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.