Naphthalene linked pyridyl urea as a supramolecular gelator: a new insight into naked eye detection of I− in the gel state with semiconducting behaviour

Abstract

The gelation and anion responsive behavior of some 3-aminopyridine-based urea molecules 1–5 have been examined. Of the different pyridyl ureas, compounds 1 and 2 form an instant gel from DMSO/H₂O and DMF/H₂O solvents. Between the gels 1 and 2, only the gel state of 2 has been noted, for the first time, to detect iodide ions over a series of other anions through a colour change involving no phase transformation. Furthermore, the gel state of 2 is a poor semiconductor and the presence of iodide ions considerably enhances its conductivity that varies with temperature.