Photoinduced Charge Separation in Arene-CO2-Re(CO)32,2’-bipyridine Complexes. Two Emitting Charge Transfer Excited States

G. TORCHIA; J. TOCHO; O. E. PIRO; P. JULIARENA; G. RUIZ; E. WOLCAN; M. R. FÉLIZ

Journal of Chemical Society, Dalton Transactions

Royal Society of Chemistry

Año: 2002 p. 2194 - 2202

Excited state properties of the newly prepared complexes R–CO2–Re(CO)3(2,2´-bipy), where R–CO2= naphthalene-2-carboxylate, anthracene-9-carboxylate, pyrene-1-carboxylate and acetate, were investigated by steady state and time resolved spectroscopy. The X-ray structure revealed that the R containing ligand is coordinated through the carboxylate group to Re(I). Results showed that two emitting excited states play a major role in the photophysics of the complexes. The fast component of the complexes luminescence was associated with the charge transfer excited state, MLCT, Re-to-2,2´-bipyridine, while experimental evidence led to the long lived component being attributed to a ligand-to-ligand charge transfer excited state. This emissive LLCT excited state can also evolve to a photodissociative state which ultimately produces the complex decarboxylation. On the other hand, the carboxylate bridge was shown to be able to impede connection between R and the Re(CO)3(2,2´-bipy) chromophore.