Hydrogen-bonded Network Structure Research Articles

Raman Spectrum of the Li2SO4-MgSO4-H2O System: Excess Spectrum and Hydration Shell Spectrum.

Lithium, as a green energy metal used to promote world development, is an important raw material for lithium-ion, lithium-air, and lithium-sulfur batteries. It is challenging to directly extract lithium resources from brine with a high Mg/Li mass ratio. The microstructure study of salt solutions provides an important theoretical basis for the separation of lithium and magnesium. The changes in the hydrogen bond network structure and ion association of the Li2SO4 aqueous solution and Li2SO4-MgSO4-H2O mixed aqueous solution were studied by Raman spectroscopy. The SO42- fully symmetric stretching vibration peak at 940~1020 cm-1 and the O-H stretching vibration peak at 2800~3800 cm-1 of the Li2SO4 aqueous solution at room temperature were studied by Raman spectroscopy and excess spectroscopy. According to the peak of the O-H stretching vibration spectrum, with an increase in the mass fraction of the Li2SO4 solution, the proportion of DAA-type and DDAA-type hydrogen bonds at low wavenumbers decreases gradually, while the proportion of DA-type hydrogen bonds at 3300 cm-1 increases. When the mass fraction is greater than 6.00%, this proportion increases sharply. Although the spectra of hydrated water molecules and bulk water molecules are different, the spectra of the two water molecules seriously overlap. The spectrum of the anion hydration shell in a solution can be extracted via spectrum division. By analyzing the spectra of these hydration shells, the interaction between the solute and water molecules, the structure of the hydration shell and the number of water molecules are obtained. For the same ionic strength solution, different cationic salts have different hydration numbers of anions, indicating that there is a strong interaction between ions in a strong electrolytic solution, which will lead to ion aggregation and the formation of ion pairs. When the concentration of salt solution increases, the hydration number decreases rapidly, indicating that the degree of ion aggregation increases with increasing concentration.

Unravelling hydrogen bond network in methanol-propanol mixtures via molecular dynamics simulation and experimental techniques

ABSTRACT Hydrogen-bonded networks in 1-propanol-methanol binary mixture are studied using molecular dynamics simulation along with experimental techniques (FTIR, dielectric spectroscopy and refractive index measurements) for the entire concentration range. The structure of hydrogen-bonded networks is studied through radial distribution function, hydrogen bond statistics and graph theoretical analysis from molecular dynamics. It is observed that the probability of hydrogen bonding is maximum in methanol molecules followed by hydrogen bonding between methanol and 1-propanol molecules and minimum among 1-propanol molecules, as the concentration changes. The graph theory results show the formation of linear chain hydrogen bond networks, with no caged structures, which is validated from the experimental results. Further, the deconvolution of the FTIR OH peak suggests the presence of linear multimers in all concentrations of the binary system. Average degree of the hydrogen-bonded networks from graph theory indicates a complex networks among pure alcohols and dimers between methanol and 1-propanol in their binary mixtures at all concentrations. The negative values of excess permittivity indicate that the components of the mixture interact in a manner such that the net dipole polarisation decreases.

Rapid Kinetic Interactions of Sugar and Sugar Alcohol with Sweet Taste Receptors on Live Cells Using Stopped-Flow Spectroscopy.

The subjective measurement of the dynamic perception of sweetness is a problem in food science. Herein, the rapid interactions of sugars and sugar alcohols with sweet taste receptors on living cells on a millisecond timescale were studied via stopped-flow fluorescence spectroscopy. According to the rapid-kinetic parameters, sweeteners were divided into two groups. Sweeteners in group I disrupted the hydrogen bond network structure of water, and the apparent rate constant (kobs) was in the range of 0.45-0.6 s-1. Sweeteners in group II promoted the hydrogen bond formation of water, and the kobs was mostly in the range of 0.6-0.75 s-1. For most sweeteners, the kobs of cell responses was negatively correlated with the apparent specific volume of sweeteners. The differences in the cellular responses may be attributed to the disturbance in the water structure. Experimental results showed that the kinetic parameters of sweet cell responses reflected the dynamic perception of sweetness. Rapid kinetics, solution thermodynamic analysis, and water structure analysis enriched the physicochemical study of the sweetness mechanism and can be used to objectively evaluate the dynamic perception of sweetness.

