Triphenylamine or carbazole-containing dibenzothiophene sulfones: Color-tunable solid-state fluorescence and hypso- or bathochromic mechanofluorochromic behaviors

Abstract

Four triphenylamine or carbazole-based highly emissive solid fluorophores (The maximum quantum yield of 42.43%) of dibenzothiophene sulfones have been successfully prepared and characterized. The solid-state emission behaviors and mechanical stimulus-responsive luminescence characteristics of all these donor-acceptor-donor (D-A-D) type or donor-π-acceptor-π-donor (D-π-A-π-D) type compounds 1–4 were investigated. Interestingly, these fluorophores 1–4 exhibited various solid-state fluorescent colors involving blue (CIE color coordinates of (0.15, 0.09)), blue-green (CIE color coordinates of (0.17, 0.43)), yellow (CIE color coordinates of (0.41, 0.56)) and brown-yellow (CIE color coordinates of (0.50, 0.50)). Furthermore, these dyes 1–4 also exhibited different mechanofluorochromic behaviors. More specifically, luminogens 1–3 showed bathochromic mechanofluorochromic phenomena. However, luminogen 4 showed distinct-different hypsochromic mechanofluorochromic phenomenon. All these observed mechanochromic emission conversions could be repeated for many cycles. Single-crystal X-ray diffraction and powder X-ray diffraction experiments demonstrated that the mechanofluorochromic behaviors of 1–4 were related to the morphology transformation from crystalline state to amorphous state.