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Eksperymentalne i teoretyczne oznaczanie konfiguracji absolutnej związków chiralnych metodami chiralooptycznymi

Kwit M.

Wiadomości Chemiczne

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2011

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[Z] 65, 1-2

33-58

EN

Chirality is of paramount importance in chemistry and life sciences. Electronic circular dichroism (ECD) as well as optical rotation (OR) are fundamental properties of chiral molecules. These chiroptical properties provide rich information about conformation and configuration of the molecules. Although empirical correlations between chiroptical phenomena, mostly ECD, and molecular stereochemistry have existed for some time, the development of new accurate theoretical methods opened new opportunities for correlation of chiroptical properties with structure. Computational chemistry has made an amazing progress during the past two decades, moving this highly specialized discipline into the mainstream, and making a renaissance in chiroptical methods. This short review is meant as an introduction to the modern approach to optical activity of chiral molecules. Some illustrative applications will put the emphasis on practical applications of the theoretical/experimental analysis of complex molecules including highly flexible bistramide C and noncovalently bonded donor-acceptor dyad. The importance of the solvent effect is briefly discussed and a typical methodology is described and its strengths and weak points are commented.

2

The Diversification of the Optical Rotation Study in the Process of Proton Transfer : Theoretical Study for Alaninamide

Zhao S. L., Kong F. Z., Zhou Z. Y., Ma H. K., Wang W. J.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 10

1807-1807

EN

The tautomerism of alaninamide induced by the intramolecular proton transfer and the reaction mechanism of that has been investigated using density functional theory calculations with B3LYP hybrid functional. Six significant possible reactant conformers as well as their transition and product state of the proton transfer were optimized at 6-311++G(2d,2p) basis set level. The geometry parameters and the relative order of the activation energy for hydrogen atom transfer of all the conformers have been systematically examined in this work. Obtained relative order of the activation energy is following Ea3 > Ea1 > Ea6 > Ea4 > Ea2 > Ea5. Study of the diversification of optical rotations in process of the intramolecular proton transfer has been performed by the calculation of the specific optical rotation values at a wavelength of 589.3 nm for incident light for the conformers of both the reactants and the products, using B3LYP method of density functional theory at 6-311++G(2d,2p) and aug-cc-pvdz basis sets, respectively. The relations between the change of the dihedral angles of the conformers and the diversification in optical rotations of both the reactant and the product conformers have been studied with a conclusion that the change of helix structures in molecule conformers in the process of tautomerization leads to the change of optical rotation. The helix structures of the conformers build up the chiralmolecules with the properties of the optical rotation.

3

Nowe optycznie czynne poli(estroimidy) i poli(amidoimidy) Cz. II. Synteza optycznie czynnych polimerów

Borycki J., Wilczek M., Kolendo A. Yu.

Polimery

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2006

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T. 51, nr 5

333-340

PL

W reakcji wybranych chlorków dikwasów zawierających ugrupowania imidowe z glikolami lub w reakcji takich dikwasów z octanami glikoli otrzymano poli(estroimidy) (PESI), a z dikwasów i diamin - poli(amidoimidy) (PAMI). Szczegółowo omówiono warunki poszczególnych typów syntez. Dobierając rozmaite substraty uzyskano polimery bardzo różnorodne pod względem budowy chemicznej. PAMI, w przeciwieństwie do PESI, charakteryzują się dobrą rozpuszczalnością w polarnych rozpuszczalnikach (DMF, DMSO) w przedziale małych stężeń (do 1 % mas.). Pomiary lepkości właściwej roztworów PAMI w DMF wskazują na małe ciężary cząsteczkowe. Założoną budowę chemiczną otrzymanych PESI i PAMI potwierdzają ich widma IR. Metodą derywatograficzną ustalono, że PAMI odznaczają się dobrą termostabilnością. Pomiary skręcalności właściwej PAMI świadczą o ich czynności optycznej. Na podstawie pomiarów wartości kąta kontaktu szeregu powłok otrzymanych z PAMI, przeprowadzonych z zastosowaniem czterech różnych cieczy pomiarowych, określono metodami Owensa-Wendta lub van Ossa swobodną energię powierzchniową (SEP) tych PAMI oraz odpowiednie składowe SEP.

EN

Polyesterimides (PESI - Table 1 and 2) were obtained in the reaction of selected chlorides of diacids, containing imide groups, with glycols or in the reaction of diacids with glycols' acetates. Polyamidoimides (PAMI - Table 3 and 4) were prepared in the reaction of selected chlorides of diacids with diamines. The conditions of the particular types of syntheses were presented in detail. The selection of various substrates let to obtain a diverse range of polymers differing in chemical structure. In contrast to PESI, PAMI polymers show good solubility in polar solvents (DMF, DMSO) in low concentrations (up to 1 wt. %). Specific viscosity of PAMI solutions in DMF suggests low molecular weight. IR spectra (Fig. 1 and 2) confirm the presupposed chemical structure of PESI and PAMI obtained (Scheme A-D). It was found by derivatography that PAMI showed good thermal stability (Fig. 3). The measurements of specific optical rotation of PAMI show that they are optically active. On the basis of measurements of contact angle with four various measurement liquids (Table 5) the surface free energy (SEP) and SEP components of PAMI (Table 6) were calculated using the method of Owens-Wendt or van Oss's one.