Chiral Iron Complexes: Syntheses, Structures And Interaction Of DNA

The phenomenon of chiral has great significance in organisms. The amino acids thatcomposed the life on earth are all right-handed. Studies found that chiral molecule has avery special role in life activities. The successful development of cisplatin anticancer drugmakes the organism role of chiral metal complex in biological processes been widly noted.In recent years, use chiral molecules interact with DNA research system as study of genetherapy has broad prospects. In this article we use multiple detection methods to studysingle-core and dual-core metal iron and nickel complexes of chiral recognition withct-DNA, and hope to provide a theoretical basis and experimental evidence for futureresearch of the efficient anti-cancer drugs. This thesis is divided into four parts.（1）Respectively reaction of （S or R）^-1-（1-naphthyl）ethamine,（S or R）^-1-（2-naphthyl）ethamine and （S or R）--methylbenzylamine with2-Pyridylaldehyde weobtained three pure Schiff base ligands. By mixing the ligands with Fe（ClO4）2three pairsof iron（II） chiral enantionmers were synthesized（1R and1S、2R and2S、3R and3S）. Thesecomplexes were characterized by elemental analyses, IR, and1H NMR methods.Furthermore, single crystal X-ray diffraction analysis was performed to confirm itsgeometry in which the iron center has been shown to be six-coordinate with an octahedralgeometry. Complexes2R and3S formed Λ and Δ these two kinds of optical isomersrespectively.（2）Explored the enantioselective binding ability of the three pairs of iron（II） chiralenantionmers （1R and1S、2R and2S、3R and3S）with calf-thymus DNA （ct-DNA）. Themethods of UV-vis, fluorescence emission, and circular dichroism spectrometry showedthat all the complexes could bind to ct-DNA with groove binding mode and showeddifferent binding affinities. The binding constant ranging from4.5×10⁵to11×10⁵M^-1and showed good binding properties. The study also showed that Δ-enantiomers exhibitedmore efficient for DNAinteraction with respect to theΛ-enantiomers.（3）Designed and synthesized three pyridine schiff base（L4、L5、L6）, with theseschiff base we synthesized a series of bimetallic supramolecular complexes[M2（L）3][ClO4]4(L=L4、L5、L6; M=Fe²⁺, Ni²⁺). The structures of these supramolecularcomplexes were characterized by IR, EIS-MS and1H NMR methods. The result showedthat these complexes are all binuclear three ligands configuration. The further molecularcomputing simulation showed that the conplexes Fe₂（L4）₃、Fe₂（L5）₃and Fe₂（L6）₃are allcolumnar structures and all with size bigger than2nm. Among them complex Fe₂（L4）₃ismeso configuration, Fe₂（L5）₃with the configuration of rac, and the configurations of twometal coordination center for Fe₂（L6）₃were fac and mer respectively.（4）The binding ability of these supramolecular complexes with ct-DNA have beeninvestigated by means of UV/Vis spectroscopy, fluorescence spectroscopy, circulardichroism spectroscopy and gel electrophoresis assay. These complexes interact stronglywith ct-DNA in the major groove and induce its condensation at low concentration. The binding constants rang from2.68×107to5.3×10⁶M^-1. Results show that the Fe（II） centercomplex exhibit higher binding affinities than the Ni（II） center complex, the order ofbonding strength is Fe₂（L6）₃>Fe₂（L5）₃>Fe₂（L4）₃>Ni₂（L6）₃>Ni₂（L5）₃>Ni₂（L4）₃. It wasfound by circular dichroism experiment that DNA preferes to bind chiral selectively withthese columnar metal complexes. Through combination of specific chiral complexes newchiral signals will be observed in circular dichroism spectrum.