Photophysical properties of [(norharmane)Re(CO)3(L)]+ complexes (L = bpy, phen or dppz). Redox behavior of the excited states and their interaction with Calf Thymus DNA

LAPPIN, ALEXANDER G.; MAISULS, IVÁN; RUIZ, GUSTAVO T.; MAISULS, IVÁN; RUIZ, GUSTAVO T.; CABRERIZO, FRANCO M.; FERRAUDI, GUILLERMO J.; CABRERIZO, FRANCO M.; FERRAUDI, GUILLERMO J.; LAPPIN, ALEXANDER G.

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2018 vol. 364 p. 169 - 176

1010-6030

The photochemical and photophysical properties of [(nHo)Re(CO)3(L)]+ complexes, where nHo = 9H-pyrido[3,4-b]indole and L = 2,2´ bipyridine (bpy), 1,10 phenantroline (phen) or dipyridil[3,2- a:2´3´-c]phenazine (dppz) were investigated by Laser Flash Photolysis (LFF) and Pulse Radiolysis (PR) techniques. While complexes with L = bpy or phen show  absorption transients compatible with MLCT(Re-->L) excited states, [(nHo)Re(CO)3(dppz)]+ showed an excited state assignable to a dppz-centered, 3pi-pi*dppz. In aqueous solutions, the last complex does not generate any absorptiontransient. However, when Calf thymus DNA was added, the same absorption spectrum was obtained. These results suggest that this complex can intercalate into DNA. The species generated in either reductive or oxidative conditions in LFF experiments were compared with those obtained in PR. Also, the quenching rate constants (kq) of the excited states with MV2+ were calculated. The intercalation of the [(nHo)Re(CO)3(dppz)]+ into DNA, increases kq ~100 times. This result is rationalized in terms of the conditions created by the intercalation using the biopolymer as a wellorganized matrix.