Network Of Intermolecular Hydrogen Bonds Research Articles

A Nickel-Based Semiconductor Hybrid Material with Significant Dielectric Constant for Electronic Capacitors.

A novel semiconducting Ni(II)-based hybrid material with the formula (C7H12N2) NiCl4, which exhibits interesting optical and electrical properties, is reported. The crystal structure was investigated using SCXRD, whereas physical properties were studied by means of thermal analysis, Ft-Infrared, optical, and electrical measurements. Its crystal packing is formed through organic rings surrounded by inorganic [NiCl4]2- tetrahedral and stacked along the a-crystallographic axis. This arrangement is stabilized by a dense network of intermolecular hydrogen bonds. The investigated compound displayed a wide absorption range across the visible spectrum, characterized by an optical gap energy of 2.64 eV, indicating its semiconducting nature and efficient sunlight absorption capabilities across various wavelengths. Such features are of utmost importance in achieving a high energy conversion efficiency in solar cell applications. Further analyses of the thermal behavior using differential scanning calorimetry revealed a single-phase transition occurring at around 413 K, which was further confirmed through electrical measurements. A deep investigation of the electric and dielectric performances demonstrated a significant dielectric constant (ε' ∼ 104) at low frequencies and low dielectric loss at high frequencies. Thus, it highlights its exceptional dielectric potential, particularly in applications related to electronic capacitors.

Proton exchange of carbonic acid and methylamine complex accelerated by a single-water molecule via intermolecular hydrogen bonding: A theoretical investigation

A theoretical investigation of the microsolvation effect on proton exchange (PE) between carbonic acid and methylamine (CA-MTA) has been explored by quantum dynamics simulations. The structural, energy, and dynamic properties of the complexes with and without an explicit water molecule are elucidated at the molecular level. The reactions have been clarified into different types: single-step PE (SSPE) and stepwise PE (SWPE). Without the water molecule, the SSPE mechanism is hardly found but observable with a low probability of 0.2. In particular, the water molecule interacting through intermolecular hydrogen-bonded network between CA and MTA could affect PE in both SSPE and SWPE mechanisms. To our findings, the existing water molecule plays the significant role in shortening intermolecular hydrogen bonding interactions within the complex resulting in increasing the probability up to 0.92. Hence, one water molecule could provide reliable results to represent the significant activity that occurs for the proton exchangeability of the CA and MTA complex.

Process intensification in the ketalization of glycerol with acetone catalyzed by NaHSO4-NaOH catalytic system

Glycerol is one cheap byproduct in production of biodiesel, and the ketalization of glycerol is one of the most important and effective way to increase its value and improve the sustainability of biodiesel. The ketalization of glycerol with acetone is always catalyzed by acid catalyst. In this work, NaOH was added into the reaction system during the ketalization process catalyzed by NaHSO4, and it was found for the first time that this process could be intensified by NaOH significantly. The acidity of acidic catalysts would affect their catalytic performance. Increasing reaction temperature and time, molar ratio of acetone to glycerol, the dosage of NaHSO4 and molar ratio of NaOH to NaHSO4 could favor for the ketalization, but the excessive formation of water and the evaporation of acetone would retard the reaction. The addition of NaOH could destroy the intermolecular hydrogen bond network of glycerol molecules, making the hydroxyl groups bared in free state, and increase the amount of electrophilic transition state of acetone, which help to promote the transformation of glycerol to solketal significantly. With the assistance of NaOH, the conversion rate of glycerol could even reach 97.58 % without extracting water continuously from the reaction system.

Explorations on the synthesis, structure, DFT, DNA binding properties and molecular docking of tridentate Schiff base Copper (II) complexes

Copper(II) Schiff base complexes of (2-Hydroxy-benzaldehyde)-amino acid have been synthesized and characterized. The complexes' single-crystal X-ray structures were studied, and it was discovered that the 4,4-bipyridine functions as a bidentate bridging ligand connecting two Cu(II) ions. In order to assemble the complicated components into a three-dimensional chain structure and arrange the 4,4-bipyridine molecules into parallel sheets, intermolecular hydrogen bonds are essential. A robust intermolecular hydrogen bond network including water oxygen atoms strengthens the connection between water molecules and phenolate oxygen atoms from the ligand, which is produced from salicylaldehyde. The complexes' interaction with DNA was investigated by UV–Visible, fluorescence and CD spectrophotometric methods, which indicate that the complexes favourably bind to the groove in the DNA. The DNA binding affinity was confirmed by molecular docking. Additionally, DFT calculations were used to determine the stable geometry for these complexes. A thorough understanding of the interactions of these synthesized complexes was achieved through an intensive molecular docking research. These findings show that the complexes have a high affinity for DNA binding and considerable groove binding. Notably, Complex 1 showed a greater affinity for DNA than Complex 2.

