Hydrogen-bonded Layers Research Articles

Crystal structure of 1,2,3,4-tetra-hydro-isoquinolin-2-ium (2S,3S)-3-carb-oxy-2,3-di-hydroxy-propano-ate monohydrate.

The crystal structure of 1,2,3,4-tetra-hydro-isoquinolin-2-ium (2S,3S)-3-carb-oxy-2,3-di-hydroxy-propano-ate monohydrate, C9H12N+·C4H5O6 -·H2O, at 115 K shows ortho-rhom-bic symmetry (space group P212121). The hydrogen tartrate anions and solvent water mol-ecules form an intricate diperiodic O-H⋯O hydrogen-bond network parallel to (001). The tetra-hydro-isoquinolinium cations are tethered to the anionic hydrogen-bonded layers through N-H⋯O hydrogen bonds. The crystal packing in the third direction is achieved through van der Waals contacts between the hydro-carbon tails of the tetra-hydro-isoquinolinium cations, resulting in hydro-phobic and hydro-philic regions in the crystal structure.

Facet-dependent dispersion and aggregation of aqueous hematite nanoparticles.

Nanoparticle aggregates in solution controls surface reactivity and function. Complete dispersion often requires additive sorbents to impart a net repulsive interaction between particles. Facet engineering of nanocrystals offers an alternative approach to produce monodisperse suspensions simply based on facet-specific interaction with solvent molecules. Here, we measure the dispersion/aggregation of three morphologies of hematite (α-Fe2O3) nanoparticles in varied aqueous solutions using ex situ electron microscopy and in situ small-angle x-ray scattering. We demonstrate a unique tendency of (104) hematite nanoparticles to maintain a monodisperse state across a wide range of solution conditions not observed with (001)- and (116)-dominated particles. Density functional theory calculations reveal an inert, densely hydrogen-bonded first water layer on the (104) facet that favors interparticle dispersion. Results validate the notion that nanoparticle dispersions can be controlled through morphology for specific solvents, which may help in the development of various nanoparticle applications that rely on their interfacial area to be highly accessible in stable suspensions.

Three peroxomorphic H2O2 adducts of antibiotic furacin: the first cases of 2D hydrogen-bonded peroxide layers and concerted flip-flop hydrogen disorder of peroxide species

The first case of flip-flop hydrogen disorder of H2O2.

Crystal structure and Hirshfeld surface analysis of a new benzimidazole compound, 3-{1-[(2-hy-droxyphen-yl)meth-yl]-1H-1,3-benzo-diazol-2-yl}phenol.

The title compound, C20H16N2O2, is composed of two monosubstituted benzene rings and one benzimidazole unit. The benzimidazole moiety subtends dihedral angles of 46.16 (7) and 77.45 (8)° with the benzene rings, which themselves form a dihedral angle of 54.34 (9)°. The crystal structure features O-H⋯N and O-H⋯O hydrogen-bonding inter-actions, which together lead to the formation of two-dimensional hydrogen-bonded layers parallel to the (101) plane. In addition, π-π inter-actions also contribute to the crystal cohesion. Hirshfeld surface analysis indicates that the most significant contacts in the crystal packing are: H⋯H (47.5%), O⋯H/H⋯O (12.4%), N⋯H/H⋯N (6.1%), C⋯H/H⋯C (27.6%) and C⋯C (4.6%).

Boosting Proton Conductivity in Hydrogen-Bonded Organic Layers by Modulating Embedded Guest Molecules

Boosting Proton Conductivity in Hydrogen-Bonded Organic Layers by Modulating Embedded Guest Molecules

A Mixed Protonic-Electronic Conductor Base on the Host-Guest Architecture of 2D Metal-Organic Layers and Inorganic Layers.

