BazTech - Yadda

1

Wpływ wiązań wodorowych na kwasowość związków chemicznych

Brzeski Jakub, Makowski Mariusz

Wiadomości Chemiczne

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2020

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[Z] 74, 9-10

629--644

EN

Both intra- and intermolecular hydrogen bonds increase the acidity of the systems in which they occur. Stabilization of the anion formed after deprotonation with a single intramolecular hydrogen bond causes a significant increase in the strength of acid in question, compared to the system in which such interaction does not exist. Hydrogen bonds, through their influence on the acid-base properties of chemical compounds, play a key role in organic chemistry, coordination chemistry, biochemistry and medicine. This paper comprise a review of the most important publications on the impact of hydrogen bonds on the acidity of chemical compounds and the relationship between the specificity of hydrogen bonds and the strength of the resulting acid. The relationship between intermolecular hydrogen bond energy and the pKa value of a given complex is thoroughly discussed in this paper. It turns out that the energy of the hydrogen bond is not related to a single value of pKa of neither the donor nor acceptor of this bond, but rather to the relative difference of these quantities. Namely, the strongest bonds are formed between those systems for which the pKa’s of a donor and acid conjugated to an acceptor differ the least. The feature that clearly correlates with the pKa value of the acid turns out to be the hydrogen bond length. The results of crystallographic studies have shown that the pKa values of C-H acids strongly correlate with the length of C-H ••• O hydrogen bonds. It is worth noting here that the correlation is much better for systems in which the formation of a hydrogen bond is not sterically hindered. In the abundance of donor and acceptor groups in the structure of an acid and its corresponding base, the anion formed after deprotonation is stabilized by phenomenon known as networking. Spreading the negative charge over a larger area of the molecule increases the stability of the anion and thus significantly increases the strength of the corresponding acid. Acids, whose acidity is mainly based on the networking are called SHEAs (single-centered hydrogen-bonded enhanced acidity acids). In addition, the effect of hydrogen bonds on the acidity of specific biochemical systems, namely nucleobases, has been discussed based on the papers by Wetmore and collaborators. It turns out that intra- and extracellular water molecules should not be overlooked when assessing the acidity of biomolecules.

2

Effect of oxidation on the wetting of coal surfaces by water: experimental and molecular dynamics simulation studies

Li E., Lu Y., Cheng F., Wang X., Miller J. D.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 4

1039--1051

EN

The wettability of coal surfaces by water continues to be one of the key factors which determines the success of coal flotation. Consequently, oxidation of coal surfaces is a fundamental issue of interest. In this work, the effect of oxidation on the wetting of coal surfaces and the interaction between water molecules and oxygen-containing sites at the coal surface was investigated based on advancing/receding contact angle measurements and molecular dynamics simulations. For the simulation studies, a flat coal surface was constructed with the assistance of the molecular repulsion between graphite surfaces and the assembly of Wiser coal molecules. Our results indicated that the simulated advancing and receding contact angles were very similar, and both of them decreased, as expected, with an increase of hydroxyl sites at the coal surface. The good agreement between the simulated advancing/receding contact angles and the experimental receding contact angle values suggested that the configuration of the systems and the set of parameters for the simulation were appropriate. The spreading of water is mainly due to the hydrogen bonds formed between the interfacial water molecules and the hydroxyl sites at the coal surface. The hydroxyl groups show stronger hydration capacity than other oxygen-containing groups according to the calculated hydrogen bonds and interaction energies.

3

Research on the Mechanical Properties and Curing Networks of Energetic GAP/TDI Binders

Ma S., Li Y., Li Y., Li G., Luo Y.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 3

