic toxicity, acquired resistance, and limited activity range, it is necessary to explore binders with different metal centers. [7 ~ 10] In general, Metal ions show a wide range of coordination numbers, allowing them to combine with many organic ligands and interact with the redox state of cells, thus changing cell vitality. [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] Cu(II) ion is a Lewis acid, which shows affinity for nitrogen and oxygen donor atoms and forms complexes with coordination numbers of 4, 5 and 6. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] As one of the essential trace elements for human body, copper have played very important roles in human metabolic process including erythrocyte formation, iron absorption and transportation as well as the respiration. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] It has been proved that it has special biological activity and catalysis to life system. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] Copper complexes exhibit a wide range of binding behaviors with DNA, including non-covalent and intercalation interactions. At the same time, it has been found that the antibacterial activity of copper complexes with nitrogen azocyclic carboxylic acids is higher than those free of nitrogen donor. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] In addition, Cu(II) coordination polymers have stronger binding affinity and better cytotoxicity as the result of the larger plane area compared with their mononuclear analogues. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] Therefore, the studying for DNA binding and antibacterial activity of copper coordination polymers has become one of the research focuses in recent years. [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eWith these in mind, compounds containing pyridine carboxylic acids represent a very attractive class of ligands for the synthesis of copper complexes as potential antibacterial agents and DNA binding agents. Therefore, based on the advantages of 2D planar network structure in combination with DNA, a new Cu(II) coordination network with high planarity based on a new nitrogen hetercarboxylic acid ligands with pyridine-2,6-dicarboxylic acid as the terminal group, \u003cem\u003ep\u003c/em\u003e-benzyloxy as the central skeleton was obtained by hydrothermal method. The compoune was well characterized by X-ray diffraction, IR spectrum, TGA and PXRD. In addition, the DNA binding effect of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and Cu (II) complexes was studied by UV-Vis and fluorescence spectra. And the antibacterial activity of the ligand and \u003cb\u003eCuNet\u003c/b\u003e was tested by hole drilling method.\u003c/p\u003e "},{"header":"2. Experimental Section","content":"\u003cp\u003e \u003cb\u003e2.1. Materials and Methods.\u003c/b\u003e \u003c/p\u003e\u003cp\u003eAll solvents and chemicals were obtained from commercial sources and used without further purification. The crystallographic data collection and refinement, the important bond lengths of \u003cb\u003eCuNet\u003c/b\u003e were described in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eThe details of instrumentation are described in supporting information.\u003c/p\u003e\u003cdiv class=\"gridtable\"\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\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCrystal data and structure refinement parameters for \u003cb\u003eCuNet\u003c/b\u003e.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChemical formula\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC\u003csub\u003e11\u003c/sub\u003eH\u003csub\u003e8\u003c/sub\u003eCuNO\u003csub\u003e6\u003c/sub\u003e\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFormula weight\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e313.72\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eT\u003c/em\u003e (K)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e173(2)\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWavelength (Å)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.71073\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrystal system, Space group\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMonoclinic, \u003cem\u003eC2/c\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eUnit cell dimensions\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ea\u003c/em\u003e = 22.5814(16) Å\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eb\u003c/em\u003e = 10.2577(5) Å, \u003cem\u003eβ =\u003c/em\u003e 97.295(6) º\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003ec\u003c/em\u003e = 9.6152(5) Å\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eV\u003c/em\u003e (Å\u003csup\u003e3\u003c/sup\u003e), \u003cem\u003eZ\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2209.2(2), 8\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eD\u003c/em\u003e\u003csub\u003ecalc\u003c/sub\u003e (Mg /m \u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.887\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAbsorption coefficient (mm\u003csup\u003e– 1\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.064\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eF\u003c/em\u003e(000)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1264\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCrystal size (mm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.16 × 0.16 × 0.18\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eθ\u003c/em\u003e ranges (°)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.91 ~ 69.8\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIndex ranges\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e–27 ≤ \u003cem\u003eh\u003c/em\u003e ≤ 21; − 11 ≤ \u003cem\u003ek\u003c/em\u003e ≤ 12; − 11 ≤ \u003cem\u003el\u003c/em\u003e ≤ 11\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eReflections collected\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7154\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIndependent reflections\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2062 [\u003cem\u003eR\u003c/em\u003e(int) = 0.028]\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eθ\u003c/em\u003e Range for data collection (°)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e99.62\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eData/restraints/parameters\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1830/0/427\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGoodness-of-fit on \u003cem\u003eF\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.542\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFinal \u003cem\u003eR\u003c/em\u003e indices [\u003cem\u003eI \u0026gt;\u003c/em\u003e 2\u003cem\u003eσ(I)\u003c/em\u003e]\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e = 0.0376, \u003cem\u003ewR\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e = 0.1525\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e indices (all data)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csub\u003e1\u003c/sub\u003e = 0.0692, \u003cem\u003ewR\u003c/em\u003e\u003csub\u003e2\u003c/sub\u003e = 0.1637\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLargest difference peak and hole(e Å\u003csup\u003e–3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.79 and − 0.62\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003cp\u003e \u003csup\u003ea\u003c/sup\u003e \u003cem\u003ew\u003c/em\u003e = 1/[\u003cem\u003eσ\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e(\u003cem\u003eF\u003c/em\u003e\u003csub\u003eo\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e)+(0.0295\u003cem\u003eP\u003c/em\u003e)\u003csup\u003e2\u003c/sup\u003e], \u003csup\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sup\u003e\u003cem\u003ew\u003c/em\u003e = 1/[\u003cem\u003eσ\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e(\u003cem\u003eF\u003c/em\u003e\u003csub\u003eo\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e)+(0.0151\u003cem\u003eP\u003c/em\u003e)\u003csup\u003e2\u003c/sup\u003e],Where \u003cem\u003eP\u003c/em\u003e = (\u003cem\u003eF\u003c/em\u003e\u003csub\u003eo\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e+ 2\u003cem\u003eF\u003c/em\u003e\u003csub\u003ec\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e) /3.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e Selected bond lengths (\u0026Aring;) and angles (˚) for \u003cstrong\u003eCuCP\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\" width=\"583\" height=\"89\"\u003e\u003c/p\u003e\n\u003ch2\u003e2.2. The synthesis of H\u003csub\u003e4\u003c/sub\u003eL\u003c/h2\u003e\u003cp\u003eThe synthetic of the ligand \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e is by four steps with chelidamic acid as starting material. (Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) The intermediate dimethyl 4-hydroxypyridine-2,6-dicarboxylate (\u003cb\u003e2\u003c/b\u003e) was prepared as referenced. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eTo a 175 mL anhydrous acetonitrile solution of dimethyl 4-hydroxypyridine-2,6-dicarboxylate (\u003cb\u003e2\u003c/b\u003e) (2.64 g, 12.5 mmol), 2.48 g (18 mmol) anhydrous potassium carbonate and 1.32 g (5 mmol) 1,4-bis(bromomethyl)benzene (\u003cb\u003e3\u003c/b\u003e) were added as a solid under stirring. The mixture was refluxed for 10 hours at 70 ~ 80 ℃ and milky suspension was observed. After refluxing 50 h, the mixture was cooled to room temperature and filtered. Acetonitrile is removed by rotary evaporator and the residue was partitioned between dichloromethane (200 mL) and water (50 mL). The organic layer was washed with 1% aqueous acetic acid, water and dried (sodium sulfate). White residue obtained by removing dichloromethane solvent through rotary evaporator, the white residue was recrystallized from ethanol to get a white crystalline sample 1,4-Bis-2,6-pyridine-dicarboxylic acid dimethyl benzene (\u003cb\u003e4\u003c/b\u003e) which was washed with cold ethanol for three times and dried in air. 2.35 g, Yield 89.69%. Anal. calcd for C\u003csub\u003e26\u003c/sub\u003eH\u003csub\u003e24\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e10\u003c/sub\u003e: C, 59.54; H, 4.61; N, 5.34. Found: C 58.86; H, 4.75; N, 5.29. \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400MHz), \u003cem\u003eδ\u003c/em\u003e(ppm): 4.02 (s, 12H, CH\u003csub\u003e3\u003c/sub\u003e); 5.26 (s, 4H, CH\u003csub\u003e2\u003c/sub\u003e); 7.50 (s, 4H, CH); 7.90 (s, 4H, CH). (Figure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e)\u003c/p\u003e\u003cp\u003eTo a 50 mL (1 mol·L\u003csup\u003e‒1\u003c/sup\u003e) lithium hydroxide aqueous solution of 8.0 g (15.27 mmol) of 1,4-Bis-2,6-pyridine-dicarboxylic acid dimethyl benzene (\u003cb\u003e4\u003c/b\u003e) was added as a solid under stirring. The mixture was refluxed for 10 h until the solution changes from white suspension to clear solution to stop the reaction, the mixture was cooled to room temperature and filtered. The filtrate was adjusted to the pH value of 1 with 3 M hydrochloric acid and white solids will be obtained by suction filtration. The solids was washed three times with deionized water and ethanol respectively, and dried under vacuum to obtain 6.45 g of ligand \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e, with a yield of 90.26%. Anal. calcd for C\u003csub\u003e22\u003c/sub\u003eH\u003csub\u003e16\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e10\u003c/sub\u003e: C, 56.42; H, 3.44; N, 5.98. Found: C, 56.61; H, 3.47; N, 5.72. \u003csup\u003e1\u003c/sup\u003eH NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, 400MHz), \u003cem\u003eδ\u003c/em\u003e(ppm): 5.40 (s, 4H, CH\u003csub\u003e2\u003c/sub\u003e); 7.54 (s, 4H, CH); 7.81 (s, 4H, CH). (Figure \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003e) IR (KBr, cm-1):3079 (w), 1656(s), 1569(s), 1407(s), 1369(m), 1337(s), 1289(w), 1116(m), 1073(s), 900(m), 808(s), 665(m).