The coupling between excited-state intramolecular proton transfer (ESIPT) reaction and excimer formation is unique. In this work, using CF3-HTTH(2,2'-(thiazolo[5,4-d]thiazole-2,5-diyl)bis(4-(trifluoromethyl)phenol) solid crystal we demonstrated the interplay between ESIPT and excimer reactions, resulting in the extensively broad multiple emissions spanning from 420 to 750 nm. Comprehensive structural, time-resolved spectroscopic and two-photon microscopic studies of CF3-HTTHin crystal lattice unveil the pre-equilibrium ESIPT between normal (N*) and tautomer (T*), for which the long population decay and well-ordered lattice packing facilitate excimeric (E*) formation, rendering N* (460 nm), T* (520 nm) and E* (600 nm) triple emissions. In stark contrast, the lower degree of packing on the solid surface prohibits excimer formation, showing ESIPT process only. The correlation between luminescence properties and packing structure sheds light on the corresponding mechanochromic effect on a basis of molecular solid architecture, gaining new insight into the aggregation-induced properties.

New insight into mechanochromism induced by excited-state intramolecular proton transfer coupled excimer reaction

2019 Spring National Meeting

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