Stiff-Stilbene-Bridged Biscalix[4]arene as a Highly Light-Responsive Supramolecular Gelator

Abstract

A newly designed stiff-stilbene functionalized biscalix[4]arene in its <i>cis</i> form <i>Z</i>-<b>1</b> could be near-quantitatively photoswitched to the <i>trans</i>-isomer <i>E</i>-<b>1</b> under irradiation of 385 nm UV light. The <i>trans</i>-biscalix[4]arene <i>E</i>-<b>1</b> was found to be a supergelator in nonpolar organic solvents, e.g., cyclohexane, hexane, pentane, and ether, with critical gelation concentrations as low as 0.2, 0.5, 0.5, and 0.4% w/v, respectively. The <i>cis</i>-<i>trans</i> configurational isomerism of biscalix[4]arene <b>1</b> resulted in distinct self-assembly modes, leading to interesting microscopic morphological changes from honeycomb and ringlike structures to rodlike dense fibrous networks.