Synthesis of TPyP: 1,3,6,8-Tetrabromopyrene (1.04 g, 2 mmol), 4-pyridinylboronic acid (983 mg, 8 mmol), DMF (200 mL) and K2CO3 (50 mL) were added to a flask and degassed by N2 bubbling for 30 minutes. Pd(PPh3)4 (40 mg, 0.035 mmol) was added and the solution was degassed for a further 10 minutes before heating to 145 °C for 48 hours. After cooling the mixture was poured into water (1 L) and stirred for 30 minutes. The precipitate was collected by filtration and washed with, water (100 mL), methanol (100 mL) and dichloromethane (100 mL) before drying under vacuum. The product was obtained as a green solid (986 mg, 1.92 mmol, 96 %). Anal. Calcd for C36H22N4: C, 84.68; H, 4.34; N, 10.97; Found: C, 84.37; H, 4.31; N, 10.73. H NMR (400 MHz, Acetic acid-d4): δ(ppm) = 9.08 (d, J 6.0 Hz, 8H), 8.41 (s, 4H), 8.36 (s, 2H), 8.17 (d, J 6.0 Hz, 8H). Crystallization of Other TBAP Phases 500 mg of as-synthesized TBAP were covered by DMF, N,N-dimethylacetamide, or N-methyl-2-pyrrolidone (40 mL) in a large vial. The mixture was sonicated for 10 min. and left overnight so all remaining undissolved material settled at the bottom of the vial. The supernatant solutions from each dipolar aprotic solvent were filtered into 5 2.5 mL vials using a 0.45 µm PTFE syringe filter to remove any particulates. The vials were closed with a plastic cap that each had a whole bore into it. These 5 vials from each solvent were then placed into larger 15 mL vials with 2 mL of each anti-solvent (CHCl3, acetone, THF, 1,4-dioxane, ethyl acetate) and were then capped tightly. Vapor diffusion of the anti-solvents into the TBAP solutions were carried out for several days until the vials were nearly full of solvent and in most cases, crystal growth had occurred. These crystals were then analyzed by single crystal x-ray diffraction. For unit cell and full collection results, see Table . The solvents N-methyl-2-pyrrolidone and N,Ndimethylacetamide lead to 1:4 solvates, which featured complementary hydrogen bonding motifs between the crystallization solvent and carboxylic acid group of TBAP (SI, Fig. 17), rather than TBAP-α, but second TBAP polymorphs can also be isolated by heating a DMF/EtOH solution at 90 °C. Time-Correlated Single Photon Counting Experiments TCSPC experiments were performed on an Edinburgh Instruments LS980-D2S2-STM spectrometer equipped with picosecond pulsed LED excitation sources and a R928 detector, with a stop count rate below 3%. An EPL-375 diode (λ = 370.5 nm, instrument response 100 ps, fwhm) was used as the light source. Suspensions were prepared by ultrasonicating the materials in water. The instrument response was measured with colloidal silica (LUDOX HS-40, Sigma-Aldrich) at the excitation wavelength. Decay times were fitted in the FAST software using suggested lifetime estimates.