Dimeric and pentameric adducts between a meso-40 pyridylporphyrin core and either one or four rhenium(I) bipyridine tricarbonyl units, fac-[Re(CO)3(bipy)(40MPyP)][CF3SO3] and fac-[{Re(CO)3(bipy)}4(40TPyP)][CF3SO3]4(40MPyP = 40-monopyridylporphyrin, 40TPyP = 40-tetrapyridylporphyrin), respectively, were synthesized and their photophysical behaviors were investigated by emission and absorption time resolved experiments. The adducts exhibit distinctive supramolecular features, different from those of the molecular components. Upon excitation of the core, the typical porphyrin fluorescence is quenched. This effect is attributed to enhanced intersystem crossing in the porphyrin unit, owing to the heavy atom effect provided by the attached rhenium unit(s). Following excitation of rhenium fragments the typical rheniumMLCTemission is not observed while partial sensitization of the porphyrin fluorescence occurs, indicating that fast intercomponent energy and/or electron transfer processes take place in competition with the intersystem crossing in the rhenium unit.
Energy transfer pathways in pyridylporphyrin Re(I) adducts
CHIORBOLI, Claudio;INDELLI, Maria Teresa;SCANDOLA, Franco;
2007
Abstract
Dimeric and pentameric adducts between a meso-40 pyridylporphyrin core and either one or four rhenium(I) bipyridine tricarbonyl units, fac-[Re(CO)3(bipy)(40MPyP)][CF3SO3] and fac-[{Re(CO)3(bipy)}4(40TPyP)][CF3SO3]4(40MPyP = 40-monopyridylporphyrin, 40TPyP = 40-tetrapyridylporphyrin), respectively, were synthesized and their photophysical behaviors were investigated by emission and absorption time resolved experiments. The adducts exhibit distinctive supramolecular features, different from those of the molecular components. Upon excitation of the core, the typical porphyrin fluorescence is quenched. This effect is attributed to enhanced intersystem crossing in the porphyrin unit, owing to the heavy atom effect provided by the attached rhenium unit(s). Following excitation of rhenium fragments the typical rheniumMLCTemission is not observed while partial sensitization of the porphyrin fluorescence occurs, indicating that fast intercomponent energy and/or electron transfer processes take place in competition with the intersystem crossing in the rhenium unit.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
