Journal of the Brazilian Chemical Society
On-line version ISSN 1678-4790
FRIN, Karina M. and IHA, Neyde Y. Murakami. Photoinduced isomerization and luminescence of fac-[Re(CO)3(ph2phen)(bpe)]+. J. Braz. Chem. Soc. [online]. 2006, vol.17, n.8, pp.1664-1671. ISSN 1678-4790. http://dx.doi.org/10.1590/S0103-50532006000800026.
The fac-[Re(CO)3(ph2phen)(trans-bpe)]PF 6 complex, ph2phen = 4,7-diphenyl-1,10-phenanthroline and trans-bpe = trans-1,2-bis(4-pyridyl)ethylene, was synthesized, characterized and its photochemical and photophysical behavior was investigated. This complex exhibits trans®cis photoisomerization of the coordinated trans-bpe ligand. The apparent quantum yields in CH3CN, determined by absorption changes, are F313 nm = 0.19 ± 0.02, F365 nm = 0.18 ± 0.04 and F404 nm = 0.18 ± 0.02. Higher true quantum yields (F365 nm = 0.40 ± 0.06) were determined by 1H NMR spectroscopy. The coordination of the trans-bpe ligand to the rhenium(I) polypyridyl complex enables a photosensitized isomerization under a lower energy region irradiation, where the free ligand does not absorb. The increasing luminescence as the photoproduct, fac-[Re(CO)3(ph2phen)(cis-bpe)] +, is formed is ascribed to the change of the lowest lying excited state from 3IL to 3MLCT. The emission exhibits a hypsochromic shift associated with the rigidochromic effect.
Keywords : photoisomerization; rhenium(I) carbonyl complexes; trans-bpe; luminescence; rigidochromic effect.