Structure Regulation of Electric Double Layer via Hydrogen Bonding Effect to Realize High-Stability Lithium-Metal Batteries

The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulating the structural chemistry of EDL via the introduction of intermolecular hydrogen bonds has been proposed(p-hydroxybenzoic acid(pHA)is selected as proof-of-concept).According to the molecular dynamics(MD)simulation and density functional theory(DFT)calculation results,the existence of hydrogen bonds realizes the anion structural rearrangement in the EDL,reduces the lowest unoccupied molecular orbital(LUMO)energy level of anions in the EDL,and the number of free solvent molecules,which promotes the formation of inorganic species-enriched SEI and eventually achieves the dendrite-free Li deposition.Based on this strategy,Li‖Cu cells can stably run over 185 cycles with an accumulated active Li loss of only 2.27 mAh cm^(-2),and the long-term cycle stability of Li‖Li cells is increased to 1200 h.In addition,the full cell pairing with the commercial LiFePO_(4)(LFP)cathodes exhibits stable cycling performance at 1C,with a capacity retention close to 90%after 200 cycles.

Halogen Bonding or Hydrogen Bonding between 2,2,6,6-Tetramethyl- piperidine-noxyl Radical and Trihalomethanes CHX3 （X=CI, Br, I）

The halogen and hydrogen bonding complexes and trihalomethanes （CHX3, X=C1, Br, I） are between 2,2,6,6-tetramethylpiperidine-noxyl simulated by computational quantum chem- istry. The molecular electrostatic potentials, geometrical parameters and interaction energy of halogen and hydrogen bonding complexes combined with natural bond orbital analysis are obtained. The results indicate that both halogen and hydrogen bonding interactions obey the order CI〈Br〈I, and hydrogen bonding is stronger than the corresponding halogen bond- ing. So, hydrogen bonding complexes should be dominant in trihalomethanes. However, it is possible that halogen bonding complex is competitive, even preponderant, in triiodomethane due to the similar interaction energy. This work might provide useful information on specific solvent effects as well as for understanding the mechanism of nitroxide radicals as a bioprobe to interact with the halogenated compounds in biological and biochemical fields.

Studies on Hydrogen Bonding Network Structures of Konjac Glucomannan

In this paper, the hydrogen bonding network models of konjac glucomannan （KGM） are predicted in the approach of molecular dynamics （MD）. These models have been proved by experiments whose results are consistent with those from simulation. The results show that the hydrogen bonding network structures of KGM are stable and the key linking points of hydrogen bonding network are at the O（6） and O（2） positions on KGM ring. Moreover, acety has significant influence on hydrogen bonding network and hydrogen bonding network structures are more stable after deacetylation.

Solvent effects on hydrogen bonding between primary alcohols and esters

The interaction by hydrogen bond formation of some primary alcohols （ l-heptanol, l-octanol and l-decanol） with esters （methyl methacrylate, ethyl methacrylate and butyl methacrylate） was investigated in non-polar solvents viz., n-heptane, CC14 and benzene by means of FTIR spectroscopy. Formation constants and free energy changes of complex formation were determined. The dependence of the equilibrium constants and free energy changes of complex formation on the alkyl chain length of both the alcohols and esters are discussed. The solvent interaction between the solute and solvent. effect on the hydrogen bond formation is discussed in terms of specific

Hydrogen Bonding-Assisted Synthesis of Silica/Oxidized Mesocarbon Microbeads Encapsulated in Amorphous Carbon as Stable Anode for Optimized/Enhanced Lithium Storage

The practical application of silica-based composites as an alternative to commercial graphite anode materials is hampered by their large volumetric expansion,poor conductivity,and low Coulombic efficiency.In this work,a novel silica/oxidized mesocarbon microbead/amorphous carbon(SiO2/O’MCMB/C)hierarchical structure in which SiO2 is sandwiched between spherical graphite and amorphous carbon shell was succes sfully fabricated through hydrogen bonding-assisted self-assembly and post-carbon coating method.The obtained three-layer hierarchical structure effectively accommodates the volumetric expansion of SiO2 and significantly enhances the electronic conductivity of composite materials.Moreover,the outer layer of amorphous carbon effectively increases the diffusion rate of lithium ions and promotes the formation of stable SEI film.As a result,the SiO2/O’MCMB/C composite exhibits superior electrochemical performance with a reversible capacity of 459.5 mA h/g in the first cycle,and the corresponding Coulombic efficiency is 62.8%.After 300 cycles,the capacity climbs to around 600 mA h/g.This synthetic route provides an efficient method for preparing SiO2 supported on graphite with excellent electrochemical performance,which is likely to promote its commercial applications.

