Photoinduced luminescence of fac-[Re(CO)3(phen)(stpy)]+ in CH3CN and PMMA

The photophysical and photochemical behavior of the fac-[Re(CO)3(phen)(stpy)]+ complex, where phen = 1,10-phenanthroline and stpy = 4-styrylpyridine, in acetonitrile solution and in poly(methyl methacrylate), PMMA, polymer film has been studied. Under irradiation, the complex exhibits trans–cis photoassisted isomerization of the coordinated ligand stpy. The apparent quantum yields determined by absorption changes in acetonitrile are Φ313 = 0.35 ± 0.02, Φ334 = 0.36 ± 0.02 and Φ365 = 0.31 ± 0.02. The 1H NMR spectra and the increasing luminescence as the photoproduct is formed corroborate the photochemical process. The observed emission of fac-[Re(CO)3(phen)(cis-stpy)]+, assigned to the lowest lying 3MLCT state, is highly sensitive to changes in the rigidity of the medium. Similar changes in absorption and emission spectra are also observed for the complex in PMMA film, a suitable medium for developing practical molecular devices.