Published online: 2020-01-23 20 Organic Materials McKeown Short Review Organic Molecules of Intrinsic Microporosity Neil B. McKeown*a a EaStCHEM School of Chemistry, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, United Kingdom
[email protected] porous molecular crystals.6 A large proportion of molec- Received: 08.10.2019 ular crystals are based on cages7 or macrocycles, both of Accepted after revision: 20.11.2019 which act as prefabricated pores,8 but others are simply DOI: 10.1055/s-0039-3402512; Art ID: om-19-0016-rev organic molecules that pack inefficiently but with a 9 License terms: crystalline order. For all of these crystalline materials, the porosity is only revealed on the removal of the solvent © 2020. The Author(s). This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial-License, of crystallization, a process often termed activation, permitting copying and reproduction so long as the original work is given appropriate which needs to occur without the structural collapse of credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/). the crystal. Despite the understandable fascination with well-ordered porous materials—many of which have Abstract Organic molecules of intrinsic microporosity (OMIMs) are aesthetically appealing crystal structures—wholly amor- rigid molecules with an awkward shape that are designed to pack space phous materials can also be highly porous as demon- inefficiently in the solid state maximizing free volume and thereby stratedbythecommerciallyubiquitousactivated generating apparent microporosity as determined by gas adsorption.