Wyniki wyszukiwania - BazTech

1

Evolution of Quantum Similarity Measures: How They Perform in Modeling Hammett Constants

Sadlej-Sosnowska N.

Polish Journal of Chemistry

|

2009

|

Vol. 83, nr 12

2215-2224

EN

This study was aimed at comparing a few measures of similarity of carboxylic acids’ molecules, based on the electronic descriptors derived from molecular wave functions. Five series of molecules were investigated: benzoic acids, thiophene-2-carboxylic acids, furane-2-carboxylic acids, trans-cinnamic acids, and 3-phenylpropionic acids. It has been previously found that in stead of comparing densities or other electronic properties of the entire molecules, it is sufficient to use the properties within a molecular fragment, active towards a given reaction. In this vein, three measures have been compared: the one pertaining to the properties of bond critical points, the one derived from atomic potentials, and that based on Fermi-hole densities, confined to the COOH group. Never the less, it appeared that other ways of defining a similarity measure may also be practical, namely that based on charges of the COOH group and that based on the properties of another molecular fragment, i.e. the substituent and the ring carbon atom connected to the so-called substituent active region. The calculations were carried out at the B3LYP/cc-pVDZ level.

2

Correlations of Charges of Substituent Active Region in C-substituted Tetrazoles with Their Gas-phase Acidity, Hammett Constants, and Charge Distribution in Tetrazolic Rings

Sadlej-Sosnowska N., Murłowska K.

Polish Journal of Chemistry

|

2008

|

Vol. 82, nr 4

935-945

EN

Electron distribution was investigated in molecules of 5C-substituted tetrazoles by means of Natural Population Analysis. The analysis of the impact of substituents on the excess of p electrons in the ring and on the uniformity of their distribution produced similar results as were recently reported for derivatives of p-benzoic acid. The significant correlation coefficients of the two properties with the Hammett constants have been found. The more uniform the p electron distribution, measured by means of standard deviation of p electrons amounts localized on individual atoms in the ring, the more acidic is the molecule. On the other hand, an increase of the p electron number in the ring brings about an opposite effect. No correlation was found between the substituent charges and the Hammett constants. However, a new variable, namely charge of the substituent active region, composed of charge of a substituent added to charge of the ring Cipso atom, was highly correlated with the Hammett constants, as well as with charge of acidic hydrogen of the >N-H group. The results prove that the set of charges of the substituent active region may be perceived as a theoretical equivalent of the experimental set of Hammett constants and that it is closely related to properties of this group of compounds.

3

Pomiary lepkości ze szczególnym uwzględnieniem cieczy nienewtonowskich

Sadlej-Sosnowska N., Ocios-Bębenek A.

Laboratorium - Przegląd Ogólnopolski

|

2008

|

nr 12

28--31

PL

W artykule przypomniano podstawowe pojęcia, przydatne w pomiarach lepkości oraz ich interpretacji. Opisano pokrótce najbardziej znane lepkościomierze (wiskozymetry) dostępne na rynku, a także omówiono ich przydatność do pomiarów lepkości cieczy nienewtonowskich. Zwrócono uwagę na fakt, że większość płynnych i półpłynnych produktów farmaceutycznych jest takimi cieczami.

EN

The publication defines same of the fundamental variables pertinent to the measurements of viscosity measurements and their interpretation. The most popular commercial viscometers are described here in brief, with their applicability for non-Newtanian liquids. lt is stressed that most liquid pharmaceutical materials are non-Newtonian.

4

Selectivity of identification of sugars using IR spectroscopy

Sadlej-Sosnowska N., Ocios A.

Chemia Analityczna

|

2008

|

Vol. 53, No. 5

639-649

EN

Sugars constitute a large family of chemical substances, some members of which are very similar to each other. Comparison of raw absorption or transmission infrared spectra has too small discriminative power to be a basis for unequivocal identification of a particular sugar. However, application of the algorithm based on the calculation of correlation coefficient between the first derivatives of the spectra of substances under comparison has demonstrated very high discriminating power. Limiting values for correlation coefficients were proposed to allow for discrimination or qualification of a sugar as identical to or different from the reference compound.

PL

Cukry stanowią dużą rodzinę substancji chemicznych, w której niektóre związki są bardzo do siebie podobne. Porównanie surowych widm w podczerwieni wykazuje zbyt małą zdolność dyskryminacji, konieczną do jednoznacznej identyfikacji badanego cukru. Natomiast zastosowanie algorytmu polegającego na obliczeniu współczynnika korelacji pomiędzy pierwszymi pochodnymi widm porównywanych substancji wykazało, że ma on wysoką zdolność dyskryminacji. Zaproponowano wartości graniczne współczynników korelacji pozwalających nazakwalifikowanie danej substancji jako różnej lub identycznej z substancją wzorcową.

5

Selectivity of identification of similar compounds by IR spectrometry

Sadlej-Sosnowska N.

Chemia Analityczna

|

2006

|

Vol. 51, No. 2

295-305

EN

This paper focuses on the investigating three methods of positive identification or discrimination of a substance when it is compared to a set of similar ones, applying the quantitative criteria. Correlation coefficients were compared between the transmission, absorption, and the first derivatives of absorption spectra. The latter was the method that proved to have the most discriminating power. The investigation involved exploring a group of structurally related compounds, namely a group of fourteen benzodiazepines. Limiting values were proposed for correlation coefficients so as to allow qualification of a substance as the same 35 the reference one.

PL

W pracy sprawdzono trzy metody pozytywnej identyfikacji lub dyskryminacji substancji porównywanej ze zbiorem substancji podobnych. Do przetestowania tych metod użyto grupy czternastu benzodiazepin. Największą zdolność dyskryminacji miaJa metoda oparta na porównaniu pierwszych pochodnych \vidm absorpcji. Zaproponowano wartości graniczne dla współczynników korelacji pozwalające na zakwalifikowanie substancji jako identj czncj z substancją porównawczą.

6

Fluorometric Determination of Stability Constants of Inclusion Complexes of Naproxen and Charged Cyclodextrins in Aqueous Solutions. Nonlinear vs Linear Data Processing

Sadlej-Sosnowska N., Gasiński Ł., Ozimiński W. P.

Polish Journal of Chemistry

|

2003

|

Vol. 77 / nr 8

1039-1048

EN

Stability constants of complexes of naproxen with monoamino-_-cyclodextrin and carboxymethyl-_-cyclodextrin in both acidic and basic solution have been determined by fluorometry and compared with those of parent _-cyclodextrin. It appeared that a charged group linked to the cyclodextrin rim decreased its complexing ability. For determination of the stability constants, nonlinear fitting has been used as well as three methods, which consist in linearization of the original hyperbolic equation. These methods of data processing have been compared.