Tailoring the interfacial interaction of collagen fiber/waterborne polyurethane composite via plant polyphenol for mechanically robust and breathable wearable substrate

Collagen fiber-waterborne polyurethane composites possess great potential applications in flexible wearable devices owing to their excellent biocompatibility, flexibility, and biodegradability. However, the weak interfacial interactions which result in poor mechanical strength and breathability, have significantly hindered their practical application. Herein, high-performance collagen fiber-based wearable substrates prepares by constructing a hydrogen-bonded cross-linked network structure using bayberry tannin, a natural plant polyphenol, as a coupling bridge to bind collagen fibers and waterborne polyurethane (WPU). The dynamic rupture and reformation of sacrificial hydrogen bonds on the molecular scale effectively dissipate energy under mechanical stress, endowing these composites with remarkable toughness and ultrahigh water vapor permeability (WVP). The resultant composite’s tensile strength and WVP are 100% and 60 times higher than WPU, respectively. Additionally, this cost-effective strategy enables easy large-scale composite production. This method guides the development of high-performance, multifunctional collagen fiber-based wearable composites while advancing the tannery solid waste circular economy.

Ultralow Coefficient of Thermal Expansion and a High Colorless Transparent Polyimide Film Realized Through a Reinforced Hydrogen-Bond Network by In Situ Polymerization of Aromatic Polyamide in Colorless Polyimide.

Colorless polyimides (CPIs) are a key substrate material for flexible organic light-emitting diode (OLED) displays and have attracted worldwide attention. Here, in this paper, the dispersion and interfacial interaction of aromatic polyamide (PA) in CPI (synthesized from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 2,2'-bis(trifluoromethyl)benzidine (TFMB)) were significantly improved by in situ polymerization, and colorless transparent macromolecular polyimide composites (CPI-PAx) were successfully prepared by PA and CPI. By adjusting the ratio of PA to CPI, a high-performance engineering plastic with excellent film-forming properties was obtained. Molecular simulations confirmed the uniform distribution of PA in CPI and its interaction in polymers. In CPI-PAx, the CPI was locked by the PA chain, and numerous molecular chains were mutually entangled to form a hydrogen-bond network structure. Due to the strong interaction between the chains imparted by the hydrogen bonds of the PA, they do not slide under external forces and heating. In addition, the additive PA has excellent dimensional stability, thermal, and mechanical properties, and CPI has outstanding optical properties, so the synthesized CPI-PAx combines the comprehensive properties of PA and CPI. The CPI-PAx has excellent thermal and mechanical properties, with a thermal decomposition temperature of 499 °C, a glass transition temperature of 385 °C, a coefficient of thermal expansion of 0.8 ppm K-1, a tensile strength of 50.9 MPa, and an elastic modulus of 3.9 GPa. Particularly, CPI-PAx has a 90% transmittance in the visible region. These data prove that the strategy of combining PA and CPI by in situ polymerization is an effective method to circumvent the bottleneck of CPI in the current flexible window application, and this design strategy is universal.

Deep eutectic solvents with N–H hydrogen bond network structure for highly efficient ammonia capture

The separation and recovery of ammonia (NH3) has been of long concern, since NH3 is not only a hazardous substance in the environment but also a critical chemical raw material. The current study developed and synthesized a series of deep eutectic solvents (DESs) using dual combinations of 1,2,3-triazole (Tri) with 1,2,4-triazle (TrZ), Imidazole (ImZ) or 1H-pyrazole (PyZ) for the absorption of ammonia. The results indicate that this kind of DESs possess satisfactory physical features, high capacities for NH3 absorption, and good selectivities of NH3/CO2, NH3/O2 and NH3/N2. At temperature of 298.15 K, TrZ + Tri (1:2) has a high absorption capacity up to 0.241gNH3·gDES−1 at 102.4 kPa, while PyZ + Tri (1:2) also shows satisfactory NH3 solubility of 0.230 gNH3·gDES−1 at 101.3 kPa, which are much greater than those of ionic liquids and DESs reported previously. TrZ + Tri (1:2) is tested to be highly reversible during ten cycles of absorption–desorption. The dissolution thermodynamic parameters of NH3 in these three DESs are calculated using a RETM equation, and the absorption mechanism is further analyzed and discussed using spectroscopic characterizations. It is especially noteworthy that quantum chemistry calculations are also used to study the interactions between NH3 and the DESs from an atomic level perspective. It is believed that the DESs developed in this study have their own potentials as absorbents for the highly efficient capture of NH3.

