Visible Enantiomer Discrimination via Diphenylalanine-Based Chiral Supramolecular Self-Assembly on Multiple Platforms

The development of enantioselective recognition is of great significance in medical science and pharmaceutical industry, which associates with the molecular recognition phenomenon widely observed in biological systems. In particular, the facile and straight achievement of visual enantioselective recognition has been drawing increasing consideration, but it is still a challenge. Herein, a heterochiral diphenylalanine-based gelator (LFDF) is synthesized, presenting left-handed nanofibers during self-assembly in ethanol, which accomplishes the phenylalaninol enantiomer recognition on multiple platforms. When adding l- or d-phenylalaninol into LFDF supramolecular solution followed by ultrasonic treatment, precipitate and gel are formed, respectively. Meanwhile, LFDF supramolecular gel completely collapses in a minute after dropping l-phenylalaninol, while the gel almost remains when d-type is employed. Moreover, a fluorescent supramolecular xerogel (ThT-LFDF) is fabricated by combining the LFDF gelator with thioflavine T (ThT), which could detect l-phenylalaninol accompanying with fluorescence quenching while d-type with barely decreasing. And the ThT-LFDF xerogel system shows a good sensitivity (reaches to ppm) for the detection of l-phenylalaninol. It is found that the chirality of the assembled nanofibers, as well as amino and carboxyl of phenylalaninol, plays a critical role on the discrimination process. The multiple and visible enantioselective recognition of phenylalaninol through chiral supramolecular self-assemblies shows potential applications in the fields of medical science and pharmaceutical industry.