Novel approach to increase chemosensing ability of fluorophore via cross-linked hydrogel film formation

Abstract

2,5-Bis(4-hydroxy-3-methoxyphenyl)thiazolo[5,4-d]thiazole (MPhTT) fluorophore as a donor–acceptor-donor (D-A-D) type sensor molecule is synthesized for further investigation of sensing ability of the molecule towards various anions and cations. The MPhTT molecule with strong photoluminescence (PL) has been determined to be sensitive against anions with an effective deprotonation mechanism. MPhTT molecule has been demonstrated to have a limited ability to recognize anions by PL response in the solution while selectively sensitive against CN− anion after being embedded into filter paper. Moreover, metal cations detection in the solution is impossible with the MPhTT fluorophore. The use of MPhTT dye as a cross-linker to prepare highly emissive PVA hydrogel films resulted in a reusable chemosensor for acid, base, CN− anion, and metal cations. The mechanical properties of the films and their swelling behavior have also been investigated to show their water-responsive mechanical properties and water intake ability for possible biomedical applications.These findings indicate that increasing the chemosensing ability of the dye by cross-linking of polymers can be used for many fluorophores as an innovative approach. The films with extended mechanical properties can be used for wound dressing, biosensors, moisture sensors, and many other applications.