A chiral BINOL-based supramolecular gel enabling sensitive enantioselective and chemoselective collapse toward histidine.

A chiral small molecule gelator ()-HL based on 1,1'-bi-2,2'-naphthol (BINOL)-phosphoric acid was designed and prepared, which spontaneously forms a stable water-induced gel. The gelation mechanism was revealed by single crystal X-ray diffraction analysis and a number of spectroscopic methods. Addition of Cu improved the gelation ability, and the resultant metal organic gel realized visual enantioselective and chemoselective recognition toward L-histidine from enantiomers of 19 amino acids gel collapse. The gel showed a highly sensitive response to L-histidine, and as low as 0.01 equiv. of L-histidine relative to the critical gelation concentration of ()-HL-Cu caused the gel to collapse. This strategy of regulating the assembly behavior through the interaction of amino acids and metal ions not only provides a simple and direct way to distinguish enantiomers, but also provides insight into how metal ions regulate the organization of biological supramolecular systems.