The pH-induced emission switching and interesting DNA-binding properties of a novel dinuclear ruthenium(II) complex.
A novel dinuclear Ru(II) complex, [(bpy)(2)Ru(ebipcH(2))Ru(bpy)(2)](ClO(4))(4), where bpy = 2,2'-bipyridine and ebipcH(2) = N-ethyl-4,7-bis([1,10]-phenanthroline[5,6-f]imidazol-2-yl)carbazole, has been newly synthesized. The pH effects on UV-vis absorption and emission spectra of the complex are studied, and ground- and excited-state ionization constants of the complex are derived. The binding of the complex to calf thymus (ct) DNA is investigated with absorption and luminescence titrations, steady-state emission quenching, and viscosity measurements. The complex acts as a pH-induced "on-off" emission switch between pH 8.0 and pH 10.0 with a maximum on-off ratio of approximately 100 which is favorably compared with the other imidazole-containing Ru(II) complex congeners, and a strong ct-DNA intercalator with an intrinsic binding constant of 1.31(+/-0.08) x 10(6) M(-)(1) in buffered 50 mM NaCl.
Liu
Furong
F
Department of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China.
Wang
Kezhi
K
Bai
Guangyao
G
Zhang
Yongan
Y
Gao
Lihua
L
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D009942:Organometallic Compounds / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D014783:Viscosity
D009942:Organometallic Compounds; D012428:Ruthenium; D004247:DNA; C427203:calf thymus DNA