Photocatalytic proton reduction by a computationally identified, molecular hydrogen-bonded framework

Aitchison, Catherine M. and Kane, Christopher M. and McMahon, David P. and Spackman, Peter R. and Pulido, Angeles and Wang, Xiaoyan and Wilbraham, Liam and Chen, Linjiang and Clowes, Rob and Zwijnenburg, Martijn A. and Sprick, Reiner Sebastian and Little, Marc A. and Day, Graeme M. and Cooper, Andrew I. (2020) Photocatalytic proton reduction by a computationally identified, molecular hydrogen-bonded framework. Journal of Materials Chemistry A, 8 (15). pp. 7158-7170. ISSN 2050-7488 (https://doi.org/10.1039/d0ta00219d)

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Abstract

We show that a hydrogen-bonded framework, TBAP-α, with extended π-stacked pyrene columns has a sacrificial photocatalytic hydrogen production rate of up to 3108 μmol g-1 h-1. This is the highest activity reported for a molecular organic crystal. By comparison, a chemically-identical but amorphous sample of TBAP was 20-200 times less active, depending on the reaction conditions, showing unambiguously that crystal packing in molecular crystals can dictate photocatalytic activity. Crystal structure prediction (CSP) was used to predict the solid-state structure of TBAP and other functionalised, conformationally-flexible pyrene derivatives. Specifically, we show that energy-structure-function (ESF) maps can be used to identify molecules such as TBAP that are likely to form extended π-stacked columns in the solid state. This opens up a methodology for the a priori computational design of molecular organic photocatalysts and other energy-relevant materials, such as organic electronics.