The key to designing and fabricating highly efficient mixed protonic-electronic conductors materials (MPECs) is to integrate the mixed conductive active sites into a single structure, to break through the shortcomings of traditional physical blending. Herein, based on the host-guest interaction, an MPEC is consisted of 2D metal-organic layers and hydrogen-bonded inorganic layers by the assembly methods of layered intercalation. Noticeably, the 2D intercalated materials (≈1.3nm) exhibit the proton conductivity and electron conductivity, which are 2.02 × 10-5 and 3.84 × 10-4 S cm-1 at 100°C and 99% relative humidity, much higher than these of pure 2D metal-organic layers (>>1.0 × 10-10 and 2.01×10-8 S cm-1 ), respectively. Furthermore, combining accurate structural information and theoretical calculations reveals that the inserted hydrogen-bonded inorganic layers provide the proton source and a networks of hydrogen-bonds leading to efficient proton transport, meanwhile reducing the bandgap of hybrid architecture and increasing the band electron delocalization of the metal-organic layer to greatly elevate the electron transport of intrinsic 2D metal-organic frameworks.

Tri-methyl-phosphine oxide dihydrate.

The title hydrate, Me3PO·2H2O, crystallizes in the ortho-rhom-bic space group Pbca with eight formula units per unit cell. The extended structure displays O-H⋯O hydrogen bonding, with Me3PO mol-ecules as acceptors and water mol-ecules acting as donors and acceptors of hydrogen bonds, forming hydrogen-bonded layers, which propagate in the ac plane.

Organic Hybrid Antimoniotungstate Layered Ionic Crystal: Synthesis, Structure, and Interlayer-Confined Proton Conduction.

A synchronous crystal- and microstructure-dependent strategy was implemented to synthesize the organic hybrid antimoniotungstate layered ionic crystal Na5.5H6.5[(SbW9O33)2{WO2(OH)}2{WO2}RuC7H3NO4]·36H2O, and the layered structure was constructed through the Na+ bridged sheet and the hydrogen-bonded layers. It displayed an effective proton conductivity of 2.97 × 10-2 S cm-1 at 348 K and 75% RH, owing to the complete interlayer confined hydrogen-bond network formed by the hydrogens of interlayer crystal waters, organic ligands ({RuC7H3NO4}2+, {C7H3NO4} is formed by the hydrolysis of pyridine 2,5-dicarboxylic acid (C7H5NO4)), and acidic protons (H+), along with the interlayer domain as a transport channel. Furthermore, the hydrogen-bond network originating from interlayer organic ligands and acidic protons was more stable at a higher temperature of 423 K, preserving a high conductivity of 1.99 × 10-2 S cm-1.

Structural Origin of Anisotropic Thermal Expansion of Molecular Crystals and Implication for the Density Rule Probed with Four ROY Polymorphs

The objective of this work was to investigate the molecular origin of the differences in the thermal expansivity of four ROY polymorphs (Y, R, OP, and ON) using variable temperature single crystal X-ray diffractometry (VT-SCXRD). Thermal expansivity was found to be directly influenced by the crystal packing and the number and type of directional interactions, such as hydrogen bonds, involved in packing. Polymorphs with layered molecular packing, i.e., ON, OP, and R, show higher volume expansivity, where the axial component of the expansion is the largest in the directions perpendicular to the hydrogen-bonded layers and the smallest along the layers. Polymorph Y shows the least volume expansivity, which corresponds to the presence of a denser hydrogen-bonded network structure in the crystal, and absence of apparent molecular layers. The largest overall expansivity is observed for polymorph ON that lacks intermolecular hydrogen bonds and exhibits a layered packing pattern along two axes. The differences in the thermal expansivity of the ROY polymorphs lead to violations of the density rule in polymorph stability prediction due to crossover in crystal density with change in temperature, which means the rank order of crystal density of polymorphs is temperature-dependent. Thus, at absolute zero, the most thermodynamically stable polymorph Y is predicted to not have the highest density, which violates the density rule. Likewise, for all enantiotropic polymorphs undergoing the density crossover phenomenon, the density rule is valid only within the temperature range bracketed by the temperatures of density crossover (Td) and thermodynamic transition (Tt). For all monotropic polymorphs, the density rule is valid only above Td.

