BODIPY-Pyrene and Perylene Dyads as Heavy-Atom-Free Singlet Oxygen Sensitizers

Dyads combining BODIPY as an electron acceptor and pyrene or perylene as electron donor subunits were prepared and their photophysical properties were studied by steady-state and transient spectroscopy. Depending on the structure of the subunits and the polarity of the media, the dyads show either bright fluorescence or photo-induced electron transfer (PeT) in solution. Charge-transfer (CT) states formed as a result of PeT and were found to yield triplet excited states of the BODIPY. In the presence of molecular oxygen, the dyads sensitize singlet oxygen (O-1(2)) with quantum yields of up to 0.75.