Understanding the crystal-packing patterns of tetrapyrroles underpins a number of objectives in materials sciences. Here, the zinc chelate of 3,13-diacetyl-10-(pentafluorophenyl)-18,18-dimethylchlorin was prepared, crystallized in the presence of tetrahydrofuran (THF), and analyzed by single-crystal x-ray diffraction (SCXRD). The zinc chlorin (Zn1) afforded a herringbone pattern of parallel columnar stacks of chlorins rotated by 67.41∘ with respect to each other. The chlorins within a column are stacked in pairs having interplanar distances of 3.289 Å within a pair and 4.407 Å between pairs. The chlorins in a pair are aligned in a “head-to-head” arrangement with cofacial π–π overlap chiefly only of the respective ring A units; the overall composition is thus of columnar stacks of slipped-stacked pairs of chlorins. Each chlorin is enantiomeric due to the coordination at the Zn(II) center of a single THF molecule; the juxtaposition of chlorin α–β faces opposite the apically ligated THF molecules affords a racemate. All chlorins in a column face in the same direction, with 3,13-acetyl groups essentially coplanar with the macrocycle and oriented toward the respective 5,15-positions (affording an O⋅⋅⋅H–C contact of 2.33 or 2.39 Å), and with interdigitation of alternating pentafluorophenyl groups in adjacent columns. A large number of SCXRD analyses of synthetic chlorins will likely be required to understand the relationship between structure and assembly patterns.