Polyvinyl alcohol flame retardant film based on halloysite nanotubes, chitosan and phytic acid with strong mechanical and anti-ultraviolet properties

The research of additive biomass flame retardants is becoming more and more popular. In this work, amino modified halloysite nanotubes (A-HNTs), chitosan (CS) and phytic acid (PA) were introduced into polyvinyl alcohol (PVA) matrix to construct PA/A-HNT/CS/PVA organic-inorganic composite film with hydrogen bond and covalent bond cross-linking network structure. Adding PA/A-HNT/CS can remarkably improve the mechanical strength, UV resistance and thermal stability of PVA film. Compared with control PVA film, the transmittance of composite film in ultraviolet region decreases from 90 % to <15 %, and the tensile strength raises from 19.8 MPa to 31.0 MPa. The thermal decomposition temperature of the composite film increases, the weight loss rate decreases obviously, and the carbon residue can reach 26 wt% at 700 °C. The limiting oxygen index increases from 18.5 % to 32.2 %. Furthermore, the addition of this flame-retardant system can obviously reduce the combustion intensity of PVA, and its flame-retardant grade can reach V-0. It is of great significance to expand the application of PVA and the development of biomass flame retardant.

Exploration of the interaction mechanism of lignocellulosic hybrid systems based on deep eutectic solvents

The interactions of three deep eutectic solvents (DES) choline chloride-glycerol (ChCl-GLY), ChCl-lactic acid (ChCl-LA) and ChCl-urea (ChCl-U) with cellulose-hemicellulose and cellulose-lignin hybrid systems were investigated using the simulated computational approach. Aiming to simulate DES pretreatment of real lignocellulosic biomass in nature. DES pretreatment could disrupt the original hydrogen bonding network structure among the lignocellulosic components and reconstruct the new DES-lignocellulosic hydrogen bonding network structure. ChCl-U had the highest intensity of action on the hybrid systems, removing 78.3% of the hydrogen bonds between cellulose-4-O-methyl Gluconic acid xylan (cellulose-Gxyl) and 68.4% of the hydrogen bonds between cellulose-Veratrylglycerol-b-guaiacyl ether (cellulose-VG), respectively. The increase of urea content facilitated the interaction between DES and lignocellulosic blend system. Finally, the addition of appropriate water (DES:H2O = 1:5) and DES formed the new DES-water hydrogen bonding network structure more favorable for the interaction of DES with lignocellulose.

Progressive Hydrophilic Processes of the Pyrite Surface in High-Alkaline Lime Systems.

Pyrite, as a disturbing gangue mineral in the beneficiation of valuable sulfide minerals and coal resources, is usually required to be depressed for floating in flotation practice. Specifically, the depression of pyrite is achieved by causing its surface to be hydrophilic with the assistance of depressants, normally with inexpensive lime used. Accordingly, the progressive hydrophilic processes of the pyrite surface in high-alkaline lime systems were studied in detail using density functional theory (DFT) calculations in this work. The calculation results suggested that the pyrite surface is prone to hydroxylation in the high-alkaline lime system, and the hydroxylation behavior of the pyrite surface is beneficial to the adsorption of monohydroxy calcium species in thermodynamics. Adsorbed monohydroxy calcium on the hydroxylated pyrite surface can further adsorb water molecules. Meanwhile, the adsorbed water molecules form a complex hydrogen-bonding network structure with each other and with the hydroxylated pyrite surface, which makes the pyrite surface further hydrophilic. Eventually, with the adsorption of water molecules, the adsorbed calcium (Ca) cation on the hydroxylated pyrite surface will complete its coordination shell surrounded by six ligand oxygens, which leads to the formation of a hydrophilic hydrated calcium film on the pyrite surface, thus achieving the hydrophilization of pyrite.

