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 i nto an n-decane Shpol'skii matrix has been studied at T = 4.2 K (0 kbar) an d at different pressures up to 14 kbar at T approximate to 5 K. This type o f matrix is used for the first time for high-pressure investigations of tra nsition metal complexes. The emitting state of Pt(2-thpy)(2) is of 3 pi pi* character with a significant MLCT admixture, and the ground state is a sin glet. 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 pressur e-induced shifts are determined. In particular, the value for the electroni c origin is with Delta<(nu)over bar>/Delta p = -(3 +/- 1) cm(-1)/kbar(-1) r elatively small, due to an apparently small inherent shift of the singlet-t riplet transition. In addition, the smallness of this value seems to be rel ated to the very weak interaction between the chromophore and the environme nt for this Shpol'skii matrix, whereby this interaction does not strongly c hange with pressure. The intensity distribution of the vibrational satellit e structure shows that the equilibrium positions of the potential hypersurf aces of ground and excited states are very similar at ambient pressure. App arently this situation is not changed up to 14 kbar.