Crystal structure and Hirshfeld surface analysis of 2-(2-oxo-3-phenyl-1,2,3,8a-tetra-hydro-quinoxalin-1-yl)ethyl acetate

In the title mol-ecule, C18H16N2O3, the di-hydro-quinoxaline moiety, with the exception of the N atom is essentially planar with the inner part of the methyl-propano-ate group (CH2-CH2-O) nearly perpendicular to it. In the crystal, inversion dimers formed by C-H⋯O hydrogen bonds are connected into oblique stacks by π-stacking and C-H⋯π(ring) inter-actions.

Crystal structure, Hirshfeld surface analysis and DFT study of 1-ethyl-3-phenyl-1,2-di-hydro-quinoxalin-2-one

In the title mol-ecule, C16H14N2O, the di-hydro-quinoxaline moiety is not planar as there is a dihedral angle of 4.51 (5)° between the constituent rings. In the crystal, C-H⋯O hydrogen bonds form helical chains about the crystallographic 21 screw axis in the b-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (51.7%), H⋯C/C⋯H (26%) and H⋯O/O⋯H (8.5%) inter-actions. The optimized structure calculated using density functional theory (DFT) at the B3LYP/6-311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated HOMO-LUMO energy gap is 3.8918 eV.

Crystal structure and Hirshfeld surface analysis of 1-[(1-butyl-1H-1,2,3-triazol-4-yl)meth-yl]-3-methyl-quinoxalin-2(1H)-one

The title compound, C16H19N5O, is built up from a planar quinoxalinone ring system linked through a methyl-ene bridge to a 1,2,3-triazole ring, which in turn carries an n-butyl substituent. The triazole ring is inclined by 67.09 (4)° to the quinoxalinone ring plane. In the crystal, the mol-ecules form oblique stacks along the a-axis direction through inter-molecular C-HTrz⋯NTrz (Trz = triazole) hydrogen bonds, and offset π-stacking inter-actions between quinoxalinone rings [centroid-centroid distance = 3.9107 (9) Å] and π-π inter-actions, which are associated pairwise by inversion-related C-HDhydqn⋯π(ring) (Dhydqn = di-hydro-quinoxaline) inter-actions. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (52.7%), H⋯N/N⋯H (18.9%) and H⋯C/C⋯H (17.0%) inter-actions.

Crystal structure and Hirshfeld surface analysis of ethyl 2-{4-[(3-methyl-2-oxo-1,2-di-hydro-quinoxalin-1-yl)meth-yl]-1H-1,2,3-triazol-1-yl}acetate

The mol-ecule of the title compound, C16H17N5O3, is build up from two fused six-membered rings linked to a 1,2,3-triazole ring, which is attached to an ethyl azido-acetate group. The di-hydro-qinoxalinone portion is planar to within 0.0512 (12) Å and is oriented at a dihedral angle of 87.83 (5)° with respect to the pendant triazole ring. In the crystal, a combination of inter-molecular C-H⋯O and C-H⋯N hydrogen bonds together with slipped π-stacking [centroid-centroid distance = 3.7772 (12) Å] and C-H⋯π (ring) inter-actions lead to the formation of chains extending along the c-axis direction. Additional C-H⋯O hydrogen bonds link these chains into layers parallel to the bc plane and the layers are tied together by complementary π-stacking [centroid-centroid distance = 3.5444 (12) Å] inter-actions. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (44.5%), H⋯O/O⋯H (18.8%), H⋯N/N⋯H (17.0%) and H⋯C/C⋯H (10.4%) inter-actions.