Twofold Axis Research Articles

Synthesis, Crystal Structure, and Magnetic Property of four Manganese(II) Complexes with Bulky Schiff bases Derived from Amantadine and Rimantadine

The reactions of manganese(II) chloride tetrahydrate and four bulky Schiff base ligands derived from amantadine (or rimantadine) and salicylaldehyde (or 4-methoxysalicylaldehyde) generated four novel complexes, C34H42Cl2MnN2O2 (I), C36H46Cl2MnN2O4 (II), C38H50Cl2MnN2O2 (III), and C40H54Cl2MnN2O4 (IV), respectively. These complexes were characterized by melting point, infrared spectra, elemental analysis, magnetic susceptibility, molar conductance and single-crystal X-ray diffraction (CIF files CCDC nos. 1 540 253 (I), 1 540 254 (II), 1 540 255 (III), 1 540 256 (IV)). Single-crystal X-ray diffraction analysis reveals that I, III and IV crystallize in the orthorhombic system with space groups P212121, Pbcn and Pcan, respectively, whereas II crystallizes in the monoclinic system with space group P21/n. Each asymmetric unit for I–IV consists of one manganese(II) atom, two Schiff base ligands and two chlorine atoms. The central manganese(II) atoms lie on a twofold rotation axis in III and IV, whereas manganese(II) atoms lie on general positions in I and II. In these complexes molecules, manganese(II) atoms is four-coordinated via two chlorine atoms and two oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry.

A Novel Cesium Pentaborate with Ribbon-Type Anionic Radical

A novel hydrated cesium hydroxypentaborate is synthesized from boric acid flux at 180°С, and its crystal structure is determined by X-ray diffraction. The compound crystallizes in the triclinic system, sp. gr. P $$\bar {1}$$ , with the parameters a = 7.8107(5) A, b = 9.1929(8) A, c = 12.3553(11) A, α = 98.98(1)°, β = 106.32(1)°, γ = 91.10(1)°, V = 839.1(1) A3, Z = 4. The structure is refined to R1 = 5.8% with anisotropic displacement parameters for all nonhydrogen atoms, with allowance for the non-merohedral twinning by a twofold axis coinciding with the b axis. The twin components were 0.546(1) and 0.454(1). The features of the hydrogen bonds in Cs[B5O7(OH)2] · 0.5H2O are analyzed in comparison with isostructural rubidium analogue. The unit-cell parameters a and c of A[B5O7(OH)2] · 0.5H2O pentaborates are found to systematically increase with an increase in the radius of A cation in the NH4 → Rb → Cs series; the small variation in the b parameter is due to the rigidity of the pentaborate chains elongated along this direction.

The atomic structures of shrimp nodaviruses reveal new dimeric spike structures and particle polymorphism

Shrimp nodaviruses, including Penaeus vannamei (PvNV) and Macrobrachium rosenbergii nodaviruses (MrNV), cause white-tail disease in shrimps, with high mortality. The viral capsid structure determines viral assembly and host specificity during infections. Here, we show cryo-EM structures of T = 3 and T = 1 PvNV-like particles (PvNV-LPs), crystal structures of the protrusion-domains (P-domains) of PvNV and MrNV, and the crystal structure of the ∆N-ARM-PvNV shell-domain (S-domain) in T = 1 subviral particles. The capsid protein of PvNV reveals five domains: the P-domain with a new jelly-roll structure forming cuboid-like spikes; the jelly-roll S-domain with two calcium ions; the linker between the S- and P-domains exhibiting new cross and parallel conformations; the N-arm interacting with nucleotides organized along icosahedral two-fold axes; and a disordered region comprising the basic N-terminal arginine-rich motif (N-ARM) interacting with RNA. The N-ARM controls T = 3 and T = 1 assemblies. Increasing the N/C-termini flexibility leads to particle polymorphism. Linker flexibility may influence the dimeric-spike arrangement.

