Fig. 1
From: Highly sensitive switching of solid-state luminescence by controlling intersystem crossing
Strategies for MRL materials by controlling intersystem crossing. a Proposed mechanism of highly sensitive On–Off MRL materials by controlling intersystem crossing of nitrophenylated AIEgens. Scale = 100 µm. b Nature transition orbitals of the lowest singlet excited state (S1) and triplet excited state (T4) of nitrobenzene. Since El-Sayed’s rule states that the multiplicity change becomes highly efficient when the spin–orbit coupling mixes two states differing in both spin and electronic configuration,T4 is the closet and a good “receiver state” in the intersystem crossing process which determines the ultrafast S1 depletion through an favored 1(n,π*) to 3(π,π*) channel. c Twisted crystal structures of typical AIEgens: triphenylamine (TPA) and tetraphenyethylene (TPE). d Molecular structures of nitro-TPAs and nitro-TPEs studied here
