In the title isonicotinohydrazide hydrate, C14H12BrN3O2·H2O {systematic name: N'-[(1E)-1-(5-bromo-2-hy-droxy-phen-yl)ethyl-idene]pyridine-4-carbohydrazide monohydrate}, the central CN2O region of the organic mol-ecule is planar and the conformation about the imine-C=N bond is E. While an intra-molecular hy-droxy-O-H⋯N(imine) hydrogen bond is evident, the dihedral angle between the central residue and the benzene rings is 48.99 (9)°. Overall, the mol-ecule is twisted, as seen in the dihedral angle of 71.79 (6)° between the outer rings. In the crystal, hydrogen-bonding inter-actions, i.e. hydrazide-N-H⋯O(water), water-O-H⋯O(carbon-yl) and water-O-H⋯N(pyrid-yl), lead to supra-molecular ribbons along the a-axis direction. Connections between these, leading to a three-dimensional architecture, are mediated by Br⋯Br halogen bonding [3.5366 (3) Å], pyridyl-C-H⋯O(carbon-yl) as well as weak π-π inter-actions [inter-centroid separation between benzene rings = 3.9315 (12) Å]. The Hirshfeld surface analysis reveals the importance of hydrogen atoms in the supra-molecular connectivity as well as the influence of the Br⋯Br halogen bonding.
In the anion of the title salt hydrate, H5N2(+)·C7H5N2O4(-)·2H2O, the carboxyl-ate and nitro groups lie out of the plane of the benzene ring to which they are bound [dihedral angles = 18.80 (10) and 8.04 (9)°, respectively], and as these groups are conrotatory, the dihedral angle between them is 26.73 (15)°. An intra-molecular amino-N-H⋯O(carboxyl-ate) hydrogen bond is noted. The main feature of the crystal packing is the formation of a supra-molecular chain along the b axis, with a zigzag topology, sustained by charge-assisted water-O-H⋯O(carboxyl-ate) hydrogen bonds and comprising alternating twelve-membered {⋯OCO⋯HOH}2 and eight-membered {⋯O⋯HOH}2 synthons. Each ammonium-N-H atom forms a charge-assisted hydrogen bond to a water mol-ecule and, in addition, one of these forms a hydrogen bond with a nitro-O atom. The amine-N-H atoms form hydrogen bonds to carboxyl-ate-O and water-O atoms, and the amine N atom accepts a hydrogen bond from an amino-H atom. The hydrogen bonds lead to a three-dimensional architecture. An analysis of the Hirshfeld surface highlights the major contribution of O⋯H/H⋯O hydrogen bonding to the overall surface, i.e. 46.8%, compared with H⋯H contacts (32.4%).
The title phosphanegold(I) thiol-ate compound, [Au(C9H9N2O3S)(C21H21P)], is a second monoclinic polymorph (space group P21/c) that complements a previously reported Cc polymorph [Broker & Tiekink (2008 ▸). Acta Cryst. E64, m1582]. An SP donor set defines an approximately linear geometry about the gold atom in both forms. The key distinguishing feature between the present structure and the previously reported polymorph rests with the relative disposition of the thiol-ate ligand. In the title compound, the orientation is such to place the oxygen atom in close contact with the gold atom [Au⋯O = 2.915 (2) Å], in contrast to the aryl ring in the original polymorph. In the crystal, linear supra-molecular chains along the a-axis direction mediated by C-H⋯π and nitro-O⋯π inter-actions are found. These pack with no directional inter-actions between them. The analysis of the Hirshfeld surfaces for both forms of [Au(C9H9N3O3S)(C21H21P)] indicates quite distinctive inter-action profiles relating to the differences in inter-molecular contacts found in their respective crystals.
In the title cluster complex hexane solvate, [Ru6(C30H32P2)(CO)22]·C6H14, two Ru3(CO)11 fragments are linked by a Ph2P(CH2)6PPh2 bridge with the P atoms equatorially disposed with respect to the Ru3 triangle in each case; the hexane solvent mol-ecule is statistically disordered. The Ru⋯Ru distances span a relatively narrow range, i.e. 2.8378 (4) to 2.8644 (4) Å. The hexyl chain within the bridge has an all-trans conformation. In the mol-ecular packing, C-H⋯O inter-actions between cluster mol-ecules, and between cluster and hexane solvent mol-ecules lead to a three-dimensional architecture. In addition, there are a large number of C≡O⋯π(arene) inter-actions in the crystal. The importance of the carbonyl groups in establishing the packing is emphasized by the contribution of 53.4% to the Hirshfeld surface by O⋯H/H⋯O contacts.
