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

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 center dot center dot center dot 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 intramolecular interactions, which include C-H center dot center dot center dot O(H), C-H center dot center dot center dot O(NO), N-H center dot center dot center dot O(H), N-H center dot center dot center dot O(NO) and C-H center dot center dot center dot pi hydrogen bonds, as well as pi center dot center dot center dot pi stacking interactions. Intermolecular N-H center dot center dot center dot O hydrogen-bonds involving the phenolic OH group are present in (1: Y = H, 4-O2N, 4-Me, 4-MeO and 4-1), but are absent in ortho-and Iri-(1: Y = 20,N) and (1: Y = 3-O2N). Instead, ortho-(1: Y = 2-O2N) exhibits intermolecular C-H center dot center dot center dot 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 olgomeric species, such as (nM + M')(+), where n is up to 4, and M' = H, Na or K.