A new perspective in understanding the processing mechanisms of traditional Chinese medicine by near-infrared spectroscopy with Aquaphotomics

The processing of traditional Chinese medicine (TCM) is a critical pharmaceutical technology that enhances the efficacy and safety of TCM. However, the underlying scientific principles of processing have remained largely unknown, hindering the development of TCM. This study examined Crataegi Fructus, which has four processed products (raw, fried, charred, and carbonized), as an example to investigate the processing mechanisms that cause differences in their clinical use. The differences between the four processed products were analyzed in terms of physical properties and chemical compositions using a metallographic microscope, scanning electron microscope, and high-performance liquid chromatography. The study also proposed a new method for investigating processing mechanisms using near-infrared spectroscopy with Aquaphotomics. The results showed that there were significant differences after processing, with a loose and porous structure formed, and the 5-hydroxymethylfurfural content increased. Additionally, raw Crataegi Fructus was found to promote an active hydrogen-bonded network, which may account for the circulation-promoting effect, while carbonized Crataegi Fructus formed a stable hydrogen-bonded network structure, thus exerting its hemostatic effect. The scientific principle of “Carbonized-processing promoting hemostatic effect” in the processing of TCM was first revealed by Aquaphotomics in this study, providing a valuable reference for future studies on the processing mechanisms of TCM.

Research on deep eutectic solvents for the construction of humidity-responsive cellulose nanocrystal composite films

Photonic crystal materials based on cellulose nanocrystals (CNC), which are environmentally responsive and green, have attracted widespread attention. To overcome the brittleness of CNC films, many researchers have explored functional additives to improve their performance. In this study, a new green deep eutectic solvents (DESs) and an amino acid-based natural deep eutectic solvents (NADESs) were introduced into CNC suspensions for the first time, and hydroxyl-rich small molecules (glycerol, sorbitol) and polymers (polyvinyl alcohol, polyethylene glycol) were coassembled with the DESs and NADESs to form three-component composite films. The CNC/G/NADESs-Arg three-component film reversibly changed color from blue to crimson as the relative humidity rose from 35 % to 100 %; additionally, the elongation at break increased to 3.05 %, and the Young's modulus decreased to 4.52 GPa. The hydrogen bond network structure provided by trace amounts of the DESs or NADESs not only improved the mechanical properties of the composite films but also increased their water absorption capacities without destroying their optical activities. This allows for the development of more stable CNC films and creates potential for biological applications in the future.

Synthesis of Carboxyl Cellulose Nanocrystals/Copper Nanohybrids to Endow Waterborne Polyurethane Film with Improved Mechanical and Antibacterial Properties

The multifunctional nanohybrid fillers have attracted widespread attention in the field of polymer nanocomposites. In this study, carboxyl cellulose nanocrystals/copper nanoparticles (TCNC/Cu NP) nanohybrids were prepared by in situ growth of copper ions on the modified carboxyl CNC, and further doped into waterborne polyurethane (WPU) via solution blending. TEM, FTIR, XRD, and UV–vis analysis were used to characterize the morphology, composition, crystallization and structure of the as-prepared nanohybrid. TCNC/Cu NP nanohybrids exhibited good dispersion and interface compatibility in WPU matrix. The nanocomposite film obtained significantly enhanced mechanical, thermal stability and scratch resistance properties, which was attributed to a hydrogen bond network structure formed in the WPU matrix. Additionally, colony count method was performed to test antibacterial properties of various films. Compared to the pure WPU film, all of nanocomposite films showed better antibacterial properties against Escherichia coli and Staphylococcus aureus. The antibacterial ratio of the WPU nanocomposite film with the addition of TCNC/Cu NP (1:1) reach 99%. Furthermore, the results of a copper ion sustained release experiment showed that the nanocomposite film had a long-term release effect, which was ascribed to the strong bonding between TCNC/Cu NP nanohybrids and WPU matrix. Thus, Cu NP was firmly embedded in the hydrogen bonding network structure formed. This work gives a new approach to prepare the antibacterial WPU film with well mechanical properties.

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.

Assisting role of water molecules in ionic recognition by 18-crown-6 ether in aqueous solutions

