Crystal structure, Hirshfeld surface analysis and density functional theory study of 1-nonyl-3-phenyl­quinoxalin-2-one

In the title mol­ecule, C(23)H(28)N(2)O, the phenyl ring is inclined to the quinoxaline ring system at a dihedral angle of 20.40 (9)°. In the crystal, C—H⋯O inter­actions between neighbouring mol­ecules form chains along the a-axis direction. Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (70.6%), H⋯C/C⋯H (15.5%) and H⋯O/O⋯H (4.6%) inter­actions. The optimized structure calculated using density functional theory at the B3LYP/6–311 G(d,p) level is compared with the experimentally determined structure in the solid state. The calculated highest occupied mol­ecular orbital (HOMO) and lowest unoccupied mol­ecular orbital (LUMO) energy gap is 3.8904 eV. Part of the n-nonyl chain attached to one of the nitro­gen atoms of the quinoxaline ring system shows disorder and was refined with a double conformation with occupancies of 0.604 (11) and 0.396 (11).