Showing papers on "Hydrogen bond published in 2022"

Design Rules of Hydrogen-Bonded Organic Frameworks with High Chemical and Thermal Stabilities.

Abstract: Hydrogen-bonded organic frameworks (HOFs), self-assembled from strategically pre-designed molecular tectons with complementary hydrogen-bonding patterns, are rapidly evolving into a novel and important class of porous materials. In addition to their common features shared with other functionalized porous materials constructed from modular building blocks, the intrinsically flexible and reversible H-bonding connections endow HOFs with straightforward purification procedures, high crystallinity, solution processability, and recyclability. These unique advantages of HOFs have attracted considerable attention across a broad range of fields, including gas adsorption and separation, catalysis, chemical sensing, and electrical and optical materials. However, the relatively weak H-bonding interactions within HOFs can potentially limit their stability and potential use in further applications. To that end, this Perspective highlights recent advances in the development of chemically and thermally robust HOF materials and systematically discusses relevant design rules and synthesis strategies to access highly stable HOFs.

Bridging Effect of S-C Bond for Boosting Electron Transfer over Cubic Hollow CoS/g-C3N4 Heterojunction toward Photocatalytic Hydrogen Production.

Abstract: The construction of interfacial effects and chemical bonds between catalysts is one of the effective strategies to facilitate photogenerated electron transfer. A novel hollow cubic CoS is derived from Co-ZIF-9 and the S-C bond is successfully constructed between CoS and g-C3N4. The S-C bond acts as a bridge for electronic transmission, allowing the rapid transmission of photoelectron to hydrogen evolution active site in CoS. In addition, the results of electrochemical impedance spectroscopy and time-resolved photoluminescence spectroscopy show that the S-C bond acts as a bridge to quickly transfer photogenerated carriers in the composite material, and achieves the effect of high-efficiency hydrogen evolution. The hydrogen production of SgZ-45 reaches 9545 μmol·g-1 in 5 h, which is 53 and 12 times that of g-C3N4 and ZIF-9, respectively. The intrinsic mechanism of photoelectron transfer through S-C bonds can be further confirmed by density functional theory (DFT) calculations. This work provides new insights for building a chemical bond electron transfer bridge between MOF derivatives and nonmetallic photocatalytic materials.

Reactivity, stability, and thermodynamics of para-methylpyridinium-based ionic liquids: Insight from DFT, NCI, and QTAIM

Abstract: Ionic liquids (ILs) have lately piqued scientific attention due to their potential applications in green transition technologies such as catalysis, electrochemistry, and photovoltaic. The investigation of structural stability, reactivity, topological analysis, and thermodynamics of 4-methylpridine (4-picoline) based ILs is carried out using an advanced computational electronic structure theory technique based on first principle density functional theory (DFT). The ILs were modeled based on the interaction of 4-methylpridine (4-picoline) ion (cation) with borate, nitrate, phosphate, carbonate, and sulfate anions which have been chemically symbolized respectively as follows: [PMHP]+[HBO3]−, [PMHP]+[HNO3]−, [PMPH]+[HPO3]−, [PHMP]+[HCO3]−, and [PHMPM]+[HSO4]−. The energy difference between HOMO - LUMO of the studied compounds were found to show a general decreasing trend in the order: [PMHP][H2BO3] > [PMHP][NO3]> [PMPH][H2PO3]> [PHMP][HCO3]> [PHMPM][HSO4] with the borate ([PMHP][H2BO3]) and sulfate ([PHMPM][HSO4]) ILs having the relatively highest and least energy gap of 6.30 and 4.14 eV respectively. Strong interaction energies of 329.50 kca/mol, 114.41 kcal/mol, 107.12 kcal/mol, 98.19 kcal/mol and 87.86 kcal/mol involving the bonding, anti – bonding and lone pair orbitals associated with the pair of ILs were obtained as a trend: [PMHP][HSO4] > [PMHP][HCO3] > [PMPH][H2BO3] > [PHMP][NO3] > [PHMPM][H2PO3]. The intermolecular hydrogen bond (H-bond) analysis between the cation and anions ILs pairs obtained from quantum theory of atoms-in-molecules (QTAIM) reveals strong, weak, and electrostatic bonds. [PMPH]+[HSO4]− ILs pair was observed to possess the highest binding energy of -20.06 kcal/mol in the same way energy decomposition analysis (EDA) reveals a relatively strong orbital interaction in the [PMPH][HSO4] ILs due to the increase in electrostatic interaction of the four O-atoms in the sulfate anion, the analysis of the thermodynamic results indicates that the syntheses of the ILs are exothermic and spontaneous.

