Weak functional group interactions revealed through metal-free active template rotaxane synthesis

• Published in: Nature communications Vol. 11; no. 1; p. 744
• Main Authors: Tian, Chong, Fielden, Stephen D P, Whitehead, George F S, Vitorica-Yrezabal, Iñigo J, Leigh, David A
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 06.02.2020; Nature Publishing Group UK; Nature Portfolio
• Subjects: Amines; Binding; By products; Catalysis; Crown ethers; Ethers; Functional groups; NMR; Nuclear magnetic resonance; Rotaxanes; Selectivity; Self-assembly; Shafts (machine elements); Solid state; Supramolecular compounds
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-14576-7

Modest functional group interactions can play important roles in molecular recognition, catalysis and self-assembly. However, weakly associated binding motifs are often difficult to characterize. Here, we report on the metal-free active template synthesis of [2]rotaxanes in one step, up to 95% yield and >100:1 rotaxane:axle selectivity, from primary amines, crown ethers and a range of C=O, C=S, S(=O) and P=O electrophiles. In addition to being a simple and effective route to a broad range of rotaxanes, the strategy enables 1:1 interactions of crown ethers with various functional groups to be characterized in solution and the solid state, several of which are too weak - or are disfavored compared to other binding modes - to be observed in typical host-guest complexes. The approach may be broadly applicable to the kinetic stabilization and characterization of other weak functional group interactions.