Exploiting the Mechanical Bond Effect for Enhanced Molecular Recognition and Sensing

Abstract

The ubiquity of charged species in biological and industrial processes has resulted in ever‐increasing interest in their selective recognition, detection and environmental remediation. Building on the established coordination chemistry principles of the chelate and macrocyclic effects, and host preorganization, supramolecular chemists seek to construct specific three‐dimensional binding cavities reminiscent of biotic systems to enhance host‐guest binding affinity and selectivity. Mechanically interlocked molecules (MIMs) present a wholly unique platform for synthetic host design, wherein topologies afforded by the mechanical bond enable the decoration of three‐dimensional cavities for non‐covalent interactions with a range of target guest geometries. Notably, MIM host systems exhibit mechanical bond effect augmented affinities and selectivities for a variety of charged guest species, compared to non‐interlocked acyclic and macrocycle host analogues. Furthermore, the modular nature of MIM synthesis facilitates incorporation of optical and electrochemical reporter groups, enabling fabrication of highly sensitive and specific molecular sensors. This review discusses the development of recognition and sensing MIMs, from the first reports in the late 20th century through to the present day, delineating how their topologically preorganized and dynamic host cavities enhance charged guest recognition and sensing, demonstrating the mechanical bond effect as a potent tool in future chemosensing materials.This article is protected by copyright. All rights reserved

Mechanically Interlocked Water-Soluble Pd6 Host for the Selective Separation of Coal Tar-Based Planar Aromatic Molecules

“…Artificial MIMs have been created using different chemical strategies. , Such strategies can be broadly divided into two categories, one where the interlocked structures are formed under kinetic control , and the second category where the structures are formed through thermodynamic control using dynamic bonds. , The first synthetic strategy suffers from low yields, and hence the second is generally favored. Using the dynamic bonding approach, multiple MIMs have been created with different topologies, , such as rotaxanes, − knots, − rings, ravels, , and catenanes. − …”

“…11,12 The first synthetic strategy suffers from low yields, and hence the second is generally favored. Using the dynamic bonding approach, multiple MIMs have been created with different topologies, 13,14 such as rotaxanes, 15−21 knots, 22−26 rings, 27 ravels, 28,29 and catenanes. 30−32 Interlocked cage-catenanes make up a class of MIMs formed from the interlocking of cage-based compounds.…”

High-Molecular-Weight Poly[2]catenanes Prepared by Hydroxyl-Alkyne Click Chemistry

“…Mechanically interlocked molecules (MIMs) − originated from two or more components connecting by mechanical bonds − in a topological way. , Due to the noncovalent binding, MIMs possess high degrees of conformational freedom and permanent spatial association. , As a representative example among MIMs, catenane − consists of two or more rings interlocked together via mechanical bonds. There are a series of motion modes in catenane structures, including elongation, ring twisting, and ring rotation, which provide the molecule with high degrees of freedom and mobility.…”

Halogen bonding aza-BODIPYs for anion sensing and anion binding-modulated singlet oxygen generation

“…Over recent years, halogen bonding (XB) interactions have been exploited for anion recognition due to their advantages in affinity, directionality and selectivity over traditionally employed interactions, such as hydrogen bonding (HB). 18,19 Within the context of optical sensing, XB interactions have additionally shown enhanced signal transduction, 20 leading to the development of an array of optical sensors for anions and other analytes. 21–25 However, optical sensors employing XB interactions for anion recognition which operate at biologically-relevant wavelengths remain scarce, and the use of aza-BODIPY compounds within this context is unprecedented.…”