Improving the texture and rheological qualities of a plant-based fishball analogue by using konjac glucomannan to enhance crosslinks with soy protein

Abstract: Global fisheries pressure generates interest in sustainable seafood production and developing plant-based seafood. This study took fishball as an example of seafood products applying konjac glucomannan (KGM) in developing plant-based fishball (PFB) analogues mimicking the texture of fishball. Increasing KGM concentration (up to 8.0%) influenced texture and rheological properties of PFB progressively, where the hardness, chewiness, and gel strength of PFB were significantly enhanced. Decreased pH value (9.38 to 7.93) and increased α-helix, β-sheet, and helix/coil ratio (1.40 to 1.70%) validated a promotion of hydrogen bonds and ordered structures by KGM. The strengthened interaction strength and hydrogen bonds formed at -OH groups of KGM and amide linkage of soy protein could be responsible for textural improvement. A more compact and regular microstructure also validated a firmer texture in PFB with higher KGM levels. Besides, KGM (3.5–8.0%) significantly decreased instantaneous compliance J 0 (101.3 × 10 −6 to 58.1 × 10 −6 Pa −1 ), indicating denser crosslinks and firmer structures. In conclusion, KGM improved the texture and viscoelasticity of PFB and had an excellent application value in developing plant-based seafood analogues. • Konjac glucomannan (KGM) combined with plant proteins serving as fishball analogue. • KGM improved the gel strength of plant-based fishball (PFB) analogue progressively. • Higher KGM addition promoted hydrogen bonds between KGM and plant proteins. • Higher KGM addition helped the formation of more compact microstructure of PFB.

Two-dimensional Organic Supramolecule via Hydrogen Bonding and π-π Stacking for Ultrahigh Capacity and Long-Life Aqueous Zinc-Organic Batteries.

Abstract: Aqueous zinc-ion batteries (ZIBs) are promising for next-generation energy storage. However, the reported electrode materials for ZIBs are facing the shortcomings including low capacity and unsatisfactory cycling stability etc. Herein, hexaazatrinaphthalene-quione (HATNQ) is reported for aqueous ZIBs. The HATNQ electrodes delivered an ultrahigh capacity (482.5 mAh g -1 at 0.2 A g -1 ) and outstanding cyclability of >10000 cycles at 5 A g -1 . The capacity sets new record for organic cathodes in aqueous ZIBs. The high performances are ascribed to the rich C=O and C=N groups that endowed HATNQ with 2D layered supramolecular structure by multiple hydrogen bonds in plane with π-π interactions out of plane, leading to enhanced charge transfer, insolubility, and rapid ion transport for fast-charge and -discharge batteries. Moreover, the 2D supramolecular structure boosted the storage of Zn 2+ /H + , particularly the storage of Zn 2+ , due to the more favorable O···Zn···N coordination in HATNQ.

