Study On Synthesis, Characteri Zation And Biological Activity Of 2-propyl-4,5-imidazole Dicarb Oxlic Acid Metal Complexes

In our research, 2-propyl-4,5- imidazoledicarboxlic acid was used to react with metal salts and eight novel metal complexes were synthesized by the solution crystallization and hydrothermal method. Complexes [1] [Ca(C8H8N2O4)2(H2O)2] Complexes [2] [Sr(C8H8N2O4)2(H2O)2] Complexes [3] [Mn(C8H8N2O4)2(H2O)2]?4H2O Complexes [4] [Cd(C8H8N2O4)2(H2O)2]?4H2O Complexes [5] [Zn(C8H8N2O4)2(H2O)2]?4H2O Complexes [6] [Mn (C8H8N2O4)2(H2O)2] ?2C3H7NO Complexes [7] [Ni (C8H8N2O4)2(H2O)2] ?2C3H7NO Complexes [8] [Cd(C8H8N2O4)2(H2O)2] ?2C3H7NOThese complexes were characterized by single crystal X-ray diffraction, and the complex [1],complex [4] and complex [6] were analyzed by thermogravimetric analyses.(1) The result shows that Complex [1] is isostructural with complex [2], which is eight-coordinated in a distorted square antiprismatic environment, The ligand donor atoms are the tertiary N atoms of the imidazole rings and the carboxylate O atoms of two chelating 2-propyl-4,5- imidazoledicarboxlic acid ligands, the carboxy oxygen atoms of two additional imidazole ligands and two water molecules. complex [3], complex [4] and complex [5] are isostructural, six-coordinated in a slightly distorted octahedral geometry defined by the tertiary N atoms of the imidazole rings and the carboxylate O atoms of two chelating 2-propyl-4,5- imidazoledicarboxlic acid ligands and two coordinate water molecules. Two free water molecules are also present in the asymmetric system. complex [6], complex [7] and complex [8] are isostructural, six-coordinate by two N,O-bidentate 2-propyl-4,5- imidazoledicarboxlic acid ligands and two DMF mole cules in a distorted octahedral environment.(2) The thermogravimetric analyses show that the complex [4] begins to decompose at 32.5℃and the structure is stable before 148.9℃, complex [7] begins to decompose at 72.88℃and the structure is stable before 146.95℃,however, complex [1] is stable until 152.4℃, therefore, the thermal stability of complex [1] is strongest, complex [4] is more stable than complex [7].A standard method of algal bioassay for evaluating the toxicity of toxic chemical was applied in the experiments. when the concentration of the metal ion reached a certain value, Platymonas subcordiformis was inhibitted, with the increasement of the concentration, the inhibitory effect become much stronger, furthermore, the toxicities of the complex [5] and [6] with the corresbonding metal salts was compared, The lowest no observable effect concentrations (LNOEC) of Zn2+,Ni2+ on the growth of Platymonas subcordiformis were obversed to be 1.5 mg/L, and respectively, and 96h-EC50s were found to be 11.19 mg/L and 9.73 mg/L, respectively.However, The lowest no observable effect concentrations (LNOEC) of complex 5 and 6 were 20 mg/L and, and 96h-EC50s were 11.19 mg/L and 9.73 mg/L respectively. Therefore the toxicities of the metal salts on the growth of Platymonas subcordiformis is much stronger than that of the complexes.The antibacterial activities against Escherichia coli bacteria under different concentrations of metallic complexes were measured by measuring the value of the absoption at the wavelength of 600nm by Microplate reader.(1) 2-propyl-4,5-imidazoledicarboxlic acid inhibitted the Escherichia coli completely at the concentration of 1250μg/mL.(2) In the selected six metal salts, CdCl2 inhibited the Escherichia coli completely at the concentration of 2500μg/mL, Cacl2 promoted the growth of Escherichia coli Apparently when the concentration reached at 625μg/mL, the speed of Escherichia coli increased significantly and quickly to achieve stable as the concentration of Cacl2 increased. Zn(CH3COO)2,Ni(NO3)2,SrCl2 and Mn(CH3COO)2.can inhibit the Escherichia coli also(3) The eight synthesized metal complexes can inhibit the growth of Escherichia coli completely. complex [1],[2],[3],[6],[8] shows eqivalent inhibitory effect with 2-propyl-4,5- imidazoledicarboxlic acid with completed Inhibitory conc entration at the value of 1250μg/mL;however, the inhibitory effect of complex [5] is stronger than the 2-propyl-4,5-imidazoledicarboxlic acid with completed Inhibitory concentration at the value of 625μg/ml; Complex [4] and complex [7] shows the strongest inhibitory effect on Escherichia coli, with completed Inhibitory concentration at the value of 312μg/mL.(4) Complexes has a much stronger inhibition on Escherichia coli than ligand and metal salts.The enhance of the inhibition related the coordination of ligand and meta salts,both oh them shown the inhibition on Escherichia coli, stronger than singal ligand or metal salt.