Reversible Chromatic Change of Supramolecular Gels for Visual and Selective Chiral Recognition of Histidine

Xuemei Xu, Xueman Zhou, Lang Qu, Lei Wang, Jintong Song, Dehua Wu, Weilan Zhou, Xiangge Zhou, Haifeng Xiang*, Jun Wang*, and Jin Liu*

ACS Appl. Bio Mater. 2020, DOI：acsabm.0c01063

In the present work, a chemical reaction has been performed for supramolecular gels to achieve multiple-stimuli-responsive smart soft materials. Simple chiral binaphthalene-based receptors can condense with histidine (His) to yield a Schiff base, which would help to achieve visual chiral recognition of unprotected l/d-His through gel formation along with specific selectivity toward 20 amino acids. Through intermolecular hydrogen bonds, the resultant Schiff base molecules assemble with excess His molecules to form three-dimensional (3D) networks of metastable cross-linked nanospheres and stable nanofibers in EtOH/water and MeOH/water, respectively. Significantly, this condensation reaction exhibits unique reversible and chromatic phenomena between sol–gel phase transitions in EtOH/water, which provide a way to design chemical reaction-based multivisual-change supramolecular gels for sensing and switching applications.