Study On The Synthesis And Biological Activity Of Pyridine Benzoic Acid Metal Complexes

The ligands of pyridine benzoic acid not only have a variety of coordination modelbut also have the potential biological activity, such as anticancer, antibacterial etc. Theatomic N and O bonded different metal ions in different modes. These ligands are used tosynthesize functional materials and active preparations. In our research, we choose4-Pyrid-3-ylbenzoic acid,5-(4-Pyridyl)-3-nitrobenzoic acid,5-(4-Pyridyl) isophthalic acid asligands. Eleven metallic complexes have been synthesized by the solve-thermal synthesisand hydrothermal method. Including3complexes based on5-(4-Pyridyl)-3-nitrobenzoicacid,5complexes built from4-Pyrid-3-ylbenzoic acid and3complexes based on5-(4-Pyridyl) isophthalic acid. These complexes were characterized by IR, elementalanalysis, thermogravimetric analyses and single crystal X-ray diffraction, in which theligands exhibit six coordination modes:(1) Connects one central ion via one carboxyl oxygen atom in mono-dentate，the other Oatom bonded one adjacent central ion in mono-dentate，so the carboxylic acid groupbridges two adjacent central ions.(complex2)(2) Connects two adjacent central ions via two carboxyl oxygen atoms in mono-dent ate.Another O atom from different carboxylic acid group bonded one central ion inmono-dent ate. In addition, monodentate coordination with one nitrogen from pyridinering.(complex3)(3) Connects two adjacent central ions via two carboxyl oxygen atoms in mono-dent ate,in addition, monodentate coordination with one nitrogen from pyridine ring.So threecenter ions are linked.(complex5,6)(4) Monodentate coordination with one nitrogen atom from pyridine ring and one carboxyloxygen atom.(complex7)(5) Chelates the central ion via two carboxyl oxygen atoms. Monodentate coordinationwith one nitrogen atom from pyridine ring.(complex8)(6) Chelates the central ion via two carboxyl oxygen atoms.Monodentate coordination withone nitrogen atom from pyridine ring. Two monodentate coordination with two Oatoms from another carboxylic acid group. So three center ions are linked.(complex10,11) The effects of complex2,3,5,8,10,11on the activity of alkaline phosphatase (AKP)of the mantle of Pinctada martensii were studied by complexes were used to affect themantlerespectively. The results showed that the activity of ALP was increased by complex3,8,10and11within certain range of concentrations, and the activity of ALP had reachedup to207.18%when the concentration of complex8was30μg/mL. While the activity ofALP was decreased by complex2and5, and the activity of ALP was only37.13%whenthe concentration of complex5was60μg/mL. According to the results, the effects ofcomplexes with the same structures and ligands on the activity of ALP varied for differentcenter ions. The biologic property of complex rest with the center metal ions and molecularstructure of it.The antibiotic activities of3ligands and8complexes were tested against Escherichiacoli, salmonella and Vibrio parahaemolyticus bacteria by the microplate method. Theresult shows that all complexes exhibit antibacterial activity under different concentrations.The comparative analysis shows the complex6has the highest inhibitory activeity againstEscherichia coli, salmonella and Vibrio parahaemolyticus when in78μg/mL,39μg/mL and78μg/mL. The asymmetric unit of complex6consists of two Co (II) ions, four ligands andtwo coordinate water molecules; each Co (II) center is hexa-coordinated with slightlydistorted octahedral coordination geometry. However, complex5with the same structure isweaker than complex6in antibiotic activity. Its inhibitory activity against Escherichia coli,salmonella and Vibrio parahaemolyticu when in312μg/mL,1250μg/mL and312μg/mL.The center ion of complex5is Cd. So different ions and different structuresdetermine antibiotic activities of complexes.