Hydrogen-bonded Layers Research Articles

μ-Adipato-bis[chlorido(2,2′:6′,2′′-terpyridine)copper(II)] tetrahydrate

In the title compound, [Cu2(C6H8O4)Cl2(C15H11N3)2]·4H2O, the dinuclear copper complex is located on a crystallographic inversion centre. Each Cu atom is in a distorted square-pyramidal coordination environment, with one O atom of an adipate dianion and three N atoms from the 2,2′:6′,2′′-terpyridine ligand occupying the basal plane, and one chlorine in the apical site. In addition, there is weak Cu—O inter­action opposite of the chlorine with a distance of 2.768 (1) Å. The adipate ligand adopts a gauche–anti–gauche conformation. The inter­stitial water mol­ecules form hydrogen-bonded tertramers that are connected to the complexes via O—H⋯O and O—H⋯Cl hydrogen bonds, thus leading to the formation of tightly hydrogen-bonded layers extending perpendicular to the b-axis direction.

Poly[{μ10-[(phosphonomethyl)iminodimethylene]diphosphonato}dithallium(I)

The title compound, [Tl2(C3H10NO9P3)]n, a TlI organic–inorganic hybrid complex, was synthesized by the reaction of nitrilo­tris(methyl­enephospho­nic acid) with thallium(I) nitrate. There are two types of Tl+ ions in the complex, with coordination numbers of eight and seven and with stereochemically active and inactive lone-pair electrons, respectively. In the crystal, the doubly deprotonated ligands form two-dimensional hydrogen-bonded layers through O—H⋯O hydrogen bonds. The NH group is involved in a trifurcated intra­molecular hydrogen bond. Coordination of the phospho­nate ligands to the Tl+ ions creates a three-dimensional structure.

The effect of the hydrocarbon–water interface structure on the behavior of an emulsion stabilized with dodecanephosphonic acid

We studied the phase transition of petroleum ether/water/n-dodecanephosphonic acid (DPA) from W/O to W/O/W emulsion when the neutralization degree (nd) of dodecanephosphonic acid (DPA) with NaOH was changed. We concluded that a phase transition from W/O emulsion to W/O/W emulsion occurs when nd ≈ 0.47 due to a change in the structure of the polar layer at the oil/water interface from a tightly hydrogen-bonded layer to a less compact layer formed by –PO 3H 2 and –PO 3H − groups in favor of an inversion. The W/O/W emulsion is probably caused by a partition of acid molecules in the water droplets interface inside the oil droplets, and monosodium phosphonate molecules at the external interface of oil droplets.

Reversible phase transition of pyridinium-3-carboxylic acid perchlorate

Pyridinium-3-carboxylic acid perchlorate was synthesized and separated as crystals. Differential scanning calorimetry (DSC) measurements show that this compound undergoes a reversible phase transition at approximately 135 K with a wide hysteresis of 15 K. Dielectric measurements confirm the transition at approximately 127 K. Measurement of the unit-cell parameters versus temperature shows that the values of the c axis and beta angle change abruptly and remarkably at 129 (2) K, indicating that the system undergoes a first-order transition at T(c) = 129 K. The crystal structures determined at 103 and 298 K are all monoclinic in P2(1)/c, showing that the phase transition is isosymmetric. The crystal contains one-dimensional hydrogen-bonded chains of the pyridinium-3-carboxylic acid cations, which are further linked to perchlorate anions by hydrogen bonds to form well separated infinite planar layers. The most distinct differences between the structures of the higher-temperature phase and the lower-temperature phase are the change of the distance between the adjacent pyridinium ring planes within the hydrogen-bonded chains and the relative displacement between the hydrogen-bonded layers. Structural analysis shows that the driving force of the transition is the reorientation of the pyridinium-3-carboxylic acid cations. The degree of order of the perchlorate anions may be a secondary order parameter.