In the title tri-substituted thio-urea derivative, C13H18N2O3S, the thione-S and carbonyl-O atoms lie, to a first approximation, to the same side of the mol-ecule [the S-C-N-C torsion angle is -49.3 (2)°]. The CN2S plane is almost planar (r.m.s. deviation = 0.018 Å) with the hy-droxy-ethyl groups lying to either side of this plane. One hy-droxy-ethyl group is orientated towards the thio-amide functionality enabling the formation of an intra-molecular N-H⋯O hydrogen bond leading to an S(7) loop. The dihedral angle [72.12 (9)°] between the planes through the CN2S atoms and the 4-tolyl ring indicates the mol-ecule is twisted. The experimental mol-ecular structure is close to the gas-phase, geometry-optimized structure calculated by DFT methods. In the mol-ecular packing, hydroxyl-O-H⋯O(hydrox-yl) and hydroxyl-O-H⋯S(thione) hydrogen bonds lead to the formation of a supra-molecular layer in the ab plane; no directional inter-actions are found between layers. The influence of the specified supra-molecular inter-actions is apparent in the calculated Hirshfeld surfaces and these are shown to be attractive in non-covalent inter-action plots; the inter-action energies point to the important stabilization provided by directional O-H⋯O hydrogen bonds.
The analysis of atom-to-atom and/or residue-to-residue contacts remains a favoured mode of analysing the mol-ecular packing in crystals. In this contribution, additional tools are highlighted as methods for analysis in order to complement the 'crystallographer's tool', PLATON [Spek (2009). Acta Cryst. D65, 148-155]. Thus, a brief outline of the procedures and what can be learned by using Crystal Explorer [Spackman & Jayatilaka (2009). CrystEngComm11, 19-23] is presented. Attention is then directed towards evaluating the nature, i.e. attractive/weakly attractive/repulsive, of specific contacts employing NCIPLOT [Johnson et al. (2010). J. Am. Chem. Soc. 132, 6498-6506]. This is complemented by a discussion of the calculation of energy frameworks utilizing the latest version of Crystal Explorer. All the mentioned programs are free of charge and straightforward to use. More importantly, they complement each other to give a more complete picture of how mol-ecules assemble in mol-ecular crystals.
The crystal and mol-ecular structures of C14H12Cl2, (I), and C14H12Br2, (II), are described. The asymmetric unit of (I) comprises two independent mol-ecules, A and B, each disposed about a centre of inversion. Each mol-ecule approximates mirror symmetry [the Cb-Cb-Ce-Ce torsion angles = -83.46 (19) and 95.17 (17)° for A, and -83.7 (2) and 94.75 (19)° for B; b = benzene and e = ethyl-ene]. By contrast, the mol-ecule in (II) is twisted, as seen in the dihedral angle of 59.29 (11)° between the benzene rings cf. 0° in (I). The mol-ecular packing of (I) features benzene-C-H⋯π(benzene) and Cl⋯Cl contacts that lead to an open three-dimensional (3D) architecture that enables twofold 3D-3D inter-penetration. The presence of benzene-C-H⋯π(benzene) and Br⋯Br contacts in the crystal of (II) consolidate the 3D architecture. The analysis of the calculated Hirshfeld surfaces confirm the influence of the benzene-C-H⋯π(benzene) and X⋯X contacts on the mol-ecular packing and show that, to a first approximation, H⋯H, C⋯H/H⋯C and C⋯X/X⋯C contacts dominate the packing, each contributing about 30% to the overall surface in each of (I) and (II). The analysis also clearly differentiates between the A and B mol-ecules of (I).
