Crystal structure, Hirshfeld surface analysis and DFT studies of 1-benzyl-3-[(1-benzyl-1H-1,2,3-triazol-5-yl)methyl]-2,3-dihydro-1H-1,3-benzodiazol-2-one monohydrate

The dihydrobenzodiazole moiety is not quite planar while the whole molecule adopts a U-shaped conformation in which there is a close approach of the two benzyl groups. Chains of alternating molecules and lattice water extending along the normal to (301) are formed by O—H⋯O and O—H⋯N hydrogen bonds.

In the title molecule, C 24 H 21 N 5 OÁH 2 O, the dihydrobenzodiazole moiety is not quite planar, while the whole molecule adopts a U-shaped conformation in which there is a close approach of the two benzyl groups. In the crystal, chains of alternating molecules and lattice water extending along [201] are formed by O-H UncoordW Á Á ÁO Dhyr and O-H UncoordW Á Á ÁN Trz (UncoordW = uncoordinated water, Dhyr = dihydro and Trz = triazole) hydrogen bonds. The chains are connected into layers parallel to (010) by C-H Trz Á Á ÁO UncoordW hydrogen bonds with the dihydrobenzodiazole units in adjacent layers intercalating to form head-to-tail -stacking [centroid-to-centroid distance = 3.5694 (11) Å ] interactions between them, which generates the overall three-dimensional structure. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from HÁ Á ÁH (52.1%), HÁ Á ÁC/CÁ Á ÁH (23.8%) and OÁ Á ÁH/ HÁ Á ÁO (11.2%) interactions. Hydrogen-bonding and van der Waals interactions are the dominant interactions 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 molecular structure in the solid state. The HOMO-LUMO behaviour was elucidated to determine the energy gap.

Chemical context
Nitrogen heterocyclic compounds are known to exhibit excellent biological and pharmaceutical activities (Olesen et al., 1994;Baxter & Clarke, 1992;Saber et al., 2020;Ré mond et al., 1997). The benzimidazole core has several active sites and provides great responsiveness, making it an excellent heterocyclic precursor in the syntheses of the new heterocyclic compounds (Saber et al., 2018a,b;Ouzidan et al., 2011;Saber et al., 2020). With respect to the biological applications of benzimidazolone derivatives, it has been shown that these compounds are found to possess potent antioxidant (Gaba et al., 2014), antiparasitic (Ayhan-Kılcıgil et al., 2007), anthelmintic (Navarrete-Vazquez et al., 2001), antiproliferative (Ravina et al., 1993), anti-HIV (Garuti et al., 2000), anticonvulsant (Rao et al., 2002), anti-inflammatory (Thakurdesai et al., 2007), antihypertensive (Serafin et al., 1989) and antitrichinellosis (Mavrova et al., 2007) activities. In addition, they are considered to be important moieties for the development of molecules of pharmaceutical interest (Mondieig et al., 2013;Lakhrissi et al., 2008). As a continuation of our research devoted to the study of the cycloaddition reactions involving benzimidazolone derivatives (Sebbar et al., 2016;Saber et al., 2020), we report herein the synthesis, the molecular and crystal structures of the title compound along with the results of the Hirshfeld surface analysis and the density functional theory (DFT) computational calculations carried out at the B3LYP/6-311 G(d,p) level in order to compare the theoretical and experimentally determined molecular structures in the solid state.

Structural commentary
The title molecule, (I), adopts a U-shaped conformation with an H20Á Á ÁC14 separation of 2.83 Å , which is very close to a normal van der Waals contact (2.90 Å ). The orientation of the C11-C17 benzyl group is partly determined by an intramolecular C13-H13Á Á ÁCg interaction, where Cg is the centroid of the triazole (C9/C10/N3-N5), ring C ( Fig. 1 and Table 1). The dihydrobenzodiazole unit is not quite planar, as indicated by the dihedral angle of 2.50 (8) between the constituent rings A (C1-C6) and B (N1/N2/C1/C6/C7) and the deviation of atom C7 by 0.0418 (14) Å out of the mean plane through the whole unit. The benzene ring D (C12-C17) is inclined to the triazole ring C by 78.91 (11) while the latter ring is inclined to the B ring by 64.70 (11) . The dihedral angle between the mean planes of the B and E (C19-C24) rings is 87.67 (8) .

Supramolecular features
In the crystal, the molecules form chains with the water molecule of crystallization, which extend along [201]  The molecular structure of the title compound with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. The O-H UncoordW Á Á ÁN Trz (UncoordW = uncoordinated water, Trz = triazole) hydrogen bond is shown by a red dashed line while the intramolecular C-HÁ Á Á(ring) interaction is depicted by a green dashed line.

