Solvent‐mediated pseudo‐quadruple hydrogen‐bond motifs in three lamotrigine–carboxylic acid complexes

Lamotrigine, an antiepileptic drug, has been complexed with three aromatic carboxylic acids. All three compounds crystallize with the inclusion of N,N‐dimethylformamide (DMF) solvent, viz. lamotriginium [3,5‐diamino‐6‐(2,3‐dichlorophenyl)‐1,2,4‐triazin‐2‐ium] 4‐iodobenzoate N,N‐dimethylformamide monosolvate, C₉H₈Cl₂N₅⁺·C₇H₄IO₂⁻·C₃H₇NO, (I), lamotriginium 4‐methylbenzoate N,N‐dimethylformamide monosolvate, C₉H₇Cl₂N₅⁺·C₈H₈O₂⁻·C₃H₇NO, (II), and lamotriginium 3,5‐dinitro‐2‐hydroxybenzoate N,N‐dimethylformamide monosolvate, C₉H₈Cl₂N₅⁺·C₇H₃N₂O₇⁻·C₃H₇NO, (III). In all three structures, proton transfer takes place from the acid to the lamotrigine molecule. However, in (I) and (II), the acidic H atom is disordered over two sites and there is only partial transfer of the H atom from O to N. In (III), the corresponding H atom is ordered and complete proton transfer has occurred. Lamotrigine–lamotrigine, lamotrigine–acid and lamotrigine–solvent interactions are observed in all three structures and they thereby exhibit isostructurality. The DMF solvent extends the lamotrigine–lamotrigine dimers into a pseudo‐quadruple hydrogen‐bonding motif.     

A pseudo‐quadruple hydrogen‐bonding motif consisting of six N—H⋯O hydrogen bonds in trimethoprim formate

The title compound, trimethoprim (TMP) formate [systematic name: 2,4‐di­amino‐5‐(3,4,5‐tri­methoxy­benzyl)­pyrimidin‐1‐ium formate], C₁₄H₁₉N₄O₃⁺·CHO₂^?, reveals a pseudo‐quadruple hydrogen‐bonding motif consisting of six N—H?O hydrogen bonds involving two unpaired TMP cations and two formate anions which are symmetrically disposed. The hydrogen‐bonding motif is strikingly comparable with that observed in other TMP salts where the amino­pyrimidine moieties of the TMP cations are centrosymmetrically paired. These conserved hydrogen‐bonding motifs may serve as robust synthons in crystal engineering and design. The characteristic pseudo‐quadruple hydrogen‐bonding motif and other intermolecular hydrogen bonds operating in the crystal form a two‐dimensional supramolecular sheet structure.     

A polymorph of butobarbital with two distinct hydrogen‐bonding motifs

N—H...O bonding in a form of 5‐butyl‐5‐ethylbarbituric acid (systematic name: 5‐butyl‐5‐ethyl‐1,3‐diazinane‐2,4,6‐trione), C₁₀H₁₆N₂O₃, produces two distinct one‐dimensional motifs, viz. tape and ladder. Both are different from the ribbon chain motif observed in two previously reported polymorphs of the same compound.     

From single‐chain folding to polymer nanoparticles via intramolecular quadruple hydrogen‐bonding interaction

Single‐chain folding via intramolecular noncovalent interaction is regarded as a facile mimicry of biomacromolecules. Single‐chain folding and intramolecular crosslinking is also an effective method to prepare polymer nanoparticles. In this study, poly(methyl methacrylate‐co?2‐ureido‐5‐deazapterines functionalized ethylene methacrylate) (P(MMA‐co‐EMA‐DeAP)) is synthesized via free radical polymerization. The single‐chain folding of P(MMA‐co‐EMA‐DeAP) and the formation of the nanoparticles in diluted solution (concentration <0.005 mg/mL) are achieved via supramolecular interaction and intramolecular collapsing during the disruption‐reformation process of the hydrogen bonding triggered by water. The size and the morphology of the nanoparticles are characterized by dynamic light scattering, transmission electron microscope, and atomic force microscope. The results show that the size of the nanoparticles depends on the molecular weight of the polymer and the loading of 2‐ureido‐5‐deazapterines functionalized ethylene methacrylate (EMA‐DeAP) on the polymer backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1832–1840     