New observations on hydrogen bonding in ice by density functional theory simulations

In this paper, we report on a series of computational simulations on hydrogen bonding in two ice phases （Ih and Ic） using CASTEP with PW91 and RPBE exchange-correlation based on ab initio density functional theory. The strength of the H-bond is correlated with intramolecular O-H stretching, and the energy splitting exists for both the H-bond and covalent O-H stretching. By analyzing the dispersion relationship of to（q）, we observe the separation of the longitudinal optic （LO） mode from transverse optic （TO） mode at the gamma point, seemingly interpreting the controversial two H-bond peaks in the vibrational spectrum of ice recorded by inelastic incoherent neutron scattering experiments. The test of ambient environment on phonon density of sates （PDOS） shows that the relaxed tetrahedral structure is the most stable structural configuration for water clusters.

SYNTHESIS AND CHARACTERIZATION OF WELL-DEFINED BLOCK COPOLYMERS CONTAINING PENDANT,SELF-COMPLEMENTARY QUADRUPLE HYDROGEN BONDING SITES

The title block copolymer (defined as PSUEA) containing pendant,self-complementary quadruple hydrogen bonding sites has been prepared successfully by three steps.First,poly(styrene-b-2-hydroxyethyl acrylate) (defined as PSHEA) was prepared by living radical polymerizing 2-hydroxyethyl acrylate (HEA) initiated by polystyrene (PSt) macro- initiator,which was prepared via nitroxide-mediated polymerization (NMP) technique.After treated by excessive 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI),...

HYDROGEN BONDING IN POLYMERIC ADSORBENTS BASED ADSORPTION AND SEPARATION

After a concise introduction of hydrogen bonding effects in solute-solute and solutesolvent bonding, the design of polymeric adsorbents based on hydrogen bonding, selectivity in adsorption through hydrogen bonding. and characterization of hydrogen bonding in adsorption and separation were reviewed with 28 references.

Hydrogen Bonding-Mediated Assembly of Perelene Dianhydride and Pyridine Derivatives

Semi-empirical AMI method was used to study 1：1 and 1：2 hydrogen bond complexes formed with perylene dianhydride and pyridine derivatives. The weak interaction energy become bigger as the number of hydrogen bonds increases. The donor groups on the host and electron-withdrawing groups on the guest molecules favor hydrogen bonding interactions, and the formation of hydrogen bonding leads to electron density flow from the host to the guest molecules. Electronic spectra of these complexes were computed using INDO/SCI method. Blue-shift of the clectronic absorption spectra for the complexes, comparing that of the host, takes place, and the first peaks for different complexes changed slightly. These are in agreement with the experimcntal results. The cause of blue-shift was discussed, and the electronic transitions were assigned based on theoretical calculations. The potential curve of double proton transfer in the complex was calculated, and the transition state and activated energy relative to the N H bond were obtained.

Substituent Effects on the Hydrogen Bonding Between Phenolate and HF, H_2O and NH_3

B3LYP/6 31+g( d ) calculations were performed on the hydrogen bonded complexes between substituted phenolates and HF, H 2O as well as NH 3. It was found that some properties of the non covalent complexes, including the interaction energies, donor acceptor (host guest) distances, bond lengths, and vibration frequencies, could show well defined substituent effects. Thus, from the substituent studies we can not only understand the mechanism of a particular non covalent interaction better, but also easily predict the interaction energies and structures of a particular non covalent complex, which might otherwise be very hard or resource consuming to be known. This means that substituent effect is indeed a useful tool to be used in supramolecular chemistry and therefore, many valuable studies remain to be carried out.

Phase Equilibria of Hydrogen Bonding Fluid in a Slit Pore with Broken Symmetry

Phase equilibria of hydrogen bonding （HB） fluid confined in a slit pore with broken symmetry were investigated by the density functional theory incorporated with modified fundamental measure theory, where the symmetry breaking originated from the distinct interactions between fluid molecules and two walls of the slit pore. In terms of adsorption-desorption isotherms and the corresponding grand potentials, phase diagrams of HB fluid under various conditions are presented. Furthermore, through phase coexistences of laying transition and capillary condensation, the effects of HB interaction, pore width, fluid-pore interaction and the broken symmetry on the phase equilibrium properties are addressed. It is shown that these factors can give rise to apparent influences on the phase equilibria of confined HB fluid because of the competition between intermolecular interaction and fluid-pore interaction. Interestingly, a significant influence of broken symmetry of the slit pore is found, and thus the symmetry breaking can provide a new way to regulate the phase behavior of various confined fluids.

