AL(DIPY)3 13k (Fig. ) crystallized with one molecule in the asymmetric unit. The molecules were tightly packed with no solvent (Fig. ) and formed weak interactions between the ester groups [C(56)-H(56 42-2.47 Å between the H and O atoms. The dihedral angles between the dipyrrin plane and the substituents were 58-77°. In contrast the acid 16 (Fig. ) crystallized with 1/2 of the molecule in the asymmetric unit which displayed a disordered benzoic acid motif. Standard intermolecular hydrogen bonds between the carboxylic acid moiety and water molecules )] with distances of 1.73-2.49 Å between H and O atoms were observed. Crystal cavities were partially occupied with solvent molecules of hexane and water. The phenyl rings were orientated out of the plane of the dipyrrin by 70-80°; however, the -COOH groups remained nearly coplanar with the phenyl ring. The acid dimer formation is well known for the organization of frameworks, and similar tris(dipyrrinato) octahedral chelates have been reported with rhodium and cobalt metal centers. Figure . View of the molecular structure in the crystal of 13h and 16 (top) and packing diagram with solvent channels of 16 viewed normal to a-axis (bottom). Thermal ellipsoids show atomic displacement at 50% probability.