Ruthenium(II) complex of Hbopip: synthesis, characterization, pH-induced luminescence "off-on-off" switch, and avid binding to DNA.
A novel ruthenium(II) complex of [Ru(bpy)2(Hbopip)](ClO4)2 (in which bpy=2,2'-bipyridine, Hbopip=2-(4-benzoxazolyl)phenylimidazo[4,5-f][1,10]phenanthroline) was synthesized and characterized. The spectrophotometric pH titrations of the complex showed that it acted as a pH-induced luminescence "off-on-off" switch: a luminescence off-on switch with a luminescence enhancement factor of IpH=3.0/IpH=1.0=20 occurring over a narrow pH range of 1.00-3.00 plus a luminescence on-off switch with a luminescence enhancement factor of 3 over a pH range of 3.20-9.40. The excited-state ionization constant of the complex derived, pKa1*=3.06, is 1.36 pKa units greater than the ground-state pKa1=1.70, and pKa2*=5.01 and pKa3*=8.22 are comparable to the ground-state pKa2=5.23 and pKa3=8.22, respectively. The complex avidly bound to calf thymus DNA with a large binding constant of (1.2+/-0.3)x10(7) M-1 in buffered 50 mM NaCl, as evidenced by UV-vis and luminescence titrations, steady-state emission quenching by [Fe(CN)6]4-, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments.
Han
Mei-Jiao
MJ
Department of Chemistry and Key Laboratory of Radiopharmaceuticals, Ministry of Education, Beijing Normal University, Beijing 100875, China.
Gao
Li-Hua
LH
Lü
Yuan-Yuan
YY
Wang
Ke-Zhi
KZ
D001667:Binding, Competitive; D002021:Buffers; D004247:DNA / Q000737:chemistry*; D004996:Ethidium / Q000737:chemistry; D005292:Ferricyanides / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007364:Intercalating Agents / Q000138:chemical synthesis*; D049449:Luminescence; D008163:Luminescent Measurements; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D017975:Ruthenium Compounds / Q000138:chemical synthesis*; D012965:Sodium Chloride / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D014783:Viscosity
C513694:(Ru(bpy)2(Hbopip))(ClO4)2; D002021:Buffers; D005292:Ferricyanides; D007364:Intercalating Agents; D009942:Organometallic Compounds; D017975:Ruthenium Compounds; D012965:Sodium Chloride; D004247:DNA; C427203:calf thymus DNA; D004996:Ethidium