Hydrogen Bonding Effects on the Photophysical Properties of 2,3-dihydro-3-keto- 1H-pyrido[3,2,1-kl] phenothiazine

Time-dependent density functional theory （TDDFT） and femtosecond transient absorption spectroscopy were used to investigate the photophysical properties of 2,3-dihydro-3-keto-lH- pyrido[3,2,1-kl]phenothiazine （PTZ4） and 3-keto-lH-pyrido[3,2,1-kl]phenothiazine （PTZ5）. The calculated results obtained from TDDFT suggest that the red-shifts of the absorption spectra of these two fluorophores in methanol are due to the formation of hydrogen-bonded complexes at the ground state. Four conformers of PTZ4 were obtained by TDDFT. The two fluorescence peaks of PTZ4 in tetrahydrofuran （THF） came from the ICT states of the four conformers. The fluorescence of PTZ4 in THF showed a dependence on the excitation wavelength because of butterfly bending. The excited state dynamics of PTZ4 in THF and methanol were obtained by transient absorption spectroscopy. The lifetime of the excited PTZ4 in methanol was 53.8 ps, and its relaxation from the LE state to the ICT state was completed within several picoseconds. The short lifetime of excited PTZ4 in methanol was due to the formation of out-of-plane model hydrogen bonds between PTZ4 and methanol at the excited state.

BASE-INDUCED RELEASE OF MOLECULES FROM HYDROGEN BONDING DIRECTED LAYER-BY-LAYER FILM

On the basis of hydrogen bonding directed layer-by-layer (LbL) assembly we have fabricated two multilayersystems, poly(acrylic acid) bearng spironaphthoxazine (PAA-SO)/poly(4-vinylpyridine) and carboxyl-terminated polyetherdendrimer (dendrimer-COOH)/poly(4-vinylpyridine). UV-Vis spectroscopy indicates that either PAA-SO or dendrimer-COOH can be released from the corresponding multilayer assemblies upon immerssion in a basic aqueous solution.Furthermore, the rate of molecule release can be controlled either by changing the pH value or by adjusting the layerstructure.

Synthesis and Structure of a La(Ⅲ) Complex of 1,10-Phenanthroline-2,9-dicarboxylate:a Three-dimensional Network via Hydrogen Bonding Interactions

A new La（Ⅲ） complex, {[La（L）（NO3）（H2O）3]·H2O}n （L = 1,10-phenanthroline- 2,9-dicarboxylate）, has been synthesized and structurally determined by X-ray diffraction analysis. The complex crystallizes in the monoclinic system, space group P21/c with a = 7.7358（17）, b = 8.1664（18）, c = 28.271（6） A, β= 95.184（4）°, V= 1778.6（7） A3, Z = 4, C14H14LaN3O11, Mr = 539.19, Dc = 2.014 g/cm^3, μ= 2.471 mm^-1, F（000） = 1056, the final R = 0.0350 and wR = 0.0659. In this complex, each metal center adopts a ten-coordination geometry formed by two N atoms from a ligand L and eight O atoms from three H2O molecules, a nitrate ion and carboxylates of two ligands. Each ligand adopts a N2,O3-pentdentate coordination mode using two N and two O atoms chelating a La（Ⅲ）, and using another O atom of carboxylate to bridge another La（Ⅲ） center resulting in a 1D helical chain molecule. Intermolecular strong O-H…O and weak C-H…O hydrogen bonds extend the 1D chain structure into a 3D supramolecular architecture.

