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Raman spectroscopy and calculations probe the impact of low-frequency vibrations in anisotropic electron–phonon interaction.
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Cocrystal screening of 4-hydroxybenzamide with a number of salicylates (salicylic acid, SA; 4-aminosalicylic acid, PASA; acetylsalicylic acid, ASA; and salicylsalicylic acid, SSA) was conducted to confirm the formation of two cocrystals,... more
Cocrystal screening of 4-hydroxybenzamide with a number of salicylates (salicylic acid, SA; 4-aminosalicylic acid, PASA; acetylsalicylic acid, ASA; and salicylsalicylic acid, SSA) was conducted to confirm the formation of two cocrystals, [SA+4-OHBZA] (1:1) and [PASA+4-OHBZA] (1:1). Their structures were determined using single-crystal X-ray diffraction, and the hydrogen-bond network topology was studied. Thermodynamic characteristics of salicylic acid cocrystal sublimation were obtained experimentally. It was proved that PASA cocrystallization with 4-OHBZA makes the drug more stable and prevents the irreversible process of decarboxylation of PASA resulting in formation of toxic 3-aminophenol. The pattern of non-covalent interactions in the cocrystals is described quantitatively using solid-state density functional theory followed by Bader analysis of the periodic electron density. It has been found that the total energy of secondary interactions between synthon atoms and the side hydroxyl group of the acid molecule in [SA+4-OHBZA] (1:1) and [PASA+4-OHBZA] (1:1) cocrystals is comparable to the energy of the primary acid-amide heterosynthon. The theoretical value of the sublimation enthalpy of [SA+4-OHBZA], 231 kJ/mol, agrees fairly well with the experimental one, 272 kJ/mol. The dissolution experiments with [SA+4-OHBZA] have proved that the relatively large cocrystal stability in relation to the stability of its components has a negative effect on the dissolution rate and equilibrium solubility. The [PASA+4-OHBZA] (1:1) cocrystal showed an enhancement of apparent solubility compared to that of the corresponding pure active pharmaceutical ingredient, while their intrinsic dissolution rates are comparable.
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Research Interests: Marine Biology, Physiology, Biophysics, Materials Science, Chemistry, and 11 moreCrystallography, Ecology, UV, Cell Biology, Medicine, Crystal structure, Ch, Si, Nmr, O, and N
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... MV Vener, IV Leontyev, Yu. A. Dyakov, MV Basilevsky,* and MD Newton* . Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow 105064, Russia, and Department of Chemistry, PO Box 5000, Brookhaven National... more
... MV Vener, IV Leontyev, Yu. A. Dyakov, MV Basilevsky,* and MD Newton* . Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow 105064, Russia, and Department of Chemistry, PO Box 5000, Brookhaven National Laboratory, Upton, New York 11973. ...
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The Cambridge Structural Database has been used to investigate the detailed environment of H2O2 molecules and hydrogen-bond patterns within “true” peroxosolvates in which the H2O2 molecules do not interact directly with the metal atoms. A... more
The Cambridge Structural Database has been used to investigate the detailed environment of H2O2 molecules and hydrogen-bond patterns within “true” peroxosolvates in which the H2O2 molecules do not interact directly with the metal atoms. A study of 65 crystal structures and over 260 hydrogen bonds reveals that H2O2 always forms two H-bonds as proton donors and up to four H-bonds as a proton acceptor, but the latter can be absent altogether. The necessary features of peroxosolvate coformers are clarified. (1) Coformers should not participate in redox reactions with H2O2 and should not catalyze its decomposition. (2) Coformers should be Bronsted bases or exhibit amphoteric properties. The efficiency of the proposed criteria for peroxosolvate formation is illustrated by the synthesis and characterization of several new crystals. Conditions preventing the H2O2/H2O isomorphous substitution are essential for peroxosolvate stability: (1) Every H2O2 in the peroxosolvate has to participate in five or six hydrogen b...
