BOSCHIBAs as a fluorescent dye of silk fibroin with mechano- and thermoresistive properties: ultrasound synthesis, photophysical characterization, X-ray analysis, and molecular docking

Abstract

In this study, a short series of Boron Schiff bases (BOSCHIBAs) was synthesized via ultrasound irradiation, significantly reducing synthesis time and enabling scalable industrial applications. The whole compounds were characterized by NMR (¹H, ¹³C{¹H}, ¹¹B{¹H}), UV, IR spectroscopy, and mass spectrometry. X-ray diffraction analysis confirmed the formation of tetra-coordinated boron heterocycle compounds. Photophysical studies revealed the fluorescent properties of the BOSCHIBAs, with quantum yields comparable to those of similar compounds. Furthermore, the BOSCHIBAs effectively stained silk fibroin fibers, exhibiting clear fluorescence patterns. Finally, we report two stimuli—thermal and mechanical milling—applied to the boron complexes, and two others—manual rubbing and cryogenic temperature—applied to the dyed silk fiber. These stimuli-responsive behaviors suggest potential applications in both biological and textile industries.