title: The interesting DNA-binding properties of three novel dinuclear Ru(II) complexes with varied lengths of flexible bridges.
abstract: Three binuclear Ru(II) complexes with two [Ru(bpy)(2)(pip)](2+)-based subunits {where bpy=2,2'-bipyridine and pip=2-phenylimidazo[4,5-f][1,10]phenanthroline} being linked by varied lengths of flexible bridges, were synthesized and characterized by (1)H NMR, elemental analysis, UV-visible (UV-vis) and photoluminescence spectroscopy. The structures of the three complexes were optimized by density functional theory calculations. The interaction of the complexes with calf thymus DNA was investigated by UV-vis and luminescence titrations, steady-state emission quenching by [Fe(CN)(6)](4-), DNA competitive binding with ethidium bromide, DNA melting experiments, and viscosity measurements. The experimental results indicated that the three complexes bound to the DNA most probably in a threading intercalation binding mode with high DNA binding constant values three orders of magnitude greater than the DNA binding constant value reported for proven DNA intercalator, mononuclear counterpart [Ru(bpy)(2)(p-mopip)](2+) {p-mopip=2-(4-methoxylphenyl)imidazo[4,5-f][1,10]phenanthroline}.
authors.affiliation: College of Chemistry, Beijing Normal University, Beijing, China.
authors.forename: Chuan-Chuan
authors.initials: CC
authors.lastname: Ju
authors.forename: An-Guo
authors.initials: AG
authors.lastname: Zhang
authors.forename: Chui-Li
authors.initials: CL
authors.lastname: Yuan
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Zhao
authors.forename: Ke-Zhi
authors.initials: KZ
authors.lastname: Wang
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry*; D001665:Binding Sites; D002413:Cations, Divalent; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D008163:Luminescent Measurements; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D010618:Phenanthrolines / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013057:Spectrum Analysis; D014783:Viscosity
chemical_list: D002413:Cations, Divalent; D009942:Organometallic Compounds; D010618:Phenanthrolines; D015082:2,2'-Dipyridyl; D012428:Ruthenium; D004247:DNA