708--725

EN

This research focused on correlations between the macroscopic mechanical performance and microstructures of energetic binders. Initially a series of glycidyl azide polymer (GAP)/toluene diisocyanate (TDI) binders, catalyzed by a mixture of dibutyltin dilaurate (DBTDL) and triphenyl bismuth (TPB), was prepared. Uniaxial tensile testing, and low-field nuclear magnetic resonance and infrared spectroscopy were then used to investigate the mechanical properties, curing networks, and hydrogen bonding (H-bonds) of these binders. Additionally, a novel method based on the molecular theory of elasticity and the statistical theory of rubber elasticity was used to analyze the integrity of the networks. The results showed that the curing parameter R strongly influences the mechanical properties and toughness of the binders, and that a tensile stress (σm) of 1.6 MPa and an elongation (εm) of 1041% was observed with an R value of 1.6. The cross-linking density increased sharply with the curing parameter, but only modestly with an R value ≥ 1.8. The proportion of H-bonds formed by the imino groups increased with the R value and reached 72.61% at an R value of 1.6, indicating a positive correlation between the H-bonds and σm. Molecular entanglement was demonstrated to increase with R and to contribute dramatically to the mechanical performance. The integrity of these networks, evaluated by a correction factor (A), varies with R, and a network of the GAP/TDI binder with an R value of 1.6 is desirable.

4

Radioisotope study of fructose adsorption at the alumina/electrolyte interface

Falkowski P., Szafran M., Skwarek E., Janusz W.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 2

1011--1022

EN

The mechanism, kinetic and static studies of fructose adsorption at the alumina/electrolyte interface using radiolabeled 14C-fructose were conducted. Pseudo 2nd order model of adsorption kinetics was found to fit best to adsorption as a function of time. The fructose adsorption was found to decrease with increasing pH of the solution. Considering the changes in concentration of surface groups at the alumina/electrolyte interface, the hydrogen bonding is the most probable mechanism of interaction of fructose with the surface. This is confirmed by calorimetric titration experiments because the measured heat of adsorption was 10.8 kJ/mol. For the system studied the coverage of surface by fructose was several times smaller than the monolayer.

5

Optimized geometry, vibration (IR and Raman) spectra and nonlinear optical activity of p-nitroanilinium perchlorate molecule: A theoretical study

Tamer O., Atalay A. S., Avci D., Atalay Y., Tarcan E., Marchewka M. K.

Materials Science Poland

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2016

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Vol. 34, No. 1

192--203

EN

The molecular modeling of p-nitroanilinium perchlorate molecule was carried out by using B3LYP and HSEH1PBE levels of density functional theory (DFT). The IR and Raman spectra were simulated and the assignments of vibrational modes were performed on the basis of relative contribution of various internal co-ordinates. NBO analysis was performed to demonstrate charge transfer, conjugative interactions and the formation of intramolecular hydrogen bonding interactions within PNAPC. Obtained large dipole moment values showed that PNAPC is a highly polarizable complex, and the charge transfer occurs within PNAPC. Hydrogen bonding and charge transfer interactions were also displayed by small HOMO-LUMO gap and molecular electrostatic potential (MEP) surface. The strong evidences that the material can be used as an efficient nonlinear optical (NLO) material of PNAPC were demonstrated by considerable polarizability and hyperpolarizability values obtained at DFT levels.

6

Acoustical studies on binary liquid mixtures of some 1,3,4-oxadiazole derivatives with acetone at 303.15 K

Alamelumangai G., Santhi N.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 5

124--133

EN

The wide spread use of 1,3,4-oxadiazoles as a scaffold in medicinal chemistry establishes this moiety as an important bioactive class of heterocycles. In the present study ultrasonic velocity (u), density (ρ) and viscosity (η) have been measured at frequency 2 MHz in the binary mixtures of 1,3,4-oxadiazole derivatives in acetone at 303.15 K using ultrasonic interferometer technique. The measured value of ultrasonic velocity, density and viscosity have been used to estimate the acoustical parameters namely adiabatic compressibility (βad), relaxation time (τ), acoustic impedance (Zi), free length (Lf), free volume (Vf) and internal pressure (πi), with a view to investigate the nature and strength of molecular interactions. The obtained result support the occurrence of molecular association through hydrogen bonding in the binary liquid mixtures.

7

Właściwości i zastosowania wody pod- i nadkrytycznej

Światła-Wójcik D.

