(2E)-3-{4-[(1H-1,3-Benzimidazol-2-yl)methoxy]-3-ethoxyphenyl}-1-(4-bromophenyl)prop-2-en-1-one monohydrate

In the title compound, C25H21BrN2O3·H2O, the benzimidazole fragment and the water molecule of crystallization are each disordered over two sets of sites of equal occupancy. The dihedral angles between the least-squares planes of the benzimidazole and the 3-ethoxy- and 4-bromobenzene rings are 86.9 (6) and 85.1 (1)°, respectively in one disorder component. The crystal packing is stabilized by intermolecular O—H⋯O, O—H⋯N and N—H⋯N hydrogen bonds, which link the molecules into chains along the a axis.

In the title compound, C 25 H 21 BrN 2 O 3 ÁH 2 O, the benzimidazole fragment and the water molecule of crystallization are each disordered over two sets of sites of equal occupancy. The dihedral angles between the least-squares planes of the benzimidazole and the 3-ethoxy-and 4-bromobenzene rings are 86.9 (6) and 85.1 (1) , respectively in one disorder component. The crystal packing is stabilized by intermolecular O-HÁ Á ÁO, O-HÁ Á ÁN and N-HÁ Á ÁN hydrogen bonds, which link the molecules into chains along the a axis.

Related literature
For the biological activity of benzimidazoles, see: Pujar et al. (1988);Bouwman et al. (1990). For the use of benzimidazoles in pest control, see: Madkour et al. (2006). For the properties and uses of chalcones, see: Dhar (1981); Dimmock et al.   Table 1 Hydrogen-bond geometry (Å , ).  Comment The benzimidazole ring system and its related compounds play an important role in pharmaceutical and agricultural fields due to their broad spectrum of biological activities (Pujar et al., 1988, Bouwman et al., 1990. The synthesis of novel benzimidazole derivatives remains a main focus of medicinal research. Benzimidazoles are also useful as insecticides, acaricides, nematocides, herbicides and other plant-protective agents in the field of pest control (Madkour et al., 2006). In recent years, attention has increasingly been given to the synthesis of benzimidazole derivatives as a source of new antimicrobial agents.

Experimental
In addition, benzimidazole derivatives have played a crucial role in the theoretical development of heterocyclic chemistry and are also used extensively in organic synthesis.
Chalcones constitute an important family of substances belonging to the flavonoids, a large group of natural and synthetic products with interesting physicochemical properties, biological activities and structural characteristics. Chalcones are highly reactive substances of varied nature. They have been reported to possess many interesting pharmacological activities (Dhar, 1981) including anti-inflammatory, antimicrobial, antifungal, antioxidant, cytotoxic, antitumor and anticancer activities (Dimmock et al., 1999;Satyanarayana et al., 2004). Chalcones are also finding application as organic nonlinear optical materials (NLO) for their SHG conversion efficiency (Sarojini et al., 2006).
The crystal structures of some benzimidazole derivatives viz., 2-chloromethyl-1H-benzimidazole nitrate (Jian et al., 2003) and 5-methoxy-1H-benzo[d]imidazole-2(3H)-thione (Odabaşoğlu et al., 2007) have been reported. Encouraged by the diverse biological activities of benzimidazoles and chalcones, it was decided to prepare a new chalcone derivative of 2-aryloxy methylbenzimidazole, thus bringing both types of functional groups together in a single molecule. This paper reports the crystal structure of the title compound, C 25 H 21 N 2 O 3 Br. H 2 O, (I).
In the title compound, (I), the benzimidazole fragment and an associated water molecule are each disordered over two positions in a ratio of 0.50 (0) and 0.50 (0) (Fig. 2). The dihedral angles between the least squares planes of the benzimidazol (0.50 (0) component) and the 3-ethoxy and 4-bromo benzene rings are 86.9 (6)° and 85.1 (1)°, respectively (Fig. 3). Bond distances and angles are in normal ranges (Allen et al., 1987). Crystal packing is stabilized by O-H···O, N-H···O and N-H···N intermolecular hydrogen bonds (Table 1) linking the molecules into one-dimensional chains along the a axis ( Fig.  4).

Experimental
A mixture of a 4-(1H-benzimidazol-2-ylmethoxy)-3-ethoxybenzaldehyde (0.005 mole) and p-bromo acetophenone (0.005 mole) in 50 ml ethanolic sodium hydroxide was stirred at 5-10°C for 3 h (Fig. 1), then maintained at room temperature for 24 h and poured into ice cold water. The precipitate that appeared after neutralization with dil. HCl was filtered off and recrystallized from 1,4-dioxane. The single crystals were grown from DMF by the slow evaporation method, with a yield of 85%.  (0)) and N2B (0.50 (0)) atoms, respectively, were placed at their disordered sites and refined by the riding model. All of the remaining H atoms were placed in their calculated positions and then refined using the riding model with atom-H lengths of 0.93Å (CH), 0.97Å (CH 2 ), 0.96Å (CH 3 ) or 0.86Å (NH). Isotropic displacement parameters for these atoms were set to 1.19-1.20 (CH, CH 2 ), 1.49 (CH 3 ) or 1.19 (NH) times U eq of the parent atom.     (2)