title: [Photoinduced electron transfer between [Ru(bpy)3]2+ and copper(II) ion in composite films mediated by DNA].
abstract: An orange-red [Ru(bpy)3]2+ -DNA-CU2 composite film (bpy = 2,2'-bipyridine) was fabricated on an indium-tin (ITO) surface based on electrostatic interactions among [Ru(bpy)3]2+, DNA and Cu2+ by using self-standing cast methods. The photoinduced electron transfer (PET) properties of the resultant composite film mediated by DNA were studied by means of steady-state and time-resolved fluorescence spectroscopy, UV-visible absorption spectroscopy, fluorescence microscopic imaging and scan electron microscopy. The [Ru(bpy)3]2+ -DNA-Cu2+ composite film with molar ratio of 10:20:1 shows an obvious absorption band (450 nm) and an intense emission peak (lamda(em) = 595 nm), whose emission exhibits a single-exponential decay with tau = 188.6 ns and is quenched by Cu2+ via DNA-mediated PET mechanism, indicating that the quenching constant is 6.94 x 10(3) L x mol(-1) and quenching rate constant is 3.80 x 10(10) L x mol(-1) x s(-1). The increasing molar ratio of Cu2+ in composite films (10-fold) leads to an 11 nm blue-shift of the emission peak, which is dramatically weakened by Cu2+ via a static quenching mechanism. In addition, compared with the emission quenching of DNA-[Ru(bpy)2 (tatp)]2+ (tatp = 1, 4, 8, 9-tetra-aza-triphenylene) tuned by Cu2+, which is present either in solutions or in composite films, Cu2+ only quenches the emission of [Ru(bpy)3]2+ bound to DNA via an electrostatic interaction mode in composite films.
authors.affiliation: School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China. zhenshen046@sina.com
authors.forename: Zhen-shen
authors.initials: ZS
authors.lastname: Jiang
authors.affiliation: School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China.
authors.forename: Min-jian
authors.initials: MJ
authors.lastname: Chen
authors.affiliation: School of Chemistry and Environment, South China Normal University, Guangzhou 510006, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Li
mesh_terms: D015082:2,2'-Dipyridyl; D003300:Copper / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D004579:Electron Transport; D004583:Electrons; D009942:Organometallic Compounds; D012428:Ruthenium / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D009942:Organometallic Compounds; D015082:2,2'-Dipyridyl; D003300:Copper; D012428:Ruthenium; D004247:DNA