\u003c/p\u003e\u003ch2\u003e2.3. The synthesis of [Cu\u003csub\u003e2\u003c/sub\u003eL(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e (CuNet)\u003c/h2\u003e\u003cp\u003eTo a 10 mL Teflon-lined glass vial containing Cu(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e·3H\u003csub\u003e2\u003c/sub\u003eO (4.8 mg, 0.02 mmol) and \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e (4.6 mg, 0.01 mmol), 6 mL H\u003csub\u003e2\u003c/sub\u003eO and 40 µL HNO\u003csub\u003e3\u003c/sub\u003e were added. The resulted suspension was ultrasound-dispersed over 30 min and placed in a tightly capped 10 mL Teflon-lined glass vial and heated under autogenous pressure at 160 ℃ for 3 days. After it was cooled to room temperature at the rate of 5 ℃·h\u003csup\u003e− 1\u003c/sup\u003e, transparent and blue flake crystals which was washed by methanol were obtained and air-dried (yield of 52.86% base on Cu(NO\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e·3H\u003csub\u003e2\u003c/sub\u003eO). Anal. Calcd for C\u003csub\u003e11\u003c/sub\u003eH\u003csub\u003e8\u003c/sub\u003eCuNO\u003csub\u003e6\u003c/sub\u003e: C, 42.11; H, 2.57; N, 4.66. Found: C, 42.16; H, 2.53; N, 4.58. IR (KBr, cm\u003csup\u003e− 1\u003c/sup\u003e):3321 (w), 3094 (w), 1730 (s), 1595 (m), 1462 (m), 1421 (m), 1371 (m), 1309 (m), 896 (m), 681 (m).\u003c/p\u003e\u003ch2\u003e2.4. DNA binding experiment\u003c/h2\u003e\u003cp\u003eIn general, the binding mode and affinity between the complex and DNA were deduced by absorption spectrum titration. [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] All spectrophotometric measurements were carried out in a constant temperature quartz sample cell at 25 ℃. The electronic absorption titration was carried out by increasing the concentration of CT-DNA, while the concentration of the substance to be measured was kept constant. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] In order to obtain the absorption spectrum, the required CT-DNA needs to be added to the test solution and reference solution to eliminate the absorption of CT-DNA itself. Based on the absorption titration data, the binding constant is obtained using the following formula:\u003c/p\u003e\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\frac{\\left[\\text{D}\\text{N}\\text{A}\\right]}{{{\\epsilon }}_{\\text{a}}–{{\\epsilon }}_{\\text{f}}} = \\frac{\\left[\\text{D}\\text{N}\\text{A}\\right]}{{{\\epsilon }}_{\\text{b}}–{{\\epsilon }}_{\\text{f}}}+ \\frac{1}{{\\text{K}}_{\\text{b}}}({{\\epsilon }}_{\\text{b}}–{{\\epsilon }}_{\\text{f}})$$\u003c/div\u003e\u003c/div\u003e\u003cp\u003ewhere [DNA] is the concentration of DNA in the base pair; ε\u003csub\u003ea\u003c/sub\u003e is the extinction coefficient observed at different DNA concentrations (A\u003csub\u003eobsd\u003c/sub\u003e/[M]); ε\u003csub\u003ef\u003c/sub\u003e corresponds to the extinction coefficient of the free compound; ε\u003csub\u003eb\u003c/sub\u003e is the extinction coefficient of the compound after fully binding to DNA; \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e is the binding constant through [DNA]/(ε\u003csub\u003ea\u003c/sub\u003e– ε\u003csub\u003ef\u003c/sub\u003e) for [DNA], the ratio of slope to intercept is \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e .\u003c/p\u003e\u003cp\u003eIn this experiment, the concentration of ligand \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e in DMF solution are 3×10\u003csup\u003e‒3\u003c/sup\u003e M. The concentration of CT-DNA in Tris-HCl/NaCl buffer solution of pH = 7.2 were 2.5×10\u003csup\u003e‒3\u003c/sup\u003e M. In a quartz cuvette of 3 mL, the above \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e or \u003cb\u003eCuNet\u003c/b\u003e solution of 25 µL was added to 2.5 mL of Tris-HCl/NaCl buffer solution (pH = 7.2), the CT-DNA above was gradually added (0 ~ 240 µL), and the changes were observed in the UV spectrum.\u003c/p\u003e\u003ch2\u003e2.5. EB-DNA fluorescence competition experiment\u003c/h2\u003e\u003cp\u003eIn order to further study the binding characteristics of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e with DNA, EB-DNA fluorescence competition experiment was carried out, because EB is an aromatic fluorescent compound that can be embedded in nuclear base molecules to detect DNA. It is reported that ethidium bromide (EB) does not show any obvious emission in Tris HCl/NaCl buffer solution with pH = 7.2. When adding ligands or complexes to the solution containing EB, no change of fluorescence spectrum was observed. However, when CT-DNA was added to EB solution, the fluorescence intensity was greatly enhanced, which was caused by EB's strong insertion of DNA base pairs. Generally, the fluorescence emitted by EB binding with DNA can compete with EB for DNA by adding other molecules, thus leading to fluorescence quenching. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] Therefore, the degree of fluorescence quenching can determine the binding degree of other molecules with CT-DNA, and the fluorescence quenching constant was calculated according to Stern-Volmer equation:\u003c/p\u003e\u003ch2\u003eI\u003csub\u003e0\u003c/sub\u003e / I = 1 + K\u003csub\u003eSV\u003c/sub\u003e [Q]\u003c/h2\u003e\u003cp\u003eI\u003csub\u003e0\u003c/sub\u003e and I are fluorescence intensities at 598 nm in the absence and presence of other molecules respectively, \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eSV\u003c/em\u003e\u003c/sub\u003e is the quenching constant of linear Stern Volmer, and [Q] is the concentration of other molecules.\u003c/p\u003e\u003cp\u003eThe CT-DNA solution used in this experiment was the same as that of the electron absorption titration experiment. The concentration of EB in Tris-HCl/NaCl buffer solution of pH = 7.2 was 2.5×10\u003csup\u003e‒3\u003c/sup\u003e M. 10 µL of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e or \u003cb\u003eCuNet\u003c/b\u003e solution was added to a 3 mL quartz cuvette with 2.5 mL of Tris-HCl/NaCl buffer respectively, and then dropped the sample solution to observe the changes in the fluorescence spectrum.