The Nucleic Acid-binding Mechanism And Spectronic Properties Studies Of Ruthenium(Ⅱ) Polypyridyl Complexes

There are two kinds of nucleic acids, which are DNA and RNA. They play an important role in the process of life, responsible for the inheritances. However, their damage or mismatch can lead to all kinds of diseases. Scientists have done their efforts to find out new kinds of agents against cancers since they find cis-platium has antitumor activities. Ruthenium(II) polypyridyl complexes have received a lot of attention owing to their lower toxicities and sensitivities for antitumor cancers. It is valuable and important to investigate their interaction with nucleic acids. The ruthenium(II) polypyridyl complexes are chiral and rigid and have a good planarity; they are chemically stable, though their photophysical properties are sensible and tunable. In addition, they have characteristic MLCT absorption spectrum in the visual region; irradiated by the visible light, the excitated MLCT state mutate the basic state, maybe companying fluorescence at about the wavelength of 610 nm. Owing to these particular properties of the ruthenium(II) polypyridyl complexes, all kinds of methods can be utilized to investigate their nuclenic binding behavior.This paper consists of five chapters.Chapter 1 is the brief of the theory about the interaction of the ruthenium(II) polypyridyl complexes with nucleic acid and their application. In chapter 2, the ruthenium(II) polypyridyl complex [Ru(bpy)2(hnip)]2+ was synthesized and conformed its purity. Spectronic methods and viscosity methods were employed to study its interaction with DNA and tRNA comparatively. The results revealed that the structures of nucleic acids influence the binding behavior of the ruthernium(II) polypyridyl complexes. The antitumor activities of [Ru(bpy)2(hnip)]2+ against four chosen cancer cells were also investigated and it displayed different sensitivities for the chosen cancer cells.In chapter 3, the ruthernium(II) polypyridyl complexes [Ru(ip)2(mfip)]2+ and [Ru(ip)2(nfip)]2+ were synthesized. Spectronic methods and viscosity methods were utilized to investigate their interaction with DNA. The results revealed that the substituent group of the intercalative ligand is one of the important factors influencing interaction of the ruthenium(II) polypyridyl complexes with DNA.In chapter 4, [Ru(bpy)2(hnip)]2+ and [Ru(ip)2(mfip)]2+ as potential fluorescence switches were further investigated because of their special structures and tunable photophysical properties. We have found that the solvents, the oxygen molecular and pH all have effects on the spectronic properties of ruthenium(II) polypyridyl complexes. The addition of Fe3+,Cu2+ and Zn2+ hardly change the fluorescent intensity of [Ru(bpy)2(hnip)]2+; on the other hand, the addition of Co2+ can partly quench the fluorescence of [Ru(bpy)2(hnip)]2+, then its fluorescence was recovered again after adding EDTA. We made our efforts to carry out pH-induced electronic absorption or fluorescence titration of [Ru(ip)2(mfip)]2+ which contains three imidazole rings. It seemed that [Ru(ip)2(mfip)]2+ had undergone three successive deprotonation processes. According to the fuction of pH and the max absorbance of a certain wavelength or the max fluorescent intensity, the three basic ion constants and the three excited ion constants were derived.