Wiadomości Chemiczne

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2010

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[Z] 64, 3-4

225-242

EN

In the last decades, sub- and supercritical water has received continuously increasing attention as a reaction medium. As safe, non-toxic, readily accessible it is used in chemical synthesis, waste destruction and biomass processing [1–4]. A broad area of technological and industrial applications of sub- and supercritical water arises from its physical and transport properties falling between those of a gas and a liquid. The solvent properties of water can rapidly change with increasing pressure and temperature [2, 5, 10]. Above the critical point (Tc = 647.1 K, Pc = 22.06 MPa) water becomes highly compressible and diffusive. The static dielectric constant approaches values characteristic for low-polar solvent (Fig. 5). Contrary to liquid water at ambient conditions, supercritical water is a poor solvent for ionic species but is well miscible with hydrocarbons and gases (Fig. 6). The ionic product of supercritical water can be a few orders of magnitude higher than in ambient water (Fig. 4) with consequent effect on the kinetics and mechanisms of chemical reactions. By adjustment of thermodynamic conditions one can tune density, viscosity, polarity or pH of water to the desired solvation properties without any change in the chemical composition. An alternation in the character of water solvent near and above the critical point is the consequence of the structural transformations in the hydrogen-bonded network. As evidenced by many experimental and simulation studies the average number of hydrogen bonds per molecule and the lifetime of H-bonds decrease with increasing temperature and decreasing density [2, 10, 19]. With respect to experiment computer simulation plays an equal, and sometimes pivotal role, in quantitative characterization and understanding of water under extreme conditions. Precise definition of an H-bond employed in computer simulation allows one to examine size and topology of clusters of hydrogen-bonded molecules for various thermodynamic states [17, 19]. Such knowledge is invaluable to link features of the hydrogen bonding with the macroscopic properties of water [10, 19]. This article provides an overview of three aspects concerning water from ambient to supercritical conditions. In Chapter 1 the physical and transport properties are reviewed. Features of hydrogen bonding and a relationship between the molecular engagement in hydrogen-bonded clusters and macroscopic properties of water are discussed in Chapter 2. Chapter 3 focuses on technological and industrial applications of sub- and supercritical water. The summary concludes on main research needs.

8

Time-Resolved Infrared Spectroscopy of Water. Relation between the OH Stretching Frequency and the OO Distance

Bratos S., Leicknam J. -C., Pommeret S.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

737-745

EN

It is shown how infrared pump-probe spectroscopy can be used to measure subpico second variations of the oxygen-oxygen distribution function in liquid water. A diluted solution HDO/D2O rather than pure H2O is considered to switch off resonant vibrational interactions between water molecules; the local structure remains unchanged in this substitution. The present study is limited to times superior to 100–200 fs. This permits to avoid problems generated by hard sphere type collisions between water mole ules, as well as the interference between ultrafast pump and probe pulses. It is then shown that the Novak-Mikenda type relations between the OH stretching frequency and the OO distance largely sur vive when going from standard to ultrafast infrared spectroscopy. More over, the infrared pump-probe profiles of OH stretching bands closely parallel the oxygen-oxygen distribution functions in this time do main. Infrared pump-probe spectroscopy is thus a use ful substitute of time-resolved X-ray diffraction in this exceptional case.

9

Synthesis, Structures, and Antibacterial Activities of 3-Methoxy-N'-(3-bromo-5-chloro-2-hydroxybenzylidene) benzohydrazide Dimethanol Solvates and 3-Hydroxy-N'-(3-bromo-5-chloro-2-hydroxybenzylidene) benzohydrazide Methanol Solvate

Zhu Q. -Y., Wei Y. -J., Wang F. -W.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 7

1233-1240

EN

Two Schiff base com pounds, C15H12BrClN2O3×2CH3OH (1) and C14H10BrClN2O3×CH3OH (2), have been synthesized by the condensation reactions of equimolar quantities of 3-bromo-5-chlorosalicylaldehyde with 3-methoxy benzohydrazide and 3-hydroxy - benzohydrazide, respectively, in methanol solutions. Compound (1) consists of a Schiff base molecule and two metha ol molecules of crystallization, while compound (2) con - sists of a Schiff base molecule and one methanol molecule of crystallization. Both com - pounds were characterized by elemental analysis, IR spectra and single-crystal X-ray diffractions. As expected, each Schiff base molecule adopts an E-configuration about the C=N double bond. In both crystal structures, molecules are linked through intermolecular hydrogen bonds and weak Br×××O or Br×××Br interactions, forming layers. Both compounds possess potent antibacterial activities.