Benzene-1,4-diboronic acid–4,4′-bipyridine–water (1/2/2)

In the presence of water, benzene-1,4-diboronic acid (1,4-bdba) and 4,4'-bipyridine (4,4'-bpy) form a cocrystal of composition (1,4-bdba)(4,4'-bpy)(2)(H(2)O)(2), in which the molecular components are organized in two, so far unknown, cyclophane-type hydrogen-bonding patterns. The asymmetric unit of the title compound, C(6)H(8)B(2)O(4).2C(10)H(8)N(2).2H(2)O, contains two 4,4'-bpy, two water molecules and two halves of 1,4-bdba molecules arranged around crystallographic inversion centers. The occurrence of O-H...O and O-H...N hydrogen bonds involving the water molecules and all O atoms of boronic acid gives rise to a two-dimensional hydrogen-bonded layer structure that develops parallel to the (01-4) plane. This supramolecular organization is reinforced by pi-pi interactions between symmetry-related 4,4'-bpy molecules.

(1R,2R,3S,6aS,7R,8R,9S,12aS)-1,2,3,7,8,9-Hexahydroxyperhydrodipyrido[1,2-a:1′,2′-d]pyrazine-6,12-dione

The crystal structure of the title compound, C12H18N2O8, exists as O—H⋯O hydrogen-bonded layers of mol­ecules running parallel to the ab plane. Each mol­ecule is a donor and acceptor for six hydrogen bonds. The absolute stereochemistry was determined by the use of d-glucuronolactone as the starting material.

Structures of dipeptides: the head-to-tail story

The hydrogen-bonding patterns in crystal structures of unprotected, zwitterionic dipeptides are dominated by head-to-tail chains involving the N-terminal amino groups and the C-terminal carboxylate groups. Patterns that include two concomitant chains, thus generating a hydrogen-bonded layer, are of special interest. A comprehensive survey shows that dipeptide structures can conveniently be divided into only four distinct patterns, differing by definition in the symmetry of the head-to-tail chains and amide hydrogen-bonding type, but also in other properties such as peptide conformation and the propensity to include solvent water or various organic guest molecules. Upon crystallization, the choice of pattern for a specific dipeptide is not random, but follows from the amino acid sequence.

3,4-O-Isopropylidene-2-C-methyl-D-galactonolactone

X-ray crystallography unequivocally confirmed the stereochemistry of the 2-C-methyl group in the title mol­ecule, C10H16O6, in which the 1,5-lactone ring exists in a boat conformation. The use of d-galactose in the synthesis determined the absolute stereochemistry. The crystal exists as O—H⋯O hydrogen-bonded layers in the ab plane, with each mol­ecule acting as a donor and acceptor for two hydrogen bonds.

Improving Mechanical Properties of Crystalline Solids by Cocrystal Formation: New Compressible Forms of Paracetamol

Poor mechanical properties of paracetamol are improved through the strategy of cocrystal formation. Mechanochemical screening by liquid-assisted grinding generated four cocrystals of paracetamol that readily form tablets by direct compression. Computational studies reveal the mechanical properties can be related to structural features, before all the formation of hydrogen-bonded layers.

Two-Dimensional Organic Brick-Wall Layers as Hosts for the Inclusion and Study of Aromatics Ensembles: Acid−Pyridine and Acid−Carbonyl Synthons for Multicomponent Materials

The compound trimesic acid (H3TMA) with 2,6-bis(4-pyridylmethylene)cyclohexanone (1) was shown to form two-/three-/four-component cocrystals or salts depending on the reaction conditions. Crystals of salt were obtained when crystallized H3TMA and 1 from MeOH alone, whereas the crystals of neutral components were obtained when crystallized from MeOH and phenol mixture. Both the structures (salt and cocrystal) exhibited huge cavities which are occupied by the self-interpenetration of the networks. This self-interpenetration of the networks found to be eschewed in favor of guest inclusion when the crystallization reactions are conducted in the presence of suitable aromatic guest molecules such as biphenyl, naphthalene, anthracene, phenanthrene, pyrene, triphenylene, and 1,4-hydroquinone. The crystal structures of cocrystals contain hydrogen-bonded layers with huge cavities, the self-interpenetrated layers have a honeycomb geometry with the cavity dimensions of 23 × 42 A2 and the guest included layers have a ...