The asymmetric unit of the title 2:1 co-crystal, 2C8H8O2·C14H14N4O2, comprises an acid mol-ecule in a general position and half a di-amide mol-ecule, the latter being located about a centre of inversion. In the acid, the carb-oxy-lic acid group is twisted out of the plane of the benzene ring to which it is attached [dihedral angle = 28.51 (8)°] and the carbonyl O atom and methyl group lie approximately to the same side of the mol-ecule [hy-droxy-O-C-C-C(H) torsion angle = -27.92 (17)°]. In the di-amide, the central C4N2O2 core is almost planar (r.m.s. deviation = 0.031 Å), and the pyridyl rings are perpendicular, lying to either side of the central plane [central residue/pyridyl dihedral angle = 88.60 (5)°]. In the mol-ecular packing, three-mol-ecule aggregates are formed via hy-droxy-O-H⋯N(pyrid-yl) hydrogen bonds. These are connected into a supra-molecular layer parallel to (12[Formula: see text]) via amide-N-H⋯O(carbon-yl) hydrogen bonds, as well as methyl-ene-C-H⋯O(amide) inter-actions. Significant π-π inter-actions occur between benzene/benzene, pyrid-yl/benzene and pyrid-yl/pyridyl rings within and between layers to consolidate the three-dimensional packing.
The crystal and mol-ecular structures of two di-phenyl-tin bis-(di-thio-carbamate)s, [Sn(C6H5)2(C5H10NOS2)2], (I), and [Sn(C6H5)2(C7H14NO2S2)2], (II), are described. In (I), in which the metal atom lies on a twofold rotation axis, the di-thio-carbamate ligand coordinates with approximately equal Sn-S bond lengths and the ipso-C atoms of the Sn-bound phenyl groups occupy cis-positions in the resulting octa-hedral C2S4 donor set. A quite distinct coordination geometry is noted in (II), arising as a result of quite disparate Sn-S bond lengths. Here, the four S-donors define a trapezoidal plane with the ipso-C atoms lying over the weaker of the Sn-S bonds so that the C2S4 donor set defines a skewed trapezoidal bipyramid. The packing of (I) features supra-molecular layers in the ab plane sustained by methyl-ene-C-H⋯π(Sn-ar-yl) inter-actions; these stack along the c-axis direction with no specific inter-actions between them. In (II), supra-molecular chains along the b-axis direction are formed by methyl-ene-C-O(ether) inter-actions; these pack with no directional inter-actions between them. A Hirshfeld surface analysis was conducted on both (I) and (II) and revealed the dominance of H⋯H inter-actions contributing to the respective surfaces, i.e. >60% in each case, and other features consistent with the description of the mol-ecular packing above.
The title compound, C16H15N5O2, adopts the shape of the letter L with the dihedral angle between the outer pyridyl rings being 78.37 (5)°; the dihedral angles between the central pyrazolyl ring (r.m.s. deviation = 0.0023 Å) and the methyl-ene-bound pyridyl and methyoxypyridyl rings are 77.68 (5) and 7.84 (10)°, respectively. Intra-molecular amide-N-H⋯N(pyrazol-yl) and pyridyl-C-H⋯O(amide) inter-actions are evident and these preclude the participation of the amide-N-H and O atoms in inter-molecular inter-actions. The most notable feature of the mol-ecular packing is the formation of linear supra-molecular chains aligned along the b-axis direction mediated by weak carbonyl-C=O⋯π(triazol-yl) inter-actions. An analysis of the calculated Hirshfeld surfaces point to the importance of H⋯H (46.4%), C⋯H (22.4%), O⋯H (11.9%) and N⋯H (11.1%) contacts in the crystal.
The X-ray crystal structure of the title phthalazin-1-one derivative, C17H16N2O3S {systematic name: 2-[(2,4,6-tri-methyl-benzene)-sulfon-yl]-1,2-di-hydro-phthalazin-1-one}, features a tetra-hedral sulfoxide-S atom, connected to phthalazin-1-one and mesityl residues. The dihedral angle [83.26 (4)°] between the organic substituents is consistent with the mol-ecule having the shape of the letter V. In the crystal, phthalazinone-C6-C-H⋯O(sulfoxide) and π(phthalazinone-N2C4)-π(phthalazinone-C6) stacking [inter-centroid distance = 3.5474 (9) Å] contacts lead to a linear supra-molecular tape along the a-axis direction; tapes assemble without directional inter-actions between them. The analysis of the calculated Hirshfeld surfaces confirm the importance of the C-H⋯O and π-stacking inter-actions but, also H⋯H and C-H⋯C contacts. The calculation of the inter-action energies indicate the importance of dispersion terms with the greatest energies calculated for the C-H⋯O and π-stacking inter-actions.
