Recent advances in stimuli-responsive framework materials: understanding their response and searching for materials with targeted behavior

Although all molecular assemblies show some degree of flexibility, the past decade has shown that there is a higher propensity among framework materials to display large-scale dynamic behavior. Beyond the seminal discoveries of the important flexibility of metal–organic frameworks (MOFs), covalent organic frameworks (COFs), hybrogen-bonded organic frameworks (HOFs) or supramolecular organic frameworks (SOFs), and many other framework materials, the field has progressed rapidly: the number of known flexible materials is ever growing, and the diversity of the types of manifestation of this flexibility appears endless. In addition, the microscopic mechanism of their behavior has been studied using a growing combination of experimental characterization techniques, in situ and in operando measurements, as well as computational simulation methods. In this Review, we present some of the significant advances in recent studies of stimuli-responsive framework materials. In particular, we highlight the novel responses that have been discovered in the past few years, the toolbox developed by researchers in the field to better understand the materials' behavior (both experimentally and computationally), and show some of the latest progress in the discovery of materials with targeted behavior, whether through de novo design or identification of known materials for new properties — similar to what is known in the field of drug discovery as repurposing.