Nada Kheira Sebbar

Crystal structure of (Z)-ethyl 2-{5-[(2-benzyl-idene-3-oxo-2,3-di-hydro-benzo[b][1,4]thia-zin-4-yl)meth-yl]-1H-1,2,3-triazol-1-yl}acetate.

The title compound, C22H20N4O3S, features two fused six-membered rings linked to a 1,2,3-triazole ring which is attached to an ethyl acetate group. The heterocycle in the benzothiazine residue has an envelope conformation with the S atom being the flap. The conformation of the ethyl acetate side chain, which is directed to the same side of the molecule as the C6 ring of the fused-ring system, may be partially established by a pair of weak intramolecular C—H⋯O(carbonyl) interactions. The three-dimensional packing is aided by intermolecular C—H⋯O and C—H⋯N interactions.

4-[(1-Benzyl-1H-1,2,3-triazol-4-yl)meth-yl]-2H-1,4-benzo-thia-zin-3(4H)-one.

In the title compound, C18H16N4OS, the six-membered heterocycle of the benzothiazine fragment exhibits a screw-boat conformation. The dihedral angles between the plane through the triazole ring and those through the fused and terminal benzene rings are 76.68 (11) and 71.0 (1)°, respectively; the benzene rings are nearly perpendicular [dihedral angle = 79.6 (1)°]. In the crystal, molecules are linked by C—H⋯N and C—H⋯O interactions, forming a three-dimensional network.

(2Z)-2-Benzyl-idene-4-(prop-2-yn-1-yl)-2H-1,4-benzo-thia-zin-3(4H)-one.

The molecule of the title compound, C18H13NOS, is build up from two fused six-membered rings, with the heterocyclic component linked to a benzylidene group and to a prop-2-yn-1-yl chain. The six-membered heterocycle adopts a distorted screw-boat conformation. The prop-2-yn-1-yl chain is almost perpendicular to the mean plane through benzothiazine as indicated by the C—N—C—C torsion angle of 86.5 (2)°. The dihedral angle between the benzene rings is 47.53 (12)°. There are no specific intermolecular interactions in the crystal packing.

Crystal structure of 4-benzyl-2H-benzo[b][1,4]thia­zin-3(4H)-one

In the title compound, C15H13NOS, the thiazine ring adopts a twisted boat conformation and the dihedral angle between the aromatic rings is 86.54 (4)°. In the crystal, molecules are linked by weak C—H⋯O interactions, resulting in chains along [010].

New Pyrazole-Hydrazone Derivatives: X-ray Analysis, Molecular Structure Investigation via Density Functional Theory (DFT) and Their High In-Situ Catecholase Activity

The development of low-cost catalytic systems that mimic the activity of tyrosinase enzymes (Catechol oxidase) is of great promise for future biochemistry technologic demands. Herein, we report the synthesis of new biomolecules systems based on hydrazone derivatives containing a pyrazole moiety (L1–L6) with superior catecholase activity. Crystal structures of L1 and L2 biomolecules were determined by X-ray single crystal diffraction (XRD). Optimized geometrical parameters were calculated by density functional theory (DFT) at B3LYP/6–31G (d, p) level and were found to be in good agreement with single crystal XRD data. Copper (II) complexes of the compounds (L1–L6), generated in-situ, were investigated for their catalytic activities towards the oxidation reaction of catechol to ortho-quinone with the atmospheric dioxygen, in an attempt to model the activity of the copper containing enzyme tyrosinase. The studies showed that the activities depend on four parameters: the nature of the ligand, the nature of counter anion, the nature of solvent and the concentration of ligand. The Cu(II)-ligands, given here, present the highest catalytic activity (72.920 μmol·L−1·min−1) among the catalysts recently reported in the existing literature.

Ethyl 2-{5-[(3-oxo-3,4-di-hydro-2H-1,4-benzo-thia-zin-4-yl)meth-yl]-1H-1,2,3-triazol-1-yl}acetate.

In the title compound, C15H16N4O3S, the six-membered heterocycle of the benzothiazine fragment exhibits a screw boat conformation. The dihedral angle between the planes through the triazole ring and the benzene ring fused to the 1,4-thiazine ring is 62.98 (11)°. The mean plane formed by the atoms belonging to the acetate group is nearly perpendicular to the triazole ring [dihedral angle = 74.65 (12)°]. In the crystal, molecules are linked by pairs of C—H⋯O interactions, forming dimeric aggregates.

Crystal structure of (E)-2-benzyl-idene-4-[(3-phenyl-4,5-di-hydro-isoxazol-5-yl)meth-yl]-2H-benzo[b][1,4]thia-zin-3(4H)-one.

In the title compound, C25H20N2O2S, the dihydroisoxazole ring exhibits an envelope conformation with the methine atom being the flap, while the 1,4-thiazine ring displays a screw-boat conformation. The six-membered ring fused to the 1,4-thiazine ring makes dihedral angles of 63.04 (2) and 54.7 (2)° with the mean planes through the five-membered heterocycle and the attached phenyl ring, respectively. The phenyl group connected to the 1,4-thiazine ring is disordered over two sites [major component = 0.57 (2)]. The most prominent interactions in the crystal structure are C—H⋯O hydrogen bonds that link molecules, forming inversion dimers, and C—H⋯N hydrogen bonds that link the dimers into columns parallel to the b axis.

Crystal structure of (Z)-2-benzyl­idene-4-methyl-2H-benzo[b][1,4]thia­zin-3(4H)-one

In the title compound, C16H13NOS, the 1,4-thiazine ring displays a screw-boat conformation. The conformation about the ethene bond [1.344 (2) Å] is Z. The plane of the fused benzene ring makes a dihedral angle of 58.95 (9)° with the pendent phenyl ring, indicating a twisted conformation in the molecule. In the crystal, molecules are linked by pairs of C—H⋯O hydrogen bonds, forming inversion dimers.

4-[(1-Benzyl-1,2,3-triazol-5-yl)meth­yl]-2H-1,4-benzo­thia­zin-3(4H)-one

The asymmetric unit of the title compound, C18H16N4OS, contains two independent molecules of similar conformation, the most relevant difference being the dihedral angle formed by the benzene rings [57.8 (2) and 52.7 (2)°]. The six-membered heterocycle of the benzothiazine fragment exhibits a screw-boat conformation in both molecules. The plane through the triazole ring is nearly perpendicular to those through the fused and terminal benzene rings [dihedral angles of 74.2 (2) and 83.2 (2)° in one molecule, and 77.8 (2) and 82.9 (2)° in the other]. In the crystal, molecules are linked by C—H⋯N and C—H⋯O hydrogen bonds into chains parallel to the a-axis direction. The crystal used was a non-merohedral twin, the refined ratio of twin components being 0.85 (10):15 (10).