Reactive azo compounds as a potential chemotherapy drugs in the treatment of malignant glioblastoma (GBM): Experimental and theoretical studies

Abstract: This research work focuses on the synthesis, spectroscopic characterization, DFT studies, and in silico molecular docking of two azo compounds; (E)-6-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-4-hydroxy-3-(phenyldiazenyl)naphthalen-2-yl hydrogen sulfite (compound A) and (E)-6-((4,6-dichloro-1,3,5-triazin-2-yl)amino)-3-((4-formylphenyl)diazenyl)-4-hydroxynaphthalen-2-yl hydrogen sulfite (compound D) to determine their application as chemotherapeutic drug for the treatment of the malignant glioblastoma multiforme (GBM). The experimental and theoretical vibrational wavenumbers of the synthesized compounds were compared and observed to be in good agreement. Density functional theory (DFT) at the B3LYP/6-311++G(d,p) level of theory was further utilized to investigate the frontier molecular orbitals, Fukui reactivity functions, excitation energies, and the natural bond orbital (NBO) analysis for the investigation of the bonding interactions of the studied compounds. The binding affinities of the studied compounds and the standard drug (temozolomide) against four different GBM proteins: 6bft, 6s79, 1Is5, and 1z2b was investigated using in silico molecular docking approach. Compound A displayed the highest relative binding affinities of -8.7 and -8.6 with 6s79 and 1Is5 proteins respectively compared to compound D with the binding affinity of -7.6. Both compounds A and D showed little to no interaction with 1z2b protein but their binding affinities with 6bft, 6s76 and 1Is5 proteins are relatively higher than those of the standard drug. Pharmacological studies also showed that both compounds exhibit good solubility in water resulting in good lipophilicity. With the obtained results, it is safe to say that the compounds and their derivatives could be considered as a potential chemotherapeutic drug for the treatment of glioblastoma or as a precursor for the synthesis of other pharmaceutical products.

Photochemical Organocatalytic Benzylation of Allylic C-H Bonds.

Abstract: We report a radical-based organocatalytic method for the direct benzylation of allylic C-H bonds. The process uses nonfunctionalized allylic substrates and readily available benzyl radical precursors and is driven by visible light. Crucial was the identification of a dithiophosphoric acid that performs two distinct catalytic roles, sequentially acting as a catalytic donor for the formation of photoactive electron donor-acceptor (EDA) complexes and then as a hydrogen atom abstractor. By mastering these orthogonal radical generation paths, the organic catalyst enables the formation of benzylic and allylic radicals, respectively, to then govern their selective coupling. The protocol was also used to design a three-component radical process, which increased the synthetic potential of the chemistry.

A versatile hydrogel network–repairing strategy achieved by the covalent-like hydrogen bond interaction

Abstract: Hydrogen bond engineering is widely exploited to impart stretchability, toughness, and self-healing capability to hydrogels. However, the enhancement effect of conventional hydrogen bonds is severely limited by their weak interaction strength. In nature, some organisms tolerate extreme conditions due to the strong hydrogen bond interactions induced by trehalose. Here, we report a trehalose network–repairing strategy achieved by the covalent-like hydrogen bonding interactions to improve the hydrogels’ mechanical properties while simultaneously enabling them to tolerate extreme environmental conditions and retain synthetic simplicity, which proves to be useful for various kinds of hydrogels. The mechanical properties of trehalose-modified hydrogels including strength, stretchability, and fracture toughness are substantially enhanced under a wide range of temperatures. After dehydration, the modified hydrogels maintain their hyperelasticity and functions, while the unmodified hydrogels collapse. This strategy provides a versatile methodology for synthesizing extremotolerant, highly stretchable, and tough hydrogels, which expand their potential applications to various conditions.

Highly Selective Separation of Benzene and Cyclohexane in a Spatially Confined Carborane Metallacage.

Abstract: Separation of light hydrocarbons (C1-C9) represents one of the "seven chemical separations to change the world". Boron clusters can potentially play an important role in chemical separation, due to their unique three-dimensional structures and their ability to promote a potentially rich array of weak noncovalent interactions. Herein, we report the rational design of metallacages with carborane functionality and cooperative dihydrogen binding sites for the highly selective capture of cyclohexane molecules. The metallacage 1, bearing the ligand 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT), can produce cyclohexane with a purity of 98.5% in a single adsorption-desorption cycle from an equimolar mixture of benzene and cyclohexane. In addition, cyclohexene molecules can be also encapsulated inside the metallacage 1. This selective encapsulation was attributed to spatial confinement effects, C-H···π interactions, and particularly dihydrogen-bond interactions. This work suggests exciting future applications of carborane cages in supramolecular chemistry for the selective adsorption and separation of alkane molecules and may open up a new research direction in host-guest chemistry.

