Synthesis And Properties Of Benzimidazole-Aromatic Acid Transition Metal Complexes

Aromatic acids and benzimidazole compounds can form complexes with transition metals.These complexes can be widely used in the fields of material chemistry,biochemistry and environmental chemistry because of thire diverse structures,good biological activities and electrochemical properties.Four transition metal complexes,Ni（bbp）SO₄（1）,Co（bbp）Cl₂（2）,Co（bia）（3）and Ni（bbop）（HO-bdc）（4）,weresynthesizedbythereactionsof1,3-bis（1H-benzo[d]-imidazol-1-yl）propane（bbp）,2-（benzimidazol-1-yl）-acetic acid（Hbia）,1,3-bis（benzimidazol-2-yl）-2-oxapropane（bbop）,5-hydroxyisophthalic acid（HO-H₂bdc）with several transition metal salts.The electrochemical properties of these four complexes were studied by cyclic voltammetry,and the results show that the electrochemical behaviors of four complexes in electrode are the irreversible 1e process.The oxidation peak currents of four complexes increased linearly with the scan rate,suggesting that the oxidation of complexes at the CPE is adsorption-controlled.The interaction of the four complexes with dsDNA and ssDNA were studied by ultraviolet-visible spectroscopy.The results showed that the interaction between four complexes and DNA might be all electrostatic.Among them,the interaction of both complexes Ni（bbp）SO₄（1）and Co（bia）（3）with ssDNA are obviously stronger than that of dsDNA.The hypochromic effect by ssDNA shows the complexes 1 and 3 could be used as a probe for recognition of ssDNA from dsDNA.DNA binding properties of four complexes were studied by UV-vis titration.The intrinsic binding constant K_b,determined from the absorbance data of the titration experiments,are 1.053×10³,4.156×10³,1.179×10³ and 3.574×10³ L·mol^-1,respectively.The slight structural differences of four complexes lead to the difference in the DNA binding and electrochemical properties of complexes.