SITE-SELECTIVE SPECTROSCOPY OF LUMINESCENT SQUARE-PLANAR PLATINUM(II) COMPLEXES

We report on the site selective luminescence spectroscopy of trans-Pt(H)Cl(PEt3)2, trans-Pt(C = CH)2(PEt3)2, and trans-Pt-(C = CPh)2(PEt3)2. All complexes give intense 77 K emission spectra and have site selective differences in their luminescence properties in a variety of rigid glasses. Depending on precise structure, site sensitivity can be very small to extremely large. The variations in behavior are explained on the basis of the charge-transfer character of the excited state, the environmental volume sampled, and the steric shielding of the excited portion of the complex. Design criteria are established for fabricating complexes that should possess high site selectivity. The parent cis-PtCl2(PEt3)2 and trans-PtCl2(PEt3)2 complexes are nonluminescent, apparently due to formation of a tetrahedral excited state.