Hydrogen‐bonded sheets in 2‐(2‐aminophenyl)‐1H‐benzimidazol‐3‐ium dihydrogen phosphate

The title salt, C₁₃H₁₂N₃⁺·H₂PO₄⁻, contains a nonplanar 2‐(2‐aminophenyl)‐1H‐benzimidazol‐3‐ium cation and two different dihydrogen phosphate anions, both situated on twofold rotation axes in the space group C2. The anions are linked by O—H...O hydrogen bonds into chains of R₂²(8) rings. The anion chains are linked by the cations, via hydrogen‐bonding complementarities and electrostatic interactions, giving rise to a sheet structure with alternating rows of organic cations and inorganic anions. Comparison of this structure with that of the pure amine reveals that the two compounds generate characteristically different sheet structures. The anion–anion chain serves as a template for the assembly of the cations, suggesting a possible application in the design of solid‐state materials.     

Green chemistry synthesis: 2‐amino‐3‐[(E)‐(2‐pyridyl)methylideneamino]but‐2‐enedinitrile monohydrate and 5‐cyano‐2‐(2‐pyridyl)‐1‐(2‐pyridylmethyl)‐1H‐imidazole‐4‐carboxamide

The title compounds, C₁₀H₉N₅O·H₂O (L1·H₂O) and C₁₆H₁₂N₆O (L2), were synthesized by solvent‐free aldol condensation at room temperature. L1, prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 1:1 molar ratio, crystallized as a monohydrate. L2 was prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 2:1 molar ratio. By varying the conditions of crystallization it was possible to obtain two polymorphs, viz. L2‐I and L2‐II; both crystallized in the monoclinic space group P2₁/c. They differ in the orientation of one pyridine ring with respect to the plane of the imidazole ring. In L2‐I, this ring is oriented towards and above the imidazole ring, while in L2‐II it is rotated away from and below the imidazole ring. In all three molecules, there is a short intramolecular N—H...N contact inherent to the planarity of the systems. In L1·H₂O, this involves an amino H atom and the C=N N atom, while in L2 it involves an amino H atom and an imidazole N atom. In the crystal structure of L1·H₂O, there are N—H...O and O—H...O intermolecular hydrogen bonds which link the molecules to form two‐dimensional networks which stack along [001]. These networks are further linked via intermolecular N—H...N(cyano) hydrogen bonds to form an extended three‐dimensional network. In the crystal structure of L2‐I, symmetry‐related molecules are linked via N—H...N hydrogen bonds, leading to the formation of dimers centred about inversion centres. These dimers are further linked via N—H...O hydrogen bonds involving the amide group, also centred about inversion centres, to form a one‐dimensional arrangement propagating in [100]. In the crystal structure of L2‐II, the presence of intermolecular N—H...O hydrogen bonds involving the amide group results in the formation of dimers centred about inversion centres. These are linked via N—H...N hydrogen bonds involving the second amide H atom and the cyano N atom, to form two‐dimensional networks in the bc plane. In L2‐I and L2‐II, C—H...π and π–π interactions are also present.     

Synthesis,Characterization, and Crystal Structure of Three Coordination Polymers from 5‐(Pyridin‐2‐ylmethyl)aminoisophthalic Acid

Three new complexes: [M(L)(H₂O)] [M = Zn ( 1 ), Co ( 2 ), Ni ( 3 ); H₂L = 5‐(pyridin‐2‐ylmethyl)aminoisophthalic acid] were synthesized under hydrothermal conditions at 180 °C and were characterized by elemental analysis, FT‐IR spectroscopy, single‐crystal X‐ray diffraction, and thermogravimetric analysis (TGA). The results of X‐ray diffraction analysis reveal that complexes 1 – 3 are isostructural and crystallize in the monoclinic system with space group P2₁/c. Each of the complexes displays a (3,3′)‐connected two‐dimensional (2D) wave‐like network with (4,8²) topology, within which five‐membered uncoplanar N,N‐chelated metallacycles are shaped. Delicate N–H ··· O and O–H ··· O hydrogen bonding interactions exist in complexes 1 – 3 . Adjacent 2D layers are linked by intermolecular interactions, resulting in the construction of extended metal‐organic frameworks (MOFs) in complexes 1 and 2 .     

