CIOP   05384
CENTRO DE INVESTIGACIONES OPTICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Photophysical properties of a novel Rhenium (I) tricarbonyl complex with norharmane as ligand
Autor/es:
MAISULS, IVÁN; CABRERIZO, FRANCO; DAVID GARA, PEDRO M.; RUIZ, GUSTAVO T.
Reunión:
Encuentro; XII Encuentro Latino Americano de Fotoquímica y Fotobiología; 2015
Resumen:
β-carbolines are a group of naturally occurring alkaloids derived from 9H-pyrido[3,4-b]indole or norharmane (nHo). These alkaloids are widespread in biological systems, having an active role in different photosensitizing processes. Tricarbonyl rhenium complexes with polypyridyl and bioactive molecules as ligands have an excellent thermal and photochemical stability being, thus, appealing candidates for diverse applications such as photodynamic therapy. We show herein preliminary results about emission spectroscopy and flash photolysis studies of a novel Re(CO)3(bpy)(nHo)+ in different solvents. UV-Vis absorption spectra show intense bands in the UV region of the spectra. These spectral features are almost identical with those found in the electronic spectrum of the free nHo ligand and are therefore assigned to IL excitations in the nHo ligand. The absorption band observed in the visible region exhibit typically intense and solvatochromic MLCT transitions from the metal d to the lowest lying ligand * orbital. Emission spectrum of the complex, recorded in methanol, shows an emitting band at ~ 450 nm due to the deactivation of the lower nHo ligand-localized state, as it was described for free nHo. Emission from MLCTRe→bpy excited state have been observed in 530-560 nm range. Moreover, the observed luminescence shows a strong dependence on the oxygen concentration. Both emission quantum yield and lifetime values, obtained in all solvents tested, are compared with those reported for free nHo. The absorption patterns of the transient were registered by laser flash photolysis experiments, exc = 351 nm. The absorption spectra in MeOH of the transient in N2 atm. showed a maximum in 370 nm and a lifetime of ~ 125 ns. The redox activity of the exited state was measured by reductive quenching using TEA. Additionally, the efficiency of singlet oxygen production was determined in acetonitrile .