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

doi:10.1002/anie.202303167

Experimental Confirmation of a Predicted Porous Hydrogen-Bonded Organic Framework

Angew Chem Int Ed Engl. 2023 Aug 21;62(34):e202303167. doi: 10.1002/anie.202303167. Epub 2023 May 3.

Authors

Caitlin E Shields¹, Xue Wang^{1

2}, Thomas Fellowes^{1

2}, Rob Clowes¹, Linjiang Chen³, Graeme M Day⁴, Anna G Slater¹, John W Ward^{1

2}, Marc A Little¹, Andrew I Cooper^{1

2}

Affiliations

¹ Materials Innovation Factory and Department of Chemistry, University of Liverpool, 51 Oxford Street, Liverpool, L7 3NY, UK.
² Leverhulme Research Centre for Functional Materials Design, University of Liverpool, 51 Oxford Street, Liverpool, L7 3NY, UK.
³ School of Chemistry and School of Computer Sciences, University of Birmingham Edgbaston, Birmingham, B15 2TT, UK.
⁴ Computational Systems Chemistry, School of Chemistry, University of Southampton B27, East Highfield Campus, University Road, Southampton, SO17 1BJ, UK.

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 m² g^-1 , as measured by nitrogen adsorption, making it one of the most porous HOFs reported to date.

Keywords: Crystal Engineering; Crystal Structure Prediction; Hydrogen-Bonded Organic Frameworks; Porous Materials.

Abstract

Grants and funding