Efficient production of chito-oligosaccharides through microwave-assisted hydrothermal and low-acid-mediated degradation and deacetylation of chitin

The conventional method for producing chitin oligosaccharides involves high-temperature hydrolysis in high-concentration acid. In this study, we present an alternative method using microwave-assisted hydrothermal and diluted acid (0.12 mol/L) hydrolysis. After batched reactions, the liquefaction rate of chitin can reach almost 50%, and the sugar product yield is about 27%. Furthermore, this method leads to the reduction of the average particle size of chitin by approximately 70%, a decrease in the degree of acetylation by about 35%, partial destruction of the intermolecular hydrogen bond network, and the breaking of glycosidic bonds. These changes result in the exposure of more hydroxyl groups and enzyme binding sites, which may facilitate a subsequent enzymatic treatment. The method is a feasible alternative to obtain chitin oligosaccharides with a low environmental impact and operating cost.

Breaking Consecutive Hydrogen‐Bond Network Toward High‐Rate Hydrous Organic Zinc Batteries

AbstractZinc batteries hold great potential for stationary energy storage but suffer from severe dendrite growth, corrosion, and hydrogen evolution troubles in aqueous electrolytes. Despite the impressive efficacy of non‐flammable hydrous organic electrolytes in addressing these problems, the insufficient ionic conductivity hinders the rate capability and practicability of hydrous organic Zn batteries. Here, methanol is proposed as a co‐solvent for ethylene glycol (EG)‐based hydrous organic electrolytes, where its methyl terminal group can interrupt the continuous intermolecular hydrogen bond network among EG. The new hydrous organic electrolyte exhibits a doubled ionic conductivity without sacrificing the exceptional nonflammability. As a result, the Zn anode exhibits a long‐term cycling stability over 4000 h at 0.5 mA cm−2, a high Coulombic efficiency of 99.5%, high‐rate capability up to 20 mA cm‒2, and impressive low‐temperature tolerance of ‒60 °C. The Zn||V2O5 pouch cell with the electrolyte is capable of operating under extreme operation conditions involving needling, package breakage, and even exposure to fire. This work paves an avenue toward electrolyte design for high‐rate practical Zn batteries and beyond.

Aqua-{μ-1,4-bis-[(1,4,7,10-tetra-aza-cyclo-dodecan-1-yl)meth-yl]benzene}(nitrato-κO)dicopper(II) tris-(nitrate) trihydrate.

In the title dinuclear CuII complex, [Cu2(NO3)(C24H46N8)(H2O)](NO3)3·3H2O, the two CuII mol-ecules both have a square-pyramidal geometry, but the ligands in the axial positions are different: a water mol-ecule and a nitrate ion. All nitrate ions, water mol-ecules, and N-H groups are involved in an inter-molecular hydrogen-bond network.

Characterizing the thermal phase behaviour of fipronil polymorphs

This manuscript reports the investigation of the polymorphic behaviour of fipronil using a systematic comparison of the thermochemical and structural properties of different crystal forms obtained in this study as well as those previously reported in literature. The analytical techniques employed include DSC, TGA, PXRD, SCXRD and hot stage microscopy. DSC proved particularly useful because it made it possible to differentiate between the two different crystal forms found in the as-received neat fipronil. The DSC scans revealed the presence of two polymorphs which had melting endotherms with peak maxima at ca. 196 °C and 205 °C, respectively. These polymorphs were successfully separated via sublimation and resulted in a metastable, lower melting polymorph in the sublimate and a thermodynamically stable, higher melting form in the sublimation residue. Clear evidence for the instability of the lower melting polymorph was found when the endotherms were examined under a range of heating rates. The proportion of the metastable form appeared to increase as the rate was increased, indicating that the metastable form underwent a solid–solid phase transition to the stable form at low heating rates. Recrystallization of fipronil from different solvents yielded five different forms. TGA curves revealed that all forms, except the acetone-derived one, were solvate pseudo-polymorphs that showed solvent loss between 60 and 100 °C. The acetone-derived sample was a hemihydrate that only started to show mass loss at 120 °C. SCXRD studies revealed that three of the five forms have similar structural characteristics, while the other two forms differ notably from each other and the rest of the structures. Despite these structural differences, all five forms exhibit near-identical intra- and intermolecular hydrogen bond networks.