Two pseudo‐polymorphic copper–benzene‐1,2,4,5‐tetracarboxylate complexes

Two pseudo‐polymorphic polymers, poly[ethylenediammonium [[aquacopper(II)]‐μ₄‐benzene‐1,2,4,5‐tetracarboxylato] dihydrate], {(C₂H₁₀N₂)[Cu(C₁₀H₂O₈)(H₂O)]·2H₂O}_n, (I), and poly[ethylenediammonium [copper(II)‐μ₄‐benzene‐1,2,4,5‐tetracarboxylato] 2.5‐hydrate], {(C₂H₁₀N₂)[Cu(C₁₀H₂O₈)]·2.5H₂O}_n, (II), contain two‐dimensional anionic layers, ethylenediammonium (H₂en) cations acting as counter‐ions and free water molecules. Although the topological structures of the two anionic layers are homologous, the coordination environments of the Cu^II centres are different. In (I), the Cu^II centre, sitting on a general position, has a square‐pyramidal environment. The two independent benzene‐1,2,4,5‐tetracarboxylate (btc) anions rest on centres of inversion. The Cu^II cation in (II) is located on a twofold axis in a square‐planar coordination. The H₂en cation is on an inversion centre and the btc ligand is split by a mirror plane. Extensive hydrogen‐bonding interactions between the complexes, H₂en cations and water molecules lead to the formation of three‐dimensional supramolecular structures.     

The hydrogen‐bonding network in deacetyl­cephalothin

The structural analysis of deacetyl­cephalothin [systematic name: (6R,7R)‐3‐hydroxy­methyl‐8‐oxo‐7‐(2‐thio­phen‐2‐yl­acetyl­amino)‐5‐thia‐1‐aza­bicyclo­[4.2.0]oct‐2‐ene‐2‐carboxylic acid], C₁₄H₁₄N₂O₅S₂, shows that the geometry of the central bicyclic moiety is close to the geometry exhibited by other biologically active cephalosporin antibiotics. The mol­ecules are arranged in a helical chain running parallel to the 2₁ axis via a strong O—H⋯O hydrogen bond. The main helices are zipped together via N—H⋯O inter­actions, forming infinite layers. The supramolecular architecture is stabilized by O—H⋯S and C—H⋯O hydrogen bonds.     

(–)‐Dioxosantadienic acid: hydrogen‐bonding patterns in a bicyclic sesquiterpenoid keto acid and its mono­hydrate

The an­hydrous form, (I), of the title compound, (?)‐2‐(1,2,3,4,4a,7‐hexa­hydro‐4a,8‐di­methyl‐1,7‐dioxo‐2‐naphthyl)­propionic acid, C₁₅H₁₈O₄, derived from a naturally occurring sesquiterpenoid, has two mol­ecules in the asymmetric unit, (I) and (I′), differing in the conformations of the saturated ring and the carboxyl group. The compound aggregates as carboxyl‐to‐ketone hydrogen‐bonding catemers [O?O = 2.776 (3) and 2.775 (3) Å]. Two crystallographically independent sets of single‐strand hydrogen‐bonding helices with opposite end‐to‐end orientation pass through the cell in the b direction, one consisting exclusively of mol­ecules of (I) and the other entirely of (I′). Three C—H?O=C close contacts are found in (I). The monohydrate, C₁₅H₁₈O₄·H₂O, (II), with two mol­ecules of (I) plus two water mol­ecules in its asymmetric unit, forms a complex three‐dimensional hydrogen‐bonding network including acid‐to‐water, water‐to‐acid, water‐to‐ketone, water‐to‐water and acid‐to‐acid hydrogen bonds, plus three C—H?O=C close contacts. In both (I) and (II), only the ketone remote from the acid is involved in hydrogen bonding.     

