Light driven isomerization of coordinated ligand and modulation offac-[Re(CO)3(phen)(trans-bpe)]PF6photoluminescence in rigid media

Abstract

The excited state reactivity and photophysical properties offac-[Re(CO)3(phen)(L)]PF6(phen = 1,10-phenanthroline, L =trans- orcis-1,2-bis(4-pyridyl)ethylene, bpe) in PMMA (poly(methyl methacrylate)) films have been investigated and compared with those in acetonitrile solution.313 or 365 nm irradiation of the rhenium complex in PMMA leads to UV-vis spectral changes due to thetrans→cisisomerization of the coordinated bpe ligand. Thefac-[Re(CO)3(phen)(cis-bpe)]+product presents a markedly enhanced luminescence due to a lower lying metal-to-ligand charge transfer (MLCT) excited state in thecisisomer. This emitting property can be conveniently applied as a probe or sensor.Thecisis omer ratio in the photostationary state (PSS) is substantially smaller in solid films than in solution. The photochemical behavior of the freetrans-1,2-bis(4-pyridyl)ethylene in PMMA is also reported to establish comparisons with the investigation carried out in acetonitrile solution as well as with the behavior of the coordinated ligand.