A Perfect Three-dimensional Hydrogen Bonding Network within Hydroxonium Hexa-aqua-magnesium(Ⅱ) Trichloride

Hydrothermal reaction of MgCl2 and ethyl tetrazolate-5-carboxylate at 160 ℃unexpectedly yielded compound {（H3O）[Mg（H2O）6]Cl3} （1）. The result of X-ray diffraction analysis indicates that 1 crystallizes in the monoclinic system, space group C2/c with a = 9.2896（3）, b = 9.5570（4）, c = 13.3169（5） A, β = 90.1221（12）°, V= 1182.28（8） A3, Z = 4, Mr = 257.78, Dc = 1.448 g/cm3, μ = 0.824 mm^-1, F（000） = 536, R = 0.0265 and wR - 0.0706. 1 is composed of one hexa-aqua-magnesium（Ⅱ） ion, one hydroxonium ion, and three chlorine anions. These three components weave a perfect three-dimensional （3D） （4,4,6,12）-connected hydrogen bonding network within 1.

Influence of Intermolecular Hydrogen Bonding to Spin Crossover Property of Iron （111） Complexes with a N3O2 Pentadentate Ligand and a Monodentate Ligand

Three iron （III） complexes with the formula of [Feat（X）L2]BPh4 were studied, in which a pentadentate Schiff-base ligand （H2L2 = bis （3-methoxysalicylideneiminopropyl） methylamine） and a counter anion BPh4 were fixed, and three monodentate ligands, 3-Mepy （3-methylpyridine）, 4-NH2py （4-aminopyridine）, and 2-Meim （2-methylimidazole） were used as the axial ligand X. The temperature dependence of magnetic susceptibility measurements demonstrated that [Fem（3-Mepy）L2]BPh4 showed a gradual spin equilibrium between HS （high-spin） （S = 5/2） and LS （low-spin） （S = 1/2） states, [Fem（4-NH2py）L2]BPh4 showed a steep SCO （spin crossover） and [FeIH（2-Melm）L2]BPh4 was in the HS state even at 100 K. The single crystal X-ray analyses demonstrated that [FelH（4-NH2py）L2]BPh4 has an one-dimensional chain structure constructed by intermolecular hydrogen bonding between 4-amino group of 4-NH2py and methoxy oxygen of adjacent molecular-cation. The crystal structure of [FenI（3-Mepy）L2]BPh4 has no such intermolecular interaction and its SCO site behaves independently, and the crystal structure of [FeIII（2-Meim）L2]BPh4 has a NH...n interaction between imidazole group of 2-Meim of cation and a phenyl group of anion BPh4. The result demonstrates that the intermolecular hydrogen bonding affects SCO profile significantly.

Synthesis and self-association of dibenzothiophene derivatives for simulation of hydrogen bonding interaction in asphaltenes

The dibenzothiophene derivatives, namely 2-（dibenzothiophene-2-carbonyl）benzoic acid and 2-（diben- zothiophene-2-carbonyl）alkyl benzoate, were synthesized and characterized by nuclear magnetic resonance （1H NMR）, matrix-assisted laser desorption/ionization time of flight mass spectrometry, and elemental analysis. The self- association behavior of these dibenzothiophene derivatives in CH2C12 and CH3CN was investigated using UV-visible absorption spectroscopy, fourier transform infrared spec- troscopy, and atomic force microscopy. It was found that the carboxylic acid exhibited a strong self-association trend in CH2C12 solution at a concentration of about 5 × 10^-7 M. Hydrogen bonding of carboxyl in the dibenzoth- iophene derivatives was confirmed to be the main driving force for the formation of the carboxylic acid aggregates.

EFFECT OF HYDROGEN BONDING ON DIRECTION OF PHOTOISOMERIZATION OF RETINOIDS:THE ORIGIN OF THE SOLVENT POLARITY EFFECT.

Studies of direction of photoisomerization of retinal,retinonitrile,a- retinonitrile and a trienenitrile analog in different solvents with varying wave- lengths of excitation and reaction temperature led to the conclusion that the well known solvent dependent photochemistry of retinoids is due to selective excitation of the hydrogen bonded species.

Studies on the Conformations and Hydrogen Bonding of ACE Inhibitory Tripeptide VEF by All-atom Molecular Dynamics Simulations and Molecular Docking

Molecular dynamic simulations and molecular docking are performed to study the conformations and hydrogen bonding interactions of ACE inhibitory tripeptide VEF. Intramolecular distance, radius of gyration, solvent-accessible surface, and root-mean-square deviations are used to characterize the properties of VEF in aqueous solution. The VEF molecule is highly flexible in water and conformations can shift between the extended and folded states. The VEF molecule exists in extended state mostly in aqueous solution and the conformations bonded with ACE are also the extended ones. The findings indicate that MD simulations have a good agreement with the molecular docking analysis.