Four N-(4-halophen-yl)-4-oxo-4H-chromene-3-carboxamides (halo = F, Cl, Br and I), N-(4-fluoro-phen-yl)-4-oxo-4H-chromene-3-carboxamide, C16H10FNO3, N-(4-chloro-phen-yl)-4-oxo-4H-chromene-3-carboxamide, C16H10ClNO3, N-(4-bromo-phen-yl)-4-oxo-4H-chromene-3-carboxamide, C16H10BrNO3, N-(4-iodo-phen-yl)-4-oxo-4H-chromene-3-carboxamide, C16H10INO3, have been structurally characterized. The mol-ecules are essentially planar and each exhibits an anti conformation with respect to the C-N rotamer of the amide and a cis geometry with respect to the relative positions of the Carom-Carom bond of the chromone ring and the carbonyl group of the amide. The structures each exhibit an intra-molecular hydrogen-bonding network comprising an N-H⋯O hydrogen bond between the amide N atom and the O atom of the carbonyl group of the pyrone ring, forming an S(6) ring, and a weak Carom-H⋯O inter-action with the O atom of the carbonyl group of the amide as acceptor, which forms another S(6) ring. All four compounds have the same supra-molecular structure, consisting of R 2 (2)(13) rings that are propagated along the a-axis direction by unit translation. There is π-π stacking involving inversion-related mol-ecules in each structure.
Keywords: chromones; conformation; crystal structure; drug design; supramolecular structure.