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... Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow 103064, Russia. J. Phys. Chem. A , 1999, 103 (9), pp 1171–1178. DOI: 10.1021/jp982859x. Publication Date (Web): February 17, 1999. Copyright © 1999 American... more
... Karpov Institute of Physical Chemistry, ul. Vorontsovo Pole 10, Moscow 103064, Russia. J. Phys. Chem. A , 1999, 103 (9), pp 1171–1178. DOI: 10.1021/jp982859x. Publication Date (Web): February 17, 1999. Copyright © 1999 American Chemical Society. Abstract. ...
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Theoretical studies of the dynamics and kinetics of proton and hydrogen atom transfer processes occupy a special place in the kinetics of chemical reactions. The transition state theory is often inapplicable to these processes due to... more
Theoretical studies of the dynamics and kinetics of proton and hydrogen atom transfer processes occupy a special place in the kinetics of chemical reactions. The transition state theory is often inapplicable to these processes due to substantial quantum effects. Different approaches to the description of these reactions are discussed and compared. Calculations for a number of particular condensed-phase reactions involving
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New zwitterionic cocrystals of fenamate drugs and diclofenac with the naturally occurring amino acidl-proline have been obtained and thoroughly characterised by a variety of experimental and theoretical techniques.
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The hybrid molecular–continuum model for polar solvation considered in this paper combines the dielectric continuum approximation for treating fast electronic (inertialess) polarization effects and a molecular dynamics (MD) simulation for... more
The hybrid molecular–continuum model for polar solvation considered in this paper combines the dielectric continuum approximation for treating fast electronic (inertialess) polarization effects and a molecular dynamics (MD) simulation for the slow (inertial) polarization component, including orientational and translational solvent modes. The inertial polarization is generated by average charge distributions of solvent particles, composed of permanent and induced (electronic) components. MD simulations are performed in a manner consistent with the choice of solvent and solute charges such that all electrostatic interactions are scaled by the factor 1/ε∞, where ε∞ is the optical dielectric permittivity. This approach yields an ensemble of equilibrium solvent configurations adjusted to the electric field created by a charged or strongly polar solute. The electrostatic solvent response field is found as the solution of the Poisson equation including both solute and explicit solvent charges, with accurate account of electrostatic boundary conditions at the surfaces separating spatial regions with different dielectric permittivities. Both equilibrium and nonequilibrium solvation effects can be studied by means of this model, and their inertial and inertialess contributions are naturally separated. The methodology for computation of charge transfer reorganization energies is developed and applied to a model two-site dipolar system in the SPC water solvent. Three types of charge transfer reactions are considered. The standard linear-response approach yields high accuracy for each particular reaction, but proves to be significantly in error when reorganization energies of different reactions were compared. This result has a purely molecular origin and is absent within a conventional continuum solvent model.
Research Interests: Engineering, Chemistry, Electrostatics, Chemical Physics, Molecular Dynamics, and 15 moreComputer Simulation, DIELECTRIC, Dipole, CHEMICAL SCIENCES, Heat Capacity, Charge transfer, Boundary Condition, Dielectric Permittivity, MD Simulation, Electric Field, Charge Distribution, Molecular Dynamic Simulation, Linear System and Response, Electrostatic interaction, and Molecular dynamic
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Research Interests: Engineering, Chemistry, Computational Chemistry, Chemical Physics, Molecular Dynamics, and 15 moreElectron Transfer, Molecular Simulation, Physical sciences, Dipole, Experimental Study, Temperature Dependence, CHEMICAL SCIENCES, Polar, Ion, Ab Initio, Elsevier, Experimental Data, MD Simulation, Charge Distribution, and Molecular Dynamic Simulation
Research Interests: Engineering, Chemistry, Kinetics, Chemical Physics, Solvation, and 15 moreElectron Transfer, Physical sciences, Dielectric Function, Activation Energy, Polarizable continuum model, CHEMICAL SCIENCES, Frequency Dependence, Fourier transform, Cross Section, Reaction Rate, Charge transfer, Integral Equation, Boundary Effect, Correlation function, and Rate Constant
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The structure, IR spectrum, and H-bond network in the serine-H(2)O and serine-H(2)O(2) crystals were studied using DFT computations with periodic boundary conditions. Two different basis sets were used: the all-electron Gaussian-type... more
The structure, IR spectrum, and H-bond network in the serine-H(2)O and serine-H(2)O(2) crystals were studied using DFT computations with periodic boundary conditions. Two different basis sets were used: the all-electron Gaussian-type orbital basis set and the plane wave basis set. Computed frequencies of the IR-active vibrations of the titled crystals are quite different in the range of 10-100 cm(-1). Harmonic approximation fails to reproduce IR active bands in the 2500-2800 frequency region of serine-H(2)O and serine-H(2)O(2). The bands around 2500 and 2700 cm(-1) do exist in the anharmonic IR spectra and are caused by the first overtone of the OH bending vibrations of H(2)O and a combination vibration of the symmetric and asymmetric bendings of H(2)O(2). The quantum-topological analysis of the crystalline electron density enables us to describe quantitatively the H-bond network. It is much more complex in the title crystals than in a serine crystal. Appearance of water leads to an increase of the energy of the amino acid-amino acid interactions, up to ~50 kJ/mol. The energy of the amino acid-water H-bonds is ~30 kJ/mol. The H(2)O/H(2)O(2) substitution does not change the H-bond network; however, the energy of the amino acid-H(2)O(2) contacts increases up to 60 kJ/mol. This is caused by the fact that H(2)O(2) is a much better proton donor than H(2)O in the title crystals.