2‐(Hydro­xy­methyl)­pyridinium di­hydrogenphosphate

The title compound, C₆H₈NO⁺·H₂PO₄⁻, consists of 2‐(hy­droxy­methyl)­pyridinium and di­hydrogen­phosphate ions. The di­hydrogen­phosphate moieties are linked into chains by pairs of P—O—H⃛O—P hydrogen bonds. The 2‐(hydroxy­methyl)­pyridinium cations are connected to the di­hydrogen­phosphate units by O—H⃛O and N—H⃛O hydrogen bonds. Weak π–π interactions help to determine the interchain packing.     

Mononuclear nickel(II) and zinc(II) complexes with deprotonated forms of the tripodal hexadentate ligand 1,3‐bis(2‐hydroxybenzylidene)‐2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methylpropane‐1,3‐diamine

In the crystal structures of both title compounds, [1,3‐bis(2‐hydroxybenzylidene)‐2‐methyl‐2‐(2‐oxidobenzylideneaminomethyl)propane‐1,3‐diamine]nickel(II) [2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methyl‐1,3‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine]nickel(II) chloride methanol disolvate, [Ni(C₂₆H_25.5N₃O₃)]₂Cl·2CH₄O, and [1,3‐bis(2‐hydroxybenzylidene)‐2‐methyl‐2‐(2‐oxidobenzylideneaminomethyl)propane‐1,3‐diamine]zinc(II) perchlorate [2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methyl‐1,3‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine]zinc(II) methanol trisolvate, [Zn(C₂₆H₂₅N₃O₃)]ClO₄·[Zn(C₂₆H₂₆N₃O₃)]·3CH₄O, the 3d metal ion is in an approximately octahedral environment composed of three facially coordinated imine N atoms and three phenol O atoms. The two mononuclear units are linked by three phenol–phenolate O—H...O hydrogen bonds to form a dimeric structure. In the Ni compound, the asymmetric unit consists of one mononuclear unit, one‐half of a chloride anion and a methanol solvent molecule. In the O—H...O hydrogen bonds, two H atoms are located near the centre of O...O and one H atom is disordered over two positions. The Ni^II compound is thus formulated as [Ni(H_1.5L)]₂Cl·2CH₃OH [H₃L is 1,3‐bis(2‐hydroxybenzylidene)‐2‐(2‐hydroxybenzylideneaminomethyl)‐2‐methylpropane‐1,3‐diamine]. In the analogous Zn^II compound, the asymmetric unit consists of two crystallographically independent mononuclear units, one perchlorate anion and three methanol solvent molecules. The mode of hydrogen bonding connecting the two mononuclear units is slightly different, and the formula can be written as [Zn(H₂L)]ClO₄·[Zn(HL)]·3CH₃OH. In both compounds, each mononuclear unit is chiral with either a Δ or a Λ configuration because of the screw coordination arrangement of the achiral tripodal ligand around the 3d metal ion. In the dimeric structure, molecules with Δ–Δ and Λ–Λ pairs co‐exist in the crystal structure to form a racemic crystal. A notable difference is observed between the M—O(phenol) and M—O(phenolate) bond lengths, the former being longer than the latter. In addition, as the ionic radius of the metal ion decreases, the M—O and M—N bond distances decrease.     

