Recognition and Stabilization of Unsaturated Fatty Acids by a Polyaromatic Receptor
Keita Niki, Takahiro Tsutsui, Masahiro Yamashina, Munetaka Akita, Michito Yoshizawa
Abstract
Selective recognition of natural fatty acids is intrinsically difficult owing to the long, flexible, and poorly interactive hydrocarbon chains. Inspired by biological recognition systems, we herein demonstrate the exclusive binding of a monounsaturated fatty acid by an artificial polyaromatic receptor from a mixture of the unsaturated and corresponding saturated substrates (i.e., oleic and stearic acids) in water. The selectivity stems from multiple CH-π/π-π interactions between the host framework and the guest in its roughly coiled conformation. Moreover, competitive binding experiments elucidate higher binding affinities of the receptor for oligo- and polyunsaturated fatty acids (e.g., α-linolenic acid and EPA). Within the receptor, the biosubstrates are remarkably stabilized against air, light, and heat owing to the polyaromatic shielding effect.