Diversified Excited-State Relaxation Pathways of Donor-Linker-Acceptor Dyads Controlled by a Bent-to-Planar Motion of the Donor

摘要

Herein, we introduce the cyclic 8 pi-electron (C8 pi) moleculeN,N '-diaryl-dihydrodibenzo[a,c]phenazine (DPAC) as a dual-functional donor to establish a series of new donor-linker-acceptor (D-L-A) dyadsDLA1-DLA5. The excited-state bent-to-planar dynamics ofDPACregulate the energy gap of the donor, while the acceptorsA1-A5are endowed with different energy gaps and HOMO/LUMO levels. As a result, the rate and efficiency of the excited-state electron transfer vs. energy transfer can be finely harnessed, which is verified via steady-state spectroscopy and time-resolved emission measurements. This comprehensive approach demonstrates, for the first time, the manifold of excited-state properties governed by bifunctional donor-based D-L-A dyads, including bent-to-planar, photoinduced electron transfer (PET) from excited donor to acceptor (oxidative-PET), fluorescence resonance energy transfer (FRET), bent-to-planar followed by electron transfer (PFET), and PET from donor to excited acceptor (reductive-PET).