3‐Acetylanilinium bromide,nitrate and dihydrogen phosphate: hydrogen‐bonding motifs in one,two and three dimensions

In the title compounds, namely 3‐acetylanilinium bromide, C₈H₁₀NO⁺·Br⁻, (I), 3‐acetylanilinium nitrate, C₈H₁₀NO⁺·NO₃⁻, (II), and 3‐acetylanilinium dihydrogen phosphate, C₈H₁₀NO⁺·H₂PO₄⁻, (III), each asymmetric unit contains a discrete cation, with a protonated amino group, and an anion. In the crystal structure of (I), the ions are connected via N—H...Br and N—H...O hydrogen bonds into a chain of spiro‐fused R²₂(14) and R²₄(8) rings. In compound (II), the non‐H atoms of the cation all lie on a mirror plane in the space group Pnma, while the nitrate ion lies across a mirror plane. The crystal structures of compounds (II) and (III) are characterized by hydrogen‐bonded networks in two and three dimensions, respectively. The ions in (II) are connected via N—H...O hydrogen bonds, with three characteristic graph‐set motifs, viz.C²₂(6), R²₁(4) and R⁴₆(14). The ions in (III) are connected via N—H...O and O—H...O hydrogen bonds, with five characteristic graph‐set motifs, viz.D, C(4), C¹₂(4), R³₃(10) and R⁴₄(12). The significance of this study lies in its illustration of the differences between the supramolecular aggregations in the bromide, nitrate and dihydrogen phosphate salts of a small organic molecule. The different geometry of the counter‐ions and their different potential for hydrogen‐bond formation result in markedly different hydrogen‐bonding arrangements.     

Lamellar aggregation and hydrogen‐bonding motifs in 3‐(amino­carbon­yl)­pyridinium perchlorate and hydrogen oxalate

In the title compounds, C₆H₇N₂O⁺·ClO₄⁻, (I), and C₆H₇N₂O⁺·C₂HO₄⁻, (II), the carboxamide plane is twisted from the plane of the protonated pyridine ring. Lamellar or sheet‐like structural features are observed through N—H⋯O and O—H⋯O hydrogen‐bonded motifs of cations and anions in (I) and (II), respectively. These sheets are aggregated through C(4) and C(5) chain motifs in (I) and (II), respectively. R₁²(4) ring motifs in (I) and R₁²(5) motifs in (II) are formed via pyridine–anion bifurcated N—H⋯O inter­actions. In (II), carboxamide groups form N—H⋯O dimers around the inversion centres of the unit cell, with R₂²(8) ring motifs. A 2₁ screw‐related helical or ribbon‐like structure along the b axis is formed in (II) through carboxamide and pyridinium N—H⋯O hydrogen bonds with the oxalate anions.     

Different hydrogen‐bonding modes in two closely related oximes

Two closely related oximes, namely 1‐chloroacetyl‐3‐ethyl‐2,6‐diphenylpiperidin‐4‐one oxime, C₂₁H₂₃ClN₂O₂, (I), and 1‐chloroacetyl‐2,6‐diphenyl‐3‐(propan‐2‐yl)piperidin‐4‐one oxime, C₂₂H₂₅ClN₂O₂, (II), despite their identical sets of hydrogen‐bond donors and acceptors, display basically different hydrogen‐bonding patterns in their crystal structures. While the molecules of (I) are organized into typical centrosymmetric dimers, created by oxime–oxime O—H...N hydrogen bonds, in the structure of (II) there are infinite chains of molecules connected by O—H...O hydrogen bonds, in which the carbonyl O atom from the chloroacetyl group acts as the hydrogen‐bond acceptor. Despite the differences in the hydrogen‐bond schemes, the –OH groups are always in typical anti positions (C—N—O—H torsion angles of ca 180°). The oxime group in (I) is disordered, with the hydroxy groups occupying two distinct positions and C—C—N—O torsion angles of approximately 0 and 180° for the two alternatives. This disorder, even though the site‐occupancy factor of the less occupied position is as low as ca 0.06, is also observed at lower temperatures, which seems to favour the statistical and not the dynamic nature of this phenomenon.     