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In this work, three new pharmaceutical salts of fenbendazole (FNB), a benzimidazole-based anthelmintic drug, with sulfonic acids have been obtained and thoroughly investigated by different analytical techniques, including thermal methods,... more
In this work, three new pharmaceutical salts of fenbendazole (FNB), a benzimidazole-based anthelmintic drug, with sulfonic acids have been obtained and thoroughly investigated by different analytical techniques, including thermal methods, infrared/Raman spectroscopy, and theoretical methods (periodic DFT computations and Bader analyses of the crystalline electronic density). Single-crystal and high-resolution synchrotron powder X-ray diffraction data for the first time made it possible to determine the crystal structures of mesylate and tosylate salts of the drug, which were further validated by dispersion-corrected density functional theory calculations. All the solid forms were stabilized by a robust R 2 2 (8) supramolecular motif formed by relatively strong N−H•••O hydrogen bonds. In the monohydrate of FNB tosylate, a considerable gain in the stabilization energy was due to the intermolecular interactions generated by the water molecules. A careful examination of the solubility−pH profile of the FNB salts revealed that, despite being thermodynamically unstable within the physiologically relevant pH range, the new solid forms demonstrated superior dissolution performance in terms of both the apparent solubility and the release rate in comparison to the parent drug. Since FNB has also been reported to possess anticancer activity, improving the drug's poor physicochemical properties through salt formation with the selected sulfonic acids is expected to promote further investigations toward repurposing of this potent compound.
Research Interests: Materials Engineering, Materials Science, Chemistry, Inorganic Chemistry, FTIR spectroscopy, and 15 moreLow Frequency, Crystal structure, Pharmaceuticals, DFT calculation, Raman, Anthelmintic, Hydrogen Bonding, pH and temperature dependence, Salt hydrates, Drug Repurposing, Benzimidazoles, Fenbendazole, Intrinsic Dissolution, Counterion, and Bader analysis
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... Journal of OrganometalGc Chen, Structures of lithium salts of substituted 1phenylpropynes: 13C NMR and MNDO study Piotr I. Dem'yanov ', Igor M. Styrkov, Dmitry P. Krut'ko, Michail V. Vener and Valery S ... 3 (a) PI... more
... Journal of OrganometalGc Chen, Structures of lithium salts of substituted 1phenylpropynes: 13C NMR and MNDO study Piotr I. Dem'yanov ', Igor M. Styrkov, Dmitry P. Krut'ko, Michail V. Vener and Valery S ... 3 (a) PI Dem'yanov, IB Fedot'eva, VS Petrosyan and OA Reutov, Vesm. ...