10

Studies on the Deamination of the Ethyl Ester of 5-Amino-3-methylisoxazole-4-carboxylic Acid

Ryng S., Szostak M.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

887-893

EN

The unusual behavior of the ethyl ester of 5-amino-3-methylisoxazole-4-carboxylic acid (1) during deamination is described. Possible explanations for the anomalies of the diazotization reaction are proposed. Deamination methods leading to ethyl ester of 3-methylisoxazole-4-carboxylic acid (5) are presented. 5 will serve as a lead compound for a new series of immunomodulatory agents.

11

Principal Components Analysis of Infrared Spectra of Liquid Acetylacetone

Czarnik-Matusewicz B., Matusiak-Kucharska M., Hawranek J. P.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

999-1011

EN

The spectrum of the absorption index in the Mid-Infrared (MIR) region was determined for intramolecularly hydrogen-bonded liquid acetylacetone from transmission studies. In the MIR region very thin layers with thick nesses of a few micrometers had to be used to obtain reliable data. The keto-enol tautomeric equilibrium in the pure liquid was studied by Principal Components Analysis (PCA) of a set of temperature dependent MIR spectra in the range from 25 to 75 graduate C. Identifications for numerous bands observed in the liquid phase were proposed basing on the results obtained by means of the separation obtained in the loadings plot.

12

Molecular Interactions and Structure of H-Bonded Complexes of Bifunctional Nitrogen-Containing Molecules

Bureiko S. F., Kucherov S. Yu., Schreiber V. M.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

771-785

EN

The results of experimental studies and quantum chemical calculations of vibrational spectra and struc ture of H-bonded complexes formed by N-containing bases 3,5-dimethylpyrazole, diphenyltriazene and diphenylformamidine with carboxylic acids and HHal are discussed. The IR spectra of solutions in CH2Cl2 and CCl4 and low temperature NMR spectra show the existence of equilibrium between monomers and cyclic selfassociates of the mole ules studied. Under the interaction with weak carboxylic acids the complexes have molecular structure with two H-bonds NH…O=C and OH…N, and the interaction with strong acids results information of cyclic H-bonded ionic pairs with proton transfer to the N atom of the base. The proton transfer in solution was observed also for open complexes with HHal. The quantum chemical DFT calulations in harmonic and an harmonic approximations confirm the formation of cyclic complexes, while the proton transfer along the OH…N bridge was supported for the complexes with strongest ac ids. It was shown that the use of variational multidimensional an harmonic approach is the most preferable for calculations of the high-frequency XH stretch in systems where the corresponding normal mode is less characteristic and involves motions of many atoms.

13

Infrared temperature studies of the polyurethane-based membrane materials

Kaczmarczyk B., Wolińska-Grabczyk A., Jankowski A.

Polish Journal of Applied Chemistry

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2009

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Vol. 53, nr 2

135-139

EN

The effcct of thermal annealing on hydrogen bonding in 4,4'-diaminodiphenylmethane-bascd segmented polyurethanes (PUU) varying in the length of the poly(tctramcthylcne oxide) (PTMO)-bascd soft segments has been studied by using Fourier transformed infrared spectroscopy (FTIR). It has been found that a significant amount of both interurcthanc and hard - soft segment hydrogen bonding exists in the investigated PUUs. The later one indicates some degree of phase mixing leading to the hard segments being mixed into the soft domains. The spectral evidence for temperature effects on the hydrogen bonding have been demonstrated, which is based on the significant changes in the relative intensities of the bands corresponding to the free and different hydrogen- bonded C=0 groups as a result of the thermal treatment.