Acylhydrazine-based reticular hydrogen bonds enable robust, tough, and dynamic supramolecular materials

Abstract: Supramolecular materials are widely recognized among the most promising candidates for future generations of sustainable plastics because of their dynamic functions. However, the weak noncovalent cross-links that endow dynamic properties usually trade off materials’ mechanical robustness. Here, we present the discovery of a simple and robust supramolecular cross-linking strategy based on acylhydrazine units, which can hierarchically cross-link the solvent-free network of poly(disulfides) by forming unique reticular hydrogen bonds, enabling the conversion of soft into stiff dynamic material. The resulting supramolecular materials exhibit increase in stiffness exceeding two to three orders of magnitude compared to those based on the hydrogen-bonding network of analogous carboxylic acids, simultaneously preserving the repairability, malleability, and recyclability of the materials. The materials also show high adhesion strength on various surfaces while allowing multiple surface attachment cycles without fatigue, illustrating a viable approach how robustness and dynamics can be merged in future material design.

Halogen hydrogen-bonded organic framework (XHOF) constructed by singlet open-shell diradical for efficient photoreduction of U(VI)

Abstract: Abstract Synthesis of framework materials possessing specific spatial structures or containing functional ligands has attracted tremendous attention. Herein, a halogen hydrogen-bonded organic framework (XHOF) is fabricated by using Cl − ions as central connection nodes to connect organic ligands, 7,7,8,8-tetraaminoquinodimethane (TAQ), by forming a Cl − ···H 3 hydrogen bond structure. Unlike metallic node-linked MOFs, covalent bond-linked COFs, and intermolecular hydrogen bond-linked HOFs, XHOFs represent a different kind of crystalline framework. The electron-withdrawing effect of Cl − combined with the electron-rich property of the organic ligand TAQ strengthens the hydrogen bonds and endows XHOF-TAQ with high stability. Due to the production of excited electrons by TAQ under light irradiation, XHOF-TAQ can efficiently catalyze the reduction of soluble U(VI) to insoluble U(IV) with a capacity of 1708 mg-U g −1 -material. This study fabricates a material for uranium immobilization for the sustainability of the environment and opens up a new direction for synthesizing crystalline framework materials.

Enhanced interfacial bonding strength of laser bonded titanium alloy/CFRTP joint via hydrogen bonds interaction

Abstract: The bonding between titanium alloy and carbon fiber reinforced thermal plastic (CFRTP) has become a favorable approach to realize lightweight fabrication in the aviation and locomotive industries. However, the metal-plastic bonded joints were generally weak. Different from the traditional interfacial bonding mechanism, the role of hydrogen bonds between functional groups at the metal-plastic interface is currently of great interest. In this work, laser joining of Ti–6Al–4V (TC4) to CFRTP was performed. To enhance the bonding strength, surface modification including micro-arc oxidation (MAO) and silane coupling agent (SCA) treatment were adopted. The results indicated that porous structure after the MAO process could increase TC4 surface roughness and promote mechanical interlocking of TC4 surface to the molten CFRTP substrate. Simultaneously, the porous structure enhanced the adsorption content of hydroxyl groups on the surface of TC4 significantly, which optimized the chemical condition of TC4 surface. Selected silane coupling agent of γ-aminopropyl triethoxysilane (KH550) could directionally introduce amino groups (-NH2) to TC4 surface, while maintaining the physical morphology of TC4 surface. Hydrogen bonds were thus induced between functional groups, which were proved by red- and blue-shift of typical functional groups wavenumber. The interfacial bonded force reached maximum value of 1813 N, which was further increased by 29.96% due to the interaction of hydrogen bonds.