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A method of calculation of a free-energy surface (FES) of the proton transfer (PT) reaction in a polar aprotic solvent is developed. This is based on the two-state (valence bond) VB description of the solute combined with recent continuum... more
A method of calculation of a free-energy surface (FES) of the proton transfer (PT) reaction in a polar aprotic solvent is developed. This is based on the two-state (valence bond) VB description of the solute combined with recent continuum medium models. Its essential new feature is an explicit quantum-chemical treatment of VB wave functions, including internal electronic structure of a
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Trimethylglycine (glycine betaine, GB) is an important organic osmolyte that accumulates in various plant species in response to environmental stresses and has significant potential as a bioactive agent with low environmental impact. It... more
Trimethylglycine (glycine betaine, GB) is an important organic osmolyte that accumulates in various plant species in response to environmental stresses and has significant potential as a bioactive agent with low environmental impact. It is assumed that the hydration of GB is playing an important role in the protective mechanism. The hydration and aggregation properties of GB have not yet been studied in detail at the atomistic level. In this work, noncovalent interactions in the GB dimer and its complexes with water and crystalline monohydrate are studied. Depending on the object, periodic and non-periodic DFT calculations are used. Particular attention is paid to the metric parameters and enthalpies of intermolecular hydrogen bonds. The identification of noncovalent interactions is carried out by means of the Bader analysis of periodic or non-periodic electron density. The enthalpy of hydrogen bonds is estimated using the Rosenberg formula (PCCP 2 (2000) 2699). The specific proton ...
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Efficient operation of organic electronic devices requires high charge‐carrier mobilities in their active layers, but only several organic semiconductors show confirmed charge‐carrier mobilities exceeding that of amorphous silicon (≈1 cm2... more
Efficient operation of organic electronic devices requires high charge‐carrier mobilities in their active layers, but only several organic semiconductors show confirmed charge‐carrier mobilities exceeding that of amorphous silicon (≈1 cm2 V−1 s−1). Charge transport in high‐mobility organic semiconductor crystals is considerably hindered by non‐local electron‐phonon interaction (NLEPI) transforming dynamic disorder induced by low‐frequency (LF) vibrations into fluctuations of charge transfer integrals. In this work, using two crystals of naphthalene diimide derivatives as an example, LF vibrational modes that strongly modulate the charge transfer integrals are computationally revealed. The importance of the discussed LF modes for limiting the charge‐carrier mobility is justified by analyzing the effect of the dynamic disorder on the charge‐carrier dynamics, estimating the charge‐carrier mobility in the two crystals, and observing quite a good agreement of the latter with the experimental values. Finally, it is shown that the contribution of various modes to the NLEPI correlates with their experimental Raman intensities. As a result, it is suggested that LF Raman spectroscopy can be used for experimental study of NLEPI, which can help with screening organic semiconductors showing high charge‐carrier mobility and promote rational design of such materials.
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2-Aminobenzimidazole peroxosolvate – the third H2O2crystalline adduct stabilized with the maximum possible number of hydrogen bonds formed by one hydrogen peroxide molecule.
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The azasydnone unit is a promising explosophoric block for future generations of highly thermostable and dense energetic materials.
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Charge-assisted hydrogen bonds (CAHBs) play critical roles in many systems from biology through to materials. In none of these areas has the role and function of CAHBs been explored satisfactorily because of the lack of data on the energy... more
Charge-assisted hydrogen bonds (CAHBs) play critical roles in many systems from biology through to materials. In none of these areas has the role and function of CAHBs been explored satisfactorily because of the lack of data on the energy of CAHBs in the condensed phases. We have, for the first time, quantified three types of CAHBs both in the condensed and gas phases for 1-(2'-hydroxylethyl)-3-methylimidazolium acetate ([C2OHmim][OAc]). The energy of conventional OH•••[OAc]- CAHBs is ~10 kcalmol-1, whereas non-conventional C(sp2)H•••[OAc]- and C(sp3)H•••[OAc]- CAHBs are weaker by ~5 - 7 kcalmol-1. In the gas phase the strength of the non-conventional CAHBs is doubled, whereas the conventional CAHBs are strengthened by <20%. The influence of cooperativity effects on the ability of the [OAc]- anion to deprotonate the imidazolium cation is evaluated. The ability to quantify CAHBs in the condensed phase on the basis of easier accessible gas-phase estimates is highlighted.
