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1

Conductance Study of the Complexation of NH4+ and Tl+ Ion with Different Crown Ethers in Binary Acetonitrile-Methanol Mixtures

Khayatian G., Karoonian F. S., Vaziri S.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 3

537-545

EN

A conductance study of the interaction of NH4 + and Tl+ ion with 18-crown-6 (18C6), ditertbutyl-dicyclohexyl-18-crown-6 ((t-but)2DC18C6), diaza-15-crown-5 (DA15C5), dibenzo-21-crown-7 (DB21C7) and dibenzo-24-crown-8 (DB24C8) in acetonitrilemethanol mixture was carried out at 25.0š0.1°C. The formation constants of the resulting 1:1 complexes were determined from the molar conductance-mole ratio data and found to vary in the order of DA15C5 > 18C6 > DB21C7 > (t-but)2DC18C6 > DB24C8, in the case of Tl+ ion in 100% MeOH, and in the order of: DA15C5 > 18C6 > (t-but)2DC18C6 > DB21C7 > DB24C8 for the NH4 + ion in 100% AN and AN-MeOH mix tures. The sta bil i - ties of the complexes for NH4 + and Tl+ ions varied in versely with the Gutmann donicity of the solvent with the ex cep tion of DA15C5-Tl+ complexes. The in fluence of substituents on the polyether ring and cavity size is discussed.

2

Effect of the Dielectric Medium on the Conformational Behaviour of Methyl 3-Nitrobenzoate

Konopacka A., Kalenik J., Pawełka Z.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 9

1583-1592

EN

Conformational analyses of methyl 3-nitrobenzoate (MNB) was performed, employing DFT, MP2, and semi-empirical quantum-chemical calculations, as well as classical methods based on atomic charge and dipole moment approximations. Properties such as the relative energies of the O-NO2 trans and O-NO2 cis isomers, their populations and dipole moments, all in vacuum, were considered first. Then the conformational trans cis equilibrium was quantitatively established by dipole moment measurements in solvents of dielectric permittivities between 2.016 and 10.34. Different approaches, based on continuum-dielectric and MSAmodels were explored to explain the contribution of the electrostatic interaction to the standard Gibbs energy change delta G° of the trans cis transformation in MNB in solution.

3

Optical Properties of Some 4-Aryl-1H-pyrazolo[3,4-b]quinolines

Kkachatryan K., Boszczyk W., Tomasik P.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 10

1645-1657

EN

Series of 6-substituted 4-(4_-tolyl)-3-methyl-1-phenyl-1H-pyrazolo[3,4-b]quinolines (1) and 4-(4_-chlorophenyl)- 3-methyl-1-phenyl-1H-pyrazolo[3,4-b]quinolines (2) were synthesized and their solution absorption and emission spectra in 10 solvents were recorded. Positions and intensity of the emission and longest wavelength absorption band as well as the quantum yield of emission and its lifetime were analysed in terms of the corresponding identity criteria involving a given parameter ifrom series (1) against the same parameters from the series (2). Mostly only tendencies to the linearity were observed in terms of the correlation coefficient.

4

Density Functional Theory Study of the Hydrogen Bonding Interaction of 1:1 Complexes of Alaninamide with Water

Zhou X., Zhou Z., Fu H.

Polish Journal of Chemistry

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2005

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Vol. 79 / nr 7

1223-1234

EN

The hydrogen bonding of 1:1 complexes formed between alaninamide and water have been investigated using DFT and MP2 methods at varied basis set levels from 6-311g to 6-311++g(d,p). Five reasonable geometries are 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 are 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 polarity of the solvent has significantly influenced the structures and the relative stabilities of different isomers.

5

Analysis of the effect of the special food additives on rheological properties of aqueous and milk solutions

Broniarz-Press L., Różański J., Różańska S.

