Crystal structure, Hirshfeld surface analysis and inter-action energy, DFT and anti-bacterial activity studies of ethyl 2-[(2Z)-2-(2-chloro-benzyl-idene)-3-oxo-3,4-di-hydro-2H-1,4-benzo-thia-zin-4-yl]acetate.

The title compound, C19H16ClNO3S, consists of chloro-phenyl methyl-idene and di-hydro-benzo-thia-zine units linked to an acetate moiety, where the thia-zine ring adopts a screw-boat conformation. In the crystal, two sets of weak C-HPh⋯ODbt (Ph = phenyl and Dbt = di-hydro-benzo-thia-zine) hydrogen bonds form layers of mol-ecules parallel to the bc plane. The layers stack along the a-axis direction with inter-calation of the ester chains. The crystal studied was a two component twin with a refined BASF of 0.34961 (5). The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (37.5%), H⋯C/C⋯H (24.6%) and H⋯O/O⋯H (16.7%) 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, C-HPh⋯ODbt hydrogen bond energies are 38.3 and 30.3 kJ mol-1. 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 has been evaluated against gram-positive and gram-negative bacteria.