INVESTIGADORES
CABRERIZO franco Martin
congresos y reuniones científicas
Título:
Photophysical properties of a novel Rhenium (I) tricarbonyl complex with norharmane as ligand
Autor/es:
I. MAISULS; P. DAVID-GARA; F. M. CABRERIZO; G. RUIZ
Reunión:
Encuentro; XII Encuentro Latinoamericano de Fotoquímica y Fotobiología (XII ELAFOT); 2015
Resumen:
β-carbolines are a group of naturally occurring alkaloids derived from9H-pyrido[3,4-b]indole or norharmane (nHo). These alkaloids are widespread inbiological systems, having an active role in different photosensitizing processes.Tricarbonyl rhenium complexes with polypyridyl and bioactive moleculesas ligands have an excellent thermal and photochemical stability being, thus,appealing candidates for diverse applications such as photodynamic therapy.We show herein preliminary results aboutemission 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 thespectra, lmáx ~ 247and 308 nm. Thesespectral features are almost identical with those found in the electronicspectrum of the free nHo ligand and are therefore assigned to p-p* excitations in the nHo ligand. Theabsorption band observed in the visible region exhibit typically intense andsolvatochromic MLCT transitions from the metal dp to the lowest lying ligand p* orbital.Emission spectrum of the complex, recorded in methanol, shows an emitting bandat ~ 450 nm due to the deactivation ofthe lower p-p* nHo ligand-localizedstate, as it was described for free nHo. Emission from MLCTRe→bpyexcited state have been observed in 530-560 nm range. Moreover, the observed luminescenceshows a strong dependence on the oxygen concentration. Both emission quantum yield and lifetime values, obtained in all solvents tested, are compared with thosereported for free nHo.The absorption patterns of the transient were registered by laser flashphotolysis experiments, lexc = 351 nm. The absorption spectra in MeOH of the transient in N2atm. showed a maximum at 370 nm and a lifetime of ~ 125 ns. The redox activity of the exited state was measured by reductivequenching using TEA. Additionally, the efficiency of singlet oxygen productionwas determined in acetonitrile.