Three‐dimensional networks in bis(imidazolium) 2,2′‐dithiodibenzoate and 4‐methylimidazolium 2‐[(2‐carboxyphenyl)disulfanyl]benzoate

Cocrystallization of imidazole or 4‐methylimidazole with 2,2′‐dithiodibenzoic acid from methanol solution yields the title 2:1 and 1:1 organic salts, 2C₃H₅N₂⁺·C₁₄H₁₀O₄S₂²⁻, (I), and C₄H₇N₂⁺·C₁₄H₁₀O₄S₂⁻, (II), respectively. Compound (I) crystallizes in the monoclinic C2/c space group with the mid‐point of the S—S bond lying on a twofold axis. The component ions in (I) are linked by intermolecular N—H...O hydrogen bonds to form a two‐dimensional network, which is further linked by C—H...O hydrogen bonds into a three‐dimensional network. In contrast, by means of N—H...O, N—H...S and O—H...O hydrogen bonds, the component ions in (II) are linked into a tape and adjacent tapes are further linked by π–π, C—H...O and C—H...π interactions, resulting in a three‐dimensional network.     

Isomorphism in 1‐(2‐halidobenzyl)‐4‐[(E)‐2‐(3‐hydroxyphenyl)ethenyl]pyridinium halide hemihydrates (halide = Cl,Br)

The crystal structures of two (E)‐stilbazolium salts, namely 1‐(2‐chlorobenzyl)‐4‐[(E)‐2‐(3‐hydroxyphenyl)ethenyl]pyridinium chloride hemihydrate, C₂₀H₁₇ClNO⁺·Cl⁻·0.5H₂O, (I), and 1‐(2‐bromobenzyl)‐4‐[(E)‐2‐(3‐hydroxyphenyl)ethenyl]pyridinium bromide hemihydrate, C₂₀H₁₇BrNO⁺·Br⁻·0.5H₂O, (II), are isomorphous; the isostructurality index is 99.3%. In both salts, the azastyryl fragments are almost planar, while the rings of the benzyl groups are almost perpendicular to the azastyryl planes. The building blocks of the structures are twofold symmetric hydrogen‐bonded systems of two cations, two halide anions and one water molecule, which lies on a twofold axis. In the crystal structure, these blocks are connected by means of weaker interactions, viz. van der Waals, weak hydrogen bonding and stacking. This study illustrates the robustness of certain supramolecular motifs created by a spectrum of intermolecular interactions in generating these isomorphous crystal structures.     

1‐Carboxymethyl‐3‐methyl‐1H‐imidazol‐3‐ium chloride 2‐(3‐methyl‐1H‐imidazol‐3‐ium‐1‐yl)acetate monohydrate: a crystal stabilized by imidazolium zwitterions

The title compound, C₆H₉N₂O₂⁺·Cl⁻·C₆H₈N₂O₂·H₂O, contains one 2‐(3‐methyl‐1H‐imidazol‐3‐ium‐1‐yl)acetate inner salt molecule, one 1‐carboxymethyl‐3‐methyl‐1H‐imidazol‐3‐ium cation, one chloride ion and one water molecule. In the extended structure, chloride anions and water molecules are linked via O—H...Cl hydrogen bonds, forming an infinite one‐dimensional chain. The chloride anions are also linked by two weak C—H...Cl interactions to neighbouring methylene groups and imidazole rings. Two imidazolium moieties form a homoconjugated cation through a strong and asymmetric O—H...O hydrogen bond of 2.472 (2) Å. The IR spectrum shows a continuous D‐type absorption in the region below 1300 cm⁻¹ and is different to that of 1‐carboxymethyl‐3‐methylimidazolium chloride [Xuan, Wang & Xue (2012). Spectrochim. Acta Part A, 96 , 436–443].     

Tolterodinium (+)‐(2R,3R)‐hydrogen tartrate

In the crystal structure of (R)‐N,N‐diisopropyl‐3‐(2‐hydroxy‐5‐methyl­phenyl)‐3‐phenyl­propyl­aminium (2R,3R)‐hydrogen tartrate, C₂₂H₃₂NO⁺·C₄H₅O₆⁻, the hydrogen tartrate anions are linked by O—H⋯O hydrogen bonds to form helical chains built from (9) rings. These chains are linked by the tolterodine molecules via N—H⋯O and O—H⋯O hydrogen bonds to form separate sheets parallel to the (101) plane.     

