A stimuli-responsive l-DOPA-based supramolecular gel for the detection of fluoride ion

Abstract

We report the rational design and synthesis of a new L-DOPA-based low molecular weight gelator where the two phenolic OH groups are protected by tertiary-butyldimethylsilyl (TBDMS) moieties. The gelator showed excellent solvent immobilizing properties in different polar aprotic solvents with minimum gelation concentrations (MGCs) of 0.3–0.5% (w/v). Various microscopic and spectroscopic techniques such as FESEM, HRTEM, FTIR, XRD, CD and rheology were used to characterize the thermoreversible supramolecular gels. Interestingly, the protection and deprotection of the TBDMS group was successfully utilized for the detection of fluoride ions visually simply by observing the gel to sol transition. Additionally, F⁻ ions could be quantitatively estimated by correlating the gel-degradation times with the fluoride ion concentrations. This is the first ever report where a key biological precursor L-DOPA and TBDMS moieties have been incorporated into the gelator structure for the detection and estimation of F⁻ ions using a visual gel-to-sol phase transition method.