Energy–Structure–Function Maps: Cartography for Materials Discovery

Abstract

Some of the most successful approaches to structural design in materials chemistry have exploited strong directional bonds, whose geometric reliability lends predictability to solid-state assembly. For example, metal–organic frameworks are an important design platform in materials chemistry. By contrast, the structure of molecular crystals is defined by a balance of weaker intermolecular forces, and small changes to the molecular building blocks can lead to large changes in crystal packing. Hence, empirical rules are inherently less reliable for engineering the structures of molecular solids. Energy–structure–function (ESF) maps are a new approach for the discovery of functional organic crystals. These maps fuse crystal-structure prediction with the computation of physical properties to allow researchers to choose the most promising molecule for a given application, prior to its synthesis. ESF maps were used recently to discover a highly porous molecular crystal that has a high methane deliverable capacity and the lowest density molecular crystal reported to date (r = 0.41 g cm⁻³, SA_BET = 3425 m² g⁻¹). Progress in this field is reviewed, with emphasis on the future opportunities and challenges for a design strategy based on computed ESF maps.

Crystal engineering is typically based on simple, intuitive rules for molecular assembly. Herein, a survey of recent breakthroughs in the use of computational crystal-structure prediction to create energy–structure–function maps that describe the relationship between a molecule and its likely solid-state physical properties is provided. These methods have the potential to change the way that functional organic solids are designed in the future.

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