Dihaloplatinum(II) complexes having diimine ligands: crystal structure, thermal properties, cytotoxicity effects against breast cancer cells and application as a precursor towards nanoparticles

The reaction of potassium tetrachloroplatinate(II) with dimethylsulfide and a mixture of HBr/KBr affords trans-[PtBr2(SMe2)2]; [PtBr2(Me2bpy)] (Me2bpy = 4,4'-dimethyl-2,2'-bipyridine) was prepared from the reaction of trans-[PtBr2(SMe2)2] with Me2bpy. The crystal structure of the yellow form of [PtBr2(bu2bpy)] (bu2bpy = 4,4'-di-tert-butyl-2,2'-bipyridine) was determined by X-ray crystallography. The X-ray single-crystal structure determination of complex [PtBr2(bu2bpy)] reveals that the platinum adopts a square planar geometry with a twofold axis through the platinum atoms. Thermal properties of the related series of diimine platinum(II) complexes [PtX2(bu2bpy)] (X = Cl, Br, I) reveal that the thermal stabilities increase [PtI2(bu2bpy)] < [PtCl2(bu2bpy)] < [PtBr2(bu2bpy)]. [PtBr2(bpy)] (bpy = 2,2'-bipyridine), [PtBr2(Me2bpy)] and [PtX2(bu2bpy)] (X = Cl, Br, I) were studied by MTT assay against two human breast cancer cell lines of MCF-7 and MDA-MB-468 with [PtCl2(bu2bpy)] having a higher cytotoxic effect towards both cancer cell lines, which shows the significant role of the halide and diimine ligand. Semi-spherical Pt(0) nanoparticles (NPCs) were prepared by the simple calcination of [PtX2(bu2bpy)] (X = Cl, Br, I) at 800 °C in air.

New Sm (III) and Nd (III) complexes: Synthesis, structural characterization and fluorescent sensing of nitro‐aromatic compounds

In this work, four new Nd (III) and Sm (III) complexes of two pentadendate ligands (L1 and L2) were prepared and their molecular structures were determined by single crystal X‐ray diffraction studies. X‐ray analysis showed that the Nd (III) and Sm (III) complexes of L1 sits on a twofold crystallographic axis while the complexes of L2 does not show crystallographically imposed symmetry. Absorption and photoluminescence properties of the complexes were studied both in the solid state and DMF solutions. The fluorescence sensing of nitro‐aromatic compounds [nitrobenzene (NB), 4‐nitrophenol (NP), 2,4‐dinitrophenol (DNP) and 2,4,6‐trinitrophenol (TNP)] were studied by photoluminescence spectroscopy. All four complexes showed better sensitivity towards nitrophenol (NP) with low LOD values.

Potassium bis(2-methyllactato)borate hemihydrate

The asymmetric unit of the title organic–inorganic hybrid salt poly[aquabis[μ3-bis(2-methyllactato)borato]dipotassium], [K(C8H12BO6)(H2O)0.5] n , consists of one bis(2-methyllactato)borate anion, one potassium cation and one water molecule that shows half occupancy due to disorder around a twofold rotation axis. The potassium cation is pseudo-octahedrally coordinated by five O atoms of four symmetry-related bis(2-methyllactato)borate ligands and by the half-occupied water molecule. O—H...O hydrogen bonds between the water molecule and one of the borate O atoms of the bis(2-methyllactato)borate ligand are present in the crystal structure.

Easy Synthesis and Crystal Structure of a Novel Ortho Hydroxyl Schiff Base Compound CH2-{CYCLO-C6H10)-NCH-C6H4-OH-2}2

A one-pot and neat reaction procedure is used for the synthesis of CH2-{cyclo-C6H10)-NCH-C6H4-OH-2}2. 1H NMR shows a mixture of ZE and EE isomers in a ratio of 2:0.9. The EE isomer is easily isolated as crystals suitable for the X-ray analysis. 1H,13C NMR and UV-visible spectra of the title compound are studied in different solvents. The crystal structure shows intramolecular H bonds as an EE isomer. The molecule lies about a twofold symmetry axis, passing through the C1 atom. The cyclo-hexyl ring C2-7 shows a chair conformation, with both C2-C1 and C5-N1 bonds in equatorial orientations. The phenolic hydrogen atom H1a forms a good hydrogen bond with the imino nitrogen atom N1 and the N1-C8 bond is short, as expected for a double bond (1.265(4) A).

