Geometric Influence on Intramolecular Photoinduced Electron Transfer in Platinum(II) Acetylide-linked Donor-Acceptor Assemblies

A new donor–acceptor system, in which the electron donor triphenylamine (TPA) and the electron acceptor C60 are bridged through a cis‐ or trans‐platinum(II) acetylide spacer have been prepared. Ground‐state studies were conducted using electrochemistry and UV/Vis spectroscopy. Fluorescence studies suggested that charge transfer is the deactivation mechanism for the singlet excited state, and this was verified by transient absorption spectroscopy. Selective photoexcitation of 1 and 2 at 387 nm leads to a fast charge transfer between the TPA and C60, which gives rise to a radical ion‐pair state (TPA.+–Pt–C60.−). Our results suggest that charge transfer is favored for the cis configuration while the presence of the trans configuration in the PtIIdiacetylide results in a longer‐lived charge separated states