2,6‐Diamino‐9H‐purine monohydrate and bis(2,6‐diamino‐9H‐purin‐1‐ium) 2‐(2‐carboxylatophenyl)acetate heptahydrate: two simple structures with very complex hydrogen‐bonding schemes

Two structures presenting an uncomplexed 2,6‐diaminopurine (dap) group are reported, namely 2,6‐diamino‐9H‐purine monohydrate, C₅H₆N₆·H₂O, (I), and bis(2,6‐diamino‐9H‐purin‐1‐ium) 2‐(2‐carboxylatophenyl)acetate heptahydrate, 2C₅H₇N₆⁺·C₉H₆O₄²⁻·7H₂O, (II). Both structures are rather featureless from a molecular point of view, but present instead an outstanding hydrogen‐bonding scheme. In compound (I), this is achieved through a rather simple independent unit content (one neutral dap and one water molecule) and takes the form of two‐dimensional layers tightly connected by strong hydrogen bonds, and interlinked by much weaker hydrogen bonds and π–π interactions. In compound (II), the fundamental building blocks are more complex, consisting of two independent 2,6‐diamino‐9H‐purin‐1‐ium (Hdap⁺) cations, one homophthalate [2‐(2‐carboxylatophenyl)acetate] dianion and seven solvent water molecules. The large number of hydrogen‐bond donors and acceptors produces 26 independent interactions, leading to an extended and complicated network of hydrogen bonds in a packing organization characterized by the stacking of interleaved anionic and cationic planar arrays. These structural characteristics are compared with those of similar compounds in the literature.     

2‐Iodo‐N‐(3‐nitrobenzyl)aniline and 3‐iodo‐N‐(3‐nitrobenzyl)aniline exhibit entirely different patterns of supramolecular aggregation

In 2‐iodo‐N‐(3‐nitro­benzyl)­aniline, C₁₃H₁₁IN₂O₂, the mol­ecules are linked into a three‐dimensional structure by a combination of C—H?O hydrogen bonds, iodo–nitro interactions and aromatic π–π‐stacking interactions, but N—H?O and C—H?π(arene) hydrogen bonds are absent. In the isomeric 3‐iodo‐N‐(3‐nitro­benzyl)­aniline, a two‐dimensional array is generated by a combination of N—H?O, C—H?O and C—H?π(arene) hydrogen bonds, but iodo–nitro interactions and aromatic π–π‐stacking interactions are both absent.     

Di­aqua­bis­(pyridine‐2‐carbox­amide‐κ2N1,O2)­nickel(II) disaccharinate tetrahydrate

In the crystal structure of the title compound, [Ni(C₆H₆N₂O)₂(H₂O)₂](C₇H₄NO₃S)₂·4H₂O or [Ni(pia)₂(H₂O)₂](sac)₂·4H₂O (pia is picolin­amide or pyridine‐2‐carbox­amide, and sac is the saccharinate anion), the Ni²⁺ cation, located on a centre of symmetry, is coordinated by two symmetry‐related aqua ligands together with a pair of symmetry‐related bidentate pia mol­ecules and exhibits a distorted octahedral environment. The unique unligated sac anion in the asymmetric unit resides on a general position and has a single negative charge. The coordinated water mol­ecules link the sac ions to the metal complex via O—H⋯O hydrogen bonds. In addition, the sac ions are linked to the metal complex via intermolecular π–π interactions between the benzene ring of the sac ion and the pyridine ring of a pia ligand. Each uncoordinated water mol­ecule is hydrogen bonded to sac moieties through O—H⋯O and O—H⋯N hydrogen bonds.     

