Post‐synthetic Breaking of Inversion Symmetry in Metal Complex‐based Host–guest Systems

Abstract Breaking of inversion symmetry is a significant structural transition that gives rise to high‐electrical and optical functionalities in solid‐state materials. In general, it is difficult to intentionally break the inversion symmetry of structures by material synthesis. However, recent advances in host–guest chemistry dealing with molecular‐based materials have demonstrated several methods for controlling the inversion symmetry of hosts by guests. This post‐synthetic dynamic manipulation produces not only polarity switching but also further multifunctionalities of host–guest composites. This study reviews studies on guest‐responsive polar materials, which are categorized into five groups: (1) guest adsorption, (2) desorption, (3) exchange control of inversion symmetry, (4) temperature‐driven polar transition of composites, and (5) enhancement of polarity by guests. By summarizing these symmetry breaking mechanisms, we provide insights into the rational design of materials with switchable polarity.