Crystal structure of oxibendazole, C12H15N3O3

The crystal structure of oxibendazole has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Oxibendazole crystallizes in space group C2/c (#15) with a = 23.18673(22), b = 5.35136(5), c = 19.88932(13) Å, β = 97.0876(9)°, V = 2449.018(17) Å3, and Z = 8. The structure consists of hydrogen-bonded layers of planar molecules parallel to the bc-plane. Strong N–H⋯N hydrogen bonds link the molecules into dimers, with a graph set R2,2(8). N–H⋯O hydrogen bonds further link these dimers into layers parallel to the bc-plane. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).

Differential Surface Interactions and Surface Templating of Nucleotides (dGMP, dCMP, dAMP, and dTMP) on Oxide Particle Surfaces.

The fate of biomolecules in the environment depends in part on understanding the surface chemistry occurring at the biological-geochemical (bio-geo) interface. Little is known about how environmental DNA (eDNA) or smaller components, like nucleotides and oligonucleotides, persist in aquatic environments and the role of surface interactions. This study aims to probe surface interactions and adsorption behavior of nucleotides on oxide surfaces. We have investigated the interactions of individual nucleotides (dGMP, dCMP, dAMP, and dTMP) on TiO2 particle surfaces as a function of pH and in the presence of complementary and noncomplementary base pairs. Using attenuated total reflectance-Fourier transform infrared spectroscopy, there is an increased number of adsorbed nucleotides at lower pH with a preferential interaction of the phosphate group with the oxide surface. Additionally, differential adsorption behavior is seen where purine nucleotides are preferentially adsorbed, with higher surface saturation coverage, over their pyrimidine derivatives. These differences may be a result of intermolecular interactions between coadsorbed nucleotides. When the TiO2 surface was exposed to two-component solutions of nucleotides, there was preferential adsorption of dGMP compared to dCMP and dTMP, and dAMP compared to dTMP and dCMP. Complementary nucleotide base pairs showed hydrogen-bond interactions between a strongly adsorbed purine nucleotide layer and a weaker interacting hydrogen-bonded pyrimidine second layer. Noncomplementary base pairs did not form a second layer. These results highlight several important findings: (i) there is differential adsorption of nucleotides; (ii) complementary coadsorbed nucleotides show base pairing with a second layer, and the stability depends on the strength of the hydrogen bonding interactions and; (iii) the first layer coverage strongly depends on pH. Overall, the importance of surface interactions in the adsorption of nucleotides and the templating of specific interactions between nucleotides are discussed.

Formation of hydrated PEG layers on magnetic iron oxide nanoflowers shows internal magnetisation dynamics and generates high in-vivo efficacy for MRI and magnetic hyperthermia

Multicore magnetic iron oxide nanoparticles, nanoflowers (NFs), have potential biomedical applications as efficient mediators for AC-magnetic field hyperthermia and as contrast agents for magnetic resonance imaging due to their strong magnetic responses arising from complex internal magnetic ordering. To realise these applications amenable surface chemistry must be engineered that maintain particle dispersion. Here a catechol-derived grafting approach is described to strongly bind polyethylene glycol (PEG) to NFs and provide stable hydrogen-bonded hydrated layers that ensure good long-term colloidal stability in buffers and media even at clinical MRI field strength and high concentration. The approach enables the first comprehensive study into the MRI (relaxivity) and hyperthermic (SAR) efficiencies of fully dispersed NFs. The predominant role of internal magnetisation dynamics in providing high relaxivity and SAR is confirmed, and it is shown that these properties are unaffected by PEG molecular weight or corona formation in biological environments. This result is in contrast to traditional single core nanoparticles which have significantly reduced SAR and relaxivity upon PEGylation and on corona formation, attributed to reduced Brownian contributions and weaker NP solvent interactions. The PEGylated NF suspensions described here exhibit usable blood circulation times and promising retention of relaxivity in-vivo due to the strongly anchored PEG layer. This approach to biomaterials design addresses the challenge of maintaining magnetic efficiency of magnetic nanoparticles in-vivo for applications as theragnostic agents. Statement of significanceApplication of multicore magnetic iron-oxide nanoflowers (NFs) as efficient mediators for AC-field hyperthermia and as contrast agents for MR imaging has been limited by lack of colloidal stability in complex media and biosystems.The optimized materials design presented is shown to reproducibly provide PEG grafted NF suspensions of exceptional colloidal stability in buffers and complex media, with significant hyperthermic and MRI utility which is unaffected by PEG length, anchoring group or bio-molecular adsorption.Deposition in the selected pancreatic tumour model mirrors liposomal formulations providing a quantifiable probe of tissue-level liposome deposition and relaxivity is retained in the tumour microenvironment.Hence the biomaterials design addresses the longstanding challenges of maintaining the in vivo magnetic efficiency of nanoparticles as theragnostic agents.

