d-(+)-Glucose triggered selective hydrometallogelation in a C3-symmetric gelator†

Abstract

A chiral and conductive hydrometallogel was synthesized using dynamic boronic acid-cis diol chemistry. A novel tris-boronic acid-functionalized C₃-symmetric gelator (MB) was obtained from a trimesic acid derivative, which upon deprotonation (MOH, M = Li, Na, K, and Cs), followed by addition of D-(+)-glucose, triggered hydrometallogel formation. Gel formation was highly selective to D-(+)-glucose among all the screened sugars. To the best of our knowledge, D-(+)-glucose-triggered hydrometallogel formation using a C₃-symmetric tris-boronic acid-derived gelator has not been reported. D-(+)-Glucose-triggered gelation was comprehensively investigated using FTIR spectroscopy, UV-vis spectroscopy, circular dichroism, FESEM, ¹H NMR spectroscopy, ESI-mass spectrometry, rheology and electrochemical impedance spectroscopy techniques. A reasonably high yield stress (6000 Pa) value was achieved for 5 wt% gel, supporting the observation of the interesting mechanical properties and robust nature of gels. Moreover, impedance spectroscopic study revealed an appreciable conductance value of 2.67 × 10⁻² S cm⁻¹, which could be further improved to 8.90 × 10⁻² S cm⁻¹ by adding excess LiOH into the gel matrix without compromising its metallogel structural integrity.