\u003c/p\u003e\u003ch2\u003e2.6. Antibacterial experiment\u003c/h2\u003e\u003cp\u003eIn this study, the antibacterial activity against Escherichia coli was studied by measuring the growth inhibition under different concentrations of \u003cb\u003eCuNet\u003c/b\u003e in the culture medium (containing 5 g·L\u003csup\u003e–1\u003c/sup\u003e yeast extract, 10 g·L\u003csup\u003e–1\u003c/sup\u003e sodium chloride and 10 g·L\u003csup\u003e–1\u003c/sup\u003e tryptone). All experiments were conducted under dark conditions. Firstly, yeast extract, NaCl and trypsin were added to warm distilled water to obtain a solution, which was further sterilized in a pressure cooker for 22 minutes. The sterilized seed solution was then inoculated with bacteria, placed in a gas bath thermostatic oscillator, and incubated at 37 ℃ for 12 hours. The activated bacterial solution with the culture medium was mixed and poured it into the culture dish. Perforated and sucked the test solution into the hole (conduct three control experiments). Finally, the culture dish was putted into a constant temperature incubator at 30 ℃, and observe the size of the zone of inhibition after 10 hours.\u003c/p\u003e"},{"header":"3. Results And Discussion","content":"\u003ch2\u003e3.1. Characterization of CuNet\u003c/h2\u003e\u003cp\u003eThe infrared spectra of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e are shown in Figure \u003cspan refid=\"MOESM3\" class=\"InternalRef\"\u003eS3\u003c/span\u003e. In the infrared spectrum of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e, the hydroxyl group of the ligand carboxylate is assigned to the band at 3079 cm\u003csup\u003e− 1\u003c/sup\u003e, the absorption band at 1730 cm\u003csup\u003e–1\u003c/sup\u003e is attributed to the C = O stretching vibration of the carboxylate, the peak of 1309 cm\u003csup\u003e–1\u003c/sup\u003e belong to the C-O stretching vibration of the carboxylate. Compared with the infrared spectrum of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e, it can be clearly observed that a broad peak of moderate intensity centered at 3321 cm\u003csup\u003e–1\u003c/sup\u003e ranging from 2976 to 3630 cm\u003csup\u003e–1\u003c/sup\u003e, indicating the existence of water in the coordination sphere of Cu (II). The υ\u003csub\u003eC=O\u003c/sub\u003e and υ\u003csub\u003eC−O\u003c/sub\u003e of the carboxylate on the pyridine have moved 74 cm\u003csup\u003e–1\u003c/sup\u003e and 20 cm\u003csup\u003e–1\u003c/sup\u003e to lower wavenumbers, respectively, indicating that both the carbonyl oxygen and the hydroxyl oxygen on the carboxylate are involved in the coordination, forming an M–O bond. In addition, in the far infrared region, it is allocated to υ \u003csub\u003eM−O\u003c/sub\u003e and υ \u003csub\u003eM−N\u003c/sub\u003e at 665 cm\u003csup\u003e–1\u003c/sup\u003e. [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] The framework of \u003cb\u003eCuNet\u003c/b\u003e is stable before 170°C, and the loss of coordination H\u003csub\u003e2\u003c/sub\u003eO molecule is observed from 170 to 200°C with a weight loss of 10.79%. After further heating, the skeleton begins to collapse and the weight loss is completed at 450°C (Fig. S4). The solid sample of \u003cb\u003eCuNet\u003c/b\u003e collected is characterized by PXRD (Fig. S5). The dry sample obtained from the synthesized complex \u003cb\u003eCuNet\u003c/b\u003e crystal is very consistent with the PXRD diagram simulated by the single crystal X-ray data, indicating that the crystal sample is pure phase.\u003c/p\u003e\u003ch2\u003e3.2 Crystal structure description\u003c/h2\u003e\u003cp\u003eSingle-crystal X-ray diffraction analysis reveals that \u003cb\u003eCuNet\u003c/b\u003e crystallized in \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003e2\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e/c\u003c/em\u003e space group of monoclinic crystal system and exhibit a two-dimensional (2D) structure with high planarity. As depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, the asymmetric unit of the \u003cb\u003eCuNet\u003c/b\u003e is constituted by one Cu(II), one half ligand \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4–\u003c/b\u003e\u003c/sup\u003e, and one water. The fully deprotonated ligand \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4–\u003c/b\u003e\u003c/sup\u003e in \u003cb\u003eCuNet\u003c/b\u003e adopts a much extended trans-configuration with µ\u003csub\u003e4\u003c/sub\u003e-bis (η\u003csup\u003e1\u003c/sup\u003e: η\u003csup\u003e1\u003c/sup\u003e: η\u003csup\u003e2\u003c/sup\u003e) coordination mode and exhibited high planarity where all of the atoms in the ligand \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4–\u003c/b\u003e\u003c/sup\u003e are in the same plane as the result of the incorporation of Cu(II). The penta-coordination sphere of \u003cb\u003eCuNet\u003c/b\u003e in tetragonal pyramidal configuration is completed by one pyridine nitrogen and two carboxylic oxygen atoms of one 2,6-pyridine dicarboxylic acid moiety of one ligand \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4‒\u003c/b\u003e\u003c/sup\u003e, one carboxylic oxygen from one 2,6-pyridine dicarboxylic acid moiety of another ligand \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4‒\u003c/b\u003e\u003c/sup\u003e as well as one coordinated water molecule. The tetragonal pyramid is realized with the bottom completed by one pyridine nitrogen atom and three oxygen from two ligand \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4‒\u003c/b\u003e\u003c/sup\u003e as well as the oxygen of coordinating water molecule acting as the top (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). Therefore, two Cu(II) ions are connected by two carboxylic oxygen atoms from two \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4‒\u003c/b\u003e\u003c/sup\u003e and form a Cu(II) dinuclear subunit. Each ligand \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4–\u003c/b\u003e\u003c/sup\u003e is bound by two such Cu(II) dinuclear subunits, meanwhile each Cu(II) dinuclear subunits is connected by three ligands \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4–\u003c/b\u003e\u003c/sup\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003eb and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). Therefore, the