18-Crown-6 ether has attracted ever-increasing attention as the functional unit of biomimetic or smart nanomaterials for membrane separation, chemical sensing, and adsorption due to its outstanding ionic recognition performance. Most anomalous phenomena point to the close association between ionic recognition and the environment of aqueous solutions. However, the specific role of water molecules in ionic recognition by 18-crown-6 ether is poorly explained. In this work, we selected different single ionic species systems (K+, Na+, Li+, Mg2+, and Fe2+) and coexisting ionic systems (K+/Na+ and K+/Mg2+) to investigate the underlying mechanism of water molecules in the ionic recognition performance of 18-crown-6 ether by molecular dynamics simulation. Results demonstrated that ionic recognition followed the order of K+ > Na+ > Li+ > Fe2+ > Mg2+. Moreover, the selectivity of K+ recognition could be enhanced in the presence of Mg2+ than Na+. Detailed microstructural analyses demonstrated that the change in the hydrogen bond network structure of water molecules played a major assisting role in recognition. For K+, only the first hydration layer existed, from which water molecules can be easily removed. However, the strong electrostatic interaction between Fe2+ or Mg2+ and water molecules ensured that the orientation of water in the first hydration layer was unaffected by other hydration layers. In addition, comparing with the co-existing ion of Na+, the stronger competitiveness of Mg2+ resulted in the greater weakening of K+ hydration and lower energy requirement for water removal near the crown ether pore.

Aqueous Proton Transportation in Graphene-Based Nanochannels.

Graphene oxide (GO) has been unveiled to exhibit high proton conductivity in a humidified or aqueous environment, making it a promising candidate to construct proton conduction nanochannels. In this work, we systematically investigate how the confinement effect and surface chemistry influence the proton transportation behavior in graphene-based nanochannels via extensive ReaxFF MD simulations. Graphene (GE), graphane (GA), and hydroxygraphane (HG) sheets were employed to mimic the graphitic and functionalized region of GO and construct nanochannels with different interlayer distances. We find that confined water molecules are stratified and their orientation is influenced by the surface chemistry, thus impacting the distribution of protons. Surface chemistry makes the compression of the hydrogen-bond network induced by the confinement effect more variable. The hydrogen-bond network between GE slabs is crushed by extreme confinement and ultrafast proton transportation behavior mainly achieved via vehicle mechanism. Meanwhile, the hydrogen-bond network and solvation structure can be kept more complete with the existence of functional groups. The hydrogen bonds formed with surface functional groups impede the transportation of water molecules but allow more Grotthuss hopping of protons to different extents. Our work clarified the proton transportation mechanism in graphene-based nanochannels with different interlayer distances and surface chemistry and can guide the future design of proton conduction devices such as proton exchange membranes.

Physically and Chemically Stable Anion Exchange Membranes with Hydrogen-Bond Induced Ion Conducting Channels.

Anion exchange membranes (AEMs) with desirable properties are the crucial components for numerous energy devices such as AEM fuel cells (AEMFCs), AEM water electrolyzers (AEMWEs), etc. However, the lack of suitable AEMs severely limits the performance of devices. Here, a series of physically and chemically stable AEMs have been prepared by the reaction between the alkyl bromine terminal ether-bond-free aryl backbone and the urea group-containing crosslinker. Morphology analyses confirm that the hydrogen bonding interaction between urea groups is capable of driving the ammonium cations to aggregate and further form continuous ion-conducting channels. Therefore, the resultant AEM demonstrates remarkable OH- conductivity (59.1 mS cm-1 at 30 °C and 122.9 mS cm-1 at 90 °C) despite a moderate IEC (1.77 mmol g-1). Simultaneously, due to the adoption of ether-bond-free aryl backbone and alkylene chain-modified trimethylammonium cation, the AEM possesses excellent alkaline stability (87.3% IEC retention after soaking in 1 M NaOH for 1080 h). Moreover, the prepared AEM shows desirable mechanical properties (tensile stress &gt; 25 MPa) and dimensional stability (SR = 20.3% at 90 °C) contributed by the covalent-bond and hydrogen-bond crosslinking network structures. Moreover, the resulting AEM reaches a peak power density of 555 mW cm-2 in an alkaline H2/O2 single fuel cell at 70 °C without back pressure. This rational structural design presented here provides inspiration for the development of high-performance AEMs, which are crucial for membrane technologies.