Mononuclear Co(III), Ni(II) and Cu(II) complexes of 2‐(2,4‐dichlorobenzamido)‐N'‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide: Structural insight and biological assay

A series of mononuclear metal complexes of Co(III), Ni(II) and Cu(II) with 2‐(2,4‐dichlorobenzamido)‐N′‐(3,5‐di‐tert‐butyl‐2‐hydroxybenzylidene)benzohydrazide ( LH ₃ ) have been synthesized and characterized using various physico‐chemical, spectroscopic and single crystal X‐ray diffraction techniques. Structural studies of [Co( LH )( LH ₂ )]·H₂O ( 4 ) revealed the presence of both amido and imidol tautomeric forms of LH ₃ , resulting in a distorted octahedral geometry around the Co(III) ion. [Ni( LH )(H₂O)]·H₂O ( 5 ) and [Cu( LH )(H₂O)]·H₂O ( 6 ) are isomorphous structures and crystallize in the monoclinic P2₁/c space group. The crystal structures of 4 , 5 and 6 are stabilized by hydrogen bonds formed by the enclathrated water molecules, C‐H···π and π···π interactions. Complexes along with the ligand ( LH ₃ ) were screened for their in vivo anti‐inflammatory activity (carrageenan‐induced rat paw edema method) and in vitro antioxidant activity (DPPH free radical scavenging assay). Metal complexes have shown significant anti‐inflammatory and antioxidant potential.     

Hydrogen‐bonded sheet structures in neutral,anionic and hydrated 6‐amino‐2‐(morpholin‐4‐yl)‐5‐nitrosopyrimidines

In each of 6‐amino‐3‐methyl‐2‐(morpholin‐4‐yl)‐5‐nitrosopyrimidin‐4(3H)‐one, C₉H₁₃N₅O₃, (I), morpholin‐4‐ium 4‐amino‐2‐(morpholin‐4‐yl)‐5‐nitroso‐6‐oxo‐1,6‐dihydropyrimidin‐1‐ide, C₄H₁₀NO⁺·C₈H₁₀N₅O₃⁻, (II), and 6‐amino‐2‐(morpholin‐4‐yl)‐5‐nitrosopyrimidin‐4(3H)‐one hemihydrate, C₈H₁₁N₅O₃·0.5H₂O, (III), the bond distances within the pyrimidine components are consistent with significant electronic polarization, which is most marked in (II) and least marked in (I). Despite the high level of substitution, the pyrimidine rings are all effectively planar, and in each of the pyrimidine components, there are intramolecular N—H...O hydrogen bonds. In each compound, the organic components are linked by multiple N—H...O hydrogen bonds to form sheets of widely differing construction, and in compound (III) adjacent sheets are linked by the water molecules, so forming a three‐dimensional hydrogen‐bonded framework. This study also contains the first direct geometric comparison between the electronic polarization in a neutral aminonitrosopyrimidine and that in its ring‐deprotonated conjugate anion in a metal‐free environment.     

Two hydrates of 2,6‐bis­(1H‐benzimidazol‐2‐yl)­pyridine

The structures of the mono‐ and sesquihydrates of 2,6‐bis(1H‐benz­imi­da­zol‐2‐yl)­pyridine (bbip) are reported. Phase (I), C₁₉H₁₃N₅·H₂O, has one water and one bbip mol­ecule in the asymmetric unit, while phase (II), C₁₉H₁₃N₅·1.5H₂O, has three water mol­ecules and two bbip mol­ecules in the asymmetric unit. The compounds exhibit very similar molecular geom­etries but different packing organizations, which result from intricate hydrogen‐bonding schemes.     

meso‐5,5,7,12,12,14‐Hexamethyl‐1,4‐diaza‐8,11‐diazoniacyclotetradecane bis(2‐naphthoate) ethanol disolvate: centrosymmetric five‐component aggregates linked into sheets by C—H⃛π(arene) hydrogen bonding

The title compound is an ethanol‐solvated salt, C₁₆H₃₈N₄²⁺·2C₁₁H₇O₂⁻·2C₂H₆O, in which the cation lies across a centre of inversion in P2₁/c. The ions are linked by N—H⃛O hydrogen bonds [H⃛O = 1.70 and 2.30 Å, N⃛O = 2.624 (2) and 3.136 (2) Å, and N—H⃛O = 178 and 151°], and the ethanol mol­ecule is linked to the anion by an O—H⃛O hydrogen bond [H⃛O = 1.90 Å, O⃛O = 2.728 (2) Å and O—H⃛O = 171°], to form a centrosymmetric five‐component aggregate. C—H⃛O hydrogen bonds and aromatic π–π‐stacking interactions are absent, but the aggregates are linked into sheets by a single C—H⃛π(arene) hydrogen bond.     