whole structure of the planar \u003cb\u003eCuNet\u003c/b\u003e can be regarded as a (2, 3)-connected network featuring a graphene topology (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). The adjacent layers are connected by forficate hydrogen bonds between coordinated water and free carboxylic oxygen atom (O − H···O = 2.69 Å/2.69 Å), which may enhance the stability of \u003cb\u003eCuNet\u003c/b\u003e (Figure S6). As shown in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the Cu − N bond length is 1.902(2) Å and that for Cu − O bond lengths range from 1.907(2) to 2.224(2) Å, which are all comparable to those previously reported Cu(II) complexes. [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] Compared with the puckered Cu(II) analogue constructed by the similar ligand where 2,6-pyridine dicarboxylic acid is spaced by more rigid benzene backbone, we can safely conclude that the ligand characteristic of more flexible spacer contributes a lot to this planar two-dimensional network. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/p\u003e\u003ch2\u003e3.3. DNA binding studies\u003c/h2\u003e\u003cp\u003eIt is necessary to check the interaction between DNA and the newly synthesized compound before estimating the anti-tumor activity of any new compound. Studying this interaction by using electronic absorption spectroscopy is one of the most common methods. [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e] In the presence and absence of CT-DNA, the changes in the absorption spectra of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e are shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ea and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ec. It can be seen that when the same concentration of CT-DNA is added to H\u003csub\u003e4\u003c/sub\u003eL and \u003cb\u003eCuNet\u003c/b\u003e, the absorption band intensity at 360 and 368 nm (π→π*) decrease, and as the concentration of CT-DNA increases, the absorption bands of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e exhibit a color reduction phenomenon of about 22.29% and 34.67%, respectively. At the same time, the color reduction phenomenon is accompanied by a change of 1 to 2 nm in red shift. According to previous reports on DNA binding, it can be known that the UV spectrum of the complex is decolorized and red-shifted, which is evidence of binding to DNA through the intercalation mode. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] The degree of decolorization of the absorption band can be used as a measure of the strength of intercalation and binding. \u003c/p\u003e\u003cp\u003eTherefore, \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and complex \u003cb\u003eCuNet\u003c/b\u003e are most likely to bind to DNA in an intercalation mode. The binding constant (\u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e) of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e to CT-DNA was determined by monitoring the change in absorbance (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eb and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003ed). The \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e are 2.26×10\u003csup\u003e4\u003c/sup\u003e M\u003csup\u003e‒1\u003c/sup\u003e (R\u003csup\u003e2\u003c/sup\u003e = 0.992) and 2.42×10\u003csup\u003e5\u003c/sup\u003e M\u003csup\u003e‒1\u003c/sup\u003e (R\u003csup\u003e2\u003c/sup\u003e = 0.997), respectively. These results indicate that the \u003cb\u003eCuNet\u003c/b\u003e penetrates more deeply into and stacks more strongly with the base pairs of the DNA than the \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e.\u003c/p\u003e\u003cp\u003eBased on the above results, two reasons are inferred: one is that the increased coordination effect of coplanar aromatic rings may lead to high affinity to DNA. [33 ~ 35] The second is the ligand charge transfer caused by the coordination of the central Cu(II) atom, which reduce the electron density on the ligand, thereby reducing the charge density of the planar conjugate system, which is conducive to the insertion of DNA base pairs. Compared with the related decumented reports, \u003cb\u003eCuNet\u003c/b\u003e showed a better affinity to the classical copper coordination polymer intercalators as summaried in Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e3\u003c/span\u003e. [36 ~ 41].\u003c/p\u003e\u003cdiv class=\"gridtable\"\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\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe comparison of the binding constants, \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e, of some copper coordination polymers with DNA.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ecoordination polymer\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e( M\u003csup\u003e–1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eReferences\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e[Cu\u003csub\u003e2\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e2\u003c/sub\u003e(dmapox)(ipa)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e[Cu\u003csub\u003e2\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e2\u003c/sub\u003e(dmapox)(tpa)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e1.22×10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003cp\u003e1.45×10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e{(Cu(phen)(trp))ClO\u003csub\u003e4\u003c/sub\u003e·3H\u003csub\u003e2\u003c/sub\u003eO}\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.24×10\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e{[Cu(4-mphen)(trp)]ClO\u003csub\u003e4\u003c/sub\u003e·3H\u003csub\u003e2\u003c/sub\u003eO}\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.77×10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[{Cu(BIG)(H\u003csub\u003e2\u003c/sub\u003eO)}\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e(ClO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e2n\u003c/sub\u003e·3nH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.25×10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