Soft Porous Crystals: Extraordinary Responses to Stimulation

TL;DR

This paper reviews theoretical methods to understand the stimuli-responsive behavior of soft porous crystals, especially MOFs, under various physical and chemical stimuli, enabling prediction and rationalization of their properties.

Contribution

It introduces a comprehensive toolbox of molecular simulation approaches to analyze the behavior of soft porous crystals, including defect impact and disordered phases.

Findings

Molecular simulations can predict stimuli-induced structural changes.

Defects significantly influence the properties of soft porous crystals.

Methodologies for studying disordered phases like MOF glasses are developed.

Abstract

Recent years have seen a large increase in the number of reported framework materials, including the nowadays-ubiquitous metal-organic frameworks (MOFs). Many of these materials show flexibility and stimuli-responsiveness, i.e. their structure can undergo changes of large amplitude in response to physical or chemical stimulation. We describe here a toolbox of theoretical approaches, developed in our group and others, to shed light into these materials' properties. We focus on their behavior under mechanical constraints, temperature changes, adsorption of guest molecules, and exposure to light. By means of molecular simulation at varying scale, we can now probe, rationalize and predict the behavior of stimuli-responsive materials, producing a coherent description of soft porous crystals from the unit cell scale all the way to the behavior of the whole crystal. In particular, we have studied the impact of defects in soft porous crystals, and developed a methodology for the study of their disordered phases (presence of correlated disorder, MOF glasses, and liquid MOFs).