(E)-2-[4-(Diethylamino)styryl]-1-methylquinolinium 4-fluorobenzenesulfonate monohydrate

In the title hydrated molecular salt, C22H25N2 +·C6H4FO3S−·H2O, the cation displays whole molecule disorder over two sets of sites in a 0.780 (5):0.220 (5) ratio. The quinolinium ring system is essentially planar, with r.m.s. deviations of 0.0162 and 0.0381 Å for the major and minor disorder components, respectively. The dihedral angles between the mean plane of the quinolinium ring system and the benzene ring are 5.1 (3) and 7.7 (11)°, respectively, for the major and minor components in the cation. In the crystal, cations, anions and water molecules are linked into chains along [010] by O—H⋯O hydrogen bonds and are further connected into a three-dimensional network by weak C—H⋯O and C—H⋯F interactions. In addition, π–π interactions with centroid–centroid distances of 3.634 (3), 3.702 (5) and 3.838 (5) Å are observed.

In the title hydrated molecular salt, C 22 H 25 N 2 + ÁC 6 H 4 FO 3 S À Á-H 2 O, the cation displays whole molecule disorder over two sets of sites in a 0.780 (5):0.220 (5) ratio. The quinolinium ring system is essentially planar, with r.m.s. deviations of 0.0162 and 0.0381 Å for the major and minor disorder components, respectively. The dihedral angles between the mean plane of the quinolinium ring system and the benzene ring are 5.1 (3) and 7.7 (11) , respectively, for the major and minor components in the cation. In the crystal, cations, anions and water molecules are linked into chains along [010] by O-HÁ Á ÁO hydrogen bonds and are further connected into a threedimensional network by weak C-HÁ Á ÁO and C-HÁ Á ÁF interactions. In addition,interactions with centroidcentroid distances of 3.634 (3), 3.702 (5) and 3.838 (5) Å are observed.

Comment
The antibacterial significance of synthetic quinolinium derivatives has been discovered by many scientists (Babalola, 1998;Collier et al., 1953;Gutsulyak, 1972). Due to these well-known bioactivities of quinolinium chemophores, our research group has designed and synthesized several quinolinium stilbene derivatives in order to investigate their ability to overcome some of Gram-positive and Gram-negative pathogenic bacteria and the title compound (I) is an example of one of these compounds of which previous examples have been reported (Chanawanno et al., 2010a,b;Fun et al., 2010).
The title compound was tested for antibacterial activities against Bacillus subtilis, Staphylococcus aureus, Enterococcus faecalis, Methicillin-Resistant Staphylococcus aureus, Vancomycin-Resistant Enterococcus faecalis, Salmonella typhi, Shigella sonnei and Pseudomonas aeruginosa, and it was found to be inactive (MICs against all strains were more than 300 µg/ml). Herein, the crystal structure of (I) is reported.

Experimental
The title compound was prepared by mixing silver (I) 4-fluorobenzenesulfonate (0.90 g, 3.16 mmol) and (E)-2-(4-(diethylamino)styryl)-1-methylquinolinium iodide (1.44 g, 3.16 mmol) in methanol (100 ml) and stirred for 0.5 h. The precipitate of silver iodide which formed was filtered and the filtrate was evaporated to give the title compound as a purple solid. Purple needle-shaped single crystals of the title compound suitable for X-ray structure determination were recrystallized from ethanol by slow evaporation at room temperature over a week, Mp. 503-505 K.

Refinement
All H atoms, excepting the water molecule hydrogen atoms, were positioned geometrically and allowed to ride on their parent atoms with d(C-H) = 0.93 Å for aromatic and CH, 9.97 Å for CH 2 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 water molecule hydrogen atoms were located from the difference map and then allowed to ride on the water oxygen atom with the U iso values being constrained to be 1.5U eq of the carrier atom. The cation is disordered over two sites with refined site occupancies of 0.780 (5) and 0.220 (5). The SHELX (Sheldrick, 2008) DELU, SIMU, SAME and FLAT restraints were used. The same U ij parameters were used for atom pairs C21B/C19B.  The asymmetric unit of (I) showing 40% probability displacement ellipsoids. Open bonds show the minor component.

Figure 2
The molecular structure of the major component A showing the configuration of diethylamino group.   The crystal packing of the major component viewed along the a axis. The O-H···O hydrogen bonds and weak C-H···O and C-H···F interactions are drawn as dashed lines.   (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.