e{[Cu\u003csub\u003e4\u003c/sub\u003eL\u003csup\u003e1\u003c/sup\u003e(4,4′-bipy)\u003csub\u003e2\u003c/sub\u003e](ClO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e·H\u003csub\u003e2\u003c/sub\u003eO}\u003csub\u003e∞\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.2×10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e{[Cu\u003csub\u003e4\u003c/sub\u003eL\u003csup\u003e2\u003c/sup\u003e(4,4′-bipy)4](ClO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e4\u003c/sub\u003e·2CH\u003csub\u003e3\u003c/sub\u003eCN·2H\u003csub\u003e2\u003c/sub\u003eO}\u003csub\u003e∞\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.1×10\u003csup\u003e5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu\u003csub\u003e2\u003c/sub\u003eL\u003csub\u003e2\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)]\u003csub\u003e∞\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.91×10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e{[Cu\u003csub\u003e2\u003c/sub\u003eL\u003csub\u003e2\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)]·H\u003csub\u003e2\u003c/sub\u003eO}\u003csub\u003e∞\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8.75×10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu(bpmt)Cl\u003csub\u003e2\u003c/sub\u003e·2DMF]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.42×10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu(bpmt)(µ-Cl)·DMSO]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.41×10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCuNet\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.42×10\u003csup\u003e5\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThis work\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003ch2\u003e3.4. EB-DNA fluorescence competition study\u003c/h2\u003e\u003cp\u003eAfter the discovery of the binding ability of the compound to DNA, some other studies were needed to confirm the binding mode and binding affinity, which was usually completed through the study of EB replacement investigations. The changes in the EB-DNA fluorescence spectrum upon addition of the sample solution dropwise to the EB-DNA solution was observed. (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003ea and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). It can be seen that when \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e solutions are added, the fluorescence intensity was obviously quenched. In addition, the fluorescence quenching data were further analyzed by Stern-Volmer relationship. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003eb and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003ed, \u003cem\u003eKsv\u003c/em\u003e values of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e were 1.4 × 10\u003csup\u003e4\u003c/sup\u003e M\u003csup\u003e− 1\u003c/sup\u003e (R\u003csup\u003e2\u003c/sup\u003e = 0.987) and 1.62 × 10\u003csup\u003e4\u003c/sup\u003e M\u003csup\u003e‒1\u003c/sup\u003e(R\u003csup\u003e2\u003c/sup\u003e = 0.997) respectively. This shows that the copper coordination polymer had a higher quenching efficiency and stronger DNA binding force than \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e. [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e] This trend was consistent with the above absorption spectrum results and it shows that the interaction of \u003cb\u003eCuNet\u003c/b\u003e with DNA was likely to be through intercalation. [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e] In addition, the \u003cem\u003eKsv\u003c/em\u003e value of \u003cb\u003eCuNet\u003c/b\u003e is comparable when compared with other copper coordination polymer as shown in Table\u0026nbsp;\u003cspan refid=\"Tab7\" class=\"InternalRef\"\u003e4\u003c/span\u003e. [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]\u003c/p\u003e\u003cdiv class=\"gridtable\"\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\u003ctable float=\"Yes\" id=\"Tab7\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe comparison of \u003cem\u003eKsv\u003c/em\u003e between copper coordination polymers and DNA.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003ecoordination polymer\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eSV\u003c/em\u003e\u003c/sub\u003e (M\u003csup\u003e− 1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu\u003csub\u003e2\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e2\u003c/sub\u003e(dmapox)(ipa)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.02 × 10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu\u003csub\u003e2\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e2\u003c/sub\u003e(dmapox)(tpa)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.40 × 10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e{(Cu(phen)(trp))ClO\u003csub\u003e4\u003c/sub\u003e·3H\u003csub\u003e2\u003c/sub\u003eO}\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.51 × 10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e{[Cu(4-mphen)(trp)]ClO\u003csub\u003e4\u003c/sub\u003e·3H\u003csub\u003e2\u003c/sub\u003eO}\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.79 × 10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu(bpmt)Cl\u003csub\u003e2\u003c/sub\u003e·2DMF]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.3× 10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu(bpmt)(µ-Cl)·DMSO]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.2× 10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu\u003csub\u003e2\u003c/sub\u003e(dmeo)(N\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.85\u0026nbsp;×\u0026nbsp;10\u003csup\u003e3\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCuNet\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.62 × 10\u003csup\u003e4\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThis work\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e\u003ch2\u003e3.5. Antimicrobial activity studies\u003c/h2\u003e\u003cp\u003eIn recent years, the transition metal complexes obtained through pyridine carboxylic acid complexes have greatly promoted the research of antibacterial drugs. [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e] Therefore, DMF test solutions with different concentrations have been prepared here, and the antibacterial activities of the synthesized \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e and \u003cb\u003eCuNet\u003c/b\u003e against Escherichia coli (Gram negative bacteria) have been tested by hole drilling method. