2-Hydroxyacetophenone arylhydrazones. Supramolecular arrangements based on C–H · · · O(H), CH · · · O(NO), N–H · · · O(H), N–H · · · O(NO), C–H · · · π or π · · · π interactions

Abstract

Abstract Crystal structures, NMR and IR spectra and EI-MS+ of 2-hydroxyacetophenone arylhydrazones, 2-HOC6H4C(Me) = NNHC6H4Y (1: Y = 2-O2N, 3-O2N, 4-O2N, 4-Me, 4-MeO, H and 4-I) are reported. Two polymorphs of (1: Y = 2-O2N), triclinic and orthorhombic forms, have been identified. While strong intramolecular O–H · · · N(H) hydrogen bonds and layers of molecules are found for all solid 1, supramolecular arrangements of individual members are various and are derived from different combinations of intermolecular interactions, which include C–H · · · O(H), C–H · · · O(NO), N–H · · · O(H), N–H · · · O(NO) and C–H · · · π hydrogen bonds, as well as π · · · π stacking interactions. Intermolecular N–H · · · O hydrogen-bonds involving the phenolic OH group are present in (1: Y = H, 4-O2N, 4-Me, 4-MeO and 4-I), but are absent in ortho-and tri-(1: Y = 2-O2N) and (1: Y = 3-O2N). Instead, ortho-(1: Y = 2-O2N) exhibits intermolecular C–H · · · O(H) hydrogen bonds, while no intermolecular hydrogen bonds involving the OH group occur in either triclinic-(1: Y = 2-O2N) or (1: Y = 3-O2N). EI+-MS revealed the presence of oligomeric species, such as (nM + M′)+, where n is up to 4, and M′ = H, Na or K.