In the title compound, C18H23N2 +·I−, the cation exists in the E configuration with respect to the ethenyl C=C bond. The pyridinium and benzene rings are nearly coplanar, making a dihedral angle of 4.63 (7)°. The two ethyl groups of the diethyl­amino substituent point in opposite directions with respect to the benzene plane. In the crystal, the cation and the iodide anion are linked by a weak C—H⋯I inter­action. The cations are stacked in an anti-parallel manner along the a axis by a π–π inter­action with a centroid–centroid distance of 3.5262 (9) Å. The crystal structure is further stabilized by C—H⋯π inter­actions.

The asymmetric unit of the title compound, C18H23N2 +·C6H5O3S−·H2O, comprises a 2-[4-(diethyl­amino)­styr­yl]-1-methyl­pyridinium cation, a benzene­sulfonate anion and a solvent water mol­ecule. One ethyl substituent of the diethyl­amino group of the cation is disordered over two positions in a 0.73789 (9):0.26211 (9) ratio. The cation exists in the E configuration with respect to the C=C bond and the π-conjugated system is essentially planar with a dihedral angle of 0.82 (10)° between the pyridinium and benzene rings. The cation and anion are almost orthogonal with a dihedral angle of 86.71 (10)° between the π-conjugated system of the cation and benzene ring of the anion. In the crystal, mol­ecules are arranged into chains along [001] and adjacent chains are linked by weak C—H⋯O inter­actions. The crystal is further stablilized by O—H⋯O hydrogen bonds and weak C—H⋯π inter­actions.

The mol­ecule of the title compound, C15H15NO2, adopts a trans conformation with respect to the methyl­idene C=N bond and is twisted with a dihedral angle of 26.31 (5)° between the two substituted benzene rings. The eth­oxy group is almost coplanar with the bound benzene ring with a C—O—C—C torsion angle of −179.08 (9)°. In the crystal, mol­ecules are linked by O—H⋯N hydrogen bonds and weak C—H⋯O inter­actions into chains propagating in the [011] and [01-1] directions. C—H⋯π inter­actions are also present.

Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.002 Å; R factor = 0.052; wR factor = 0.148; data-to-parameter ratio = 20.7.There are two independent molecules in the asymmetric unit of the title compound, C 16 H 17 NO 4 , with similar conformations but some differences in their bond angles. Each molecule adopts a trans configuration with respect to the methylidene C N bond and is twisted with a dihedral angle between the two substituted benzene rings of 80.52 (7) in one molecule and 83.53 (7) in the other. All methoxy groups are approximately coplanar with the attached benzene rings, with C methyl -O-C-C torsion angles ranging from À6.7 (2) to 5.07 (19) . In the crystal, independent molecules are linked together by O-HÁ Á ÁN and O-HÁ Á ÁO hydrogen bonds and a -interaction [centroid-centroid distance of 3.6030 (9) Å ], forming a dimer. The dimers are further linked by weak C-HÁ Á ÁO interactions and another -interaction [centroidcentroid distance of 3.9452 (9) Å ] into layers lying parallel to the ab plane. Related literature

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.