Dependence of an anion template on amino acid binding in DMSO/H2O by a chiral Ag/urea-based tweezer

Abstract

A chiral “dual-tweezer” compound containing anion-binding pockets, {[Ag(MeBzUTh)₂]}₂(CF₃CO₂)₂, has been prepared and shown to bind both alanine and phenylalanine in DMSO/H₂O. The trifluoroacetate counter-anion gives enhanced binding through a template effect compared to other species. Interactions between the guest carboxylate and both the urea groups and the argentophilically bound Ag₂ core drive binding, with selectivity achieved through a sterically protected pocket defined by chiral methylbenzyl units giving a more pronounced ¹H NMR response for phenylalanine.