Tris(1,10-phenanthroline-κ2 N,N′)cobalt(II) bis(2,4,5-tricarboxybenzoate) monohydrate

In the complex cation of the title salt, [Co(C12H8N2)3](C10H5O8)2·H2O, the CoII cation is situated on a twofold rotation axis and is coordinated in a distorted octahedral manner by six N atoms from three chelating 1,10-phenanthroline (phen) ligands. In the crystal, the non-coordinating 2,4,5-tricarboxybenzoate anions interact with each other via O—H...O hydrogen bonds, generating a two-dimensional network parallel to (100). Adjacent sheets are connected by waterO—H...Ocarboxylate hydrogen bonds, resulting in a three-dimensional network structure that surrounds the complex cations.

Crystal structures of [IrCl2(NHCHPh)((dppm)(C(N2dppm))-κ3 P,C,P')]Cl·5.5MeCN and [IrI(NHCHPh)(((dppm)C(N2))-κ2 P,C)(dppm-κ2 P,P')]I(I3)·0.5I2·MeOH·0.5CH2Cl2: triazene fragmentation in a PCN pincer iridium complex.

The structure of [IrCl2(C58H51N3P4)]Cl·5.5CH3CN or [IrCl2(NHCHPh)(((dppm)C(N2dppm))-κ 3P,C,P)]Cl·5.5CH3CN [3, dppm = bis-(di-phenyl-phos-phino)methane; systematic name: di-chlorido(1,1,3,3,7,7,9,9-octa-phenyl-4,5-di-aza-1,3λ5,7λ4,9-tetra-phosphanona-3,5-dien-6-yl-κ2 P 1,P 9)-(phenyl-methanimine-κN)iridium(III) chloride aceto-nitrile hemihendeca-solvate], resulting from an oxygen-mediated cleavage of a triazeneyl-idene-phospho-rane ligand producing a diazo-methyl-ene-phospho-rane and a nitrene moiety, which in turn rearrange via a Staudinger reaction and a 1,2-hydride shift to the first title complex, involves a six-coordinate IrIII complex cation coordinated by a facial PCP pincer ligand, a benzaldimine and two chlorido ligands. The pincer system features a five- and a seven-membered ring, with the central divalent carbon of the PCP pincer ligand being connected to a phosphine and a diazo-phospho-rane. The chlorido ligands are positioned trans to the central carbon atom and to the phospho-rus donor of the seven-membered ring of the pincer system, respectively. A chloride ion serves as counter-ion for the monocationic complex. The structure of [IrI(C26H22N2P2)(C26H22P2)(C6H7N)]I(I3)·0.5I2·CH3OH·0.5CH2Cl2 or [IrI(NHCHPh)((dppm)C(N2)-κ 2P,C)(dppm-κ 2P,P')]I(I3)·0.5I2·CH3OH·0.5CH2Cl2 {4, systematic name: (4-diazo-1,1,3,3,-tetra-phenyl-1,3λ4-diphosphabutan-4-yl-κP 1)iodido[methyl-enebis(di-phenyl-phosphine)-κ2 P,P'](phenyl-methanimine-κN)iridium(III) iodide-triiodide-di-chloro-methane-iodine-methanol (2/2/1/1/2)}, accessed via treatment of the triazeneyl-idene-phospho-rane complex [Ir((BnN3)C(dppm)-κ 3P,C,N)(dppm-κ 2P,P')]Cl with hydro-iodic acid, consists of a dicationic six-coordinate IrIII complex, coordinated by a bidentate diazo-methyl-ene-phospho-rane, a benzaldimine, a chelating dppm moiety and an iodido ligand. The phospho-rus atoms of the chelating dppm are trans to the central carbon atom of the diazo-methyl-ene-phospho-rane and the iodide ligand, respectively. Both an iodide and a triiodide moiety function as counter-ions. The aceto-nitrile solvent mol-ecules in 3 are severely disordered in position and occupation. In 4, the I3 - anion is positionally disordered (ratio roughly 1:1), as is the I- anion with a ratio of 9:1. The di-chloro-methane solvent mol-ecule lies near a twofold rotation axis (disorder) and was refined with an occupancy of 0.5. Another disorder occurs for the solvent methanol with a 1:1 ratio.

Crystal structure of 4-[(2-hy-droxy-3-meth-oxy-benz-yl)amino]-benzoic acid hemihydrate.

In the crystal of the title vanilline derivative, 2C15H15NO4·H2O, the secondary amine mol-ecule is accompanied by half equivalent of water. The mol-ecule is non-planar, with torsion angle Car-yl-CH2-NH-Car-yl of -83.9 (2)°. In the crystal, the system of O-H⋯O hydrogen bonds, including bridging water mol-ecules residing on crystallographic twofold axes, results in a two-dimensional layered structure. Within the layers, there are also weak N-H⋯π inter-actions involving the vanilline benzene ring.

