Synthesis, Characterization And Mechanism Studies Of 2,2'-Biimidazole Metal Complexes With Efficient DNA Cleavage Activity

The 21st century is the century of life science. Molecular biology develops quickly and flourishingly in the extent and depth, promoting the progress of the power of our society at very fast speed. Accordingly, biology inorganic chemistry becomes one of the forward fields which have been studied actively. Nucleic acid, as the main compose of organism, is not only the carrier of inherit information of organism, but also the substance base of genie expression. The technique of rupture and gene recombine with nucleic acid is the core in the molecular biology and the gene engineering. However, artificial nuclease limits itself, though it is crucial in the technical of oriental cleavage. Thus, it is so important to explore metal complexes being artificial nucleases in the field of bioinorganic chemistry.2,2'-biimidazole(H2biim), as a bidentate chelating ligand with multi-proton donor sites, is able to coordinate to metals with three reversible types of protonated and deprotonated modes: neutral (H2biim), mono-deprotonated (monoanion, Hbiim-), and di-deprotonated (dianion, biim2-) types. The imidazole group of protein histidine residue has been demonstrated as an important binding site for a wide variety of metalioprotein. This kind of coordination is so significative for the functions of metalioprotein. Based on that, we attempt to find new effective cleavage regents by studying the biimidazole metal complexes.In this paper, a series of biimidazole metal complexes were synthesized and characterized with elemental analysis, infrared spectra and X-ray diffraction. We also studied their reaction with plasmid pBR322 DNA and the cleavage mechanism. The work mentioned below was carried out:1. Having summarized the actuality of the biimidazole complexes, we have synthesized many complexes and studied the biology activity firstly. In addition, it is still so significative in researching the structure speciality and coordination chemistry.2. Firstly, the biimidazole complexes of Cu Co Ni Mn were synthesizedand characterized. We obtained the crystal structure of Cu,.5Cl3(H2biim)2(l), [Co(H2biim)3](NO3)3 (2) and[Co(H2biim)2](NO3)2-2H2O(3).3. We have designed and synthesized the novel mix-coordinated complex of [CuCl(H2biim)(H2O)][Cu(ida)Cl]-H2O(4), and also obtained its crystal structure. The result shows that it belongs to triclinic, P-l group, a = 6.7053 (18)A, b=8.823(2)A, c=14.547(4)A, (3=101.316(3)°, y = 103.116(4)°, Z=2, Dx =2.020 Mg m-3. Within the cation, atom Cul is bonded to two atoms N of the 2,2'-biimidazole ligand, atom O of the aqua ligand and atom Cl, the coordinated atoms around Cul are coplanar. In the anion, atom Cu2 is coordinated by an O,N,O'-tridentate iminodiacetato ligand (with two deprotonated carboxylate groups) and atom C12, the coordinatedatoms and Cu2 are also coplanar. The cations and anions are arranged alternately and vertically along the a axis.4. Metal complexes were selected as the appropriate for the study of cleavage plasmid pBR322DNA by gel electrophoresis technique. The results showed complexes (4) could cleave DNA effectively in the presence of ascorbic acid at physiological pH and temperature, it could cleave the super-coiled DNA into nicked and linear DNA. Furthermore, we are studying the reaction mechanism that the Cu complex cleaves DNA.5. The l,l'-Dimethyl-2,2'-biimidazole (Dmbiim) were designed and synthesized because H2biim can't be dissolved the general solvents. Then, we got the crystal structure of Cu2[(Dmbiim)4H2O]- (C1O4)4-3H2O (5), it belongs to monoclinic, P21/n, a =10.160(2)A, b=12.991(3)A, c=20.646(4)A, p=101.43(3)°, Z=4, Dx=1.504 g cm"3. The whole crystal structure is like a cage with two copper atoms bridged by Dmbiim.6. Metal complex (5) was researched as the appropriate for the study of cleavage plasmid pBR322 DNA by gel electrophoresis technique. The results showed complexes (5) can effectively cleave DNA in the presence of ascorbic acid at physiological pH and temperature, it could...