The asymmetric unit of the centrosymmetric title salt solvate, 2C17H17F6N2O+· C4H4O4 2-·CH3CH2OH, (systematic name: 2-{[2,8-bis-(tri-fluoro-meth-yl)quinolin-4-yl](hy-droxy)meth-yl}piperidin-1-ium butane-dioate ethanol monosolvate) comprises two independent cations, with almost superimposable conformations and each approximating the shape of the letter L, a butane-dioate dianion with an all-trans conformation and an ethanol solvent mol-ecule. In the crystal, supra-molecular chains along the a-axis direction are sustained by charge-assisted hy-droxy-O-H⋯O(carboxyl-ate) and ammonium-N-H⋯O(carboxyl-ate) hydrogen bonds. These are connected into a layer via C-F⋯π(pyrid-yl) contacts and π-π stacking inter-actions between quinolinyl-C6 and -NC5 rings of the independent cations of the asymmetric unit [inter-centroid separations = 3.6784 (17) and 3.6866 (17) Å]. Layers stack along the c-axis direction with no directional inter-actions between them. The analysis of the calculated Hirshfeld surface reveals the significance of the fluorine atoms in surface contacts. Thus, by far the greatest contribution to the surface contacts, i.e. 41.2%, are of the type F⋯H/H⋯F and many of these occur in the inter-layer region. However, these contacts occur at separations beyond the sum of the van der Waals radii for these atoms. It is noted that H⋯H contacts contribute 29.8% to the overall surface, with smaller contributions from O⋯H/H⋯O (14.0%) and F⋯F (5.7%) contacts.
In the title compound, [Zn(C4H8NOS2)2(C12H10N4)], the ZnII atom exists within a NS4 donor set defined by two chelating di-thio-carbamate ligands and a pyridyl-N atom derived from a terminally bound 4-pyridine-aldazine ligand. The distorted coordination geometry tends towards square-pyramidal with the pyridyl-N atom occupying the apical position. In the crystal, hydroxyl-O-H⋯O(hydrox-yl) and hydroxyl-O-H⋯N(pyrid-yl) hydrogen-bonding give rise to a supra-molecular double-chain along [1-10]; methyl-C-H⋯π(chelate ring) inter-actions help to consolidate the chain. The chains are connected into a three-dimensional architecture via pyridyl-C-H⋯O(hydrox-yl) inter-actions. In addition to the contacts mentioned above, the Hirshfeld surface analysis points to the significance of relatively weak π-π inter-actions between pyridyl rings [inter-centroid distance = 3.901 (3) Å].
The title compound, C10H13NOS, is a second monoclinic polymorph (space group P21/c, Z' = 2) of the previously reported C2/c (Z = 1) polymorph [Tadbuppa & Tiekink (2005 ▸). Z. Kristallogr. New Cryst. Struct. 220, 395-396]. Two independent mol-ecules comprise the asymmetric unit of the new polymorph and each of these exists as a thioamide-thione tautomer. In each molecule, the central CNOS chromophore is strictly planar [r.m.s. deviations = 0.0003 and 0.0015 Å] and forms dihedral angles of 6.17 (5) and 20.78 (5)° with the N-bound 3-tolyl rings, thereby representing the major difference between the mol-ecules. The thione-S and thio-amide-N-H atoms are syn in each mol-ecule and this facilitates the formation of an eight-membered thio-amide {⋯SCNH}2 synthon between them; the dimeric aggregates are consolidated by pairwise 3-tolyl-C-H⋯S inter-actions. In the extended structure, supra-molecular layers parallel to (102) are formed via a combination of 3-tolyl-C-H⋯π(3-tol-yl) and weak π-π inter-actions [inter-centroid distance between 3-tolyl rings = 3.8535 (12) Å]. An analysis of the Hirshfeld surfaces calculated for both polymorphs reveals the near equivalence of one of the independent mol-ecules of the P21/c form to that in the C2/c form.
The asymmetric unit of the title compound, [Cd2(C12H10N2)3(C6H12NOS2)4]·4C2H3N, comprises a Cd(II) atom, two di-thio-carbamate (dtc) anions, one and a half trans-1,2-dipyridin-4-yl-ethyl-ene (bpe) mol-ecules and two aceto-nitrile solvent mol-ecules. The full binuclear complex is generated by the application of a centre of inversion. The dtc ligands are chelating, one bpe mol-ecule coordinates in a monodentate mode while the other is bidentate bridging. The resulting cis-N2S4 coordination geometry is based on an octa-hedron. Supra-molecular layers, sustained by hy-droxy-O-H⋯O(hy-droxy) and hy-droxy-O-H⋯N(bpe) hydrogen bonding, inter-penetrate to form a three-dimensional architecture; voids in this arrangement are occupied by the aceto-nitrile solvent mol-ecules. Additional inter-molecular inter-actions falling within the specified framework have been analysed by Hirshfeld surface analysis, including π-π inter-actions.
