Fluoride-responsive gelator and colorimetric sensor based on simple and easy-to-prepare cyano-substituted amide

Abstract

A new and easy-to-prepare gelator based on cyano-substituted amide (BPNIA) was designed and synthesized. BPNIA could form thermoreversible gel in DMSO–H₂O (v/v, 9 : 1) and ultrasound-stimulated gel in DMSO. FT-IR, UV–vis and XRD spectra indicated that the gelator molecules self-assemble into a fibrous network resulting from the cooperation of intermolecular hydrogen bonding, π–π stacking and cyano interactions. BPNIA can act as a highly selective colorimetric sensor for fluoride in DMSO, overcoming the interference of H₂PO₄⁻, AcO⁻ and other halide anions. The deprotonation of the NH groups is responsible for the dramatic color change from colorless to yellow. Interestingly, the organogel of BPNIA could allow a two channel fluoride response by proton controlled reversible sol–gel transition and color changes.