Encapsulating Organic Crystals (EnOCs)

Achieving efficient capture, storage and release of small molecules is a challenge. Most materials that can harbor small molecules have been studied in the context of gas storage or separation. Formulations for hazardous reagents have only recently attracted attention, when organic compounds were discovered that encapsulate a broad range of guest molecules in crystals. Such encapsulating organic crystals (EnOCs) can suppress problematic properties of reagents and allow for controlled release in reaction mixtures. Unlike materials used for gas storage, which possess permanent porosity, their cavities are not held together by covalent or strong noncovalent interactions. Instead, EnOCs crystallize with the help of weaker packing forces. Substituted tetraaryladamantane octaethers can form high-loading inclusion compounds with reagents as guests, but they can also transition into tightly packed, solvate-free forms. Here we highlight the differences between EnOCs and known porous materials and discuss the potential of EnOCs as formulations in organic synthesis.