Crystal structure of baricitinib, C16H17N7O2S

The crystal structure of baricitinib has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Baricitinib crystallizes in space group I2/a (#15) with a = 11.81128(11), b = 7.06724(6), c = 42.5293(3) Å, β = 91.9280(4)°, V = 3548.05(5) Å3, and Z = 8. The crystal structure is characterized by hydrogen-bonded double layers parallel to the ab-planes. The dimers form a graph set R2,2(8). The sulfone ends of the molecules reside in the interlayer regions. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).

Synthesis and structures of copper coordination polymers incorporating a bis-pyridyl-bis-amine ligand

A new bis-pyridyl-bis-amine ligand, namely N,Nʹ-bis(pyridin-3-ylmethyl)-1,2-ethylenediamine (bpmen), has assembled with Cu(II) salts of sulfate and nitrate to yield corresponding Cu coordination polymers {[Cu(H2bpmen)(H2O)4](SO4)2∙2H2O}n (1) and {[Cu(bpmen)](NO3)}n (2). Compound 1 has a cationic simple coordination chain structure, where the Cu(II) center has an octahedral geometry consisting of N2O4 donors and the protonated H2bpmen2+ ligand suits a bis-monodentate coordination mode with the –CH2NHCH2CH2NHCH2- backbone in a GGTGG conformation, where G and T devoted as gauche and trans conformations, respectively. Numerous hydrogen-bonding interactions make 1 to form a three-dimensional neutral supramolecular hydrogen-bonded net. For synthesizing 2, the starting Cu(II) cations are reduced to Cu(I) cations by bpmen ligands during the assembly process. Compound 2 has a cationic double-stranded zigzag chain structure, where the Cu(I) center has a tetrahedral geometry composing of N4 donors and the bpmen ligand adopts a chelating-bridging mode with the –CH2NHCH2CH2NHCH2- backbone in a TGGTT conformation. A variety of framework … nitrate hydrogen-bonding interactions results in a two-dimensional neutral supramolecular hydrogen-bonded layer. Thermogravimetric (TG) analysis showed that the coordination frameworks of 1 and 2 after releasing lattice and coordination water molecules are thermally stable up to approaching 252 and 210 ​°C, respectively. Solid-state emission spectra of 1 and 2 exhibited no and weak luminescence emission bands, respectively, upon irradiation.

Crystal structure, DFT-study and NLO properties of the novel copper(I) nitrate π,σ-coordination compound based on 1-allyl-3-norbornan-thiourea

This work is directed toward the synthesis, structural characterization and NLO properties investigation of the novel copper(I) nitrate π,σ-coordination compound [Cu(Anor)(CH3CN)](NO3) (1) based on 1-allyl-3-norbornan-thiourea (Anor). In the crystal structure of both Anor and 1, the organic part is disordered because of the superposition of (2S)-exo and (2R)-exo enantiomers. The Anor ligand in 1 acts as a bridging ligand, connecting Cu(I) ions into the cationic coordination polymer {[Cu(Anor)(CH3CN)]+}n through η2-allyl group and the thiourea S atom. The H atoms of the –NH– groups in the Anor structure participate in NH···S hydrogen bonding and form an infinite hydrogen-bonded layer, while the same ligand groups in the organometallic chain of 1 are linked by bifurcated NH···O bonds to the two O atoms of the same NO3– anion. The second-order nonlinear optical properties for Anor and coordination compound 1 were studied at 1064 nm generated by a nanosecond pulsed Nd:YAG laser. The corresponding values of the average first-order NLO hyperpolarizabilities calculated by the DFT method and the B3LYP functional for the Anor ligand molecule and the cation fragment confirm the experimentally determined much higher second-harmonic generation efficiency for compound 1.

