Experimental Confirmation of a Predicted Porous Hydrogen‐Bonded Organic Framework
Caitlin E. Shields, Xue Wang, Thomas Fellowes, Rob Clowes, Linjiang Chen, Graeme M. Day, Anna G. Slater, John W. Ward, Marc A. Little, Andrew I. Cooper
Abstract
Abstract Hydrogen‐bonded organic frameworks (HOFs) with low densities and high porosities are rare and challenging to design because most molecules have a strong energetic preference for close packing. Crystal structure prediction (CSP) can rank the crystal packings available to an organic molecule based on their relative lattice energies. This has become a powerful tool for the a priori design of porous molecular crystals. Previously, we combined CSP with structure‐property predictions to generate energy‐structure‐function (ESF) maps for a series of triptycene‐based molecules with quinoxaline groups. From these ESF maps, triptycene trisquinoxalinedione (TH5) was predicted to form a previously unknown low‐energy HOF (TH5‐A) with a remarkably low density of 0.374 g cm −3 and three‐dimensional (3D) pores. Here, we demonstrate the reliability of those ESF maps by discovering this TH5‐A polymorph experimentally. This material has a high accessible surface area of 3,284 m 2 g −1 , as measured by nitrogen adsorption, making it one of the most porous HOFs reported to date.