Dynamic Cyclodipeptide Clamps as Enantioselective Receptors toward Vitamin K1

We report the design of folded cyclodipeptides that show dynamic and adaptive conformational transitions responding to solvents and enantioselective recognition of a biomolecule, vitamin K1 (VK1). Postmodification of phenylalanine-based cyclodipeptides with polycyclic aromatic hydrocarbons (pyrene, anthracene, and phenanthrene) produced chiral folded structures. Compared with other solvents, these cyclodipeptides exhibit ultrahigh sensitivity to dimethyl sulfoxide (DMSO), which induces a conformational transition from parallel to perpendicular dimerization. It leads to a reversed screw sense of the chromophores, facilitating tunable chiroptical properties. In a mixed DMSO/water system, the folded cyclodipeptides perform as efficient molecular clamps that recognize VK1 through charge-transfer complexation. Additionally, d,d- and l,l-configured cyclodipeptides displayed enantioselective recognition of VK1, as evidenced by differences in binding affinity, circularly polarized luminescence and self-assembled nanoarchitectures. This study provides approaches for artificial receptors and chiral sensing based on cyclopeptides.