Bis{4-[(E)-2-(1H-indol-3-yl)ethen­yl]-1-methyl­pyridinium} 4-fluoro­benzene­sulfonate nitrate 0.25-hydrate1

In the title compound, 2C16H15N2 +·C6H4FO3S−·NO3 −·0.25H2O, the two cations are nearly planar, with dihedral angles of 1.34 (14) and 4.6 (2)°, respectively, between the pyridinium and indole rings. The cations each adopt E configurations with respect to the C=C bonds and are inclined to each other with a dihedral angle of 77.66 (5)°. The ethenyl group of one cation is disordered over two sites with occupancies of 0.685 (12) and 0.315 (12), and the sulfonate group of the 4-fluoro­benzene­sulfonate anion is also disordered with occupancies of 0.535 (10) and 0.465 (10) for the two sets of O atoms. The anion is also inclined to the two cations, with dihedral angles between the mean planes of the benzene ring and the π-conjugated systems of the cations of 24.72 (11) and 79.83 (11)°. In the crystal structure, the cations are stacked in an anti­parallel fashion into columns approximately along the a axis and are further linked through the anions into a three-dimensional network via N—H⋯O and C—H⋯O inter­actions. The water mol­ecule forms O—H⋯O hydrogen bonds to the nitrate anion and C—H⋯π inter­actions are also observed

(E)-1-Methyl-4-[2-(2-naphth­yl)vin­yl]pyridinium iodide1

In the title compound, C18H16N+·I−, the cation is disordered over two orientations related by a 180° rotation about its long axis with occupancies of 0.554 (7) and 0.446 (7). Both disorder components exist in an E configuration. The dihedral angle between the pyridinium ring and the naphthalene ring system is 4.7 (6)° in the major disorder component and 1.6 (8)° in the minor component. In the crystal structure, centrosymmetrically related cations are stacked along the a axis, with significant π–π inter­actions between the pyridinium ring and the naphthalene ring system [centroid-centroid distance = 3.442 (9) Å]. The iodide ions are located between adjacent columns of cations. The cations are linked to the iodide ions by C—H⋯I inter­actions. Weak C—H⋯π inter­actions involving the methyl group are also observed

2-[(E)-2-(4-Chloro­phen­yl)ethen­yl]-1-methyl­pyridinium 4-chloro­benzene­sulfonate

In the title salt, C14H13ClN+·C6H4ClO3S−, the cation exists in an E configuration with respect to the ethynyl bond and is approximately planar, with a dihedral angle of 3.4 (2)° between the pyridinium and benzene rings. The anion is approximately perpendicular to the cation plane, the benzene ring of the anion making dihedral angles of 89.4 (2) and 89.9 (2)°, respectively, with the pyridinium and benzene rings of the cation. In the crystal structure, the cations are linked into a chain along the c axis by C—H⋯Cl inter­actions. The anions are linked to the adjacent cation chains by C—H⋯O and C—H⋯Cl inter­actions, forming a two-dimensional network parallel to the bc plane. The crystal structure is further stabilized by C—H⋯π inter­actions. A π–π inter­action is also observed between the pyridinium ring and the benzene ring of the cation with a centroid–centroid distance of 3.668 (3) Å

1-Methyl-2-[(E)-2-(2-thien­yl)ethen­yl]quinolinium 4-bromo­benzene­sulfonate

In the title compound, C16H14NS+·C6H4BrO3S−, the cation exists in an E configuration and is essentially planar, the dihedral angle between the quinolinium and thio­phene rings being 3.45 (9)°. The anion is inclined to the cation with dihedral angles of 75.43 (8) and 72.03 (11)°, respectively between the benzene ring and the quinolinium and thio­phene rings. In the crystal, the cations and anions are arranged individually into separate chains along the c axis. The cation chains are stacked in an anti­parallel manner along the a axis by π⋯π inter­actions with centroid–centroid distances of 3.7257 (13) and 3.7262 (14) Å. Weak C—H⋯O and C—H⋯π inter­actions link the cations and anions into a three-dimensional network. Short Br⋯S [3.7224 (5) Å] and Br⋯O [3.4267 (16) Å] contacts are also observed

2-[(E)-2-(4-Ethoxy­phen­yl)ethen­yl]-1-methyl­pyridinium iodide monohydrate

In the title compound, C16H18NO+·I−·H2O, the cation is essentially planar, with a dihedral angle of 3.13 (16)° between the pyridinium and benzene rings. The mol­ecule adopts an E configuration with respect to the alkene double bond. In the crystal structure, the cations are packed in an anti-­parallel manner through π–π inter­actions between adjacent pyridinium and benzene rings along the a axis, with centroid-to-centroid distances of 3.615 (2) and 3.630 (2) Å. Water mol­ecules bind the iodide ions through O—H⋯I hydrogen bonds into layers. These layers link with the cations through weak C—H⋯O and C—H⋯I inter­actions

