Photophysics of monodisperse platinum-acetylide oligomers: Delocalization in the singlet and triplet excited states

A series of monodisperse Pt-acetylide polymers that contain the [-C≡C-(p-C6H4)-C≡C-(t-Pt(PBu3)2)-]n repeat unit has been prepared for n = 1, 2, 3, 4, 5, and 7. The photophysical properties of the series provide information concerning the relationship between the oligomer length and delocalization in the singlet and triplet excited states of the π-conjugated electron system. The results imply that the singlet excited state is delocalized over approximately 6 repeat units; however, the triplet state is considerably more localized. The triplet energy is almost invariant with oligomer length, but the phosphorescence spectra and triplet nonradiative decay rates indicate that the electron-vibrational coupling in the triplet state decreases with increasing oligomer length. Copyright © 2002 American Chemical Society.