Extreme UV Resist Exhibiting Synergism between Chemical and Physical Crosslinking Mechanisms.

Carbon-fluorine bonds in fluorinated molecules can undergo homolytic cleavage reactions when electrons are injected, and the resulting radicals combine to form network structures characterized by reduced solubility. This crosslinking chemistry suggests a new category of patterning materials that function under electron beam (e-beam) and extreme ultraviolet (EUV) lithographic conditions. Although this chemistry enables the production of 50 nm or smaller-sized features of simple fluoroalkylated polymers, it is limited by the need for relatively large amounts of irradiation energy to achieve required solubility changes. Therefore, this study was undertaken to devise a sensitivity-enhancing strategy based on a synergistic combination of radical crosslinking and hydrogen-bonding interactions between highly fluoroalkylated copolymers. An alternating copolymer was synthesized using tert-butoxystyrene and a fluoroalkylated maleimide, the former of which produces active hydrogens through catalytic acidolysis reactions. When the polymer was blended with a catalytic amount of a photoacid generator and subjected to lithographic patterning tests under e-beam and EUV irradiation, the deprotection reactions of tert-butoxy moieties proceeded at room temperature and led to a solubility decrease. We presume the small number of hydroxyl moieties produced formed an intermolecular hydrogen-bonding network, which acted synergistically with the covalent crosslinks generated by C-F bonds. When 30 nm features of copolymer thin films were fabricated by EUV lithography, sensitivity was improved by 25-34% without significant deterioration of pattern quality, especially line-edge roughness. These results demonstrate that EUV resists with improved patterning capabilities can be achieved by combining catalytic acidolysis reactions and noncatalytic crosslinking chemistry.

Natural crystalline fibers of (E)-(R)-4-thujanol: green kilogram production from a selected wild thyme. X-ray and NMR characterization of a spiral structure

(E)-(R)-4-Thujanol present in thyme essential oils is an important aromatic ingredient for food, cosmetic and pharmaceutical applications. Until now, its extraction was challenging due to its low content in classical aromatic plants such as thyme or marjoram. Although this molecule is synthetically available, there is no production on an industrial scale because of very time-consuming and expensive chemical processes. We report here for the first time a new eco-responsible method to produce (E)-(R)-4-thujanol crystals on a kilogram scale. This new milestone is based on 2 fundamental research gaps: i) the selection of a wild thyme (Thymus vulgaris) for its high content of (E)-(R)-4-thujanol and its careful harvesting in the hills of French Provence and ii) a steam distillation producing an organic aromatic oil which aggregates spontaneously due to a favorable amphipathic partition at the air-water interface. Gas chromatography revealed a composition made of (E)-(R)-4-thujanol (76%), thymol (5%), β-myrcene (2,8%) and other minor monoterpenes. The white aggregate submitted to a cycle of sublimation/crystallization, led to accumulating translucent fibers made of (E)-(R)-4-thujanol (98%). X-ray diffraction unambiguously demonstrated that crystals of (E)-(R)-4-thujanol form a trimer (monoclinic asymmetric (C2)) unit composed of three independent (E)-(R)-4-thujanol molecules. The trimer is further organized into a chiral P-type supramolecular helix of trimers through a network of intermolecular hydrogen bonds. This study is based on the cheap, easy and eco-responsible kilogram production of (E)-(R)-4-thujanol crystals may open up new opportunities for the flavor, fragrance and pharmaceutical industries. Fibers of (E)-(R)-4-thujanol may also have applications as bio-active fibrous assemblies.

