Protonation regulates intermolecular interaction force to achieve reversible ACQ-AIE conversion

In recent years, there has been a lot of focus on aggregation-induced emission materials, and most of the research has focused on the unidirectional conversion from ACQ (aggregation-causing quenching) to AIE (aggregation-induced emission), which inevitably requires complex chemical synthesis and cumbersome processes, and molecules with reversible ACQ and AIE conversion characteristics are rarely reported. In order to achieve a reversible conversion based on a single material between ACQ and AIE properties, we have developed a new functional material, DBPZ-2 (1,4-bis((4-(benzo[c] (Li et al., 2020; Hu et al., 2014; Song et al., 2024) [1,2,5]thiadiazol-4-yl)piperazin-1-yl)methyl)benzene). This compound exhibits AIE properties under neutral conditions, and interestingly, it exhibits significant ACQ properties when protonated, and then restores AIE properties after simple deprotonation. Furthermore, the sensitive response of DBPZ-2 to pH can be used as a fluorescent probe to monitor the changes in the pH value of cellular lysosomes, which brings hopes for future research on lysosomal biology and related diseases.