A new, deep quinoxaline-based cavitand receptor for the complexation of benzene.

We report the synthesis of a new macrocyclic receptor, namely 2,8,14,20-tetra-hexyl-4,24:6,10:12,16:18,22-O,O'-tetra-kis-[2,3-di-hydro-[1,4]dioxino[2,3-g]quinoxalin-7,8-di-yl]resorcin[4]arene, DeepQxCav, obtained by the addition of ethyl-ene glycol di-tosyl-ate to an octa-hydroxy quinoxaline cavitand. A 1:1 supra-molecular complex of this cavitand with benzene has been obtained and analysed through X-ray diffraction analysis. The complex, of general formula C92H88O16N8·C6H6, crystallizes in the space group C2/c, with the cavitand host located about a twofold rotation axis. The benzene guest, which is held inside the cavity by C-H⋯π inter-actions and dispersion forces, is disordered over two equivalent sites, one in a general position and one lying on a twofold axis. The crystal structure features C-H⋯O hydrogen bonds and C-H⋯π inter-actions involving the alkyl chains, the aromatic rings, and the O atoms of the dioxane moiety of the resorcinarene scaffold. The crystal studied was refined as a two-component twin.

Crystal structure of tris-(2,2'-bi-pyridine)-cobalt(II) bis-(1,1,3,3-tetra-cyano-2-eth-oxy-propenide).

In the title compound, [Co(C10H8N2)3](C9H5N4O)2, the tris-(2,2'-bi-pyridine)-cobalt(II) dication lies across a twofold rotation axes in the space group C2/c. The N atoms of the three bi-pyridine ligands form a distorted octa-hedron around the cobalt ion. All the N atoms of the polynitrile 1,1,3,3-tetra-cyano-2-eth-oxy-propenide anions participate in C-H⋯N hydrogen bonds ensuring crystal cohesion and forming a three-dimensional structure. The structure is further stabilized by C-H⋯π(cation) and anion⋯π(cation) inter-actions.

Crystal structure and Hirshfeld surface analysis of N,N'-[ethane-1,2-diylbis(-oxy)]bis-(4-methyl-benzene-sulfonamide).

In the mol-ecule of the title compound, C16H20N2O6S2, the mid-point of the C-C bond of the central ethane moiety is located on a twofold rotation axis. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds into supra-molecular chains propagating along the [101] direction. Hirshfeld surface analysis and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H⋯H (43.1%), O⋯H/H⋯O (40.9%), C⋯H/H⋯C (8.8%) and C⋯C (5.5%) inter-actions.

Easy synthesis and crystal structure of a novel ortho hydroxyl Schiff base compound CH2—{cyclo-C6H10)—NCH—C6H4—OH-2}2

A one-pot and neat reaction procedure is used for the synthesis of CH2—{cyclo-C6H10)—NCH—C6H4—OH-2}2. 1H NMR shows a mixture of ZE and EE isomers in a ratio of 2:0.9. The EE isomer is easily isolated as crystals suitable for the X-ray analysis. 1H,13C NMR and UV-visible spectra of the title compound are studied in different solvents. The crystal structure shows intramolecular H bonds as an EE isomer. The molecule lies about a twofold symmetry axis, passing through the C1 atom. The cyclo-hexyl ring C2—7 shows a chair conformation, with both C2—C1 and C5—N1 bonds in equatorial orientations. The phenolic hydrogen atom H1a forms a good hydrogen bond with the imino nitrogen atom N1 and the N1—C8 bond is short, as expected for a double bond (1.265(4) Å).

A 1:2 co-crystal of 2,2'-di-thiodi-benzoic acid and benzoic acid: crystal structure, Hirshfeld surface analysis and computational study.