Hydrogen bond networks enhance the safety of energetic salts azobistetrazole-1,1′-dioxy dimethylbiguanide

Weak interaction is an important force widely existing in material molecules, which may affect the structure and even properties of materials, mainly including π stacking, hydrogen bond network and van der Waals force, etc. The π-stacking and hydrogen bonding networks in energetic materials have a particularly significant impact on their safety. 1,1′-dihydroxy-azobistetrazole (H2AzTO) with abundant hydrogen bond acceptor and dimethyl biguanide (DMG) with abundant hydrogen bond donor was selected as starting materials, then a new energetic salt with strong hydrogen bond network structure, azobistetrazole-1,1′-dioxy-dimethyl biguanide (DMGAzTO), was synthesized through an acid-base neutralization reaction. The structure of DMGAzTO was characterized by FT-IR, 1H NMR, 13C NMR, EA, and SC-XRD, and the thermal stability and non-isothermal thermal decomposition reaction kinetics of DMGAzTO were studied by DSC and TGA methods. The HOF, detonation velocity, and pressure (D, P) were calculated by Born-Haber cycle and K-J empirical formula. The friction and impact sensitivity (FS and IS) of the compound were examined using a BAM sensitivity tester. Results show that the DMGAzTO salt belongs to the 1:1 type with a molecule of bound water; the peak temperature of thermal decomposition is 502 K; the thermal weight loss rate is 82%; the theoretically calculated D and P are 8217 m s−1 and 27.1 GPa, and the FS and IS are 30 J and 360 N, respectively.

Study of microwave non-thermal effects on hydrogen bonding in water by Raman spectroscopy

Microwave chemistry plays an important role in organic synthesis. It has been debatable whether or not there are microwave non-thermal effects. Through analyzing the Raman spectra of pure water under two different heating methods (oil bath and microwave), the existence of microwave non-thermal effect is verified in this paper. The findings demonstrate that temperature has a significant impact on the Raman shift of the OH stretching band, which shifts to a high wave number as temperature rises and deforms the hydrogen bond (HB) network structure. Because microwave electric fields selectively heat water molecules (polar molecules) and destroy hydrogen bond structures in water, results in microwave heating more severe destruction of fully hydrogen-bonded structure than oil bath and transforms it more quickly into the partially hydrogen-bonded and free H2O structure. Under the non-thermal effects of microwaves, hydrogen bonds that initially existed as stable tetrahedral structures are transformed into chain-like structures more rapidly. By comparing the Raman shift, it can be found that the microwave non-thermal effect can affect the hydrogen bonding in water for a long time (>1h). This study provides an experimental basis for enriching the mechanism of microwave non-thermal effects on hydrogen bonding.

Chemo-mechano-structural interplay in fully hydrated ion clusters on hexagonal boron nitride nanosheet surfaces

The theoretical understanding of the coupling relationship between ionic thermodynamics and electron kinetics in the vicinity of fluid–solid interfaces is highly important. In this study, the chemo–mechano–structural interplay of the hydrated ion cluster that governs the equilibrium state in adsorption is elucidated using all-atom model computations. Specifically, the physicochemical properties of four (sodium, chloride, hydronium, and ammonium) fully hydrated ions in bulk solution and on the surface of a hexagonal boron nitride nanosheet (hBNNS) substrate were comparatively investigated. The results suggest that the intrinsic structure and charged state of these ions are key in determining the internal structure—symmetry, water ligand alignment, and hydrogen-bonded network structure—of the hydrated ion clusters. The shape of the hydrated ion cluster has a significant impact on the mechanical behavior during inner-sphere adsorption of the ion. Furthermore, the electron kinetics of the hydrated ion–hBNNS interface are strongly dependent on the arrangement of the water ligands and water network inside the ion cluster. This study is the first to elucidate the coupled mechanism of multiple hydrated ion clusters, providing new insights into the molecular scale understanding of electrical double-layer electrode, desalination separator, and proton transport membrane systems in practical engineering.

Proton Conduction of Zn(II) Bisphosphonate Driven by the H-Bond Interaction of Water Molecules, [PO3] Groups, and NH3+

A metal phosphonate of [Zn3(HL)2(H2O)6]·3.27H2O (1) (H5L = 2-amino-1-hydroxypropane-1,1-diphosphonic acid) with a one-dimensional chain structure was synthesized. Complex 1 possesses NH3+, abundant water molecules, and a diversified hydrogen bond network structure, which contributes to achieve high proton conductivity. Proton-conduction studies indicate that complex 1 shows the highest proton conductivity of 6.38 × 10–3 S/cm at 363 K and 98% RH as well as outstanding cyclic stability for at least 18 h. Additionally, the Arrhenius activation energy (Ea) of 1 obtained at 291–363 K is 0.256 eV, suggesting that the proton conduction follows a typical Grotthuss mechanism. Analysis indicates that the prominent proton conductivity of 1 is driven by the H-bond interaction of water molecules, [PO3] groups, and NH3+.