Crystal structure, Hirshfeld surface analysis and inter­action energy, DFT and anti­bacterial activity studies of (Z)-4-hexyl-2-(4-methyl­benzyl­­idene)-2H-benzo[b][1,4]thia­zin-3(4H)-one

The title compound, C22H25NOS, consists of methyl­benzyl­idene and benzo­thia­zine units linked to a hexyl moiety, where the thia­zine ring adopts a screw-boat conformation. In the crystal, inversion dimers are formed by weak C—HMthn⋯OBnzthz hydrogen bonds and are linked into chains extending along the a-axis direction by weak C—HBnz⋯OBnzthz (Bnz = benzene, Bnzthz = benzo­thia­zine 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%) inter­actions. Hydrogen bonding and van der Waals inter­actions are the dominant inter­actions in the crystal packing. Computational chemistry indicates that in the crystal, the C—HBnz⋯OBnzthz and C—HMthn⋯OBnzthz 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 mol­ecular structure in the solid state. The HOMO—LUMO behaviour was elucidated to determine the energy gap. Moreover, the anti­bacterial activity of the title compound was evaluated against gram-positive and gram-negative bacteria.