International Journal of Applied Mechanics and Engineering

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2005

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Vol. 10, no spec

175-181

EN

The object of the studies was to determine the effect of various additives and solvents to Na-CMC, Guar gum (two different weight-average molecular weight), Xanthan gum and Arabic gum solutions on the change of their rheological properties. The additives studied were sodium chloride and saccharose. The solvents used were water and milk. The rheological properties of Na-CMC and guar gums solutions were described by Ostwald-de Waele power-law. Xanthan gum solutions had rheological properties described by Herschel-Bulkley equation. Arabic gum was characterized by Newtonian properties for aqueous solution and shear-thinning properties for milk solutions.

6

Study of Complex Formation of n-Alkylammonium Cations by Dibenzo-18-crown-6, Dibenzo-21-crown-7, and Dibenzo-24-crown-8 in Acetonitrile, Nitromethane and Nitrobenzene Solvents and Their Binary Mixtures Using Conductometric Method

Sadeghi S., Valavi

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 9

1175-1184

EN

The complex formation of ammonium and four n-alkylammonium perchlorate salts with dibenzo-18-crown-6 (DB18C6), dibenzo-21-crown-7 (DB21C7) and dibenzo-24-crown-8 (DB24C8) was studied by conductometry in acetonitrile (AN), nitrobenzene (NB) and nitromethane (NM) solvents at different temperatures and their binary mixtures at 25°C. The stability constants of the resulting 1:1 complexes were determined and found to decrease in the order: DB21C7 > DB18C6 > DB24C8. Number of hydrogen atoms on the ammonium group available for bonding to the crown ethers was the most important factor in determining complex stability constant.The influence of other factors such as the size of the macrocyclic cavity, steric effect of the alkyl group attached to the + NH3 group, and the Gutmann donicity of the solvents on stability of the complexes were studied. In all cases, the stability constants of the resulted complexes in solvents used varied in the order: NB > NM> AN. Standard enthalpies and entropies of the complex formation were obtained from the temperature dependence of the stability constants. Obtained thermodynamic parameters were sensitive to the type of solvent. The enthalpy - entropy compensation effect was investigated in general complexation of cations with crown ethers.

7

Excited State Proton Transfer Reaction in a New Benzofuryl 3-Hydroxychromone Derivative: The Influence of Low-Polar Solvents

Demchenko A., Ercelen S., Roshal A. D., Klymchenko A.S.

Polish Journal of Chemistry

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2002

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Vol. 76 / nr 9

1287-1299

EN

Unique properties of a new 3-hydroxychromone derivative 2-(6-diethylaminobenzo[ b]furan-2-yl)-3-hydroxychromone (FA) in its ability to exhibit excited-state intramolecular proton transfer (ESIPT) reaction are described. In contrast to all other chromone and flavone derivatives studied, in low-polar solvents it exhibits in emission, together with the tautomer (T*) band, an intensive band of the normal (N*) form. Previously the intensive N* form in emission was observed only in highly polar, mostly protic solvents. While its absorption spectra are sensitive to H-bond acceptor properties of the solvent, the fluorescence spectra are not. This suggests that intermolecular H-bonds with a solvent, if they exist in the ground state, are reorganized in the excited state in favor of intramolecular bond, which is the pathway for ESIPT reaction. The energy difference, _N* - _T*, between N* and T* emission maxima is in almost ideal correlation with the Reichardt solvatochromic parameter EN T . This suggests the use of FAas a highly sensitive polarity sensor.Agood correlation between _N* - _T*, and the ratio of the N* and T* band intensities is observed. This allows to observe the solvent effects on a manifold increased level of sensitivity. The analysis based on Lippert and Bakhshiev equations and the quantum- chemical calculations suggest a substantial increase of the dipole moment on electronic excitation to the N* state. The appearance of the N* form in emission may be the result of its dielectric stabilization.

8

Thermal Decomposition of 2,2’-Azoisobutyronitrile. The Polymerisation Rate of Acrylonitrile in N,N-dimethylformamide

Szafko J., Pabin-Szafko B.

