Complexation-driven assembly of imine-linked helical receptors showing adaptive folding and temperature-dependent guest selection.

Song, Geunmoo; Lee, Seungwon; Jeong, Kyu-Sung · Nat Commun · 2024

basic_science · Level V

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Abstract

The development of synthetic receptors capable of selectively binding guests with diverse structures and multiple functional groups poses a significant challenge. Here, we present the efficient assembly of foldamer-based receptors for monosaccharides, utilising the principles of complexation-induced equilibrium shifting and adaptive folding. Diimine 4 can be quantitatively assembled from smaller components when D-galactose is added as a guest among monosaccharides we examined. During this assembly, dual complexation-induced equilibrium shifts toward both the formation of diimine 4 and the conversion of D-galactose into α-D-galactofuranose are observed. Diimine 6 is quantitatively assembled in the presence of two different guests, methyl β-D-glucopyranoside and methyl β-D-galactopyranoside, resulting in the formation of two dimeric complexes: (6-MP)<sub>2</sub>⊃(methyl β-D-glucopyranoside)<sub>2</sub> and (6-MM)<sub>2</sub>⊃(methyl β-D-galactopyranoside∙2H<sub>2</sub>O)<sub>2</sub>, respectively. These two complexes exhibit distinct folding structures with domain-swapping cavities depending on the bound guest and temperature. Interestingly, (6-MM)<sub>2</sub>⊃(methyl β-D-galactopyranoside∙2H<sub>2</sub>O)<sub>2</sub> is exclusively formed at lower temperatures, while (6-MP)<sub>2</sub>⊃(methyl β-D-glucopyranoside)<sub>2</sub> is only formed at higher temperatures.