14

Synthesis, Structures, and Antimicrobial Activity of Two Schiff Bases Derived from 3-Hydroxybenzohydrazide and 3-Alkoxysalicylaldehyde

Wang F. H., Wei Y. I., Zhu Q. Y.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 11

2089-2094

EN

Two isostructural Schiff base compounds, N c-[(2-hydroxy-3-methoxy)benzylidene]-3-hydroxybenzohydrazide monohydrate (1) and N c-[(2-hydroxy-3-ethoxy)benzyl idene]-3-hydroxybenzohydrazide monohydrate (2), have been synthesized by the condensation of 3-hydroxybenzohydrazide with 3-methoxysalicylaldehyde and 3-ethoxy salicyl aldehyde, respectively. The compounds have been characterized by el e men tal anal y sis, IR spectra, and single crystal X-ray diffraction. Each compound consists of a Schiff base molecule and a water of crystallization. In the crystal, molecules are linked through intermolecular O-HźźźO and N-HźźźO hydrogen bonds, forming layers parallel to the bc plane. The antimicrobial activity of the compounds has been tested.

15

Excited-state Solvation of Rhodamines: Dielectric and Specific Contributions

Ferreira J. A. B., Costa S. M. B.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 4

893-899

EN

Primary to tertiary amine based compounds of the form 9'-(2-ester-carbonyl)-phenyl- 3',6'-bis-(amino)-xanthylium) are studied as models for this class of compounds as regards the S1S0 shifts in solution. The magnitude of the solvatochromic shift decreases from primary amine to tertiary amine rhodamine chromophore. Primary aminoxanthylium spectral energy at maximum absorption decreases with the solvent electronic polarization whilst it increases with the orientational polarization function, suggesting extensive reorientation in the dipolar moment upon S1S0 excitation. By contrast, upon electronic excitation smaller dipolar moment variations are found in N-alkyl rhodamines, respectively with secondary and tertiary amine groups. Primary and secondary amine rhodamines' NH groups establish strong interactions with electron rich atomic centers of solvent molecules increasing the electronic stabilization energy.

16

Investigations of hydrogen bonding in the poly(urethane-urea)-based membrane materials by using FTIR spectroscopy

Wolińska-Grabczyk A., Kaczmarczyk B., Jankowski A.

Polish Journal of Chemical Technology

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2008

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Vol. 10, nr 4

53-56

EN

FTIR analysis was used to study the hydrogen bonding in 4,4'-diaminodiphenylmethane-based segmented poly(urethane-urea)s varying in the length of the poly(tetramethylene oxide) (PTMO)-based soft segments. Experiments were designed to follow the IR absorption of both the NH and carbonyl regions as a function of temperature in order to directly investigate the extent and strength of the hydrogen bonds, and thereby to gain some information about the possible alteration of the initial phase-segregated morphology as a result of the applied thermal treatment.

17

Zastosowanie przybliżenia hybrydowego B3LYP w badaniu oddziaływań międzycząsteczkowych pomiędzy harmanem a akryloamidem

Kowalska A., Stobiecka A.

Zeszyty Naukowe. Chemia Spożywcza i Biotechnologia / Politechnika Łódzka

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2007

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Z. 71

59-69

PL

W niniejszej pracy zastosowano przybliżenie hybrydowe B3LYP w badaniu oddziaływań międzymolekularnych, których wynikiem jest powstanie wiązania wodorowego w układzie 1:1 harman/akryloamid. Obliczono optymalizację geometrii oraz częstotliwości drgań czterech możliwych konfiguracji układu 1:1 harman/akryloamid z wykorzystaniem metody B3LYP/6-31G(d,p). Następnie, dla rozważanych układów obliczono energię stabilizacji z uwzględnieniem poprawki na błąd superpozycji bazy (BSSE) oraz poprawki na energię drgań w temperaturze zera bezwzględnego (ZPVE). Ponadto wyznaczono również entalpię i energię swobodną asocjacji badanych układów. Na podstawie uzyskanych wyników obliczeń wskazano najbardziej stabilną konfigurację kompleksu harman/akryloamid.