The crystal structures of two ammonium salts of 2-amino-4-nitro-benzoic acid are described, namely di-methyl-aza-nium 2-amino-4-nitro-benzoate, C2H8N+·C7H5N2O4-, (I), and di-butyl-aza-nium 2-amino-4-nitro-benzoate, C8H20N+·C7H5N2O4-, (II). The asymmetric unit of (I) comprises a single cation and a single anion. In the anion, small twists are noted for the carboxyl-ate and nitro groups from the ring to which they are connected, as indicated by the dihedral angles of 11.45 (13) and 3.71 (15)°, respectively; the dihedral angle between the substituents is 7.9 (2)°. The asymmetric unit of (II) comprises two independent pairs of cations and anions. In the cations, different conformations are noted in the side chains in that three chains have an all-trans [(+)-anti-periplanar] conformation, while one has a distinctive kink resulting in a (+)-synclinal conformation. The anions, again, exhibit twists with the dihedral angles between the carboxyl-ate and nitro groups and the ring being 12.73 (6) and 4.30 (10)°, respectively, for the first anion and 8.1 (4) and 12.6 (3)°, respectively, for the second. The difference between anions in (I) and (II) is that in the anions of (II), the terminal groups are conrotatory, forming dihedral angles of 17.02 (8) and 19.0 (5)°, respectively. In each independent anion of (I) and (II), an intra-molecular amino-N-H⋯O(carboxyl-ate) hydrogen bond is formed. In the crystal of (I), anions are linked into a jagged supra-molecular chain by charge-assisted amine-N-H⋯O(carboxyl-ate) hydrogen bonds and these are connected into layers via charge-assisted ammonium-N-H⋯O(carboxyl-ate) hydrogen bonds. The resulting layers stack along the a axis, being connected by nitro-N-O⋯π(arene) and methyl-C-H⋯O(nitro) inter-actions. In the crystal of (II), the anions are connected into four-ion aggregates by charge-assisted amino-N-H⋯O(carboxyl-ate) hydrogen bonding. The formation of ammonium-N-H⋯O(carboxyl-ate) hydrogen bonds, involving all ammonium-N-H and carboxyl-ate O atoms leads to a three-dimensional architecture; additional C-H⋯O(nitro) inter-actions contribute to the packing. The Hirshfeld surface analysis confirms the importance of the hydrogen bonding in both crystal structures. Indeed, O⋯H/H⋯O inter-actions contribute nearly 50% to the entire Hirshfeld surface in (I).
The common feature of the mol-ecular structures of the title compounds, [Zn(C5H10NS2)2(C5H5NO)], (I), and [Zn(C4H8NOS2)2(C5H5NO)], (II), are NS4 donor sets derived from N-bound hy-droxy-pyridyl ligands and asymmetrically chelating di-thio-carbamate ligands. The resulting coordination geometries are highly distorted, being inter-mediate between square pyramidal and trigonal bipyramidal for both independent mol-ecules comprising the asymmetric unit of (I), and significantly closer towards square pyramidal in (II). The key feature of the mol-ecular packing in (I) is the formation of centrosymmetric, dimeric aggregates sustained by pairs of hy-droxy-O-H⋯S(di-thio-carbamate) hydrogen bonds. The aggregates are connected into a three-dimensional architecture by methyl-ene-C-H⋯O(hy-droxy) and methyl-C-H⋯π(chelate) inter-actions. With greater hydrogen-bonding potential, supra-molecular chains along the c axis are formed in the crystal of (II), sustained by hy-droxy-O-H⋯O(hy-droxy) hydrogen bonds, with ethyl-hydroxy and pyridyl-hydroxy groups as the donors, along with ethyl-hydroxy-O-H⋯S(di-thio-carbamate) hydrogen bonds. Chains are connected into layers in the ac plane by methyl-ene-C-H⋯π(chelate) inter-actions and these stack along the b axis, with no directional inter-actions between them. An analysis of the Hirshfeld surfaces clearly distinguished the independent mol-ecules of (I) and reveals the importance of the C-H⋯π(chelate) inter-actions in the packing of both (I) and (II).