High-Pressure Polymorphs Nucleated and Stabilized by Rational Doping under Ambient Conditions.

High-pressure polymorphs can be obtained and stabilized at ambient pressure by utilizing dopants with more voluminous molecules, inducing internal strain in the structures. This effect has been confirmed for doped resorcinol and imidazole derivatives by nucleating and stabilizing their high-pressure phases under ambient conditions. The dopant molecular volume and concentration, as well as the bulk modulus of the polymorph in the binary system, are related to the stability region in the single-component phase diagram. High-pressure isothermal and isochoric recrystallizations yielded pure single crystals of resorcinol ε above 0.20 GPa and a new polymorph ζ above 0.70 GPa. These recrystallizations of pure resorcinol revealed within 1 GPa of the p–T phase diagram the boundaries and the stability regions of four resorcinol polymorphs α, β, ε, and ζ, contrary to the compression experiments on ambient-pressure polymorphs α and β, when the high-pressure phases were hidden behind the wide hysteresis extending to nearly 5 GPa. The hysteresis, originating from the H-bonding networks, hinders the formation of polymorphs ε and ζ when polymorphs α and β are compressed without melting or dissolving the crystals. Polymorph ζ is the only known resorcinol structure built of hydrogen-bonded layers.

Polymorphs of phenazine hexacyanoferrate(II) hydrate: supramolecular isomerism in a 2D hydrogen-bonded network.

The crystal structures of two polymorphs of a phenazine hexacyanoferrate(II) salt/cocrystal, with the formula (Hphen)3[H2Fe(CN)6][H3Fe(CN)6]·2(phen)·2H2O, are reported. The polymorphs are comprised of (Hphen)2[H2Fe(CN)6] trimers and (Hphen)[(phen)2(H2O)2][H3Fe(CN)6] hexamers connected into two-dimensional (2D) hydrogen-bonded networks through strong hydrogen bonds between the [H2Fe(CN)6]2- and [H3Fe(CN)6]- anions. The layers are further connected by hydrogen bonds, as well as through π-π stacking of phenazine moieties. Aside from the identical 2D hydrogen-bonded networks, the two polymorphs share phenazine stacks comprising both protonated and neutral phenazine molecules. On the other hand, the polymorphs differ in the conformation, placement and orientation of the hydrogen-bonded trimers and hexamers within the hydrogen-bonded networks, which leads to different packing of the hydrogen-bonded layers, as well as to different hydrogen bonding between the layers. Thus, aside from an exceptional number of symmetry-independent units (nine in total), these two polymorphs show how robust structural motifs, such as charge-assisted hydrogen bonding or π-stacking, allow for different arrangements of the supramolecular units, resulting in polymorphism.

Di-μ-benzoato-di-μ-ethano-lato-tetra-kis-[μ3-5-(hy-droxy-meth-yl)-2-methyl-4-(oxidometh-yl)pyridin-1-ium-3-olato]tetra-kis-[μ3-5-(hy-droxy-meth-yl)-2-methyl-4-(oxidometh-yl)pyridin-3-olato]di-μ3-oxido-hepta-manganese(II,III) ethanol octa-solvate.