EN

In this study the hydrogen bonded interactions between harmane and acrylamide have been investigated using B3LYP/6-31G(d,p) method. Four reasonable geometries of harmane/acrylamide complex have been considered. The equilibrium structures and vibrational frequencies of the interacting systems have been determined. Three stable structures and one structure corresponding to the transition state have been found. Stabilization energies of the molecular systems under study have been estimated taking into account the zero-point vibrational energies (ZPVE) and the basis set superposition error (BSSE) corrections. In addition, some thermodynamical parameters of harmane/ acrylamide complexes have been calculated and the most stable harmane/ acrylamide complex has been found. Finally, the spectroscopic parameters of N-H stretching vibration in the most stable harmane/acrylamide complex have been compared to those corresponding to isolated harmane molecule in order to calculate their shifts due to the hydrogen bond formation.

18

Hydratacja protonu w roztworze wodnym

Śmiechowski M., Stangret J.

Wiadomości Chemiczne

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2007

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[Z] 61, 1-2

99-116

EN

The phenomena behind proton hydration in aqueous solution are still far from being fully understood and have attracted scientific attention for many decades now. This article reviews the current state of studies of this seemingly simple system, focusing particularly on the most popular techniques applied: computational chemistry, vibrational spectroscopy and diffraction methods. The picture of proton transfer via the Grotthuss mechanism, has lately been critically examined basing on up-to-date experimental and computational data, but it is still found relevant in biological systems, e.g. in proton-transferring proteins. The lengthy and heated debate on the identity of hydrated proton in an aqueous solution has focused for many years on two isomeric structures, the so-called "Eigen cation" and "Zundel cation". The findings of the last decade have proved that these two forms coexist in a dynamic equilibrium, and that the answer to this problem may as well be in the middle. The most recent reports from the last few years are reviewed here in considerable detail.

19

Investigation on the Hydrogen Bonding Interaction of Complexes of 2-Butanimine with Water

Fu H., Zhou X. M., Jiang C. Y., Zhou Z. Y.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 9

1667-1667

EN

The hydrogen bonding of 1:1 complexes formed between 2-butanimine and water has been investigated using DFT and MP2 methods at varied basis set levels from 6-311G to 6-311++G(d,p). Four reason able geom tries were considered with the global minimum being a cyclic double-hydrogen bonded structure. The optimized geometric parameters and interaction energies for various isomers at different levels were estimated. The IR intensities and vibrational frequency shifts are reported. The solvent effects on the geometries of the complex have also been investigated using SCRF calculations at the B3LYP/6-311++G(d,p) level. The results indicate that the polarity of the solvent has played an important role on the structures and the relative stabilities of different isomers.

20

Infrared and Raman Intensities in Proper and Improper Hydrogen-Bonded Systems

Jabłoński M., Sadlej A.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 5-6

767-782

EN

The IR intensities and Raman activities of the C–H stretchingmode as well as some other spectroscopic and structural features of NCHźźźNCH and F3CHźźźNCH are calculated in the MP2 approximation with a variety of correlation consistent basis sets. In agreement with earlier studies the traditional hydrogen bond in NCHźźźNCH results in the elongation of the C–H bond distance in the proton donor and the red shift of the corresponding vibration frequency. The opposite changes are found in F3CHźźźNCH. The IR intensity of the C–H stretching band in the NCHźźźNCH dimer markedly increases whereas for the blue-shifting F3CHźźźNCH complex the IR intensity of the corresponding band is significantly reduced. The Raman activity of the C–H stretching band in both investigated complexes increases upon the hydrogen bond formation. These results are analysed in terms of the interaction induced dipolemoments and polarizabilities, and their derivatives with respect to the C–H bond distance. The difference between IR intensities of the C–H stretching band calculated for NCHźźźNCH and F3CHźźźNCH is, however, a particular feature of the F3CHźźźNCH complex and cannot be used to distinguish between traditional and improper hydrogen bonds. Neither the Raman activities offer such a possibility. The present study of interaction induced properties shows that the blue shift of the X–H frequency in systems with improper hydrogen bonds is primarily due to particular features of the electronic structure of the proton donor.