(E)-2-[4-(Diethylamino)styryl]-1-methylquinolin-1-ium 4-chlorobenzenesulfonate monohydrate

The asymmetric unit of the title hydrated salt, C22H25N2 +·C6H4ClO3S−·H2O, comprises two 2-[4-(diethylamino)styryl]-1-methylquinolin-1-ium cations, two 4-chlorobenzenesulfonate anions and two solvent water molecules. One ethyl group of both cations displays disorder over two positions in a 0.659 (2):0.341 (2) ratio in one molecule and in a 0.501 (2):0.499 (2) ratio in the other. The sulfonate group of one anion is also disordered over two positions in a 0.893 (7):0.107 (7) ratio. The dihedral angle between the mean plane of the quinolinium ring system and that of benzene ring is 10.57 (18)° in one cation and 14.4 (2)° in the other. In the crystal, cations, anions and water molecules are linked into chains along the [010] direction by O—H⋯Osulfonate hydrogen bonds, together with weak C—H⋯Osulfonate and C—H⋯Cl interactions. The cations are stacked by π–π interactions, with centroid–centroid distances in the range 3.675 (2)–4.162 (3) Å.

The asymmetric unit of the title hydrated salt, C 22 H 25 N 2 + Á-C 6 H 4 ClO 3 S À ÁH 2 O, comprises two 2-[4-(diethylamino)styryl]-1-methylquinolin-1-ium cations, two 4-chlorobenzenesulfonate anions and two solvent water molecules. One ethyl group of both cations displays disorder over two positions in a 0.659 (2):0.341 (2) ratio in one molecule and in a 0.501 (2):0.499 (2) ratio in the other. The sulfonate group of one anion is also disordered over two positions in a 0.893 (7):0.107 (7) ratio. The dihedral angle between the mean plane of the quinolinium ring system and that of benzene ring is 10.57 (18) in one cation and 14.4 (2) in the other. In the crystal, cations, anions and water molecules are linked into chains along the [010] direction by O-HÁ Á ÁO sulfonate hydrogen bonds, together with weak C-HÁ Á ÁO sulfonate and C-HÁ Á ÁCl interactions. The cations are stacked byinteractions, with centroid-centroid distances in the range 3.675 (2)-4.162 (3) Å .

Comment
The bioactivity of compounds containing the quinolinium chemophore has been the subject of a number of reports (Barchéchath et al., 2005;Chanawanno et al., 2010a, 2010band Bolden et al., 2013. The title quinolinium derivative (I) was synthesized and tested for antibacterial activities against gram positive bacteria including Bacillus subtilis,

Enterococcus faecalis, Staphylococcus aureus, Methicillin-Resistant Staphylococcus aureus and Vancomycin-Resistant
Enterococcus faecalis, and gram negative bacteria including Pseudomonas aeruginosa, Shigella sonnei and Salmonella typhi. Our antibacterial assay has shown that (I) is strongly active against B. subtilis and P. aeruginosa with a minimum inhibition concentration (MIC) of 9.37 µg/ml for both strains. In addition (I) also showed moderate activity against E.
faecalis with an MIC value of 37.5 µg/ml. Herein the crystal structure of (I) is reported.
Brown block-shaped single crystals of the title compound suitable for X-ray structure determination was recrystallized from ethanol by slow evaporation at room temperature over a few weeks, Mp. 471-473 K.

Refinement
All H atoms were positioned geometrically and allowed to ride on their parent atoms with d(O-H) = 0.76-0.85 Å, d(C-H) = 0.93 Å for aromatic and CH, 0.97 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 water and methyl H atoms and 1.2U eq for the remaining H atoms. A rotating group model was used for the methyl groups. The two cations (molecules A and B) and one anion (molecule B) are disordered over two sites with refined site occupancies ratios of 0.659 (2):0.0.341 (2), 0.501 (2):0.499 (2) and 0.893 (7):0.107 (7), respectively.

Figure 1
The asymmetric unit of (I) showing 40% probability displacement ellipsoids and the atom-numbering scheme. Open bonds show the minor disorder component.  The molecular structure of the major component A showing the configuration of diethylamino group. Only cation A is shown.

Figure 3
The molecular structure of the minor component X showing the configuration of diethylamino group which differs from that of the major component A. Only cation A is shown.   π-π interactions between the aromatic rings of the major disorder components of the cations.   (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.