Hirshfeld surface analysis
In order to visualize the intermolecular interactions in the crystal of the title compound, a Hirshfeld surface (HS) analysis (Hirshfeld, 1977;Spackman & Jayatilaka, 2009) was carried out using Crystal Explorer 17.5 (Turner et al., 2017). In the HS plotted over d norm (Fig. 4), white areas indicates contacts with distances equal to the sum of van der Waals radii, and the red and blue colours indicate distances shorter (in close contact) or longer (distinct contact), respectively, than the van der Waals radii (Venkatesan et al., 2016). The bright-red spots appearing near O1 and hydrogen atom H2B indicate their roles as the respective donors and acceptors. The shape-index of the HS is a tool to visualize thestacking by the presence of adjacent red and blue triangles; if there are no adjacent red and/or blue triangles, then there are nointeractions.   Table 1 Hydrogen-bond geometry (Å , ).

Figure 4
View of the three-dimensional Hirshfeld surface of the title compound plotted over d norm in the range À0.5603 to 1.3285 a.u.
Hirshfeld surface of the title compound plotted over shape-index.
The overall two-dimensional fingerprint plot, Fig. 6a, and those delineated into HÁ Á ÁH, HÁ Á ÁC/CÁ Á ÁH, HÁ Á ÁO/OÁ Á ÁH, HÁ Á ÁN/NÁ Á ÁH, CÁ Á ÁC and CÁ Á ÁN/NÁ Á ÁC contacts (McKinnon et al., 2007) are illustrated in Fig. 6b-g, respectively, together with their relative contributions to the Hirshfeld surface. The most important interaction (Table 2) is HÁ Á ÁH, contributing 52.1% to the overall crystal packing, which is reflected in Fig. 6b as widely scattered points of high density due to the large hydrogen content of the molecule with the tip at d e = d i = 1.00 Å . The presence of C-HÁ Á Á interactions give rise to pairs of characteristic wings in the fingerprint plot delineated into HÁ Á ÁC/CÁ Á ÁH contacts (23.8% contribution to the HS), The Hirshfeld surface analysis confirms the importance of H-atom contacts in establishing the packing. The large number of HÁ Á ÁH, HÁ Á ÁC/CÁ Á ÁH and HÁ Á ÁO/OÁ Á ÁH interactions suggest that van der Waals interactions and hydrogen bonding play the major roles in the crystal packing (Hathwar et al., 2015).

Database survey
An N-substituted benzoimidazol-2-one analogue (Saber et al., 2018a,b;Saber et al., 2020) and other similar compounds have also been reported (Belaziz et al., 2012(Belaziz et al., , 2013Bouayad et al., 2015). In derivatives of benzimidazolin-2-one in which both nitrogen atoms form exocyclic C-N bonds, the bicyclic ring system is either planar, has a slight twist end-to-end, or, in the cases where the exocyclic substituents form a ring, has a very shallow bowl shape.

DFT calculations
The optimized structure of the title compound, (I), in the gas phase was generated theoretically via density functional theory (DFT) using standard B3LYP functional and 6-311 G(d,p) basis-set calculations (Becke, 1993) as implemented in GAUSSIAN 09 (Frisch et al., 2009). The theoretical and experimental results are in good agreement (Table 3). The highest-occupied molecular orbital (HOMO), acting as an electron donor, and the lowest-unoccupied molecular orbital (LUMO), acting as an electron acceptor, are very important parameters for quantum chemistry. When the energy gap is small, the molecule is highly polarizable and has high chemical reactivity. The DFT calculations provide some important information on the reactivity and site selectivity of the molecular framework. E HOMO and E LUMO clarify the inevitable charge-exchange collaboration inside the studied material, electronegativity (), hardness (), potential (), electrophilicity (!) and softness () are recorded in Table 4. The significance of and is to evaluate both the reactivity and stability. The electron transition from the HOMO to the LUMO energy level is shown in Fig. 8. The HOMO and LUMO are localized in the plane extending over the whole 1benzyl-3-[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]-2,3-dihydro-1H-1,3-benzodiazol-2-one hydrate ring. The energy band gap [ÁE = E LUMO -E HOMO ] of the molecule is 5.3468 eV, and the frontier molecular orbital energies, E HOMO and E LUMO are À6.1633 and À0.8166 eV, respectively.

Figure 8
The energy band gap of the title compound, (I).
1). The isolated solid product was recrystallized from ethanol to afford yellow crystals (yield: in 19%).

Refinement
The experimental details including the crystal data, data collection and refinement are summarized in Table 5. Hydrogen atoms were included as riding contributions in idealized positions with C-H = 0.95-0.99 Å and U iso (H) = 1.2U eq (C).

Funding information
The support of NSF    program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018 (Sheldrick, 2015b); molecular graphics: DIAMOND (Brandenburg & Putz, 2012); software used to prepare material for publication: SHELXL2018 (Sheldrick, 2015b). where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.22 e Å −3 Δρ min = −0.21 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger. Hatoms attached to carbon were placed in calculated positions (C-H = 0.95 -0.99 Å) while those attached to oxygen were placed in locations derived from a difference map and their coordinates adjusted to give O-H = 0.87 Å. All were included as riding contributions with isotropic displacement parameters 1.2 -1.5 times those of the attached atoms.