Pressure-induced variations of MLCT and ligand-centered luminescence spectra in square-planar platinum(II) complexes

Solid-state luminescence spectra of five crystalline platinum(II) complexes at variable pressure and temperature are presented and compared. Maxima occur between 14 000 cm−1 and 15 600 cm−1 (approximately 700–640 nm) at ambient temperature and pressure. Spectra can be broad bands, characteristic of MLCT transitions, or vibronically structured, characteristic of intraligand transitions. Both pressure and temperature variations can lead to distinctive changes in the luminescence spectra that differ between these two types of transitions. MLCT band maxima show shifts on the order of −20 cm−1/kbar to lower energy; in contrast, ligand-centered luminescence bands do not show significant shifts between ambient pressure and 40 kbar.

MLCT luminescence transitions of square-planar platinum(II) complexes show small shifts to lower energy with increasing pressure. Ligand-centered (LC) transitions in similar compounds do not show significant shifts, providing an experimental criterion to distinguish different types of luminescence transitions.Figure optionsDownload as PowerPoint slide