title: pH- and DNA-induced dual molecular light switches based on a novel ruthenium(II) complex.
abstract: A novel Ru(II) complex, [Ru(bpy)(2)(btppz)]Cl(2), where bpy=2,2'-bipyridine and btppz=benzo[h]tripyrido[3,2-a:2',3'-c:2'',3''-j]phenazine, has been synthesized and characterized. The pH effects on UV-visible (UV-vis) absorption and emission spectra of the complex have been studied and ground- and excited-state ionization constants of the complex have been derived. The calf thymus DNA (ct-DNA) binding properties of the complex were investigated with UV-vis absorption and luminescence spectrophotometric titrations, steady-state emission quenching by [Fe(CN)(6)](4-), DNA competitive binding with ethidium bromide, DNA melting experiments, reverse salt titrations and viscosity measurements. The complex was demonstrated to act as dual molecular switches: pH-induced "on-off" emission switch with an on-off intensity ratio of approximately 54 which is favorably compared with those reported for structurally analogous Ru(II) complexes, and a DNA molecular light switch with a luminescence enhancement factor of 22 as it intercalatively bound to the DNA.
authors.affiliation: College of Chemistry and Key Laboratory of Radiopharmaceuticals, Ministry of Education, Beijing Normal University, Beijing 100875, China.
authors.forename: Yan-Min
authors.initials: YM
authors.lastname: Chen
authors.forename: Yan-Ju
authors.initials: YJ
authors.lastname: Liu
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.forename: Ke-Zhi
authors.initials: KZ
authors.lastname: Wang
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D006575:Heterocyclic Compounds, 3-Ring / Q000138:chemical synthesis / Q000737:chemistry*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000138:chemical synthesis / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D012428:Ruthenium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D006575:Heterocyclic Compounds, 3-Ring; D006576:Heterocyclic Compounds, 4 or More Rings; D012428:Ruthenium; D004247:DNA; C427203:calf thymus DNA