Substituent-modulated aggregation-induced emission and solid-state acid/base sensing applications of pyrazole-based donor-acceptor derivatives

AIE-active luminophores ( PYZ1−PYZ4 ) containing substituted pyrazole as a donor and cyanomethylene/benzothiazole as acceptor units have been synthesized and thoroughly characterized by IR, 1 H/ 13 C NMR, HRMS and single crystal X-ray diffraction analyses. These new systems exhibited efficient aggregation induced emission and solid-state emission with good quantum yield . Interestingly, these compounds display acid/base-induced reversible solid-state fluorescence switching, and could be used as a solid-state acid/base sensor. Structure-property relationship investigations clearly showed that structural changes strongly influence photophysical properties of these compounds. We report synthesis, characterization and photophysical properties of a series of novel pyrazole-based donor-acceptor derivatives ( PYZ1 − PYZ4 ) displaying substituent-dependent efficient aggregation-induced emission, solvent polarity/viscosity dependent emissions, and acid/base-induced reversible solid-state fluorescence switching.