Our work in the area of synthesis of polynuclear manganese complexes and their magnetic properties led to the synthesis and crystallization of the title compound, [Mn7(C8H9NO3)4(C8H10NO3)4(C2H5O)2(C7H5O2)2O2]·8C2H5OH. Herein, we report the molecular and crystal structure of the title compound, which was synthesized by the reaction of Mn(C6H5COO)2 with pyridoxine (PNH2, C8H11NO3) followed by the addition of tetra-methyl-ammonium hydroxide (TMAOH). The core of this centrosymmetric complex is a cage-like structure consisting of six MnIII ions and one MnII ion bound together through Mn-O bonds. The compound crystallizes in hydrogen-bonded layers formed by O-H⋯N hydrogen bonds involving the aromatic amine group of the ligand PN2- with the neighboring O atoms from the PNH- ligand. The crystal structure has large voids present in which highly disordered solvent mol-ecules (ethanol) sit. A solvent mask was calculated and 181 electrons were found in a volume of 843 Å3 in one void per triclinic unit cell. This is consistent with the presence of seven ethanol mol-ecules per formula unit, which accounts for 182 electrons per unit cell. Additionally, one ethanol mol-ecule was found to be ordered in the crystal.

Layer-by-Layer Assembled Hydrogen-Bonded Multilayer Poly(2-oxazoline) Membranes for Aqueous Separations

Preparation of multilayer films using the layer-by-layer (LbL) technique via hydrogen bonding has recently gained increasing research interest and has potential in diverse areas of research, especially in the biomedical field. However, the scope of these hydrogen-bonded multilayer films in separation science is quasi-unexplored. In this work, ultrathin multilayer membranes were prepared by the LbL deposition of tannic acid (TA) and poly(2-alkyl-2-oxazoline)s via hydrogen-bonding (HB) and hydrophobic interactions. The potential of these membranes in aqueous filtrations was demonstrated as they show high retention (>95%) for both positively (malachite green oxalate) (MGO) and negatively charged (Rose Bengal) (RB) dyes and even 95% retention for the much smaller and neutral micropollutant bisphenol A (BPA) (228 g/mol). Nanofiltration (NF) performances of three variants of poly(2-alkyl-2-oxazoline), namely, poly(2-methyl-2-oxazoline) (PMEOx), poly(2-ethyl-2-oxazoline) (PEtOx), and poly(2-n-propyl-2-oxazoline) (PPropOx), were compared revealing an increase in retention and decrease in permeance with increasing hydrophobicity of the poly(2-alkyl-2-oxazoline)s. Even though the reported HB multilayer membranes appear to be promising candidates for aqueous filtrations, their permeance is currently still about an order of magnitude too low for real-life applications due to the formation of rather dense hydrogen-bonded layers.

Supramolecular architectures and photoluminescent properties of triethanolammonium 4-nitrobenzoate salt and its Ni(II) complexes

Single crystals of new organic salt (HTEA)(4NB) (1) and its different types of Ni(II) complexes obtained from the same system NiCl2-compound 1 under various experimental conditions: [Ni(4NB)(TEA)(H2O)](4NB) (2), [Ni(4NB)(TEA)(H2O)](4NB)∙H2O (3), [Ni(TEA)2](4NB)2 (4) and Ni(BIC)2 (5), where TEA = triethanolammine, 4NB = 4-nitrobenzoate and BIC = N,N-bis(2-hydroxyethyl) glycinate, were successfully synthesized and structural characterized by FTIR spectroscopy and single crystal X-ray analysis. All new compounds represent supramolecular systems assembled by combining two or three organizing forces: metal-coordination (2–5), hydrogen bonds (1–5) and π-π stacking interactions (1–4). In compounds 2 and 3 the Ni(II) atom has an identical NO5 environment, while in complex 4 and 5 the metal centres have a N2O4 coordination core. The ionic coordination complexes 2–4 are arranged into 2D hydrogen-bonding layers and further assembled via π-π stacking interactions in supramolecular 3D network structures, while complex molecules of 5 are organized into a hydrogen-bonded network. This study emphasizes the first structurally characterized binary glycinate Ni(II) complex obtained from NiCl2·6H2O-(HTEA)(4NB) system. Comparative solid-state photoluminescent study of four Ni(II) coordination compounds and initial organic salt reveals a correlation between crystal structure/packing and luminescent properties.