Redetermination and absolute configuration of pruniflorone M monohydrate

The title xanthone known as pruniflorone M (systematic name: (2R)-5,10-dihy­droxy-2-hy­droxy­methyl-1,1-dimethyl-1H-furo[2,3-c]xanthen-6-one), crystallized in a monohydrate form, C18H16O6·H2O. It was isolated from the green fruits of Cratoxylum formosum ssp. pruniflorum. The structure of the title compound has been reported previously [Boonnak et al. (2010 ▶). Aust. J. Chem. 63, 1550–1556], but we report here the absolute configuration determined using Cu Kα radiation. There are two crystallograpically independent mol­ecules in the asymmetric unit, which differ slightly in the bond angles. The hy­droxy­methyl substituents at position 2 of the furan rings of both pruniflorone M mol­ecules adopt R configurations. In both mol­ecules, the three rings of the xanthone skeleton are approximately coplanar, with an r.m.s. deviation of 0.0124 (2) Å for one mol­ecule and 0.0289 (2) Å for the other, and the furan ring adopts an envelope conformation. In the crystal, mol­ecules of pruniflorone M and water are linked into a two-dimensional network by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions. The crystal structure is further consolidated by π–π inter­actions with centroid–centroid distances in the range 3.5987 (13)–3.7498 (14) Å. Short C⋯C [3.378 (3) Å] and O⋯O [2.918 (3) Å] contacts are also observed

1-Methyl-4-[(E)-2-(2-thien­yl)ethen­yl]pyridinium 4-chloro­benzene­sulfonate1

In the title compound, C12H12NS+·C6H4ClO3S−, the cation is almost planar and exists in the E configuration. The cations and anions form alternate layers parallel to the ab plane. Within each layer, both cations and anions form chains directed along the b axis. The mol­ecules are inter­connected by weak C—H⋯O inter­actions into a three-dimensional network. The crystal structure is further stabilized by C—H⋯π inter­actions involving the thio­phene ring. The sulfonate and thio­phene groups are involved in weak intra­molecular C—H⋯O and C—H⋯S inter­actions, respectively. The latter intra­molecular hydrogen bonds produce S(5) ring motifs

2-[(E)-2-(1H-Indol-3-yl)ethen­yl]-1-methyl­pyridinium 4-chloro­benzene­sulfonate1

In the title compound, C16H15N2 +·C6H4ClO3S−, the cation exists in an E configuration with respect to the central C=C bond and is approximately planar, with a dihedral angle of 2.95 (5)° between the pyridinium and indole rings. The mean plane of the π-conjugated system of the cation and the benzene ring of the anion are inclined to each other at a dihedral angle of 69.65 (4)°. In the crystal packing, the cations are stacked in an anti­parallel manner along the a axis, resulting in a π–π inter­action with a centroid–centroid distance of 3.5889 (7) Å. The anions are linked into a chain along the a axis by weak C—H⋯O inter­actions. The cations are linked with the anions into a three-dimensional network by N—H⋯O hydrogen bonds and weak C—H⋯O inter­actions. There are also short O⋯Cl [3.1272 (10) Å] and C⋯O [3.1432 (14)–3.3753 (14) Å] contacts. The crystal structure is further stabilized by C—H⋯π inter­actions

2-[(E)-4-(Dimethyl­amino)­styr­yl]-1-methyl­pyridinium 4-chloro­benzene­sulfonate monohydrate1

In the title hydrated mol­ecular salt, C16H19N2 +·C6H4ClO3S−·H2O, the 2-[4-(dimethyl­amino)­styr­yl]-1-methyl­pyridinium cation exists in an E configuration with respect to the C=C bond and is slightly twisted, with the dihedral angle between the pyridinium and benzene rings being 9.33 (10)°. In the crystal structure, the packing is stabilized by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions, which link the cations, anions and water mol­ecules into chains propagating in [010]. These chains are stacked along the a axis by π–π inter­actions, with centroid-to-centroid distances of 3.6429 (12) and 3.6879 (12) Å; weak C—H⋯π inter­actions are also observed

(E,E)-1,2-Bis[1-(2-bromo­phen­yl)ethyl­idene]hydrazine

In the title compound, C16H14Br2N2, the complete molecule is generated by a crystallographic twofold axis. The dihedral angle between the two benzene rings is 35.28 (8)° and that between the best planes of two ethyl­idinehydrazine N—N=C—Me units is 87.67 (11)°. Each of these N/N/C/C planes makes a dihedral angle of 63.81 (10)° with the adjacent benzene ring. In the crystal, the mol­ecules are arranged into a layer parallel to the ac plane through C—H⋯π inter­actions. C⋯Br short contacts [3.4032 (18)–3.5969 (19) Å] are also observed