Precise assembly/disassembly of homo-type and hetero-type macrocycles with photoresponsive and non-photoresponsive dynamic covalent bonds†

Abstract

Dynamic covalent macrocycles offer the advantage of tunable ring-opening/ring-closure and structural transformation, but their control with precision remains a daunting task due to the labile nature of reversible bonds. Herein we demonstrate the precise formation/scission of covalent macrocycles with varied sizes by contrasting the reactivity, stability, and degradability of light-active and light-inactive dynamic covalent bonds. The incorporation of photoswitchable and non-photoresponsive aldehyde sites into one single dialdehyde component afforded the creation of [1 + 1] type macrocycles with primary diamines of suitable lengths. The manipulation of light and acid/base stimuli allowed on-demand breaking/remaking of macrocycles, achieving the interconversion between macrocyclic and linear skeletons. Moreover, a combination of the dialdehyde, primary diamines, and secondary diamines enabled the construction of hetero-type [2 + 1 + 1′] macrocycles via enhanced discrimination and hierarchical assembly. Light-induced kinetic locking/unlocking of dynamic bonds further afforded macrocycle-to-macrocycle conversion when needed. Through leveraging controllable covalent connection/disconnection, switchable formation/disintegration of mechanically interlocked catenanes was further accomplished. The results described showcase the potential of photoinduced dynamic covalent chemistry for preparing complex architectures and should set the stage for molecular recognition, dynamic assemblies, synthetic motors, and responsive materials.