Responsive pillar[n]arene materials

Abstract

Intelligent materials with responsive behaviors toward external stimuli, such as light, temperature, pH, redox, and solvent have been increasingly fascinating. Reversible noncovalent interactions provide an efficient way to construct stimuli‐responsive materials. Macrocyclic compounds, such as cyclodextrins, cucurbit[n]urils, calix[n]arenes, crown ethers, and related macrocycles, are useful skeletons for constructing such materials through host–guest interactions. Pillar[n]arenes are pillar‐shaped macrocyclic hosts developed by our groups in 2008, in which the repeated 1,4‐dialkoxybenzene units are connected by methylene bridges at the para position. The versatile functionality, easy modification, excellent size‐dependent host–guest complexation, and adjustable electron density of the cavity endow pillar[n]arenes with excellent properties compared with other cyclic host molecules. Moreover, the unique planar chirality and chirality inversion generated by unit rotation make pillar[n]arenes ideal platforms for investigating chirality inversion, induction, and transformation. In this review, we describe stimuli‐responsive topological, optical, chiroptical, supramolecular assemblies, and solid‐state materials based on the host–guest complexation and structural regulation of pillar[n]arenes.