Research Interests: Biochemistry, Neuroscience, Biophysics, Chemistry, Biotechnology, and 15 moreSpectroscopy, Space Science, Medicine, Ionic Liquids, Physical sciences, Noncovalent interactions, Hydrogen Bond, CHEMICAL SCIENCES, Cooperativity, Complexes, Oh, Gas Phase, Magnitude, Imidazolium Cation, and Interaction energy
In this chapter we will consider molecular crystals with normal hydrogen bonds in which the donor A:H interacts with an acceptor :B. The so-called “bifurcated” and “trifurcated” H-bonds [1] as well as the new multiform unconventional... more
In this chapter we will consider molecular crystals with normal hydrogen bonds in which the donor A:H interacts with an acceptor :B. The so-called “bifurcated” and “trifurcated” H-bonds [1] as well as the new multiform unconventional Hbonds [2] are beyond the scope of the present chapter. We will focus on the proton dynamics in molecular crystals with strong and moderate H-bonds [3] in the ground electronic state. Attention will be focused on the interpretation of the structural and spectroscopic manifestations of the dynamics of the bridging proton as established in X-ray, neutron diffraction, infrared, and inelastic neutron scattering (INS) studies of H-bonded crystals. Various theoretical approaches have been developed for the description of the structure, spectral properties, and proton tunneling in H-bonded systems [4–7]. Computations for particular H-bonded species in the gas phase have been performed [8]. Due to strong environmental effects the applicability of gas-phase calculations to the proton dynamics in H-bonded crystals is questionable. Many theoretical approaches are based on oversimplified models (harmonic potentials and one-dimensional treatment of proton tunneling) and they usually contain parameters obtained from the experiment to be interpreted. This is why a consistent view on hydrogen bonding phenomenon in molecular crystals is still far from being achieved. The aims of this article are: 1. To show that a uniform and noncontradictory description of the specific properties of molecular crystals with quasi-linear H-bonds can be obtained in terms of a two-dimensional (2D) treatment assuming strong coupling between the protontransfer coordinate and a low-frequency vibration. 2. To interpret experimental structural and spectroscopic regularities of crystals with a quasi-symmetric A A H fragment using a model 2D potential energy surface (PES).
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The structure and spectroscopic properties of the 1:1 complexes of substituted pyridines with benzoic acid and phenol derivatives in aprotic solvents are studied using B3LYP functional combined with the polarizable continuum model... more
The structure and spectroscopic properties of the 1:1 complexes of substituted pyridines with benzoic acid and phenol derivatives in aprotic solvents are studied using B3LYP functional combined with the polarizable continuum model approximation. Two extreme structures are investigated: the state without (HB) and with proton transfer (PT). In the presence of an external electric field the O...N distance is contracted and the PT state does appear. The PT state of both the pyridine-benzoic and the pyridine-phenol complexes displays the only IR-active band in the 2800-1800 frequency region, which is located around 2000 cm(-1). However, the nature of the band is different for these two complexes. In the pyridine-benzoic acid complex it is practically a pure stretching vibration of the HN(+) group, while in the pyridine-phenol complex it is the mixed vibration of the bridging proton. A specific feature of the PT state in the pyridine-phenol complex is an IR-intensive band near 600 cm(-1), associated with the asymmetric stretching vibrations of the O(-)...HN(+) fragment. Its intensity is reciprocally proportional to the O...N distance. The appearance of this band provides an efficient criterion to differentiate between the HB and PT states of the 1:1 complexes of phenols with pyridines in aprotic solvents.
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Proton forms of zeolite chabazite (H-SSZ-13) loaded with 1 to 4 water molecules per acid site are examined by density functional theory with periodic boundary conditions. Equilibrium structures are determined by localizing minima on the... more
Proton forms of zeolite chabazite (H-SSZ-13) loaded with 1 to 4 water molecules per acid site are examined by density functional theory with periodic boundary conditions. Equilibrium structures are determined by localizing minima on the potential energy surface and harmonic vibrational frequencies are calculated. Average structures, proton dynamics and anharmonic spectra at finite temperature (350 K) are determined by molecular dynamics (MD). The protonation state is found to depend on the number of water molecules per acid site (loading) following the trend of increasing proton affinity with increasing cluster size. Single water molecules are not protonated, the protonated water dimer is the most stable equilibrium structure with the PBE functional, but not with BLYP. MD shows that even with PBE, the protonated water dimer is not stable at finite temperature. The protonated water trimer may be formed as a short-lived species, but the protonated water tetramer is the smallest stable protonated cluster. For the same global loading (2 : 1), a heterogeneous distribution of adsorbed water molecules over the cells is more stable than a homogeneous one (1 : 1/3 : 1 vs. 2 : 1/2 : 1 for a double cell), i.e. non-protonated and protonated water clusters may exist simultaneously in polyhydrated H-SSZ13. Adsorption energies (0 K) per water molecule decrease from 71 to 51 kJ mol(-1) for n = 1 to n = 4.