Control of Molecular Packing in the ET Based Conductor by Supramolecular Mellitate Networks (ET = Bis(ethylenedithio)tetrathiafulvalene)

Electrochemical oxidation of bis(ethylenedithio)terathiafulvalene (ET) with mellitic acid and pyridine in methanol produces a partially oxidized salt of [ET]3[C6(COO)6H42-]2[C5H5NH+]2·CH3OH·2H2O (1). In the crystal of 1, mellitate anions form a two-dimensional hydrogen-bonding double-sheet layer with pyridinium, methanol, and water. ET molecules are packed between the layers, forming a two-dimensional conducting sheet. The ET arrangement in the sheet resembles that in α-ET2I3, which has a metal-to-insulator transition. The transition into insulating states is completely suppressed in 1 due to the close packing of ET molecules in the supramolecular mellitate network.

Poly[[diaqua(μ3-2,2-dimethylmalonato)cadmium(II)] tetrahydrate

In the title complex, {[Cd(C(5)H(6)O(4))(H(2)O)(2)].4H(2)O}(n), the dimethylmalonate-cadmium metal-organic framework co-exists with an extended structure of water molecules, which resembles a sodalite-type framework. In the asymmetric unit, there are five independent solvent water molecules, two of which are in special positions. The Cd atoms are eight-coordinated in a distorted square-antiprismatic geometry by six O atoms of three different dimethylmalonate groups and by two water molecules, and form a two-dimensional honeycomb layer parallel to the bc plane. Two such layers sandwich the hydrogen-bonded water layer, which has a sodalite-type structure with truncated sodalite units composed of coordinated and solvent water molecules. This work is the first example of a dimethylmalonate cadmium complex containing truncated sodalite-type water clusters.

Synthesis, structure and properties of Nickel(II) and Cobalt(II) compounds with 1,5-dinitronaphthalene-3,7-dicarboxylate

Two metal–organic compounds, [Co 2(NNDC) 2(H 2O) 6]·2H 2O ( 1) and [Ni(NNDC)(H 2O) 4] n ( 2) (where H 2NNDC = 1,5-dinitronaphthalene-3,7-dicarboxylic acid) have been synthesized under hydrothermal reaction conditions, which are characterized by single crystal X-ray determination, IR and Thermogravimetric Analysis (TGA). Compound 1 consists of binuclear Co(II) molecules with di(μ-aqua)di(μ-carboxylato) bridges. In the compound, each dicarboxylate ligand bridges metal ions using only one carboxylate group, with the other carboxylate group involved in extensive hydrogen bonding with coordinated and uncoordinated water molecules. The 1,5-dinitronaphthalene groups serve as pillars between the hydrogen-bonded layers in which the dinuclear moieties are connected through the O–H⋯O⋯H–O hydrogen bonds mediated by uncoordinated carboxylate groups and lattice water molecules. In 2, the ligands serve as long bridges to link the metal ions into infinite chains. The uncoordinated oxygen atoms of carboxylate are hydrogen bonded to coordinated water molecules from the same and different chains to link the metal spheres into (4,4) layers, which are formally pillared by the 1,5-dinitronaphthalene spacers to generate a 3D architecture with the α-Po topology. Based on a model taking into account both magnetic coupling and single-ion magnetic effects, detailed magnetic analysis on the Co(II) compound revealed a ferromagnetic intradimer interaction through the mixed aqua and carboxylate bridges.

