Luminescence and spectroscopic studies of organometallic rhodium and rhenium multichromophore systems carrying polypyridyl acceptor sites and phenylethynyl antenna subunits
Sprache des Titels:
Englisch
Original Kurzfassung:
The synthesis, structure, photophysics, and spectroscopic characterization of two novel
organometallic rhodium and rhenium multichromophore photosensitizers carrying a central 2,2´-
bipyridyl acceptor moiety is reported. Due to the presence of rigid phenylethynyl substituents in their
5,5´-position acting as intramolecular antenna groups, these compounds display perturbed excited
state properties and a modified luminescence behaviour compared to the unsubstituted parent
systems. The rhodium derivative is characterized by a weak blue-green intraligand (IL)
phosphorescence occurring only at low temperatures. In the rhenium complex both a blue-green
ligand-based luminescence and a red phosphorescence of metal-to-ligand charge transfer (MLCT)
origin is observed at room temperature in solution. In rigid 77 K matrix the lowest-lying excited state
levels approximate in energy and a structured luminescence band occurs which is ascribed to a ligand
phosphorescence with admixed MLCT character.