A disposable paper-based microfluidic electrochemical cell equipped with graphite-supported gold nanoparticles modified electrode for gallic acid determination

The combination of µPAD with electrochemical transducers has gained advantages of miniaturization, high sensitivity, selectivity, simplicity of instrumentation, portability, rapid analysis, and so on. In this work, the development of a 3D paper-based microfluidic electrochemical device (3D-ePAD) for the determination of gallic acid (GA) was presented. The 3D-ePAD is composed of three electrodes (working, reference, and counter electrodes) in which the hydrophilic area of the working electrode was manually screen-printed and modified with graphite-supported AuNPs(AuNPs/C) ink. The evaluation of the electrochemical oxidation process of GA at modified and unmodified electrodes at 3D-ePAD indicated the improvement of anodic current responses at the AuNPs/C modified electrode which can be attributed to the intermolecular hydrogen-bonded network between AuNPs and GA. For quantitative determination of GA, the amperometric experiments were investigated under optimal conditions in which a linear relationship between the GA concentration and the recorded current was achieved. The sensor displays a good linear range of 1.0 to 100.0 μM and 0.1 to 2.0 mM for GA determination. The limit of detection (LOD) of 0.89 μM was achieved for GA by 3D-ePAD. Conclusively, the 3D-ePAD was performed successfully for the determination of GA in tea samples.

Antioxidant and Biocompatible CO2‐Based Biocomposites from Vegetable Wastes for Active Food Packaging

AbstractIn this study, an innovative and scalable strategy is developed to valorize vegetable wastes as valuable and cost‐effective natural antioxidant resources in the development of CO2‐based biocomposites. The dried vegetable stems (parsley and spinach) are firstly micronized and then incorporated into a CO2‐derived poly(propylene carbonate) (PPC) polymer matrix by hot compression molding technique. The vegetable waste microparticles are found to be homogenously dispersed within the PPC matrix. Due to the establishment of a strong intermolecular hydrogen bond network between PPC and vegetable waste microparticles, the obtained biocomposites exhibit improved mechanical properties compared to pure PPC, comparable to these of common plastics use for packaging materials. The water barrier properties of the developed biocomposites are also promising for packaging applications. Additionally, the developed biocomposites are found to be biocompatible and show effective antioxidant scavenging activity against 2,2′‐azinobis(3‐ethylbenzothiazoline‐6‐sulfonic acid) radical cation (ABTS•+). Therefore, these antioxidant and biocompatible biocomposites deriving from CO2 greenhouse gas and industrial agro‐food wastes are of great interest for active food packaging applications.

Supramolecular Helical Assemblies of Dirhodium(II) Paddlewheels with 1,4-Diazabicyclo[2.2.2]octane: A Remarkable Substituent Effect on the Helical Sense Preference and Amplification of the Helical Handedness Excess of Metallo-Supramolecular Helical Polymers.

We report unique coordination-driven supramolecular helical assemblies of a series of dirhodium(II) tetracarboxylate paddlewheels bearing chiral phenyl- or methyl-substituted amide-bound m-terphenyl residues with triethylene glycol monomethyl ether (TEG) or n-dodecyl tails through a 1:1 complexation with 1,4-diazabicyclo[2.2.2]octane (DABCO). The chiral dirhodium complexes with DABCO in CHCl3/n-hexane (1:1) form one-handed helical coordination polymers with a controlled propeller chirality at the m-terphenyl groups, which are stabilized by intermolecular hydrogen-bonding networks between the adjacent amide groups at the periphery mainly via a cooperative nucleation-elongation mechanism as supported by circular dichroism (CD), vibrational CD, and variable-temperature (VT) absorption and CD analyses. The VT visible-absorption titrations revealed the temperature-dependent changes in the degree of polymerization. The columnar supramolecular helical structures were elucidated by X-ray diffraction and atomic force microscopy. The helix sense of the homopolymer carrying the bulky phenyl and n-dodecyl substituents is opposite those of other chiral homopolymers despite having the same absolute configuration at the pendants. A remarkably strong "sergeants and soldiers" (S&S) effect was observed in most of the chiral/achiral copolymers, while the copolymers of the bulky chiral phenyl-substituted dirhodium complexes with n-dodecyl chains displayed an "abnormal" S&S effect accompanied by an inversion of the helix sense, which could be switched to a "normal" S&S effect by changing the solvent composition. A nonracemic dirhodium complex of 20% enantiomeric excess bearing the less bulky chiral methyl substituents with n-dodecyl chains assembled with DABCO to form an almost one-handed helix (the "majority rule" (MR) effect), whereas the three other nonracemic copolymers showed a weak MR effect.

