Investigation of sublimation with and without dissociation in the chloride and nitrate salts of 4-(1-hydroxy-1,2-diphenylethyl)pyridine

We observed sublimation–dissociation and recrystallization under ambient pressure when a single crystal of 1H+·Cl− (4-(1-hydroxy-1,2-diphenylethyl)pyridinium chloride) was heated. The native organic moiety (1) crystallized on the mother crystal on distinct surfaces, providing an excellent example of molecular structure–macroscopical property relationship which can be explained by partial isostructurality. Under similar conditions the nitrate salt of the same compound, 1H+·NO3− (4-(1-hydroxy-1,2-diphenylethyl)pyridinium nitrate), sublimed and recrystallized without dissociation. The two crystal structures of the salts are isostructural, but Hirshfeld surface analysis shows significant differences between the intermolecular interactions which explain their different thermal behavior in the crystalline phase. Computational studies in the gas phase provide a theoretical understanding of the solid state behavior.