New basis sets for the evaluation of interaction‐induced electric properties in hydrogen‐bonded complexes

Interaction‐induced static electric properties, that is, dipole moment, polarizability, and first hyperpolarizability, of the CO? (HF)_n and N₂? (HF)_n, n = 1–9 hydrogen‐bonded complexes are evaluated within the finite field approach using the Hartree–Fock, density functional theory, Møller–Plesset second‐order perturbation theory, and coupled cluster methods, and the LPol‐n (n = ds, dl, fs, fl) basis sets. To compare the performance of the different methods with respect to the increase of the complex size, we consider as model systems linear chains of the complexes. We analyze the results in terms of the many‐body and cooperative effects. © 2012 Wiley Periodicals, Inc.     

Supra­molecular hydrogen‐bonding networks in bis­(adeninium) phthalate phthalic acid 1.45‐hydrate

In the title compound, 2C₅H₆N₅⁺·C₈H₄O₄²⁻·C₈H₆O₄·1.45H₂O, the asymmetric unit comprises two adeninium cations, two half phthalate anions with crystallographic C₂ symmetry, one neutral phthalic acid mol­ecule, and one fully occupied and one partially occupied site (0.45) for water mol­ecules. The adeninium cations form N—H⋯O hydrogen bonds with the phthalate anions. The cations also form infinite one‐dimensional polymeric ribbons via N—H⋯N inter­actions. In the crystal packing, hydrogen‐bonded columns of cations, anions and phthalate anions extend parallel to the c axis. The water mol­ecules crosslink adjacent columns into hydrogen‐bonded layers.     

A proton induced conformational change in metal complexes with potential hydrogen bonding triplet motifs

Biguanide-like bidentate ligands in a variety of transition metal complexes of different geometries exhibit conformational changes upon protonation/deprotonation that alter their capacity to recognise complementary hydrogen bonding motifs.     

Intermolecular dihydrogen‐ and hydrogen‐bonding interactions in diammonium closo‐decahydrodecaborate sesquihydrate

The asymmetric unit of the title salt, 2NH₄⁺·B₁₀H₁₀²⁻·1.5H₂O or (NH₄)₂B₁₀H₁₀·1.5H₂O, (I), contains two B₁₀H₁₀²⁻ anions, four NH₄⁺ cations and three water molecules. (I) was converted to the anhydrous compound (NH₄)₂B₁₀H₁₀, (II), by heating to 343 K and its X‐ray powder pattern was obtained. The extended structure of (I) shows two types of hydrogen‐bonding interactions (N—H...O and O—H...O) and two types of dihydrogen‐bonding interactions (N—H...H—B and O—H...H—B). The N—H...H—B dihydrogen bonding forms a two‐dimensional sheet structure, and hydrogen bonding (N—H...O and O—H...O) and O—H...H—B dihydrogen bonding link the respective sheets to form a three‐dimensional polymeric network structure. Compound (II) has been shown to form a polymer with the accompanying loss of H₂ at a faster rate than (NH₄)₂B₁₂H₁₂ and we believe that this is due to the stronger dihydrogen‐bonding interactions shown in the hydrate (I).     