Structural and biochemical analysis of the PTPN4 PDZ domain bound to the C-terminal tail of the human papillomavirus E6 oncoprotein.

High-risk genotypes of human papillomaviruses (HPVs) are directly implicated in various abnormalities associated with cellular hyperproliferation, including cervical cancer. E6 is one of two oncoproteins encoded in the HPV genome, which recruits diverse PSD-95/Dlg/ZO-1 (PDZ) domain-containing human proteins through its C-terminal PDZ-binding motif (PBM) to be degraded by means of the proteasome pathway. Among the three PDZ domain-containing protein tyrosine phosphatases, protein tyrosine phosphatase non-receptor type 3 (PTPN3) and PTPN13 were identified to be recognized by HPV E6 in a PBM-dependent manner. However, whether HPV E6 associates with PTPN4, which also has a PDZ domain and functions as an apoptosis regulator, remains undetermined. Herein, we present structural and biochemical evidence demonstrating the direct interaction between the PBM of HPV16 E6 and the PDZ domain of human PTPN4 for the first time. X-ray crystallographic structure determination and binding measurements using isothermal titration calorimetry demonstrated that hydrophobic interactions in which Leu158 of HPV16 E6 plays a key role and a network of intermolecular hydrogen bonds sustain the complex formation between PTPN4 PDZ and the PBM of HPV16 E6. In addition, it was verified that the corresponding motifs from several other high-risk HPV genotypes, including HPV18, HPV31, HPV33, and HPV45, bind to PTPN4 PDZ with comparable affinities, suggesting that PTPN4 is a common target of various pathogenic HPV genotypes.

Bis(2,6-diisopropylphenyl) tellurone: a well-defined monomeric diorganotellurone without cocrystallized solvents and without stabilizing intramolecular contacts.

Only two crystal structures of diorganotellurones have been reported to date, both of which contain cocrystallized solvents and one of which is stabilized by intramolecular Te-N secondary bonding interactions. This work describes the crystal structure of bis(2,6-diisopropylphenyl) tellurone, (C12H17)2TeO2 or C24H34O2Te, the first well-defined diorganotellurone without cocrystallized solvents and without stabilizing intramolecular contacts. The molecule has crystallographic twofold symmetry, with half the molecule as the asymmetric unit. The molecular structure is compared to previously reported tellurones and those computed at the density functional theory DFT/B3PW91 level. The molecules form two-dimensional layers as a result of a weak intermolecular hydrogen-bonding network. The layers are then stacked in an antiparallel manner to form the crystal packing structure. The Hirshfeld surface analysis was employed to visualize and quantify the intermolecular contacts in the molecular crystal structure, and the contribution of O...H and H...H interactions was found to be the dominating factor.

Polymeric coordination complex of lithium(I) with aqua and cyanurate ligands.

The polymeric title complex, poly[hexa-μ-aqua-diaquatetra-μ-cyanurato-tetralithium] [Li4(C3H2N3O3)4(H2O)7] n , synthesized at room temperature from an aqueous solution of lithium hydroxide and cyanuric chloride, crystallizes in the triclinic space group P . There are two distinct Li+ cations in the asymmetric unit, one of which, Li1, has distorted trigonal-bipyramidal geometry and is coordinated via oxygen to two cyanurate anions occupying equatorial positions, and three water mol-ecules, two in the axial positions and the third in an equatorial position. One of the axial water ligands and the equatorial water ligand are involved in bridging to a crystallographically equivalent Li1 cation. A centre of inversion lies between the two Li1 cations and the Li1⋯Li1 distance is 3.037 (5) Å. The remaining axial water ligand bridges to the second Li cation, Li2, which is disordered over two crystallographic sites with approximately equal occupancy, and has an Li1⋯Li2 distance of 3.438 (7) Å. The terminal Li2 cation is coordinated to three water mol-ecules and an oxygen atom from a cyanuric anion and has a distorted tetra-hedral geometry. A three-dimensional network of inter-molecular hydrogen bonds involving N-H⋯O, O-H⋯O and O-H⋯N inter-actions serves to hold the structure together. The title compound was further characterized using IR and UV-vis spectroscopy and TG-DTA analysis.

