Syntheses, crystal structures, spectroscopic characterizations, DFT calculations, hirshfeld surface analyses and monte carlo simulations of novel long-chain alkyl-substituted 1,4-benzothiazine derivatives

In this work, three novel long-chain alkyl substituted 1,4-benzothiazine derivatives have been synthesized by alkylation reactions under phase transfer catalysis conditions. The obtained compounds (4, 5 and 6) obtained were characterized using ¹H- and ¹³C- NMR spectroscopy and X-ray. Their molecular and crystal structures have been determined by single-crystal X-ray diffraction techniques. The experimental data, were compared with the predicted ones spectral data were also obtained using density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory. In addition, the closest contacts between the active atoms of the compounds were identified through Hirshfeld surface analyses. According to Monte Carlo simulations, the new compounds can act as good corrosion inhibitors for iron and as moderate ones for copper and aluminum metals.