Crystal structure, Hirshfeld surface analysis and DFT studies of 1-benzyl-3-[(1-benzyl-1-1,2,3-triazol-5-yl)meth-yl]-2,3-di-hydro-1-1,3-benzo-diazol-2-one monohydrate.

In the title mol-ecule, CHNO·HO, the di-hydro-benzo-diazole moiety is not quite planar, while the whole mol-ecule adopts a U-shaped conformation in which there is a close approach of the two benzyl groups. In the crystal, chains of alternating mol-ecules and lattice water extending along [201] are formed by O-H⋯O and O-H⋯N (UncoordW = uncoordinated water, Dhyr = di-hydro and Trz = triazole) hydrogen bonds. The chains are connected into layers parallel to (010) by C-H⋯O hydrogen bonds with the di-hydro-benzo-diazole units in adjacent layers inter-calating to form head-to-tail π-stacking [centroid-to-centroid distance = 3.5694 (11) Å] inter-actions between them, which generates the overall three-dimensional structure. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (52.1%), H⋯C/C⋯H (23.8%) and O⋯H/H⋯O (11.2%) inter-actions. Hydrogen-bonding and van der Waals inter-actions are the dominant inter-actions in the crystal packing. Density functional theory (DFT) optimized structures at the B3LYP/ 6-311 G(d,p) level are compared with the experimentally determined mol-ecular structure in the solid state. The HOMO-LUMO behaviour was elucidated to determine the energy gap.