TBAP was crystallized by vapor diffusion of CHCl3 into a saturated N,N-dimethylformamide (DMF) solution. The crystallization solvent was then exchanged with acetone, and the acetone was subsequently removed from the crystal pores at 120 °C under dynamic vacuum (SI, Figures , Table ). The desolvated crystal structure, TBAP-α, which has C2/c symmetry is in excellent agreement with the predicted low-density TBAP structure, 1 (Figures ). The crystal structure of TBAP-α, as determined at 25 °C, had a packing distance between pyrene cores of 3.93 Å, which is slightly longer than 3.85 Å reported for the γ-polymorph of pyrene recorded at 0.3 GPa and 25 °C. We carried out sorption measurements to estimate the surface area of TBAP-α, which was found to match our ESF map predictions (Brunauer-Emmett-Teller surface area, SABET = 2001 -2270 m 2 g -1 , SI, Figures ; ESF map prediction = 2273 m 2 g -1 ). This is also in agreement with the report by Yin et al. These three crystalline solids, TPhP-α, TPyP-α, TBAP-α, display different π-π stacking modes of pyrene cores, and the TBAP-α structure features a high surface area. These three crystalline solids are therefore good candidates to investigate the effect of crystal structure on photocatalytic activity in molecular crystals.