Theoretical Studies On The Interaction Properties Of Series Of Ru (Ⅱ) Polypyridyl Complexes With DNA

During the past decades, many Ru(II) complexes with polypyridyl ligandshave received widely attentions because of their superior performance in anticancer drugs.The earliest research is mature Ru(II) complex [Ru(bpy)2(dppz)]2+interacting with DNA,and large numbers of new Ru(II) complexes were obtained by changing the main ligand orancillary ligands of the complex. Moreover, these complexes have been synthesized andcharacterized experimentally, and much time and money is cost. If the DNA-interactionproperties of complexes will be predicted firstly, the complexes with poor performanceshould not be studied experimentally. Therefore, theoretical studies of interactions betweencomplexes and DNA will lay an important significance.(1)Theoretical studies of the electronic structures, DNA-photocleavage and spectralproperties of a series of Ru (II) polypyridyl complexes1-3[Ru(bpy)2(ddt)]2+,[Ru(bpy)2(dta)]2+and [Ru(bpy)2(dpt)]2+have been carried out using the density functionaltheory. The trend in the photocleavage abilities of these complexes was reasonablyexplained by their excited-state redox potentials. The complex4[Ru(bpy)2(dph)]2+with ahigher excited-state reductive potential was designed based on the electronic-structureproperties of complexes1-3, and the complex4with stronger DNA-photocleavage abilitywas predicted. The calculated absorption spectra of these complexes are in satisfyingagreement with the experimental ones. Moreover, the intense experimental absorptionbands of these complexes are theoretically explained in detail and the effect of the mainligands on the electronic absorption spectra was also investigated.(2)Theoretical studies of the DNA-binding properties, spectral properties andDNA-photocleavage properties of Ru (II) polypyridyl complexes1-3[Ru(bpy)2(PRIP)]2+、[Ru(dmb)2(PRIP)]2+and [Ru(phen)2(PRIP)]2+have been carried out using the densityfunctional theory. The conclusions show the following:(1) The larger the conjugated areaof the ancillary ligands of complexes possesses, the stronger the DNA-binding affinitiesare. With the great steric hindrance of ancillary ligands, the complexes can only partiallyinsert into the DNA base-pairs, leading to the affinities of complexes binding to DNAreduced.(2) There is some relationship between the position of the maximum absorption peak in the range of200-300nm and the affinities of complexes binding to DNA, themaximum absorption wavelength will blue shift when the bingding affinity increases.(3)Based on their excited-state reduction potentials and reorganization energies, a preliminaryconclusion can be drawn that the effect of ancillary ligand on the photocleavage abilitiy isconsistent with that on the DNA-binding affinity.(3)Theoretical studies of the DNA-binding properties and spectral properties of Ru (II)polypyridyl complexes1-3[Ru(bpy)2(PRIP)]2+、[Ru(dmb)2(PRIP)]2+and[Ru(phen)2(PRIP)]2+with intramolecular hydrogen bonds have been carried out using thedensity functional theory. The conclusions show the following:(1) The formation of theintramolecular hydrogen bond in the main ligand can increase the conjugated plane area,and thus enhance the DNA-binding affinity.(2) The computed electronic absorptionspectra in aqueous solution of complexes1-3using the TDDFT method have a goodaggrement with the experimental results(4)Theoretical studies of the DNA-binding properties of two series of Ru (II)polypyridyl complexes1-4[Ru(bpy)2(ipbp)]2+,[Ru(phen)2(ipbp)]2+and[Ru(bpy)2(actatp)]2+,[Ru(phen)2(actatp)]2+have been carried out using the densityfunctional theory. The conclusions show the following:(1) when the conjugated plane areaof main ligand is not too large, the larger the conjugated plane area of the ancillary ligandis, the stronger the DNA-binding affinity is.(2) When the conjugated plane area of themain ligand is too large, the larger the conjugated plane area of the ancillary ligand is, theweaker the affinity of DNA-binding is.(3) The effect of the main ligand on theDNA-binding affinity is stronger than that of the ancillary ligand.