Electrochemical and electrogenerated chemiluminescent studies of a trinuclear complex, [((phen)2Ru(dpp))2RhCl2]5+, and its interactions with calf thymus DNA.
The electrochemical behavior of a trinuclear ruthenium(II)-containing complex, [((phen)(2)Ru(dpp))(2)RhCl(2)](5+) (where phen = 1,10-phenanthroline, dpp = 2,3-bis(2-pyridyl)pyrazine), was studied in acetonitrile (MeCN) and aqueous solutions. In MeCN containing 0.10 M tetra-n-butylammonium perchlorate (TBAP), the complex displayed a reversible, overlapping Ru(II/III) redox process with E(1/2) = +1.21 V vs Ag/Ag(+) (10 mM), an irreversible reduction of Rh(III/I) at -0.73 V vs Ag/Ag(+), and two quasi-reversible dpp/dpp(-) couples with E(1/2) = -1.11 and -1.36 V vs Ag/Ag(+) at a Pt electrode with a scan rate of 50 mV s(-1). In 0.20 M Tris buffer solution (pH 7.4), an irreversible, overlapping Ru(II/III) oxidation at +1.48 V vs Ag/AgCl (3 M KCl), and an irreversible reduction of Rh(III/II) at -0.78 V vs Ag/AgCl were observed at a glassy carbon electrode with a scan rate of 50 mV/s. Investigations on the electrogenerated chemiluminescence (ECL) of the complex revealed that 2-(dibutylamino) ethanol (DBAE) was superior to tri-n-propylamine (TPrA) as an ECL coreactant within their entire concentration range of 10-100 mM in MeCN, and in aqueous media, as low as 1.0 nM of the complex can be detected using TPrA coreactant ECL. A maximum ECL emission of 640 nm, which is about 55 nm blue shift to its fluorescence, was observed in MeCN with DBAE as a coreactant. Interactions of the complex with calf thymus DNA (ctDNA) were conducted with a flow-cell based quartz-crystal microbalance, and a binding constant of 2.5 x 10(5) M(-1) was calculated on the basis of the Langmuir isotherm equation.
Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg, Mississippi 39406, USA.
Shijun
S
Wang
Jenifer
J
Milam
André C
AC
Ohlin
Varma H
VH
Rambaran
Eva
E
Clark
Woodrow
W
Ward
Luke
L
Seymour
William H
WH
Casey
Alvin A
AA
Holder
Wujian
W
Miao
D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D053837:DNA Cleavage; D004563:Electrochemistry / Q000379:methods*; D007700:Kinetics; D008163:Luminescent Measurements / Q000379:methods*; D009942:Organometallic Compounds / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D012238:Rhodium / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
D009942:Organometallic Compounds; D012428:Ruthenium; D004247:DNA; C427203:calf thymus DNA; D012238:Rhodium