Phenyl‐ring rotational disorder in the two‐dimensional hydrogen‐bonded structure of the 1:1 proton‐transfer salt of the diazo‐dye precursor 4‐(phenyldiazenyl)aniline (aniline yellow) with l‐tartaric acid

In the structure of the 1:1 proton‐transfer compound from the reaction of l ‐tartaric acid with the azo‐dye precursor aniline yellow [4‐(phenyldiazenyl)aniline], namely 4‐(phenyldiazenyl)anilinium (2R,3R)‐3‐carboxy‐2,3‐dihydroxypropanoate, C₁₂H₁₂N₃⁺·C₄H₅O₆⁻, the asymmetric unit contains two independent 4‐(phenyldiazenyl)anilinium cations and two hydrogen l ‐tartrate anions. The structure is unusual in that all four phenyl rings of the two cations have identical rotational disorder with equal occupancy of the conformations. The two hydrogen l ‐tartrate anions form independent but similar chains through head‐to‐tail carboxyl–carboxylate O—H...O hydrogen bonds [graph set C(7)], which are then extended into a two‐dimensional hydrogen‐bonded sheet structure through hydroxy O—H...O hydrogen‐bonded links. The anilinium groups of the 4‐(phenyldiazenyl)anilinium cations are incorporated into the sheets and also provide internal hydrogen‐bonded extensions, while their aromatic tails are layered in the structure without significant association except for weak π–π interactions [minimum ring centroid separation = 3.844 (3) Å]. The hydrogen l ‐tartrate residues of both anions exhibit the common short intramolecular hydroxy–carboxylate O—H...O hydogen bonds. This work provides a solution to the unusual disorder problem inherent in the structure of this salt, as well as giving another example of the utility of the hydrogen tartrate anion in the generation of sheet substructures in molecular assembly processes.     

Brucine salts of l‐α‐hydr­oxy acids: brucinium hydrogen (S)‐malate penta­hydrate and anhydrous brucinium hydrogen (2R,3R)‐tartrate at 130 K

The structures of two brucinium (2,3‐dimeth­oxy‐10‐oxostrychnidinium) salts of the α‐hydr­oxy acids l ‐malic acid and l ‐tartaric acid, namely brucinium hydrogen (S)‐malate penta­hydrate, C₂₃H₂₇N₂O₄⁺·C₄H₅O₅⁻·5H₂O, (I), and anhydrous brucinium hydrogen (2R,3R)‐tartrate, C₂₃H₂₇N₂O₄⁺·C₄H₅O₆⁻,(II), have been determined at 130 K. Compound (I) has two brucinium cations, two hydrogen malate anions and ten water mol­ecules of solvation in the asymmetric unit, and forms an extensively hydrogen‐bonded three‐dimensional framework structure. In compound (II), the brucinium cations form the common undulating brucine sheet substructures, which accommodate parallel chains of head‐to‐tail hydrogen‐bonded tartrate anion species in the inter­stitial cavities.     

[{Na(7‐Nitro‐5‐sulfonate‐naphthalene‐1,4‐dicarboxy‐acid (H2O)2}·H2O]n: A Water‐Soluble 2D Layer Polymeric Complex with Microporous Molecular Channels

The X‐ray crystallographic studies are reported for a water‐soluble sodium complex of organic acid, {[Na(NSNDC)(H₂O)₂]·H₂O}_n, (NSNDC = 7‐Nitro‐5‐sulfonate‐napthalene‐1,4‐dicarboxy‐acid). It contains layers of vertically oriented NNSDC‐anions sandwiching cations and water molecules. The rows of anions are linked in a direction by sodium ions and along b by hydrogen bonding, which have microporous channels (9.410 × 3.210Ų) along the crystallographic b‐axis. Considering the Na coordination environments, π‐π stacking interaction between aryl ring and hydrogen bonds, the title compound represents a stably 2D infinitely extended structure.     