In the title compound, C12H15N3O5S, a tris-ubstituted thio-urea derivative, the central CN2S chromophore is almost planar (r.m.s. deviation = 0.018 Å) and the pendant hy-droxy-ethyl groups lie to either side of this plane. While to a first approximation the thione-S and carbonyl-O atoms lie to the same side of the mol-ecule, the S-C-N-C torsion angle of -47.8 (2)° indicates a considerable twist. As one of the hy-droxy-ethyl groups is orientated towards the thio-amide residue, an intra-molecular N-H⋯O hydrogen bond is formed which leads to an S(7) loop. A further twist in the mol-ecule is indicated by the dihedral angle of 65.87 (7)° between the planes through the CN2S chromophore and the 4-nitro-benzene ring. There is a close match between the experimental and gas-phase, geometry-optimized (DFT) mol-ecular structures. In the crystal, O-H⋯O and O-H⋯S hydrogen bonds give rise to supra-molecular layers propagating in the ab plane. The connections between layers to consolidate the three-dimensional architecture are of the type C-H⋯O, C-H⋯S and nitro-O⋯π. The nature of the supra-molecular association has been further analysed by a study of the calculated Hirshfeld surfaces, non-covalent inter-action plots and computational chemistry, all of which point to the significant influence and energy of stabilization provided by the conventional hydrogen bonds.
The title 2:1 co-crystal, 2C7H5NO4·C14H14N4O2, in which the complete di-amide mol-ecule is generated by crystallographic inversion symmetry, features a three-mol-ecule aggregate sustained by hydroxyl-O-H⋯N(pyrid-yl) hydrogen bonds. The p-nitro-benzoic acid mol-ecule is non-planar, exhibiting twists of both the carb-oxy-lic acid and nitro groups, which form dihedral angles of 10.16 (9) and 4.24 (4)°, respectively, with the benzene ring. The di-amide mol-ecule has a conformation approximating to a Z shape, with the pyridyl rings lying to either side of the central, almost planar di-amide residue (r.m.s. deviation of the eight atoms being 0.025 Å), and forming dihedral angles of 77.22 (6)° with it. In the crystal, three-mol-ecule aggregates are linked into a linear supra-molecular ladder sustained by amide-N-H⋯O(nitro) hydrogen bonds and orientated along [10-4]. The ladders are connected into a double layer via pyridyl- and benzene-C-H⋯O(amide) inter-actions, which, in turn, are connected into a three-dimensional architecture via π-π stacking inter-actions between pyridyl and benzene rings [inter-centroid distance = 3.6947 (8) Å]. An evaluation of the Hirshfeld surfaces confirm the importance of inter-molecular inter-actions involving oxygen atoms as well as the π-π inter-actions.
The asymmetric unit of the title salt, C14H16N4O2 (2+)·2C9H5O6 (-), comprises half a dication, being located about a centre of inversion, and one anion, in a general position. The central C4N2O2 group of atoms in the dication are almost planar (r.m.s. deviation = 0.009 Å), and the carbonyl groups lie in an anti disposition to enable the formation of intra-molecular amide-N-H⋯O(carbon-yl) hydrogen bonds. To a first approximation, the pyridinium and amide N atoms lie to the same side of the mol-ecule [Npy-C-C-Namide torsion angle = 34.8 (2)°], and the anti pyridinium rings are approximately perpendicular to the central part of the mol-ecule [dihedral angle = 68.21 (8)°]. In the anion, one carboxyl-ate group is almost coplanar with the ring to which it is connected [Cben-Cben-Cq-O torsion angle = 2.0 (3)°], whereas the other carboxyl-ate and carb-oxy-lic acid groups are twisted out of the plane [torsion angles = 16.4 (3) and 15.3 (3)°, respectively]. In the crystal, anions assemble into layers parallel to (10-4) via hy-droxy-O-H⋯O(carbon-yl) and charge-assisted hy-droxy-O-H⋯O(carboxyl-ate) hydrogen bonds. The dications are linked into supra-molecular tapes by amide-N-H⋯O(amide) hydrogen bonds, and thread through the voids in the anionic layers, being connected by charge-assisted pyridinium-N-O(carboxyl-ate) hydrogen bonds, so that a three-dimensional architecture ensues. An analysis of the Hirshfeld surface points to the importance of O-H⋯O hydrogen bonding in the crystal structure.