A phosphorated spirobi[thioxanthene] host matrix enables high-efficiency simple white thermally activated delayed fluorescence diodes

Host matrix is crucial for optimizing exciton allocation in all Thermally activated delayed fluorescence (TADF) white Organic light-emitting diodes (OLED). However, only few spiro hosts are competent since unbalanced steric and electronic effects. Herein, a new spiro core 9,9′-spirobi[thioxanthene] (ST) based host STDPO is reported, whose two peripheral diphenylphosphine oxide (DPPO) groups are incorporated to construct tridimensional steric hindrance and Intermolecular hydrogen bond (IHB) network. As consequence, STDPO achieves the high enough first triplet (T1) energy level of 2.93 eV and favorable electron mobility (µe) by the level of 10−5 cm2 V−1 s−1. Simultaneously, the well-modulated intermolecular interactions in STDPO matrix give rise to the synergistic effect of blue and yellow TADF dopants in exciton utilization. The increased rate constants and efficiencies of radiative transitions and reduced nonradiative rate constants render a photoluminescence quantum yield as high as 90% and 100% exciton utilization efficiency of dually doped white TADF film. STDPO further endowed its single-emissive-layer TADF WOLEDs with the record ηPE of 71.8 lm W−1 achieved by spiro hosts.

Intermolecular hydrogen bond ruptured by graphite with different lamellar number.

Intermolecular hydrogen bonds are formed through the electrostatic attraction between the hydrogen nucleus on a strong polar bond and high electronegative atom with an unshared pair of electrons and a partial negative charge. It affects the physical and chemical properties of substances. Based on this, we presented a physical method to modulate intermolecular hydrogen bonds for not changing the physical–chemical properties of materials. The graphite and graphene are added into the glycerol, respectively, by being used as a viscosity reducer in this paper. The samples are characterized by Raman and 1H-nuclear magnetic resonance. Results show that intermolecular hydrogen bonds are adjusted by graphite or graphene. The rheology of glycerol is reduced to varying degrees. Transmission electron microscopes and computer simulation show that the spatial limiting action of graphite or graphene is the main cause of breaking the intermolecular hydrogen bond network structure. We hope this work reveals the potential interplay between nanomaterials and hydroxyl liquids, which will contribute to the field of solid–liquid coupling lubrication.

Monoazo (Monohydrazone) pigments based on benzimidazolones

Abstract A series of azo pigments containing the benzimidazolone ring were introduced in the mid to late twentieth century as high-performance organic pigments in the yellow, orange, red, and brown shade areas. The structures of the commercial benzimidazolone azo pigments are derived from either the monoazoacetoacetanilide or monoazonaphtharylamide classical azo pigments systems and exist in the ketohydrazone tautomeric forms. The high-performance properties of the pigments have been attributed to a network of intermolecular hydrogen bonds involving the benzimidazolone group, and efficient molecular packing, as demonstrated by X-ray crystal structure determinations. The manufacturing processes leading to the pigments involve traditional diazotization and azo coupling reaction procedures, although they require special conditioning aftertreatments to optimize their performance. Although benzimidazolone azo pigments were initially developed for the coloration of plastics, they have probably had a greater impact on the paint industry. The application properties of the benzimidazolone azo pigments are discussed for individual products.

Performances of novel poly(diaryloxyphosphazene) based heat shielding materials with various fibrous reinforcements

AbstractElastomeric heat shielding materials (EHSMs) are necessary to protect combustion chambers of solid rocket motors during their working. Poly(diaryloxyphosphazene) (PDPP) elastomers own inherent thermal stability and flame retardancy because the backbone of alternating phosphorus and nitrogen atoms can be a novel promising polymer matrix toward EHSMs. The present study deals with the development of a novel PDPP based EHSMs with several different fibrous reinforcements, including Kevlar, polyimide, and carbon short fibers. It is found that PDPP/Kevlar composites show outstanding tensile strength and ablation resistance because of their strong interfacial bonding between matrix and fibers which benefits from the possible network of intermolecular hydrogen bonds. PDPP/carbon composites produce a compact charred layer due to their high char yields of carbon fibers. These results improve the understanding of the role of polyphosphazenes with different kinds of fibers on ablation mechanisms, which enable the possibility to exploit intrinsic properties of polyphosphazenes.