Supramolecular Structures with the 2‐Propyl‐4,5‐dicarboxy‐1H‐imidazole Ligand: Hydrothermal Synthesis,Structures, and Photoluminescence

Self‐assembly of the rigid organic ligand 2‐propyl‐4,5‐dicarboxy‐1H‐imidazole ( L ) with different metal ions (Zn²⁺, Ni²⁺, Cu²⁺, Cd²⁺) led to four new complexes, namely, [M( L )(phen)] [M = Zn ( 1 ); Ni ( 2 ); Cd ( 3 )] and [Cu( L )( 4 )] (phen = 1,10‐phenanthroline). Their structures were determined by single‐crystal X‐ray diffraction analyses, and they were further characterized by elemental analysis, IR spectroscopy, and thermogravimetric analysis. Whereas compounds 1 , 2 , and 3 are discrete units, hydrogen‐bonding interactions play a vital role in these complexes. Compounds 1 and 2 form one‐dimensional (1D) and two‐dimensional (2D) structures through hydrogen‐bondinginteractions with helical character. In 1 , the hydrogen bonds (O–H ··· O) alternately bridge the M^II cations of the discrete units to form a one‐dimensional (1D) infinite helical chain. Complex 2 forms a 2D helical layer through parallel hydrogen bonds (N/O–H ··· O/N) between two adjacent helical chains. In 3 , the hydrogen bonds (N–H ··· O) connect adjacent discrete units into a ten‐membered ring with extension into a one‐dimensional double‐chain supramolecular structure. Complex 4 is a two‐dimensional gridlike (4,4) topological layer which is extended to a 3D network by hydrogen bonding. The solid‐state fluorescence spectrum of complex 3 was determined.     

Proton‐transfer and non‐transfer in compounds of quinoline and quinaldic acid with l‐tartaric acid

The structures of two compounds of l ‐tartaric acid with quinoline, viz. the proton‐transfer compound quinolinium hydrogen (2R,3R)‐tartrate monohydrate, C₉H₈N⁺·C₄H₅O₆⁻·H₂O, (I), and the anhydrous non‐proton‐transfer adduct with quinaldic acid, bis­(quinolinium‐2‐carboxyl­ate) (2R,3R)‐tar­taric acid, 2C₁₀H₇NO₂·C₄H₆O₆, (II), have been determined at 130 K. Compound (I) has a three‐dimensional honeycomb substructure formed from head‐to‐tail hydrogen‐bonded hydrogen tartrate anions and water mol­ecules. The stacks of π‐bonded quinolinium cations are accommodated within the channels and are hydrogen bonded to it peripherally. Compound (II) has a two‐dimensional network structure based on pseudo‐centrosymmetric head‐to‐tail hydrogen‐bonded cyclic dimers comprising zwitterionic quinaldic acid species which are inter­linked by tartaric acid mol­ecules.     

l‐Cysteinium semioxalate

The title salt, C₃H₈NO₂⁺·C₂HO₄⁻, formed between l ‐cysteine and oxalic acid, was studied as part of a comparison of the structures and properties of pure amino acids and their cocrystals. The structure of the title salt is very different from that formed by oxalic acid and equivalent amounts of d ‐ and l ‐cysteine molecules. The asymmetric unit contains an l ‐cysteinium cation and a semioxalate anion. The oxalate anion is only singly deprotonated, in contrast with the double deprotonation in the crystal structure of bis(dl ‐cysteinium) oxalate. The oxalate anion is not planar. The conformation of the l ‐cysteinium cation differs from that of the neutral cysteine zwitterion in the monoclinic and orthorhombic polymorphs of l ‐cysteine, but is similar to that of the cysteinium cation in bis(dl ‐cysteinium) oxalate. The structure of the title salt can be described as a three‐dimensional framework formed by ions linked by strong O—H...O and N—H...O and weak S—H...O hydrogen bonds, with channels running along the crystallographic a axis containing the bulky –CH₂SH side chains of the cysteinium cations. The cations are only linked through hydrogen bonds via semioxalate anions. There are no direct cation–cation interactions via N—H...O hydrogen bonds between the ammonium and carboxylate groups, or via weaker S—H...S or S—H...O hydrogen bonds.     

