Synthesis, Crystal Structure And DNA Binding Properties Of Three Kinds Of Pyridine-based Transition Metal Complexs

As the most important genetic substance in organisms, deoxyribonucleic acid （DNA）plays a key role at the process of storing, copying and transmitting gene messages. Researchof the genetic material-DNA has always been one of the most important issues in the field oflife sciences. For the purpose of exploring the structure and function of DNA, scientists hasbeen designing and synthesizing different kinds of DNA targeted small molecules compound,for example transition metal complexs, then investigate the binding properties between them,which will help us deepening the understanding of the life phenomenon essence from themolecular level. Those theoretical research results can help people explore the mechanism ofsome certain diseases from gene level, which providing the guidance function in newpharmaceuticals development, design and screening. This instructional function showimportant theoretical significance and application value in the fields of molecular biology,bio-engineering and some other related field.The main line of this thesis is developing new transition metal complexs by the methodof coordinating three different transition metal copper, cobalt and iron with good planimetricpyridines ligands. Then those complexs structure were characterized by the measure of X-raydiffraction, Elemental analysis and infrared spectrum, and the binding properties of DNAwere carried out in methods of ultraviolet spectra, fluorescence spectrum, electrochemistry,viscosity and gel electrophoresis. This thesis is consist of the following four parts.Part one: We focused on introducing some useful information of DNA structure, mainmechanism between DNA with metal complex, and some familiar methods used in DNAbinding research were also been provided. At the same time, research progress of metalcomplex was also summarized in this thesis. Finally, we emphasize the significance of thisresearch.Part two: A kind of mononuclear copper（Ⅱ） complex [Cu（PC）₂]·H₂O with thepyridine-2-carboxylate （PC） ligand was synthesized. The structure of the complex had beensystematically characterized by X-ray crystallography, elemental analysis and infraredspectrum. At the same time, ultraviolet spectra, fluorescence spectrum, and viscositymeasures were used to study the interaction of complex with Herring sperm DNA.Furthermore, the cleavage activity of copper（Ⅱ） complex to pBR322DNA under thepresenting of ascorbic acid used as reducing reagent was investigate in the Agarose gel electrophoresis experiment. Those results indicated this copper（Ⅱ） complex could bind toDNAwith intercalative mode, and exhibited biological activity of cleavage DNAcapability inthe present of ascorbic acid.Part three: A novel mononuclear ternary cobalt（Ⅱ） complex containing mixed-ligands ofglycollic acid （GA） and1,10-phenathroline （phen）,[Co（GA）₂（phen）]·2H₂O was synthesizedand its structure was characterized by IR, element analysis and X-ray diffraction methods.Crystal date suggested that the complex crystallizes in monoclinic system, space group C2/c.The central cobalt（Ⅱ） ion was corordinated with two GA and one phen ligands, displaying adistorted octahedron coordination geometry. The interaction of the complex with DNA wasinvestigated by electronic absorption spectroscopy, fluorescence spectroscopy and viscositymethods. All the results revealed that the cobalt（Ⅱ） complex could interact with DNA via atypical intercalation mode with the binding constant of3.8×104L/mol. Agarose gelelectrophoresis assays further showed that [Co（GA）₂（phen）]·2H₂O showed cleavage abilitytowards supercoiled plasmid pBR322DNA in the presence of H₂O2, exhibiting an artificialnuclease activity.Part four: Mixed valence state iron complex [Fe^Ⅱ（phen）₂][Fe^Ⅲ（PDC）₂]2containingligands of2,6-Pyridinedicarboxylic acid （PDC） and1,10-phenathroline （phen） had beensynthesized. And the structure of complex was measured by IR spectrum, Elemental analysisand X-ray diffraction crystallography. The crystal date indicated that iron complex was makeup of one [Fe^Ⅱ（phen）₂2]+cation and two [Fe^Ⅲ（PDC）₂]-anion. The mechanism of theinteraction between complex and DNA had been studied by electronic absorption spectrum,competitive ethidium bromide （EB） fluorescence spectrum and electrochemistry experiments.The achieved results revealed that the binding mode of complex and DNA was complicated,and the most probability mode was intercalation mode accompanied by electrostatic bonding.In addition, complex exhibited different enrichment and dissociation process in the surface ofmodified electrode of ssDNA/GCE and dsDNA/GCE, which indicating the iron complexpossess the potentiality to be a electrochemically hybridization indicator.