Recent progress in controlling photophysical processes of donor-acceptor arrays involving perylene diimides and boron-dipyrromethenes

This review summarizes recent studies concerning photophysical processes of donor-acceptor arrays involving perylene diimides and boron-dipyrromethenes (BODIPYs), and discusses fundamental photophysical properties, electron transfer in donor-acceptor arrays in solution and in aggregate systems, and applications to solar cells and sensors in biological systems (for BODIPYs). These compounds are generally characterized as fluorescent dyes and exhibit poor efficiency in intersystem crossing in direct excitation. However, a few studies have reported that the intersystem crossing is strongly induced by the following methodologies: presence of heavy atoms including metal ions; presence of radical substituents; charge recombination of the generated charge separated states; and hyperfine interactions in long-separated radical pairs. These methodologies are useful to selectively generate locally excited triplet states or charge separated states with minimal loss of deactivation to the singlet ground states. In this review, these methodologies are also introduced and discussed.