Mechanochromism, thermochromism, protonation effect and discrimination of CHCl3 from organic solvents in a Et2N-substituted Salicylaldehyde Schiff base

Multi-stimuli-responsive materials, which can show color/fluorescence change in response to external chemical or physical stimuli, have received increasing attention due to the capacities for facile realization of multifunctional sensing. Herein, we presented a Et2N-substituted salicylaldehyde Schiff base compound (DDHAC) with multi-stimuli-responsive behaviors. An investigation of the photophysical properties in solution demonstrated DDHAC was an excited-state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) active molecule. Owing to structural flexibility from salicylaldehyde Schiff base, the compound displayed reversible mechanochromic and thermochromic behavior, which were associated with the crystalline-to amorphous and crystalline-to-crystalline, respectively. Moreover, the Et2N group endowed DDHAC with the capability that response of protonation. Due to its protonation effect, DDHAC could serve as a unique optical probe for discriminating CHCl3 from organic solvents assisted by UV irradiation. The selectivity was attributed to the interaction of DPPTP with HCl gas from photodecomposition product of chloroform.

Automated summary

In this study, a multi-stimuli-responsive compound DDHAC was presented, showing photophysical properties in solution and reversible mechanochromic and thermochromic behavior. The Et2N group endowed DDHAC with protonation capability, making it a unique optical probe for discriminating CHCl3 from organic solvents. The selectivity was attributed to the interaction of DPPTP with HCl gas from photodecomposition product of chloroform.