1-Methyl-2-[(E)-2,4,5-trimethoxystyryl]pyridinium benzenesulfonate monohydrate

The asymmetric unit of the title compound, C17H20NO3 +·C6H5O3S−·H2O, comprises two 1-methyl-2-[(E)-2,4,5-trimethoxystyryl]pyridinium cations, two benzenesulfonate anions and two water molecules. The cations exist in the E conformation with respect to the C=C bond; one cation is essentially planar while the other is slightly twisted, the dihedral angles between the pyridinium and phenyl rings being 1.23 (14) and 6.64 (13)°, respectively. In the crystal, cations, anions and water molecules are linked by O—H⋯O hydrogen bonds and weak C—H⋯O interactions into chains along the b axis. π–π interactions with centroid–centroid distances in the range 3.5557 (16)–3.6876 (16) Å are observed. C—H⋯π interactions and a C⋯O short contact [2.94 (4) Å] are also observed.


Related literature
Cg5 and Cg6 are the centroids of the C18A-C23A and C18B-C23B rings, respectively. Hydroxylated stilbenes are widely found in nature and also show interesting biological activities (Ko et al., 1999;Park et al., 2008;Roupe et al., 2006;Son et al., 2007). Resveratrol, a well known hydroxylated stilbene, is an isolated bioactive substance found in grapes and red wine (Kimura, 2005). It has shown various bioactivities such as antibacterial (Nitta et al., 2002), antiplasmodial (Son et al., 2007, antioxidant (Olas & Wachowicz 2002), anti-inflammatory (Elmali et al., 2006 and anticancer activities (Kimura, 2005). Due to these activities, it led us to synthesize the hydroxylated pyridinium stilbenes and to evaluate their antimicrobial activity. The title compound (I) is a hydroxylated pyridinium stilbene derivative which was synthesized and tested for antibacterial activity against the Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Methicillin-Resistant Staphylococcus aureus, Vancomycin-Resistant Enterococcus faecalis, Pseudomonas aeruginosa, Salmonella typhi and Shigella sonnei, but unfortunately it was found to be inactive.

D-HÁ
Herein we report the crystal structure of (I). N1B/C1B-C5B pyridinium rings. The bond lengths of (I) are in normal ranges (Allen et al., 1987) and are comparable to those in related structures (Fun et al., 2011;Mueangkeaw et al., 2010).

Experimental
The title compound was synthesized by mixing a 1:1 molar ratio of 1-methyl-2-[(E)-2,4,5-trimethoxystyryl]pyridinium iodide (0.10 g, 0.24 mmol) which was prepared according to the previous method (Mueangkeaw et al., 2010) and silver (I) benzenesulfonate (Chanawanno et al., 2010) (0.06 g, 0.24 mmol) in methanol (50 ml). The mixture immediately yielded a grey precipitate of silver iodide. After stirring the mixture for ca. 30 min, the precipitate of silver iodide was removed and the resulting solution was evaporated yielding the title compound as an orange solid. Orange block-shaped single crystals of (I) suitable for x-ray structure determination were recrystallized from DMSO by slow evaporation at room temperature over a few weeks, Mp. 455-456 K.

Refinement
All H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(O-H) = 0.92 -1.07 Å, d(C-H) = 0.93 Å for aromatic and CH and 0.96 Å for CH 3 atoms. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups.
The SO 3 group of one benzenesulfonate is disordered over two positions with the refined site-occupancy ratio of 0.948 (4):0.052 (4).  The molecular structure of the title compound, with 50% probability displacement ellipsoids and the atom-numbering scheme.  The crystal packing of the title compound viewed approximately down the a-axis. Only the major component is shown.

Computing details
For clarity, only H atoms involved in hydrogen bonds are shown. Hydrogen bonds are shown as dashed lines.

1-Methyl-2-[(E)-2,4,5-trimethoxystyryl]pyridinium benzenesulfonate monohydrate
Special details Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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.  Hydrogen-bond geometry (Å, º) Cg5 and Cg6 are the centroids of the C18A-C23A and C18B-C23B rings, respectively.