2,8-Dimethyltricyclo[5.3.1.13,9]dodecane-syn-2,syn-8-diol–propanoic acid (1/1)

The racemic title compound, C14H24O2·C3H6O2, crystallizes in the monoclinic space group P21/c as a 1:1 diol/carboxylic acid cocrystal, A–B. The lattice incorporates infinite chains of the alcohol–carboxylic acid–alcohol supra­molecular synthon, (⋯O—H⋯O=C(R)—O—H⋯O—H⋯), in which the hydrogen-bonded mol­ecules (A—B—A)n surround a pseudo-threefold screw axis. The carboxylic acid group functions like an extended alcohol hydr­oxy group. Each diol, A, takes part in two such threefold screw arrangements, leading to a hydrogen-bonded layer structure, with adjacent layers containing diol mol­ecules of opposite handedness. The central C atom of the propano bridge is disordered over two sites of occupancies 0.75 (1) and 0.25 (1). The methyl group of the propanoic acid molecule is disordered over two sites of occupancies 0.68 (1) and 0.32 (1).

Hydrogen-Bonded Polymer Nanotubes in Water

Intermolecular hydrogen bonding, not hydrophobic interaction, is the driving force for the spontaneous self-assembly of glycosylated polyoxazoline chains into nanotubes in dilute aqueous solution. The structural information is encoded in the relatively simple molecular structure of chains consisting of a tertiary polyamide backbone (hydrogen-accepting) and glucose side chains (hydrogen-donating). The formation of the nanotubes should occur through bending and closing of a 2D hydrogen-bonded layer of interdigitated polymer chains.

Co-crystallisation of benzoic acid derivatives with N-containing bases in solution and by mechanical grinding: stoichiometric variants, polymorphism and twinning

Benzoic acid, salicylic acid and o-acetylsalicylic acid (aspirin) have been co-crystallised with diazabicyclo[2.2.2]octane (DABCO), piperazine, phenazine and 2-aminopyrimidine, using solution and solvent-drop grinding methods. Two of the resulting co-crystals, benzoic acid/DABCO (2 : 1) and benzoic acid/2-aminopyrimidine (2 : 1), form different polymorphs using the two distinct preparative techniques. In both systems, the polymorph obtained by grinding has a higher crystal density and packing coefficient than the polymorph obtained from solution. For benzoic acid/piperazine (2 : 1), salicylic acid/DABCO (2 : 1), salicylic acid/phenazine (2 : 1) and salicylic acid/N,N′-diacetylpiperazine (2 : 1) (derived from reaction between aspirin and piperazine), the same crystal form is obtained in bulk from solution and by solvent-drop grinding. For salicylic acid/N,N′-diacetylpiperazine (2 : 1), rapid cooling of an acetone solution produces single crystals of a different polymorph. Benzoic acid/2-aminopyrimidine also forms a 1 : 1 co-crystal from methanol solution on seeding with the material produced by grinding. For aspirin/DABCO (2 : 1), co-crystallisation was achieved only using solvent-drop grinding. Interactions between benzoic acid molecules in the co-crystals frequently resemble those in benzoic acid itself. For salicylic acid, two of the co-crystals have a layered structure in which the hydroxyl group is isolated within the layer, and the interlayer interactions also resemble those in benzoic acid. For aspirin, co-crystallisation with DABCO disrupts the layered structure and intermolecular interactions between acetyl groups. In benzoic acid/2-aminopyrimidine (2 : 1), insertion of base induces twinning based on two possibilities for the arrangement of adjacent hydrogen-bonded layers.

Competition between hydrogen bonding and arene–perfluoroarene stacking. X-Ray diffraction and molecular simulation on 5,6,7,8-tetrafluoro-2-naphthoic acid and 5,6,7,8-tetrafluoro-2-naphthamide crystals

Single crystal X-ray diffraction and PIXEL calculation of intermolecular pair energies, with partitioning into coulombic and dispersive factors, have been performed on the title crystals with the aim of testing the relative efficiency of molecular recognition synthons. X-Ray diffraction reveals that the crystals contain extended hydrogen-bonded layers, with various degrees of aromatic ring overlap between the layers. The calculation of molecular pair energies quantitatively reveals that the primary binding force in these crystals is hydrogen bonding, and that the arene–perfluoroarene stacking mode becomes less important, or almost optional. The various degrees of offset between overlapping aromatic rings found in the present crystals, also in comparison with some non-hydrogen bonding analogs, suggest a transition from perfect, highly stabilizing ArH–ArF overlap, to the less favourable, but still energetically stabilizing, ArF–ArF and ArH–ArH overlaps. The selectivity towards ArH–ArF stacking is not overwhelming.