dl‐Alaninium semi‐oxalate monohydrate

The structure of the title compound, C₃H₈NO₂⁺·C₂HO₄⁻·H₂O, is formed by two chiral counterparts (l ‐ and d ‐alaninium cations), semi‐oxalate anions and water molecules, with a 1:1:1 cation–anion–water ratio. The structure is compared with that of the previously known anhydrous dl ‐alaninium semi‐oxalate [Subha Nandhini, Krishnakumar & Natarajan (2001). Acta Cryst. E 57 , o666–o668] in order to investigate the role of water molecules in the crystal packing. The structure of the hydrate resembles that of anhydrous alaninium semi‐oxalate, with the water molecule incorporated into the general three‐dimensional network of hydrogen bonds where it forms four hydrogen bonds with neighbours disposed tetrahedrally about it. Although the main structural motifs in the hydrate and in the anhydrous form are topologically similar, the incorporation of water molecules in the network results in significant geometric distortion. There are several types of hydrogen bond in the crystal structure of the hydrate, two of which (O—H...O bonds between the semi‐oxalate anions and O—H...O hydrogen bonds between water and alaninium cations) are very short. Such hydrogen bonds between semi‐oxalate anions are also present in the anhydrous form of this compound. Short distances between semi‐oxalate anions in neighbouring chains in the hydrate alternate with longer ones, whereas in the anhydrous structure they are equidistant. Despite the similarity of these compounds, dehydration of the hydrate on storage is not of a single‐crystal to single‐crystal type, but gives a polycrystalline pseudomorph, preserving the crystal habit. This transformation proceeds through the formation of an intermediate compound, presumably a hemihydrate.     

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.     

l‐Leucinium perchlorate

Crystals of l ‐leucinium perchlorate, C₆H₁₄NO₂⁺·ClO₄⁻, are built up from protonated l ‐leucinium cations and perchlorate anions. l ‐Leucinium cations related by a twofold screw axis are inter­connected by N—H⋯O hydrogen bonds into zigzag chains parallel to [010]. The O atoms of the perchlorate anions act as acceptors of hydrogen bonds that link the l ‐leucinium chains into separated but inter­acting two‐dimensional layers parallel to (001). Since the title compound crystallizes in a non‐centrosymmetric space group, it can be useful as a material for non‐linear optics. The efficiency of second harmonic generation is about twice that of K₂[HPO₄].     

Three‐dimensional hydrogen‐bonded structures in the 1:1 proton‐transfer compounds of l‐tartaric acid with the associative‐group monosubstituted pyridines 3‐aminopyridine, 3‐carboxypyridine (nicotinic acid) and 2‐carboxypyridine (picolinic acid)

The 1:1 proton‐transfer compounds of l ‐tartaric acid with 3‐aminopyridine [3‐aminopyridinium hydrogen (2R,3R)‐tartrate dihydrate, C₅H₇N₂⁺·C₄H₅O₆⁻·2H₂O, (I)], pyridine‐3‐carboxylic acid (nicotinic acid) [anhydrous 3‐carboxypyridinium hydrogen (2R,3R)‐tartrate, C₆H₆NO₂⁺·C₄H₅O₆⁻, (II)] and pyridine‐2‐carboxylic acid [2‐carboxypyridinium hydrogen (2R,3R)‐tartrate monohydrate, C₆H₆NO₂⁺·C₄H₅O₆⁻·H₂O, (III)] have been determined. In (I) and (II), there is a direct pyridinium–carboxyl N⁺—H...O hydrogen‐bonding interaction, four‐centred in (II), giving conjoint cyclic R₁²(5) associations. In contrast, the N—H...O association in (III) is with a water O‐atom acceptor, which provides links to separate tartrate anions through O_hydroxy acceptors. All three compounds have the head‐to‐tail C(7) hydrogen‐bonded chain substructures commonly associated with 1:1 proton‐transfer hydrogen tartrate salts. These chains are extended into two‐dimensional sheets which, in hydrates (I) and (III) additionally involve the solvent water molecules. Three‐dimensional hydrogen‐bonded structures are generated via crosslinking through the associative functional groups of the substituted pyridinium cations. In the sheet struture of (I), both water molecules act as donors and acceptors in interactions with separate carboxyl and hydroxy O‐atom acceptors of the primary tartrate chains, closing conjoint cyclic R₄⁴(8), R₃⁴(11) and R₃³(12) associations. Also, in (II) and (III) there are strong cation carboxyl–carboxyl O—H...O hydrogen bonds [O...O = 2.5387 (17) Å in (II) and 2.441 (3) Å in (III)], which in (II) form part of a cyclic R₂²(6) inter‐sheet association. This series of heteroaromatic Lewis base–hydrogen l ‐tartrate salts provides further examples of molecular assembly facilitated by the presence of the classical two‐dimensional hydrogen‐bonded hydrogen tartrate or hydrogen tartrate–water sheet substructures which are expanded into three‐dimensional frameworks via peripheral cation bifunctional substituent‐group crosslinking interactions.     