Fibres & Textiles in Eastern Europe

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2002

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Vol. 8, no. 4 (39)

11--15

EN

The initial rate of acrylonitrile (M) polymerisation initiated by 2,2'-azoisobutyronitrile (AIBN) in solutions with N,N-dimethylformamide (S) over the entire range of variations of the monomer-solvent mixture composition [expressed by the monomer mole fraction (xM)] at 60°C was investigated. The polymerisation rate (Rp) was found to be given by Rp =K[tylda][AIBN] 0.5 [M]n, where - K[tylda] the overall rate constant is a function of xM for n=1. The variability of K[tylda] was interpreted in accordance with the model of the solvation of initiator (I) by monomer (M) and solvent (S). According to this model, three double solvated forms MIM, SIM and SIS exist in the solution, which initiate the polymerisation of acrylonitrile independently of each other. Hence, the total rate of polymerisation is the sum of the partial rates of solvated forms occurring in the system. The possibility of describing the kinetic data by other polymerisation theories (diffusion, electron-donor-acceptor (EDA) complex and ’hot radicals‘) has also been discussed.

PL

Metodą dylatometryczną określono początkową szybkość polimeryzacji (Rp) akrylonitrylu (M) w N, N-dimetyloformamidzie (S) inicjowaną 2,2'-azoizobutyronitrylem (AIBN) w funkcji składu mieszaniny monomer-rozpuszczalnik. Stwierdzon, że Rp =K[tylda][AIBN] 0.5 [M]n. Dla n=1 występuje zależność K[tylda]=f(xM) (zależność stężeniowa) globalnej stałej szybkości polimeryzacji od stężenia monomeru (xM). Zależność wyjaśniano przez przyjęcie modelu solwatacji inicjatora (I) przez monomer (M) i rozpuszczalnik (S). Model solwatacji pozwolił wyprowadzić równanie kinetyczne (równanie 23), które opisuje zależność eksperymentalną K[tylda] =f(xM). Opis wyników eksperymentalnych przez model solwatacji przedstawiono na tle innych interpretacji według teorii „dyfuzyjnej", kompleksu EDA (elektronowo-donorowego) oraz „gorących rodników."

9

Synthesis and Properties of Azoles and Their Derivatives : Part XLI : Stereoselectivity and Kinetic Study of the [2+3]Cycloaddition of E-B-Nitrostyrene to Z-C,N-Diphenylnitrone

Barański A.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 10

1711-1717

EN

Stereoselectivity and the kinetics of the reaction of E-B-nitrostyrene to Z-C,N-diphenylnitrone at different temperatures and in several solvents have been studied. From the results obtained, it is evident that the reaction shows the properties of a one-step concerted process, so that it can be considered a typical [2+3]cycloaddition process.

10

Kinetics of the reaction of 2,3,5,6-tetrachloro-1,4-benzoquinone with imidazole in acetonitrile and benzene

Dworniczak M., Przybyszewska M., Jarczewski A.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 1

108-112

EN

Nucleophilic vinylic substitution of 2,3,5,6-tetrachloro-1,4-benzoquinone by imidazole in acetonitrile and benzene has been studied spectrophotometrically. The reaction product is the diaminodichlorosubstituted quinone. The values of the activation parameters indicate that there is a considerable charge separation in the transition state. The reaction mechanism is discussed.

11

Interaction of sodium and potassium ions with the cis isomers of dicyclohexyl-18-crown-6 in nonaqueous media

Wagner-Czauderna E., Filipek S., Kalinowski M.K.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 10

2294-2302

EN

The formation constants, K-s for 1:1 complexes of the cis-syn-cis and cis-anti-cis isomers of dicyclohexyl-18-crown-6 with sodium and potassium cations have been electrochemically determined in 10 nonaqueous (protic and aprotic) media. Linear correlations were obtained for log K-s with standard Gibbs transfer energies of the cation from water to a given solvent. The cis-anti-cis isomer was found to be a weaker complexer than the cis-syn-cis one and this was elucidated in terms of the ligand solvation. Energy-minimized structures of the ligands and complexes suuuounded by methanol and acetonitrile molecules were established by molecular dynamics computations.