Synthesis, Crystal Structure And Interaction With Ct-DNA Of Copper, Nickel Complexes With Benzimidazole

Deoxyribonucleic acid （DNA） is an important macromolecule in organism, it hasgreat significance in the Heredity and Variation for all life. The interaction of smallmolecules and DNA is an important research topic in life science, biochemistry andmedicine; it can not only clarify drugs mechanism of action, but also can providetheoretical direction for the design of drugs.Benzimidazole is one of heterocyclic compounds with π–π conjugate, which hasbeen widely used in medicine, biological chemistry and analytical chemistry becauseof the high affinity effect to the DNA sequence and has the biological activity ofantiseptic and anti-viral. The transition metal complexes of Benzimidazole exist in avariety of important biological molecules which form coordinations withhistidine imidazole nitrogen and metal ion, such as Urease, Tyrosinase, AscorbateOxidase and Superoxide Dismutase, these enzymes play an important rolein the metabolism of life. So the research of the interaction between transition metalcomplexes of Benzimidazole and DNA has important theoretical significancefor the synthesis and development of efficiency and low toxicity of drugs.In this paper the research work mainly includes the following aspects:1. The complex of [Cu （IDB） Cl₂] CH₃OH （1） has been synthesized and thecrystal structure has been determined by single crystal X–ray diffraction. The Crystalstructure analysis shows that the complex （1） belongs to Orthorhombic system withspace group Pbca, a=1.36957（16） nm, b=1.42730（16） nm, c=1.8331（2） nm, α=β=γ=90°, Z=8, the final R1=0.0412，wR2=0.0903. The five–coordinate copper （II） isa distorted square pyramid with three nitrogen atoms of the ligand （IDB） and twochlorine ions.2. The complex of [Ni （EDTB）]2（ClO₄）2CH₃CH₂CH₂CH₂OH （2） has beensynthesized and the crystal structure has been determined by single crystal X–raydiffraction. The Crystal structure analysis shows that the complex （2） belongs toTriclinic system with space group Pī, a=1.02297（12） nm, b=1.28181（15） nm,c=1.8530（2） nm, α=72.470°, β=77.400°, γ=81.603°, Z=2. The nickel （II） ion formed six-coordinated and distorted octahedral coordination geometry, which is coordinatedwith two amine nitrogen atoms [N （1）, N （2）] and four nitrogen atoms [N（3）, N（5）,N（7）, N（9）] of benzimidazole groups from the ligand EDTB.3. The interaction of complexes [Ni （IDB）2][C6H4（OH） COO] ClO4CH3CH2OH H2O （3） and [Ni （EDTB）] Cl₂3CH₃CH₂OH2H₂O （4） with ct–DNAhad been investigated by UV–visible spectra and fluorescence spectra at thephysiological conditions. The binding constant （Kb） and the binding stoichiometry （n）of the [Ni （IDB）₂][C₆H₄（OH） COO] ClO4CH₃CH₂OH H₂O （3） to ct–DNA werecalculated from fluorescence spectra at different temperatures. The binding mode ofthe interaction between complexes （3） and （4） and ct–DNA were obtained fromEthidium Bromide （EB） competitive experiment. The absorbance of complexes （3）and （4） descend with increasing concentration of ct–DNA. These results indicatedthat the complexes could bind to ct–DNA by intercalation.