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Acoustical studies on molecular interaction of 1,3,4-pyrazoline derivatives using ultrasonic technique at 303.15 K

Santhi A. R. N.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 20, iss. 1

100--115

EN

The acoustical parameters for the binary liquid mixtures containing Pyrazoline derivatives in DMF have been estimated at 303.15 K, from the measured values of ultrasonic velocity (U), density (ρ) and viscosity (η). From these data some of acoustical parameters such as adiabatic compressibility (β), free length (Lf), acoustic impedance (Z), Rao’s constant (R), molar compressibility (W), relaxation time (τ), free volume (Vf) and internal pressure (πi), etc., have been computed using the standard relations. The results have been discussed in terms of molecular interactions.

2

Characterization of the Structure of PDP-DPPC Bilayers by DFT and PM3 Calculations

Cieślik-Boczula K., Koll A.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 5-6

1081-1093

EN

The character of 3-pentadecylphenol (PDP)-dipalmitoylophosphatidylcholine (DPPC) interactions in a bilayer system was investigated using DFT and semi-empirical calculations. The obtained results were supported by ATR-IR spectra. The strongest intermolecular hydrogen bond was found between the phenolic OH and the PO2 groups of the DPPC molecule. The presence of water and hydrocarbon chains slightly weakens the strength of this PDP-DPPC interaction. In contrast to a pureDPPC bilayer, thewater molecules do not destroy the H-bonds formed by PO2 moieties and even enhance the total energy of the interaction. Both the van derWaals’interactions in the hydrophobic core of the PDP-DPPC aggregate and the intermolecular H-bond in the hydrophilic part make this complex more rigid, which influences its physical and chemical properties.

3

Interaction in mixed amphotericin B / sterols monolayers spread at the air / water interface

Dynarowicz-Łątka P., Seoane J. R., Trillo J. M., Mouzo O. C., Parada M. C.

Bulletin of the Polish Academy of Sciences. Chemistry

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1999

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Vol. 47, No.2

153-166

EN

Different methods for studying molecular interaction between film-forming components in Langmuir monolayers were applied and compared for the mixed systems of amphotericin B with four different sterols: cholesterol, ergosterol, stigmasterol and B-sitosterol. Among the sterols studied, ergosterol exhibits the strongest interaction with amphotericin B and B-sitosterol the weakest. Cholesterol and stigmasterol show interme-diate behaviour. As a consequence of the interactions, deviations from ideality are ob-served; negative at low and positive at high surface pressures. 1'he interactions are most pronounced for monolayers with the mole fraction of amphotericin Xa == 0.5 and 0.7 which lea.ds to the formation of an amphotericin B-sterol complexes of 2:1 stoichiometry. The obtained results support pharmacological assumption that amphotericin B has a greater affinity to ergosterol than to other sterols. Also the presence of amphotericin B-sterol com-plexes of 2: 1 stoichiometry, responsible for the formation of channels in cell membranes, has been confirmed.

4

Molecular interaction in Langmuir monolayers - statistical thermodynamics approach

Dynarowicz-Łątka P., Jawień W., Minones Trillo J., Vila Romeu N., Conde Mouzo O.

Bulletin of the Polish Academy of Sciences. Chemistry

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1998

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Vol. 46, No. 2

195-206

EN

A regular solution theory for a two-dimensional system with three components of different molecular sizes, adapted from statistical thermodynamics, is used to derive equations describing parameters related to the molecular interactions in mixed Langmuir monolayers. The theory has been applied by examining interactions at the interface for the mixed system of 1-hexadecanol and 1,16-hexadecanediol spread at the water/air interface, basing on experimental data of surface pressure/area (/area (p/A) isotherms. The obtained results show that the attractive forces between film-forming molecules are much stronger than those between particular amphiphiles and water.