The asymmetric unit of the title 1:2 co-crystal, C14H10O4S2·2C7H6O2, comprises half a mol-ecule of di-thiodi-benzoic acid [systematic name: 2-[(2-carb-oxy-phen-yl)disulfan-yl]benzoic acid, DTBA], as the mol-ecule is located about a twofold axis of symmetry, and a mol-ecule of benzoic acid (BA). The DTBA mol-ecule is twisted about the di-sulfide bond [the C-S-S-C torsion angle is -83.19 (8)°] resulting in a near perpendicular relationship between the benzene rings [dihedral angle = 71.19 (4)°]. The carb-oxy-lic acid group is almost co-planar with the benzene ring to which it is bonded [dihedral angle = 4.82 (12)°]. A similar near co-planar relationship pertains for the BA mol-ecule [dihedral angle = 3.65 (15)°]. Three-mol-ecule aggregates are formed in the crystal whereby two BA mol-ecules are connected to a DTBA mol-ecule via hy-droxy-O-H⋯O(hydroxy) hydrogen bonds and eight-membered {⋯HOC=O}2 synthons. These are connected into a supra-molecular layer in the ab plane through C-H⋯O inter-actions. The inter-actions between layers to consolidate the three-dimensional architecture are π-π stacking inter-actions between DTBA and BA rings [inter-centroid separation = 3.8093 (10) Å] and parallel DTBA-hy-droxy-O⋯π(BA) contacts [O⋯ring centroid separation = 3.9049 (14) Å]. The importance of the specified inter-actions as well as other weaker contacts, e.g. π-π and C-H⋯S, are indicated in the analysis of the calculated Hirshfeld surface and inter-action energies.

The Molecular Organization of Human cGMP Specific Phosphodiesterase 6 (PDE6): Structural Implications of Somatic Mutations in Cancer and Retinitis Pigmentosa

In the cyclic guanosine monophosphate (cGMP) signaling pathway, phosphodiesterase 6 (PDE6) maintains a critical balance of the intracellular concentration of cGMP by catalyzing it to 5′ guanosine monophosphate (5′-GMP). To gain insight into the mechanistic impacts of the PDE6 somatic mutations that are implicated in cancer and retinitis pigmentosa, we first defined the structure and organization of the human PDE6 heterodimer using computational comparative modelling. Each subunit of PDE6αβ possesses three domains connected through long α-helices. The heterodimer model indicates that the two chains are likely related by a pseudo two-fold axis. The N-terminal region of each subunit is comprised of two allosteric cGMP-binding domains (Gaf-A & Gaf-B), oriented in the same way and interacting with the catalytic domain present at the C-terminal in a way that would allow the allosteric cGMP-binding domains to influence catalytic activity. Subsequently, we applied an integrated knowledge-driven in silico mutation analysis approach to understand the structural and functional implications of experimentally identified mutations that cause various cancers and retinitis pigmentosa, as well as computational saturation mutagenesis of the dimer interface and cGMP-binding residues of both Gaf-A, and the catalytic domains. We studied the impact of mutations on the stability of PDE6αβ structure, subunit-interfaces and Gaf-cGMP interactions. Further, we discussed the changes in interatomic interactions of mutations that are destabilizing in Gaf-A (R93L, V141 M, F162 L), catalytic domain (D600N, F742 L, F776 L) and at the dimer interface (F426A, F248G, F424 N). This study establishes a possible link of change in PDE6αβ structural stability to the experimentally observed disease phenotypes.

Molecular basis for the acid-initiated uncoating of human enterovirus D68

Enterovirus D68 (EV-D68) belongs to a group of enteroviruses that contain a single positive-sense RNA genome surrounded by an icosahedral capsid. Like common cold viruses, EV-D68 mainly causes respiratory infections and is acid-labile. The molecular mechanism by which the acid-sensitive EV-D68 virions uncoat and deliver their genome into a host cell is unknown. Using cryoelectron microscopy (cryo-EM), we have determined the structures of the full native virion and an uncoating intermediate [the A (altered) particle] of EV-D68 at 2.2- and 2.7-Å resolution, respectively. These structures showed that acid treatment of EV-D68 leads to particle expansion, externalization of the viral protein VP1 N termini from the capsid interior, and formation of pores around the icosahedral twofold axes through which the viral RNA can exit. Moreover, because of the low stability of EV-D68, cryo-EM analyses of a mixed population of particles at neutral pH and following acid treatment demonstrated the involvement of multiple structural intermediates during virus uncoating. Among these, a previously undescribed state, the expanded 1 ("E1") particle, shows a majority of internal regions (e.g., the VP1 N termini) to be ordered as in the full native virion. Thus, the E1 particle acts as an intermediate in the transition from full native virions to A particles. Together, the present work delineates the pathway of EV-D68 uncoating and provides the molecular basis for the acid lability of EV-D68 and of the related common cold viruses.

