title: Dual molecular light switches for pH and DNA based on a novel Ru(II) complex. A non-intercalating Ru(II) complex for DNA molecular light switch.
abstract: A new Ru(II) complex of [Ru(phen)(2)(Hcdpq)](ClO(4))(2) {phen = 1,10-phenanthroline, Hcdpq = 2-carboxyldipyrido[3,2-f:2',3'-h]quinoxaline} was synthesized and characterized. The spectrophotometric pH and calf thymus DNA (ct-DNA) titrations showed that the complex acted as a dual molecular light switch for pH and ct-DNA with emission enhancement factors of 17 and 26, respectively. It was shown to be capable of distinguishing ct-DNA from yeast RNA with this binding selectivity being superior to two well-known DNA molecular light switches of [Ru(bpy)(2)(dppz)](2+) {bpy =2,2'-bipyridine, and dppz = dipyrido-[3,2-a:2',3'-c]phenazine}and ethidium bromide. The complex bond to ct-DNA probably in groove mode with a binding constant of (4.67 ± 0.06) × 10(3) M(-1) in 5 mM Tris-HCl, 50 mM NaCl (pH = 7.10) buffer solution, as evidenced by UV-visible absorption and luminescence titrations, the dependence of DNA binding constants on NaCl concentrations, DNA competitive binding with ethidium bromide, and emission lifetime and viscosity measurements. To get insight into the light-switch mechanism, theoretical calculations were also performed by applying density functional theory (DFT) and time-dependent DFT.
authors.affiliation: College of Chemistry, Beijing Normal University, Beijing 100875, P.R. China.
authors.forename: An-Guo
authors.initials: AG
authors.lastname: Zhang
authors.forename: You-Zhuan
authors.initials: YZ
authors.lastname: Zhang
authors.forename: Zhi-Ming
authors.initials: ZM
authors.lastname: Duan
authors.forename: Ke-Zhi
authors.initials: KZ
authors.lastname: Wang
authors.forename: Hui-Bo
authors.initials: HB
authors.lastname: Wei
authors.forename: Zu-Qiang
authors.initials: ZQ
authors.lastname: Bian
authors.forename: Chun-Hui
authors.initials: CH
authors.lastname: Huang
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry* / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D008027:Light; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011789:Quantum Theory; D012428:Ruthenium / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D013237:Stereoisomerism; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D009942:Organometallic Compounds; D012965:Sodium Chloride; D012428:Ruthenium; D004247:DNA; C427203:calf thymus DNA