Intercalation of fac-(4,4’-bpy)ReI(CO)3(dppz)+, dppz = dipyridil[3,2-a:2’3’-c]phenazine, in polynucleotides. On the UV-vis photophysics of the Re(I) intercalate and the redox reactions with pulse radiolysis-generated radicals

G.T. RUIZ; M.P. JULIARENA; R.O. LEZNA; E.WOLCAN; M.R. FÉLIZ; G. FERRAUDI

JOURNAL OF THE CHEMICAL SOCIETY, DALTON TRANSACTIONS

Año: 2007 vol. 20 p. 2020 - 2029

0300-9246

Abstract The intercalation of fac-[(4,4´-bpy)ReI(CO)3(dppz)]+ (dppz = dipyridyl[3,2-a:2´3´-c]phenazine) in polynucleotides, poly[dAdT]2 and poly[dGdC]2, where A= adenine, G = guanine, C = cytosine and T = thymine, is a major cause of changes in the absorption and emission spectra of the complex. A strong complex–poly[dAdT]2 interaction drives the intercalation process, which has a binding constant, Kb ~ 1.8 × 105 M−1. Pulse radiolysis was used for a study of the redox reactions of e−aq, C•H2OH and N3• radicals with the intercalated complex. These radicals exhibited more affinity for the intercalated complex than for the bases. Ligand-radical complexes, fac-[(4,4´-bpy•)ReI(CO)3(dppz)] and fac-[(4,4´-bpy)ReI(CO)3(dppz•)], were produced by e−aq and C•H2OH, respectively. A Re(II) species, fac-[(4,4´-bpy)ReII(CO)3(dppz)]2+, was produced by N3• radicals. The rate of annihilation of the ligand-radical species was second order on the concentration of ligand-radical while the disappearance of the Re(II) complex induced the oxidative cleavage of the polynucleotide strand.