High-Pressure, Low-Temperature Emission Studies of a Metal−Organic Platinum(II) Compound in a Shpol'skii Matrix

The emission of Pt(2-thpy)2 (2-thpy- = 2-(2-thienylpyridinate)) doped into an n-decane Shpol'skii matrix has been studied at T = 4.2 K (0 kbar) and at different pressures up to 14 kbar at T ≈ 5 K. This type of matrix is used for the first time for high-pressure investigations of transition metal complexes. The emitting state of Pt(2-thpy)2 is of 3ππ* character with a significant MLCT admixture, and the ground state is a singlet. The spectra are well resolved and thus show the electronic origin (0−0 transition) of the most intensively emitting triplet sublevel as well as a number of vibrational Franck−Condon satellites. The corresponding pressure-induced shifts are determined. In particular, the value for the electronic origin is with Δν̄/Δp = −(3 ± 1) cm-1/kbar-1 relatively small, due to an apparently small inherent shift of the singlet−triplet transition. In addition, the smallness of this value seems to be related to the very weak interaction between the chromophore and the environment for this Shpol'skii matrix, whereby this interaction does not strongly change with pressure. The intensity distribution of the vibrational satellite structure shows that the equilibrium positions of the potential hypersurfaces of ground and excited states are very similar at ambient pressure. Apparently this situation is not changed up to 14 kbar.