2,3-Dihydro-1,3-benzothiazol-2-iminium hydrogen oxydiacetate: a combined structural and theoretical study

In the title compound, C(7)H(7)N(2)S(+).C(4)H(5)O(5)(-), the ions are connected by N-H...O hydrogen bonds. The hydrogen oxydiacetate residues are linked together by O-H...O hydrogen bonds disordered about centres of inversion into hydrogen-bonded ribbon layers crosslinked by weak C-H...O and stacking interactions. The cation exists mainly in the 2,3-dihydro-1,3-benzothiazol-2-iminium form, with a small participation of the 2-aminobenzothiazolium form, based on the structural data and quantum mechanical calculations. This study provides structural insights relevant to the biochemical activity of benzothiazole molecules.

Two complexes crystallizing from the aqueous system Ni2+ - tacn -[Ni(CN)4]2− ( tacn = 1,4,7-triazacyclononane)

Two new complexes [Ni(tacn)2][Ni(CN)4]·2H2O (1) and Ni(tacn)Ni(CN)4·H2O (2) (tacn = 1,4,7-triazacyclononane) have been synthesized from water and characterized by chemical analysis and infrared spectroscopy. Single-crystal X-ray structure analysis of 1 revealed an ionic structure built up of [Ni(tacn)2]2+ and [Ni(CN)4]2− complex ions without coordinated water. While cationic Ni(II) atom is octahedrally coordinated by two tridentate tacn ligands with Ni–N bonds from 2.101(3)–2.118(3) Å, the anionic Ni(II) atom is square planar with Ni–C bonds from 1.866(4) to 1.880(3) Å. An extended hydrogen bonding system connects complex cations, complex anions and water yielding hydrogen-bonded layers. Magnetic study of 1 revealed a decrease of the effective magnetic moment from 2.90 (300 K) to 2.43 μB at 1.8 K due to zero-field splitting. Fitting of the susceptibility data yielded g = 2.05, D/hc = 3.82 cm–1 and E/hc = 0.23 cm–1. IR spectral data indicate the presence of bridging cyano ligands in the structure of 2.

Supramolecular assemblies in the crystals of carboxylate salts prepared from a ferrocene β-aminoalcohol

(Ferrocenylmethyl)(2-hydroxyethyl)amine ( 1) reacts with mono- (CH 3CO 2H and PhCO 2H) and dicarboxylic acids (HO 2C(CH 2) n CO 2H ( n = 0–2), ( E)- and ( Z)-HO 2CCH CHCO 2H) to give the respective carboxylates, viz [ 1H](RCO 2) ( 2, R = CH 3; 3, R = Ph), [ 1H] 2(O 2C(CH 2) n CO 2) ( 4, n = 0; 5, n = 1; 6, n = 2), [ 1H] 2(( E)-O 2CCH CHCO 2) ( 7) and [ 1H] 2(( Z)-HO 2CCH CHCO 2) ( 8), as defined crystalline solids. Crystal structures of 2– 8 have been determined by single-crystal X-ray diffraction analysis, revealing extensive hydrogen bonding interactions based predominantly on charge-supported N +–H···O − and O–H···O − hydrogen bonds, and on C–H···O contacts. Whereas the crystal assemblies of the monocarboxylate salts propagate preferentially in one dimension ( 2: cross-linked chains, 3: columnar stacks), those of the salts prepared from the dicarboxylic acids (including hydrogenmaleate 8) are best described as layered composite arrays resulting via alternation of polar, hydrogen-bonded layers and of non-polar sheets constituted by the ferrocenyl substituents.