Macrocyclic Hamilton receptor-shuttling dynamics in [2]rotaxanes

TL;DR

This study investigates the movement of macrocycles in [2]rotaxanes with hydrogen bonding receptors using NMR, revealing how different stations influence ring shuttling dynamics, including a fast shuttling rate in a two-station system.

Contribution

It provides new insights into how hydrogen bonding motifs and station variations affect macrocycle shuttling in [2]rotaxanes, combining experimental NMR analysis with dynamic studies.

Findings

Fast shuttling at 72 kHz observed in two-station rotaxane.

Hydrogen bonding interactions selectively influence macrocycle movement.

Station variation impacts the dynamics of macrocycle shuttling.

Abstract

Inherent movement of a macrocycle comprising a multi-site hydrogen bonding Hamilton-type receptor in a series of [2]rotaxanes was investigated by dynamic and VT NMR. In these rotaxanes the varying nature and number of hydrogen-bond motifs and stations on the molecular axles influenced ring dynamics. Triazole stations interact selectively by hydrogen bonding with the isophthalamide amide bonds present in the Hamilton macrocycle and fast shuttling (72 kHz at 25 {\deg}C) was observed in a two station variant.