Four New Compounds Based on Terephthalate and 2‐(4‐Pyridyl)benzimidazole Ligands

Four new compounds based on H₂BDC and PyBIm [H₂BDC = 1,4‐benzenedicarboxylatic acid, PyBIm = 2‐(4‐pyridyl)benzimidazole], (PyBIm)(H₂BDC)_0.5 ( 1 ), Co(PyBIm)₂(HBDC)(BDC)_0.5 ( 2 ), Ni(PyBIm)₂(HBDC)(BDC)_0.5 ( 3 ), and Zn(BDC)(PyBIm) · H₂O ( 4 ), were synthesized by hydrothermal methods and characterized by X‐ray diffraction. Compound 1 contains two types of hydrogen bonding N–H ··· N and O–H ··· N, which connect the molecules into a two‐dimensional (2D) layer. Complex 2 crystallizes isostructural to 3 in triclinic space group P$\bar{1}$ , in 1D chains. The hydrogen‐bonding interactions between uncoordinated N, N–H and COOH groups in 2 connect the 1D chains into a 2D layer. Complex 4 displays a 1D structure, which is finally extended to a 3D supramolecular framework by hydrogen bonding and π–π packing interactions. The magnetic properties of compounds 2 and 3 were studied as well.     

Interaction of thiamine with anions in the triclinic form of thiamine iodide: 3‐[(4‐amino‐2‐methylpyrimidin‐5‐yl)methyl]‐5‐(2‐hydroxyethyl)‐4‐methyl‐1,3‐thiazol‐3‐ium iodide 1.25‐hydrate

The asymmetric unit of the title compound, C₁₂H₁₇N₄OS⁺·I⁻·1.25H₂O, contains two crystallographically independent molecules. Both formula units assume the usual F conformation and have the hydroxyethyl group disordered over two sites, each with half occupation. Two thiamine cations are linked by hydrogen bonds into a cyclic dimer. These dimers are further connected by base‐pairing hydrogen bonds into a chain along [010]. The stacked dimers form channels, which are occupied by iodide anions. The cations and anions are associated by N—H...I hydrogen bonds, C—H...I interactions and I...thiazolium ring close contacts. The interactions between thiamine and the iodide anions are similar to those observed in monoclinic thiamine iodide 1.5‐hydrate [Hu & Zhang (1993). J. Inclusion Phenom. Mol. Recognit. Chem. 16 , 273–281].     

Ammonium N‐(6‐amino‐3,4‐di­hydro‐3‐methyl‐5‐nitro­so‐4‐oxopyrimidin‐2‐yl)­glycinate monohydrate forms hydrogen‐bonded bilayers

In the title compound, NH₄⁺·C₇H₈N₅O₄⁻·H₂O, the independent components are linked into bilayers by an extensive series of two‐centre N—H⃛O hydrogen bonds [H⃛O = 1.85–1.96 Å, N⃛O = 2.776 (2)–2.840 (2) Å and N—H⃛O = 149–172°], and by asymmetric three‐centre N—H⃛(O)₂, O—H⃛(N,O) and O—H⃛(O)₂ hydrogen bonds.     

2,6‐Bis[(2‐hydroxy‐3‐methoxybenzylidene)hydrazinocarbonyl]pyridine monohydrate

In the title compound, C₂₃H₁₉N₅O₆·H₂O, the two components are linked into complex chains by a combination of two independent O—H...O and two independent N—H...O hydrogen bonds. The complex chains are linked into a two‐dimensional sheet network viaπ–π stacking interactions and C—H...O hydrogen bonds.