A new bis-acylhydrazone fluorescence sensor for the detection of ClO- with mechanochromic and thermochromic properties.

This study reports the successful synthesis of a novel bis-acylhydrazone fluorescence sensor, named SR, through a straightforward Schiff base reaction. SR demonstrated the ability to self-assemble in ethanol, forming a homogeneous and stable supramolecular gel (SR-G) with a critical micelle concentration (CMC) of 1.6 wt% and a gel-to-sol transition temperature (Tgel) of 62 °C. Photoluminescence characterization revealed that SR-G exhibited a maximum emission peak at 507 nm under 412 nm excitation, producing yellow-green fluorescence. Notably, while SR-G showed negligible fluorescence in solution, its emission intensity increased progressively with decreasing temperature during the gelation process. SR-G displayed exceptional selectivity for hypochlorite (ClO-), exhibiting a pronounced fluorescence quenching effect without interference from competing anions, with a detection limit of 2.71 × 10-6 M. Additionally, SR-G was successfully fabricated into a fluorescent film for ClO- recognition. Furthermore, based on the mechanochromic and thermochromic properties of SR, it has been developed into pressure-sensitive writing materials and temperature monitoring materials, demonstrating significant application potential.