Crystal structure, Hirshfeld surface analysis and DFT studies of (E)-4-methyl-2-{[(2-methyl-3-nitro-phen-yl)imino]-meth-yl}phenol

The title compound, C15H14N2O3, was prepared by condensation of 2-hy-droxy-5-methyl-benzaldehyde and 2-methyl-3-nitro-phenyl-amine in ethanol. The configuration of the C=N bond is E. An intra-molecular O-H⋯N hydrogen bond is present, forming an S(6) ring motif and inducing the phenol ring and the Schiff base to be nearly coplanar [C-C-N-C torsion angle of 178.53 (13)°]. In the crystal, mol-ecules are linked by C-H⋯O inter-actions, forming chains along the b-axis direction. The Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (37.2%), C⋯H (30.7%) and O⋯H (24.9%) inter-actions. The gas phase density functional theory (DFT) optimized structure at the B3LYP/ 6-311 G(d,p) level is compared to the experimentally determined mol-ecular structure in the solid state. The HOMO-LUMO behaviour was elucidated to determine the energy gap.

Crystal structure, Hirshfeld surface analysis and DFT studies of 2-[(2-hy-droxy-5-methyl-benzyl-idene)amino]-benzo-nitrile

The title compound, C15H12N2O, was synthesized by condensation reaction of 2-hy-droxy-5-methyl-benzaldehyde and 2-amino-benzo-nitrile, and crystallizes in the ortho-rhom-bic space group Pbca. The phenol ring is inclined to the benzo-nitrile ring by 25.65 (3)°. The configuration about the C=N bond is E, stabilized by a strong intra-molecular O-H⋯N hydrogen bond that forms an S(6) ring motif. In the crystal, C-H⋯O and C-H⋯N inter-actions lead to the formation of sheets perpendicular to the a axis. C-H⋯π inter-actions, forming polymeric chains along the a-axis direction, connect these sheets into a three-dimensional network. A Hirshfeld surface analysis indicates that the most important contributions for the packing arrangement are from H⋯H and C⋯H/H⋯C inter-actions. The density functional theory (DFT) optimized structure at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined mol-ecular structure and the HOMO-LUMO energy gap is given.

Crystal structure, Hirshfeld surface analysis and DFT studies of 4-methyl-2-({[4-(tri-fluoro-meth-yl)phen-yl]imino}-meth-yl)phenol

The title compound, C15H12F3NO, crystallizes with one mol-ecule in the asymmetric unit. The configuration of the C=N bond is E and there is an intra-molecular O-H⋯N hydrogen bond present, forming an S(6) ring motif. The dihedral angle between the mean planes of the phenol and the 4-tri-fluoro-methyl-phenyl rings is 44.77 (3)°. In the crystal, mol-ecules are linked by C-H⋯O inter-actions, forming polymeric chains extending along the a-axis direction. The Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from C⋯H/H⋯C (29.2%), H⋯H (28.6%), F⋯H/H⋯F (25.6%), O⋯H/H⋯O (5.7%) and F⋯F (4.6%) inter-actions. The density functional theory (DFT) optimized structure at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined mol-ecular structure in the solid state. The HOMO-LUMO behaviour was elucidated to determine the energy gap. The crystal studied was refined as an inversion twin.

Crystal structure and DFT computational studies of (E)-2,4-di-tert-butyl-6-{[3-(tri-fluoro-meth-yl)benz-yl]imino-meth-yl}phenol

The title compound, C23H28F3NO, is an ortho-hy-droxy Schiff base compound, which adopts the enol-imine tautomeric form in the solid state. The mol-ecular structure is not planar and the dihedral angle between the planes of the aromatic rings is 85.52 (10)°. The tri-fluoro-methyl group shows rotational disorder over two sites, with occupancies of 0.798 (6) and 0.202 (6). An intra-molecular O-H⋯N hydrogen bonding generates an S(6) ring motif. The crystal structure is consolidated by C-H⋯π inter-actions. The mol-ecular structure was optimized via density functional theory (DFT) methods with the B3LYP functional and LanL2DZ basis set. The theoretical structure is in good agreement with the experimental data. The frontier orbitals and mol-ecular electrostatic potential map were also examined by DFT computations.