Supramolecular Chromaticity and Thermoresponsive Hydrogels: A Self-Assembly Study on Maleamic Acid-Based Amphiphiles

A new class of homologous low molecular weight amphiphiles based on maleamic acid was synthesized and investigated in terms of its self-assembly behavior in bulk and in solution. The unexpected yellow color as bulk material and in organic solvents was revealed by means of spectroscopic and theoretical investigations to originate from intermolecular π-π interactions yielding supramolecular chromophores. It was found that the length of the alkyl chain of the amphiphiles and the resulting hydrophilic/lipophilic balance dictates the aggregation mode in bulk. One special compound exhibiting an n-tetradecyl chain was found to form stable thermoreversible supramolecular hydrogels in aqueous sodium hydroxide solutions. The corresponding hydrogels feature a rare cellular bilayer-based morphology and can be transferred into viscoelastic solutions upon heating and vice versa.