Ammonium N‐acetyl‐l‐threoninate and methyl­ammonium N‐acetyl‐l‐threoninate

Ammonium N‐acetyl‐l ‐threoninate, NH₄⁺·C₆H₁₀NO₄^?, and methyl­ammonium N‐acetyl‐l ‐threoninate, CH₆N⁺·­C₆H₁₀NO₄^?, crystallize in the orthorhombic P2₁2₁2₁ and monoclinic P2₁ space groups, respectively. The two crystals present the same packing features consisting of infinite ribbons of screw‐related N‐acetyl‐l ‐threoninate anions linked together through pairs of hydrogen bonds. The cations interconnect neighbouring ribbons of anions involving all the nitrogen‐H atoms in three‐dimensional networks of hydrogen bonds. The hydrogen‐bond patterns include asymmetric `three‐centred' systems. In both structures, the Thr side chain is in the favoured (g^?g⁺) conformation.     

Optically Active Hexaazamacrocycles: Protonation Behavior and Chiral‐Anion Recognition

The protonation features of two optically active 22‐membered hexaazamacrocycles possessing one ( L1 ) or two ( L2 ) (R,R)‐cyclohexane‐1,2‐diamine moieties have been studied by means of potentiometric ¹H‐ and ¹³C‐NMR techniques. This study allows the determination of the basicity constants and the stepwise protonation sites. The presence of the cyclohexane decreases the protonation ability, and this effect can be explained in terms of conformational and electrostatic factors. Binding of different chiral dicarboxylates has been studied by potentiometry. Macrocycle L2 presents higher anion‐complexation equilibrium constants than L1 . The stability of the diastereoisomeric complexes depends on the pH, and the structures of the macrocycles and anions. Receptor L1 ⋅6 H⁺ shows moderate D ‐selectivity towards tartrate anion, whereas L2 ⋅6 H⁺ exhibits a good preference for N‐Ac‐D ‐aspartate. Both protonated L1 and L2 form strong complexes with N‐Ac‐glutamate, and the stoichiometry of the complex depends on the degree of protonation and the absolute configuration of the anion. For this last anion, both azamacrocycles exhibit a clear D ‐preference.     

Coulombic interactions,hydrogen bonding and supramolecular chirality in pyridinium trifluoromethanesulfonate

The title compound, C₅H₆N⁺·CF₃SO₃⁻, was serendipitously crystallized in the chiral space group P4₃2₁2. The component entities associate into hydrogen‐bonded helical chains, which propagate along the a and b axes of the crystal, with an alternating disposition of the cations and anions along the chain. N—H...O charge‐assisted hydrogen bonds, from each pyridinium cation to two adjacent trifluoromethanesulfonate anions and from every anion to two different cations, direct the formation of the supramolecular chiral arrays. The crystal packing exhibits nonconventional C—H...O and C—H...F hydrogen bonds between the components. The observed structure demonstrates induction of supramolecular chirality by a combination of Coulombic attractions and intermolecular hydrogen bonds.     

Conductive Nanoscopic Fibrous Assemblies Containing Helical Tetrathiafulvalene Stacks

Tetrathiafulvalenes (TTF) S‐TTF and R‐TTF having four chiral amide end groups self‐organize into helical nanofibers in the presence of 2,3,5,6‐tetrafluoro‐7,7′,8,8′‐tetracyano‐p‐quinodimethane (F₄TCNQ). The intermolecular hydrogen bonding among chiral amide end groups and the formation of charge‐transfer complexes results in a long one‐dimensional supramolecular stacking, and the chirality of the end groups affects the molecular orientation of TTF cores within the stacks. Electronic conductivity of a single helical nanoscopic fiber made of S‐TTF and F₄TCNQ is determined to be (7.0±3.0)×10^?4 S cm^?1 by point‐contact current‐imaging (PCI) AFM measurement. Nonwoven fabric composed of helical nanofibers shows a semiconducting temperature dependence with an activation energy of 0.18 eV.     

Hydro­gen‐bonding patterns in 2‐amino‐4,6‐di­methyl­pyrimidinium hydrogen sulfate

In the title compound, C₆H₁₀N₃⁺·HSO₄⁻, the asymmetric unit consists of a hydrogen sulfate anion and a 2‐amino‐4,6‐di­methyl­pyrimidinium cation. The hydrogen sulfate anions self‐assemble through O—H⋯O hydrogen bonds, forming supramolecular chains along the b axis, while the organic cations form base pairs via N—H⋯N hydrogen bonds. The amino­pyrimidinium cations join to the sulfate anions via a pair of hydrogen bonds donated from the pyrimidinium protonation site and from the exo amine group cis to the protonated site.     