Epoxy‐based networks combining chemical and supramolecular hydrogen‐bonding crosslinks

We combine the supramolecular chemistry of heterocyclic ureas with the chemistry of epoxides to synthesize new crosslinked materials incorporating both chemical and supramolecular hydrogen‐bonded links. A two‐step facile and solvent‐free procedure is used to obtain chemically and thermally stable networks from widely available ingredients: epoxy resins and fatty acids. The density of both chemical and physical crosslinks is controlled by the stoichiometry of the reactants and the use of a proper catalyst to limit side reactions. Depending on the stoichiometry, a wide range of thermomechanical properties can be attained. The method can be used to produce elastomeric objects of complex shapes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1133–1141, 2010     

5‐Oxocyclooctanecarboxylic acid: hydrogen‐bonding pattern and conformational disorder in a medium‐ring ɛ‐keto acid

Molecules of the title compound, C₉H₁₄O₃, adopt a chiral `boat–chair' conformation, in which the carboxyl group avoids potential cross‐ring ketone interactions by an outward `equatorial' orientation. The asymmetric unit contains two such mol­ecules, one conformationally fixed without disorder, (I), and the other, (I′), extensively disordered, both in the bond lengths and angles of the carboxyl and by a coupled `up‐down' conformational disordering [ratio of 60:40 (1)] of the remote ends of the boat–chair system. Each mol­ecule in the asymmetric unit forms a centrosymmetric hydrogen‐bonded carboxyl dimer with a second mol­ecule of its own type. For (I), O?O = 2.658 (3) Å and O—H?O = 174°. For (I′), O?O = 2.653 (3) Å and O—H?O = 165°. A number of intermolecular C=O?H—C close contacts are found.     

Construction of different supramolecular polymer systems by combining the host–guest and hydrogen‐bonding interactions

Poly(ethylene glycol) (PEG) can form either the inclusion complex with α‐cyclodextrins (α‐CDs) through host–guest interactions or the interpolymer complex with poly(acrylic acid) (PAA) through hydrogen‐bonding interaction. Mixing α‐CD, PEG, and PAA ternary components in an aqueous solution, the competition between host–guest and hydrogen‐bonding interactions occurs. Increasing feed ratio of α‐CD:EG:AA from 0:1:1 to 0.2:1:1 (molar ratio), various interesting supramolecular polymer systems, such as hydrogen‐bonding complex, dynamic polyrotaxane, crystalline inclusion complex, and thermoresponsive hydrogel, are successively obtained. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1114–1120, 2008     

Polymer/clay nanocomposites through multiple hydrogen‐bonding interactions

An 2‐ureido‐4[1H]pyrimidinone (UPy) motif with self‐association capability (through quadruple hydrogen bonds) was successfully anchored onto montmorillonite clay layers. Polymer/clay nanocomposites were prepared by specific hydrogen bonding interactions between surface functionalized silica nanoclays and UPy‐bonded supramolecular poly(ethylene glycol) or poly(?‐caprolactone). The mixed morphologies including intercalated layers with a non‐uniform separation and exfoliated single layers isolated from any stack were determined by combined X‐ray diffraction and transmission electron microscopic measurements. Thermal analyses showed that all nanocomposites had higher decomposition temperatures and thermal stabilities compared with neat polymer. The differential scanning calorimetric data implied that the crystallinity of polymers did not show essential changes upon introduction of organomodified UPy clays. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 650–658     

Fluoride anion sensing mechanism of a BODIPY‐linked hydrogen‐bonding probe

The sensing mechanism of a fluoride‐anion probe BODIPY‐amidothiourea ( 1c ) has been elucidated through the density functional theory (DFT) and time‐dependent density functional theory (TDDFT) calculations. The theoretical study indicates that in the DMSO/water mixtures the fluorescent sensing has been regulated by the fluoride complex that formed between the probe 1c /two water molecules and the fluoride anion, and the excited‐state intermolecular hydrogen bond (H‐B) plays an important role in the fluoride sensing mechanism. In the first excited state, the H‐Bs of the fluoride complex 1cFH₂ are overall strengthened, which induces the weak fluorescence emission. In addition, molecular orbital analysis demonstrates that 1cFH₂ has more obvious intramolecular charge transfer (ICT) character in the S₁ state than 1cH₂ formed between the probe 1c and two water molecules, which also gives reason to the weaker fluorescence intensity of 1cFH₂ . Further, our calculated UV‐vis absorbance and fluorescence spectra are in accordance with the experimental measurements. © 2018 Wiley Periodicals, Inc.