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ABSTRACT The infrared (IR) spectra of water–ethanol (EtOH) solutions of HCl are measured over a wide range of acid concentration at fixed H2O―EtOH ratios (1 : 1, 1 : 2, and 1 : 40). In these systems, different proton disolvates with... more
ABSTRACT The infrared (IR) spectra of water–ethanol (EtOH) solutions of HCl are measured over a wide range of acid concentration at fixed H2O―EtOH ratios (1 : 1, 1 : 2, and 1 : 40). In these systems, different proton disolvates with (quasi)symmetrical H-bonds are formed. Their structure and vibrational features are revealed by the density functional theory method coupled with the polarizable continuum model of solvation. In dilute acidic solutions, the Zundel-type H5O2+ ion is mainly formed. In concentrated HCl solutions, the ions (H2O···H···O(H)Et)+ and (Et(H)O···H···O(H)Et)+ with the quasi-symmetrical O···H+···O unit having O···O separation &lt;2.45 Å appear. The first ion characterized by the IR-intensive band around 1800 cm−1 is mainly formed in the 1 : 1 water–ethanol systems. The second ion exists in the 1 : 2 and 1 : 40 water–ethanol systems. Its spectroscopic signatures are the groups of the IR-intensive bands around 800 and 1050 cm−1. In highly concentrated HCl solutions with the 1 : 40 water–ethanol ratio, a neutral Et(H)O···H+···Cl− complex exists. Copyright © 2013 John Wiley &amp; Sons, Ltd.
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Second order Møller-Plesset perturbation theory and density functional theory are employed to localize several stationary points on the potential energy surface of the cyclic methanol tetramer. Two cyclic isomers are identified: one of S4... more
Second order Møller-Plesset perturbation theory and density functional theory are employed to localize several stationary points on the potential energy surface of the cyclic methanol tetramer. Two cyclic isomers are identified: one of S4 symmetry, with methyl groups in up-down-up-down configuration, and a second one of Ci symmetry, with the methyl groups in up-up-down-down configuration. The latter minimum is 360
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Ability to form a strong quasisymmetric H-bond is a fundamental property of the proton. This H-bond determines the stability of the proton hydrates and acid–base complexes, which defines the specific features (catalytic, electrochemical,... more
Ability to form a strong quasisymmetric H-bond is a fundamental property of the proton. This H-bond determines the stability of the proton hydrates and acid–base complexes, which defines the specific features (catalytic, electrochemical, etc.) of acidic solutions. The protonated water dimer can be treated as a simplest stable proton hydrate in aqueous acid solutions. Its lifetime is larger than characteristic
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Abstract Ab initio calculations at the MP2 level of theory, with a 6–31 G basis set which includes polarization functions on the atoms involved in the H bond, are performed on the hydrogen-bonded phenol-NH 3 complex. The equilibrium O…N... more
Abstract Ab initio calculations at the MP2 level of theory, with a 6–31 G basis set which includes polarization functions on the atoms involved in the H bond, are performed on the hydrogen-bonded phenol-NH 3 complex. The equilibrium O…N distance ( R e ) is equal to 2.837 A. The potential profile along the proton coordinate at a fixed O…N distance V ( r , R e ) only one minimum. Its shape is verified by calculation of the OH stretch frequency. The Lippincott-Schroeder potential is able to reproduce the shape of the V ( r , R e ) function for systems with an OH…N fragment in the gas phase only if some its parameters are calibrated to fit high-level ab initio data.