No abstract

Natural products have stood out due to their wide range of biological activities.

Four sulfonamide-chalcone derivatives were prepared and their crystal structure were elucidated by single-crystal X-ray diffraction technique. They were synthesized by Claisen-Schmidt condensation reaction between N-(4-acetylphenyl)benzenesulfonamide or N-(4-acetylphenyl)-2,5-dichlorobenzenesulfonamide with benzaldehyde or p-nitrobenzaldehyde. Values of Z' > 1 are found in three compounds as a consequence of conformerism. The chalcone molecular backbones are featured by different levels of planarity in their conformers. Another conformational variability is in its benzenesulfonamide moiety. In the compound came from N-(4-acetylphenyl) benzenesulfonamide and benzaldehyde, there is a rotation of ca. 180° on the bond axis bridging the sulfonamide and chalcone motifs of one conformer if the two others are taken as references. The cytotoxic activity of all compounds synthesized here and of two other related sulfonamide chalcones was also assessed against three cancer cell lines (SF-295, HCT-8 and MDA-MB-435). The para-nitro compounds were the most active ones among all those tested, regardless of substitution pattern in benzenesulfonamide core.

The structures of two arylsulfonamide para-alkoxychalcones, namely, N-{4-[(E)-3-(4-methoxyphenyl)prop-2-enoyl]phenyl}benzenesulfonamide, C22H19NO4S, (I), and N-{4-[(E)-3-(4-ethoxyphenyl)prop-2-enoyl]phenyl}benzenesulfonamide, C23H21NO4S, (II), reveal the effect of the inclusion of one -CH2- group between the CH3 branch and the alkoxy O atom on the conformation and crystal structure. Although the molecular conformations and one-dimensional chain motifs are the same in both structures, their crystallographic symmetry, number of independent molecules and crystal packing are different. The crystal packing of (I) is stabilized by weak C-H...π and π-π interactions, while only C-H...π contacts occur in the structure of (II). The role of the additional methylene group in the crystal packing can also be seen in the fact that the alkoxy O atom is an acceptor in nonclassical hydrogen bonds only in the para-ethoxy analogue, (II). The remarkable similarity between the crystal packing features of (I) and (II) lies in the formation of N-H...O hydrogen-bonded ribbons, a synthon commonly found in related compounds.