Syndiotactic‐specific radical polymerization of N,N‐dimethylacrylamide in the presence of tartrates: A proposed mechanism for the polymerization

Radical polymerization of N,N‐dimethylacrylamide (DMAAm) was investigated in the presence of tartrates, such as diethyl L ‐tartrate, diisopropyl L ‐tartrate, and di‐n‐butyl L ‐tartrate, in toluene at low temperatures. Syndiotactic polymers were obtained in the presence of tartrates, whereas isotactic polymers were obtained in the absence of tartrates. The syndiotactic‐specificity increased with increasing amount of tartrates and with decreasing polymerization temperature. NMR analysis suggested that DMAAm and tartrates formed a 1:1 complex through double hydrogen bonding. A mechanism for the syndiotactic‐specific radical polymerization of DMAAm is proposed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1192–1203, 2009     

The supramolecular architecture in 4,4′‐bipyridinium bis(hydrogen oxalate)

The asymmetric unit of the title compound, C₁₀H₁₀N₂²⁺·2C₂HO₄⁻, consists of one half of a 4,4′‐bipyridinium cation, which has inversion symmetry, and a hydrogen oxalate anion, in which an intramolecular hydrogen bond exists. The cations and anions are connected by O—H...O, N—H...O and C—H...O hydrogen bonds, forming a two‐dimensional network, whereas π–π stacking interactions involving the 4,4′‐bipyridinium cations lead to the formation of a three‐dimensional supramolecular structure. An unusual deca‐atomic ring is formed between two hydrogen oxalate anions, which are linked side‐to‐side via O—H...O hydrogen‐bonding interactions.     

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.     

Two polyoxometallate‐based supramolecular compounds influenced by the ratio between the polyoxometallate anion and organic cation

Two polyoxometallate‐based compounds, tris[1,1′‐(butane‐1,4‐diyl)bis(1H‐imidazol‐3‐ium)] bis[tetracosa‐μ₂‐oxido‐dodecaoxido‐μ₁₂‐phosphato‐dodecamolybdenum(VI)], (C₁₀H₁₆N₄)₃[PMo₁₂O₄₀]₂, (I), and 1,1′‐(butane‐1,4‐diyl)bis(1H‐imidazol‐3‐ium) 1‐[4‐(1H‐imidazol‐1‐yl)butyl]‐1H‐imidazol‐3‐ium tetracosa‐μ₂‐oxido‐dodecaoxido‐μ₁₂‐phosphato‐dodecamolybdenum(VI) dihydrate, (C₁₀H₁₆N₄)(C₁₀H₁₅N₄)[PMo₁₂O₄₀]·2H₂O, (II), were synthesized by hydrothermal techniques at different pH values. The stoichiometric ratio between the polyoxometallate (POM) anions and organic cations is 2:3 in (I), with one of the cations lying on an inversion centre. The doubly protonated 1,1′‐(butane‐1,4‐diyl)diimidazole (BIM) cations are linked to the [PMo₁₂O₄₀]³⁻ anions by hydrogen bonds to form a three‐dimensional supramolecular network. The stoichiometric ratio of POM anions and organic cations is 1:2 in (II), and the anion is located about a centre of inversion. The partly protonated BIM cations and solvent water molecules form hydrogen bonds with the [PMo₁₂O₄₀]³⁻ anions, yielding a two‐dimensional supramolecular layer. The different lattice architectures of (I) and (II) may be governed by the ratio between the POM anions and organic cations, which, in turn, is determined by the pH value.     

l‐Methioninium chloride and l‐seleno­methioninium chloride at 103 K

The crystal structures of the title compounds, (S)‐1‐carboxy‐3‐(methyl­sulfanyl)­propanaminium chloride, C₅H₁₂NO₂S⁺·Cl⁻, and (S)‐1‐carboxy‐3‐(methyl­selanyl)­propanaminium chloride, C₅H₁₂NO₂Se⁺·Cl⁻, are isomorphous. The proton­ated l ‐methionine and l ‐seleno­methionine mol­ecules have almost identical conformations and create very similar contacts with the Cl⁻ anions in the crystal structures of both compounds. The amino acid cations and the Cl⁻ anions are linked viaN—H⋯Cl⁻ and O—H⋯Cl⁻ hydrogen bonds.