Di-nuclear {(NN)(CO) _(3) Re} _(2) ( trans -bpe)(PF _(6) ) _(2) complexes, NN = 4,7-diphenyl-1,10-phenanthroline (ph _(2) phen) or 4,7-dichloro-1,10-phenanthroline (Cl _(2) phen) and trans -bpe = trans -1,2-bis(4-pyridyl)ethylene, were synthesized and characterized by ~(1) H NMR and UV-visible spectroscopy. Irradiation of acetonitrile solutions led to ~(1) H NMR and UV-visible spectral changes ascribed to trans -to- cis photoisomerization processes showing that the presence of another Re( I )-moiety does not preclude the photoisomerization process. Quantum yields for the di-nuclear isomerization of {(ph _(2) phen)(CO) _(3) Re} _(2) ( trans -bpe) ~(2+) were higher than those for the corresponding mono-nuclear compound process. Additionally, the higher quantum yield obtained with 254 nm irradiation for {(Cl _(2) phen)(CO) _(3) Re} _(2) ( trans -bpe) ~(2+) showed, for the first time, that the singlet pathway could also be accessed in addition to the usually observed triplet one. The luminescence in fluid solution observed for the {(NN)(CO) _(3) Re} _(2) ( cis -bpe) ~(2+) complexes is able to efficiently photosensitize the generation of singlet O _(2) .
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