Conglomerate formation and crystal structure of 4-phenyl-1,3-thiazolidin-2-one

Racemic 4-phenyl-1,3-thiazolidin-2-one (4-PTO) crystallizes in the form of conglomerate. The conglomerate formation has been confirmed by analyzing Weissenberg X-ray photographs and IR, Raman spectra of the racemate and the enantiopure 4-PTO crystals. The crystal structure of 4-PTO has been determined by X-ray diffraction, and the structural features are compared with those of other 4-phenyl-1,3-oxazolidin-2-one derivatives in order to understand the structural factors leading to the conglomerate formation. In 4-PTO crystals, the N-H⋯O intermolecular hydrogen bonds are formed between the amide groups of neighboring molecules in a homochiral zigzag chain. In addition, the intermolecular S⋯O close contacts are observed between the thioether and the carbonyl groups in the same chain unit. Moreover, the phenyl groups of homochiral 4-PTO molecules of different chain units take the T-shaped stacking orientation to each other due to the aromatic CH/π interaction. These structural factors altogether reinforce the homochiral supramolecular assembly of chain structural units in the 4-PTO crystal.