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003ea, the concentration of the test solution is 0.70 mg/mL, the antibiotic is cefradine, and DMF is used as the blank control. The size of the bacteriostatic circle of various test solutions records by the camera. It can be clearly seen that the bacteriostatic circles of DMF, copper nitrate, and \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e are relatively small, less than 10 mm. However, the bacteriostatic circles of \u003cb\u003eCuNet\u003c/b\u003e and cefradine are relatively larger, and the size of the bacteriostatic circles is 17.5 mm and 18.2 mm, respectively. These results indicate that the antibacterial activity of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e is basically low, while the antibacterial activity of \u003cb\u003eCuNet\u003c/b\u003e and Cefradine are comparable. This may be because when Cu(II) atoms coordinate with \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e, partial charge sharing occurs, leading to electron delocalization in the system, which makes the antibacterial activity of complex \u003cb\u003eCuNet\u003c/b\u003e much higher than that of \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e. [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]\u003c/p\u003e\u003cp\u003eTo further evaluate the antibacterial performance of the \u003cb\u003eCuNet\u003c/b\u003e against Escherichia coli, the inhibition zones of three different concentrations (0.35, 0.70 and 1.40 mg/mL) were measured (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003eb). At the above concentrations, the zone of inhibition for \u003cb\u003eCuNet\u003c/b\u003e are 11.5, 17.5, and 18 mm, respectively, which indicates that its antibacterial zone increases with the increase of \u003cb\u003eCuNet\u003c/b\u003e concentration. But when the concentration increases of \u003cb\u003eCuNet\u003c/b\u003e from 0.7 to 1.4 mg/mL, the inhibitory effect of \u003cb\u003eCuNet\u003c/b\u003e did not significantly increase, and its antibacterial effect was almost equivalent to that of cefradine, indicating that it has relatively good antibacterial activity when the concentration of \u003cb\u003eCuNet\u003c/b\u003e is 0.70 mg/mL. For DMF, copper nitrate and \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e, the antibacterial activity is relatively small, and its zone of inhibition hardly changes as the concentration increases. The biological study in the case of the antibacterial assay discloses that the coordination polymer has higher antibacterial activity than ligands. Such improved activity can be explained on the basis of the theory of chelation. [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e] In addition, a comparison between the antibacterial activity of \u003cb\u003eCuNet\u003c/b\u003e and some other copper coordination polymers has been provided as compiled in Table\u0026nbsp;\u003cspan refid=\"Tab8\" class=\"InternalRef\"\u003e5\u003c/span\u003e, and it shows that \u003cb\u003eCuNet\u003c/b\u003e has better antibacterial activity than other copper coordination polymer. [48 ~ 53]\u003c/p\u003e\u003cdiv class=\"gridtable\"\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\u003ctable float=\"Yes\" id=\"Tab8\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eA comparison of the antibacterial activity of copper coordination polymers.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"3\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCoordination polymer\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAgainst E. coli (mm)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRef.\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[NaCu\u003csub\u003e2\u003c/sub\u003e(pdc)\u003csub\u003e2\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e4\u003c/sub\u003e(OH)]\u003csub\u003en\u003c/sub\u003e (1)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo effect\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[NaCu\u003csub\u003e2\u003c/sub\u003e(pdc)\u003csub\u003e2\u003c/sub\u003e(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e4\u003c/sub\u003e(OH)]\u003csub\u003en\u003c/sub\u003e (1-sono)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCP-1(Cu)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e49\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSLys-Cu(II)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu(pdc)\u003csub\u003e2\u003c/sub\u003e(DMA)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e (BCP-1)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo effect\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu(pdc)\u003csub\u003e2\u003c/sub\u003e(DMA)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e (BCP-2)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu\u003csub\u003e2\u003c/sub\u003e(bdc)\u003csub\u003e2\u003c/sub\u003e(dabco)] (CB)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo effect\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu\u003csub\u003e2\u003c/sub\u003e(bdc)\u003csub\u003e2\u003c/sub\u003e(dabco)] (CS)\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e52\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu(dipic)(4-picoline)]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e[Cu(H-dipic)(4-picoline)]\u003csub\u003en\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCuNet\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e17.