【作者】 帅丽；

【导师】 肖小明；

【作者基本信息】 湖南师范大学 ， 有机化学， 2006， 硕士

【摘要】 本文绪论简要介绍了过渡金属配合物及过渡金属多吡啶类配合物的研究意义、范围与发展趋势;小分子配合物与DNA作用的研究进展;2,6-二（苯并咪唑-2′）吡啶的研究进展等。 使用微波辐射合成2,6-二（苯并咪唑-2′）吡啶（H₂bzimpy）,并测得其晶体结构,重要晶体数据如下:a=1.8840（3）,b=1.8446（3）,c=1.03400（18）nm,β=104.818（3）°,Z=4,V=3.4739（10）nm³。 在室温下测试了四种不同有机溶剂中DNA与H₂bzimpy相互作用的荧光光谱。结果表明,在DMF（N,N-二甲基甲酰胺）和甲醇中,H₂bzimpy的荧光强度随着DNA量的增多而显著增强,这是由于平面构型的H₂bzimpy插入DNA分子沟槽中,免受游离水分子的荧光猝灭作用,H₂bzimpy荧光强度增强。然而,丙酮和乙腈这两种溶剂使DNA整体外形结构变短,DNA分子收缩至球形,最终DNA的构象由B型向A型转变,阻止H₂bzimpy插入DNA分子中,H₂bzimpy被游离的水分子猝灭,荧光强度降低。 使用红外、核磁、元素分析等手段对[Eu（H₂bzimpy）（Hbzimpy）（NO₃）]（NO₃）、[Dy（Hbzimpy）₂]（NO₃）进行表征。从紫外光谱、荧光光谱和黏度三方面研究了这两种配合物与DNA作用。紫外光谱实验中,两种配合物与DNA作用时吸收强度都减少,吸收峰没有发生明显红移。其中,随着DNA量的增多,[Eu（H₂bzimpy）（Hbzimpy）（NO₃）]（NO₃）荧光强度明显减弱,DNA溶液黏度随着[Eu（H₂bzimpy）（Hbzimpy）（NO₃）]（NO₃）/[DNA]的增大而减少。[Dy（Hbzimpy）₂]（NO₃）荧光强度随着DNA量的增多而升高。荧光猝灭实验表明,DNA对[Dy（Hbzimpy）₂]（NO₃）的发射荧光具有保护作用,更多还原

【Abstract】 In this paper, the meaning and future of transition metal complexes and polypyridyl transition metal complexes, the development of small complexes binding with DNA and the studying of 2,6-bis（benzimidazol-2-yl）pyridine （H2bzimpy） have been discussed.H₂bzimpy has been synthesized rapidly by microwave irradiation and characterized by single crystal X-ray diffraction. It crystallizes in the monoclinic system, with space group P2₁/c. The lattice parameters are: a =1.8840（3）, b =1.8446（3）, c=1.03400（18） nm, β=104.818（3） °, Z=4, V=3.4739（10）nm³.The luminescence intensity of H₂bzimpy exhibits an obvious enhancement when DNA is added in the solvent of DMF and methanol. However, the luminescence intensity decreases when DNA is added in the solvent of acetone and CH₃CN. The distance between both neighboring base plans decreases in acetone and CH3CN. And DNA shrinks further. Finally, the conformation of DNA historians formed from B form to A form. Although the conformation of DNA changes in organic solvents, it does not denatured or dehelix.The coordination compounds of Eu（Ⅲ） and Dy（Ⅲ） with 2,6-bis（benzimidazol-2-yl）pyridine were synthesized and characterized by NMR, infrared spectroscopy and elemental analysis etc. And the binding of Eu（Ⅲ） and Dy（Ⅲ） complexes with calf thymus DNA have also been investigated by absorption, luminescence titration and viscosity measurements. The Eu（Ⅲ） complex [Eu（H₂bzimpy）（Hbzimpy）（NO₃）] （NO₃）, where H₂bzimpy is a planar ligand with an extended aromatic system, has been found to bind to DNA with an apparent binding constant of （2.08 ±0.02）×10⁴ mol^-1.L. The effect of [Eu（H₂bzimpy）（Hbzimpy）（NO3）]（NO3） on the viscosity of DNA clearly shows that the Eu（III） complex partly intercalate into the DNA base pairs. The result of absorption titration indicates that the complex binds to DNA with moderate strength. Fluorescence study shows that the fluorescence intensity of the complex decreases with increasing concentrations of DNA, which is due to the photoelectron transfer. The salt effect of Eu（III） complex shows that it doesn’t bind with DNA by surface banding. The experimental results show that Eu（III） complex could partly intercalates into DNA base pairs via the ligand H2bzimpy. To the Dy（III） complex, [Dy（Hbzimpy）2]（NO3）, absorption titration shows that the complex binds to DNA with an apparent binding constant of （3.74±0.02）X 104 mol’1 ? L. The experiment results of fluorescence study viscosity measurements and salt effects of Dy（III） complex indicate that this complex bind to DNA through a partial intercalative mode, which is the same with Eu（III） complex. In summary, the results show that Dy（III） complex also could partly intercalates into DNA base pairs via the ligand H2bzimpy.In addition, the UV spectra and fluorescence spectra of H2bzimpy and [Dy（Hbzimpy）2]（NO3） are very sensitive to solution pH, especially for the complex of Dy （III）. Since the complex acts as dibasic acids, in which N-H protons on benzimidazole moieties are responsible for a deprotonation site. Both reduction potentials are strongly dependent on the solution pH, which leads to the basis of a proton-induced molecular switch. In inverse, the deprotonation of N-H protons can influence the electric charge distribution, electrochemical behavior and spectra property.更多还原