Photoinduced Energy- and Electron-Transfer Processes in a Side-to-Face Ru II-Porphyrin/Perylene-bisimide Array

A side-to-face array DPy-gPBI[Ru(4-tBuTPP)(CO)]2, based on a “green” perylene bisimide chromophore sandwiched between two RuII-porphyrins, has been prepared by self-assembly. Its photophysical properties have been characterized in detail by a combination of steady-state and time-resolved techniques upon selective excitation of the two different components. Different photoinduced processes are observed as a function of the excitation wavelength. Electron transfer quenching is attained upon “red light” excitation of the perylene unit, whilst an energy transfer pathway is followed upon “green light” excitation of the metallo-porphyrin moiety. Regardless of the excitation wavelength efficient population of the triplet excited state of the perylene chromophore is achieved. The photophysical results are discussed within the framework of classical electron transfer theory and compared with those of a previously reported system.