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eThis work\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eHerein, a new copper coordination net (\u003cb\u003eCuNet\u003c/b\u003e) based on a multidentate pyridine carboxylic ligand where two 2,6-pyridine dicarboxylic cavities are spaced by \u003cem\u003ep\u003c/em\u003e-benzyloxy is prepared hydrothermally and well characterized. Crystal structure analysis demonstrates that \u003cb\u003eCuNet\u003c/b\u003e is a highly planar network which is similar to graphene. Electron absorption titration and EB-DNA competition experiments showed that \u003cb\u003eCuNet\u003c/b\u003e had higher ability to bind DNA through intercalation than other copper coordination polymers. In addition, the bacteriostatic exploration based on Escherichia coli exhibited that \u003cb\u003eCuNet\u003c/b\u003e had excellent antibacterial performance and is comparable to cefradine and other copper coordination polymers. This study enriched the DNA binding and antibacterial performance of copper coordination polymers.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eASSOCIATED CONTENT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCrystallographic files in CIF format have been deposited with the Cambridge Crystallographic Data Center with deposition numbers CCDC\u0026nbsp;2257062.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding Author\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e*E-mail: [email protected].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eACKNOWLEDGMENTS\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Natural Science Foundation of China (grants 22161025).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAlbogami S (2022) Comprehensive analysis of gene expression profiles to identify differential prognostic factors of primary and metastatic breast cancer. Saudi Journal of Biological Sciences, 29, 7: 103318.\u003c/li\u003e\n\u003cli\u003eMitsuo S, Shames DS, Gazdar AF, Minna JD (2007)A Translational View of the Molecular Pathogenesis of Lung Cancer. \u003cem\u003eJournal of Thoracic Oncology\u003c/em\u003e, 2(4): 327-343.\u003c/li\u003e\n\u003cli\u003eFujita S, Masago K (2021) Alteration of DNA mismatch repair capacity underlying the co-occurrence of non-small-cell lung cancer and nonmedullary thyroid cancer. 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Journal of Molecular Structure, 1267: 133521.\u003c/li\u003e\n\u003cli\u003eBatool SS, Gilani SR, Zainab SS, Tahir MN, Harrison WTA, Haider MS, Syed Q, Mazhar S, Shoaib M (2021) Synthesis, crystal structure, thermal studies and antimicrobial activity of a new chelate complex of copper(II) succinate with N,N,N\u0026prime;,N\u0026prime;-tetramethylethylenediamine. Journal of Coordination Chemistry, 1225: 129261.\u003c/li\u003e\n\u003cli\u003eSiddiqi ZA, Khalid M, Kumar S, Shahid M, Noor S (2010) Antimicrobial and SOD activities of novel transition metal complexes of pyridine-2,6-dicarboxylic acid containing 4-picoline as auxiliary ligand. European journal of medicinal chemistry, 45(1): 264-269.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme 1","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":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-2838938/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2838938/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe DNA binding and the antibacterial activities of metal organic compounds have great significance for the development of anticancer drugs. In this study, a copper coordination network, [Cu\u003csub\u003e2\u003c/sub\u003eL(H\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e2\u003c/sub\u003e]\u003csub\u003en\u003c/sub\u003e (\u003cb\u003eCuNet\u003c/b\u003e), based on \u003cb\u003eH\u003c/b\u003e\u003csub\u003e\u003cb\u003e4\u003c/b\u003e\u003c/sub\u003e\u003cb\u003eL\u003c/b\u003e where 2,6-pyridine-dicarboxylic acid moieties are spaced by \u003cem\u003ep\u003c/em\u003e-benzyloxy, is prepared hydrothermally. Single crystal X-ray analysis demonstrates that the fully deprotonated ligand \u003cb\u003eL\u003c/b\u003e\u003csup\u003e\u003cb\u003e4\u0026ndash;\u003c/b\u003e\u003c/sup\u003e with high planarity in \u003cb\u003eCuNet\u003c/b\u003e adopts a bis-\u0026micro;\u003csub\u003e2\u003c/sub\u003e-η\u003csup\u003e1\u003c/sup\u003e: η\u003csup\u003e1\u003c/sup\u003e: η\u003csup\u003e2\u003c/sup\u003e coordination mode to bind four Cu(II) to render a graphene-like network, which is further propped up to a 3D supramolecular framework through the hydrogen bonds between coordinated water and uncoordinated carboxyl oxygen. Considering its highly planar structural feature and excellent antibacterial properties of Cu(II), the DNA binding and antibacterial performance were explored. The UV-Visible absorption titration and EB-DNA competition determination exhibited that \u003cb\u003eCuNet\u003c/b\u003e bound DNA in an intercalation mode with the higher binding constant \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003eb\u003c/em\u003e\u003c/sub\u003e of 2.42 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e M\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and the comparable quenching constant \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003esv\u003c/em\u003e\u003c/sub\u003e of 1.62 \u0026times; 10\u003csup\u003e4\u003c/sup\u003e M\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e upon compared with the documented DNA linkers. In addition, the antibacterial activity test demonstrates that \u003cb\u003eCuNet\u003c/b\u003e exhibits comparable inhibitory effect on Escherichia coli with that of cefradine at the concertation of 0.70 mg/mL. This work has certain significance for the development of metal drugs.\u003c/p\u003e","manuscriptTitle":"DNA binding and Antibacterial study of a new highly planar Cu(II) Network","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-04-24 14:21:23","doi":"10.21203/rs.3.rs-2838938/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"42e1caae-895d-4ff5-abc6-7134a3304c2b","owner":[],"postedDate":"April 24th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-09-13T04:44:13+00:00","versionOfRecord":[],"versionCreatedAt":"2023-04-24 14:21:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2838938","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2838938","identity":"rs-2838938","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}