The Importance of CH···X (X = O, π) Interaction of a New Mixed Ligand Cu(II) Coordination Polymer: Structure, Hirshfeld Surface and Theoretical Studies

In this study, a new equimolar (1:1:1) mixed ligand Cu(II) polymer, [Cu(IDA)(ImP)]n (1) with iminodiacetato (IDA) and imidazo[1,2-a]-pyridine (ImP) was synthesized and characterized by single crystal X-ray diffraction analysis. X-ray crystallography reveals that compound (1) consists of polymeric zigzag chain along [010] the carboxylate carbonyl oxygen atom by two-fold symmetry screw axis. The solid-state structure is stabilized through C–H···O hydrogen bonds and C–H···π interactions that lead the molecules to generate two-dimensional supramolecular assemblies. The intricate combinations of hydrogen bonds and C–H···π interactions are fully described along with computational studies. A thorough analysis of Hirshfeld surface and fingerprint plots elegantly quantify the interactions involved within the structure. The binding energies associated with the noncovalent interactions observed in the crystal structure and the interplay between them were calculated using theoretical DFT calculations. Weak noncovalent interactions were analyzed and characterized using Bader’s theory of ‘‘atoms-in-molecules’’ (AIM). Finally, the solid-state supramolecular assembly was characterized by the “Noncovalent Interaction” (NCI) plot index.

Auxiliary subunits keep AMPA receptors compact during activation and desensitization.

Signal transduction at vertebrate excitatory synapses involves the rapid activation of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionate) receptors, glutamate-gated ion channels whose four subunits assemble as a dimer-of-dimers. Technical advances in cryo-electron microscopy brought a slew of full-length structures of AMPA receptors, on their own and in combination with auxiliary subunits. These structures indicate that dimers might undergo substantial lateral motions during gating, opening up the extracellular layer along the central twofold symmetry axis. We used bifunctional methanethiosulfonate cross-linkers to calibrate the conformations found in functional AMPA receptors in the presence and absence of the auxiliary subunit Stargazin. Our data indicate that extracellular layer of AMPA receptors can get trapped in stable, opened-up conformations, especially upon long exposures to glutamate. In contrast, Stargazin limits this conformational flexibility. Thus, under synaptic conditions, where brief glutamate exposures and the presence of auxiliary proteins dominate, extracellular domains of AMPA receptors likely stay compact during gating.

Crystal structures of two stilbazole derivatives: bis-{(E)-4-[4-(di-ethyl-amino)-styr-yl]-1-methyl-pyridin-1-ium} tetra-iodido-cadmium(II) and (E)-4-[4-(di-ethyl-amino)-styr-yl]-1-methyl-pyridin-1-ium 4-meth-oxy-benzene-sulfonate monohydrate.

The title mol-ecular salts, (C18H23N2)2[CdI4], (I), and C18H23N2 +·C7H7O4S-·H2O, (II), are stilbazole, or 4-styryl-pyridine, derivatives. The cation, (E)-4-[4-(di-ethyl-amino)-styr-yl]-1-methyl-pyridin-1-ium, has a methyl group attached to pyridine ring and a diethyl amine group attached to the benzene ring. The asymmetric unit of salt (I), comprises one cationic mol-ecule and half a CdI4 dianion. The Cd atom is situated on a twofold rotation axis and has a slightly distorted tetra-hedral coordination sphere. In (II), the anion consists of a 4-meth-oxy-benzene-sulfonate and it crystallizes as a monohydrate. In both salts, the cations adopt an E configuration with respect to the C=C bond and the pyridine and benzene rings are inclined to each other by 10.7 (4)° in (I) and 4.6 (2)° in (II). In the crystals of both salts, the packing is consolidated by offset π-π stacking inter-actions involving the pyridinium and benzene rings, with centroid-centroid distances of 3.627 (4) Å in (I) and 3.614 (3) Å in (II). In the crystal of (II), a pair of 4-meth-oxy-benzene-sulfonate anions are bridged by Owater-H⋯Osulfonate hydrogen bonds, forming loops with an R 2 4(8) motif. These four-membered units are then linked to the cations by a number of C-H⋯O hydrogen bonds, forming slabs lying parallel to the ab plane.