Crystal structure, Hirshfeld surface analysis and inter-action energy, DFT and anti-bacterial activity studies of (Z)-4-hexyl-2-(4-methyl-benzyl-idene)-2H-benzo[b][1,4]thia-zin-3(4H)-one.

The title compound, C(22)H(25)NOS, consists of methyl-benzyl-idene and benzo-thia-zine units linked to a hexyl moiety, where the thia-zine ring adopts a screw-boat conformation. In the crystal, inversion dimers are formed by weak C-H(Mthn)⋯O(Bnzthz) hydrogen bonds and are linked into chains extending along the a-axis direction by weak C-H(Bnz)⋯O(Bnzthz) (Bnz = benzene, Bnzthz = benzo-thia-zine and Mthn = methine) hydrogen bonds. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (59.2%) and H⋯C/C⋯H (27.9%) inter-actions. Hydrogen bonding and van der Waals inter-actions are the dominant inter-actions in the crystal packing. Computational chemistry indicates that in the crystal, the C-H(Bnz)⋯O(Bnzthz) and C-H(Mthn)⋯O(Bnzthz) hydrogen-bond energies are 75.3 and 56.5†kJ†mol(-1), respectively. Density functional theory (DFT) optimized structures at the B3LYP/ 6-311†G(d,p) level are compared with the experimentally determined mol-ecular structure in the solid state. The HOMO-LUMO behaviour was elucidated to determine the energy gap. Moreover, the anti-bacterial activity of the title compound was evaluated against gram-positive and gram-negative bacteria.