A fluorinated cyclometalated Pt(II) complex bearing a phosphine ligand:photophysical and theoretical investigations

In recent decades, numerous researchers have extensively explored luminescentcyclometalated platinum(II) complexes, and the number of publications in this area of study isgrowing. Various uses for the luminous cycloplatinated complexes include light-emittingdevices, dye-sensitized solar cells, photoswitches, photocatalysts, and chemical or biologicalsensors[۱]. The principal chromophore involved in producing room-temperature phosphorescenceis the cyclometalated ligand. In addition, heavy metals like Pt induce high spin-orbit couplingand allow singlet-triplet intersystem crossing. The photophysical characteristics of suchcomplexes are greatly influenced by the auxiliary ligands, in addition to the previously listedparameters. These ligands control the electron density at the metal center and, consequently, thedegree of metal to ligand charge transfer (MLCT) in the lowest energy transition [۲].Herein, a heteroleptic cycloplatinated(II) complex [Pt(p-MeC۶H۴)(dfppy)(PPh(EtCN)۲)],dfppy=۲-(۲,۴-difluorophenyl)pyridinate; and PPh(EtCN)۲ = bis(۲-cyanoethyl)phenylphosphine,was synthesized and characterized. The complex exhibits greenish-blue phosphorescence underUV light at room temperature in the solid state, with mostly well-structured emission bands inthe range of ۴۵۰–۴۹۰ nm (solid and CH۲Cl۲ fluid solution states, ۲۹۸ and ۷۷ K). Their emissionsappear as structured bands, which indicates that the emissions mainly originate from theelectronic transitions in the ligand with a small contribution of metal to ligand and/or ligand toligand charge transfers. To rationalize the experimental photophysical data, density functionaltheory (DFT) and time-dependent DFT (TD-DFT) calculations were employed for all thecomplexes.

Keywords:

Phosphine , Cycloplatinated(II) , Photophysics , Theoretical elucidation