Milica Rančić

Substituent and solvent effects on intramolecular charge transfer of 5-arylidene-2,4-thiazolidinediones.

The absorption spectra of twelve 5-arylidene-2,4-thiazolidinediones were recorded in twenty one solvents in the range from 300 to 600 nm. The effect of specific and non-specific solvent-solute interactions on the absorption maxima shifts were evaluated by using the Catalán solvent parameter set. Furthermore, the experimental findings were interpreted with the aid of ab initio MP2 and time-dependent density functional (TD-DFT) methods. It was found that different substituents significantly change the extent of conjugation in the molecules and further affect their intramolecular charge transfer character.

Novel modified nanocellulose applicable as reinforcement in high-performance nanocomposites

The influence of modification and vacuum/supercritical CO2 (scCO2) drying methods on the surface properties, morphology and thermal stability of cellulose nanocrystals (NC) was presented in this study. Introduction of reactive vinyl groups on NC surface was performed by either direct esterification with oleic acid, linseed or sunflower oil fatty acids; or by amidation of maleic acid/ethylene diamine with methyl ester of fatty acid. Obtained modified NC (m-NC) were characterized using FTIR and Raman spectroscopy; and by determination of acid, iodine and ester values. Structural analysis of m-NC showed varieties of forms, from spongy to nanostructural non-uniform layered morphology with observable agglomeration, which confirmed morphology dependence on modification/processing methods Thermogravimetry-MS spectrometry showed different thermal stability and degradation pathways of NC/m-NC. Incorporation of 1 wt% of reactive m-NC in unsaturated polyester lead to high performance nanocomposites and contributed to increase of stress at break in the range from 76 to 93%.

SUBSTITUENT EFFECTS ON CHROMATOGRAPHIC RETENTION DATA OF 5-ARYLIDENE-2,4-THIAZOLIDINEDIONES IN QSAR METHODOLOGY

Quantitative structure-retention relationship (QSRR) study of retention data of thirteen 5-arylidene-2,4-thiazolidinediones obtained by reversed phase HPTLC. The effect of substituents attached to aryliden ring on the properties of TZD molecule, whose retention is closely correlated to the inhibitory activity, was investigated. PCA was used to show similarities/dissimilarities among the compounds. Stepwise regression models were calculated for each mobile phase modifier used. The obtained models were characterized by good fit and predictive abilities. The descriptors included in the models are connected with both lipophilic and donor/acceptor interactions.

Synthesis of Methyl 2-(5-Arylidene-2,4-dioxotetrahydrothiazol-3-yl)propionates

A series of methyl 2-(arylidene-2,4-dioxotetrahydrothiazol-3-yl)propionates were prepared. A study of the 3D structure was performed. The log P values are given for all the synthesized compounds.

A study of the barrier properties of polyethylene coated with nanocellulose/magnetite composite film

The morphological, thermal and barrier properties of low-density polyethylene/polycaprolactone-modified nanocellulose hybrid materials were investigated in this study. Nanocellulose/magnetite (NC-Fe3O4) nanocompo- site and maleic acid functionalized NC/magnetite (NCMA-Fe3O4) nanocom- posite were prepared and used as fillers at various concentrations (5, 10 and 15 wt. %) in the polycaprolactone (PCL) layer. PE was coated with a PCL/NC/ /magnetite layer. The addition of the filler did not unfavorably affect the inherent properties of the polymer, especially its barrier properties. Oxygen permeation measurements showed that the oxygen barrier properties of mag- netite enriched PCL film were improved due to the chemical activity of the added material. The highest level of the barrier capacity was observed for PE samples coated with a PCL-based composite with NCMA-Fe3O4 micro/nano- filler, which implies a significant contribution of the surface modification of the nanocellulose with maleic anhydride residue to the improved barrier pro- perties.

Solvent and structural effects in tautomeric 2(6)-hydroxy-4-methyl-6(2)-oxo-1-(substituted phenyl)-1,2(1,6)-dihydropyridine-3-carbonitriles: UV, NMR and quantum chemical study.

The state of the tautomeric equilibria of 2(6)-hydroxy-4-methyl-6(2)-oxo-1-(substituted phenyl)-1,2(1,6)-dihydropyridine-3-carbonitriles, 2-PY/6-PY, was evaluated using experimental and theoretical methodology. The experimental data were interpreted with the aid of time-dependent density functional (TD-DFT) method. Electron charge density was obtained by the use of Quantum Theory of Atoms in Molecules, i.e. Baders analysis. Linear solvation energy relationships (LSER) rationalized solvent influence on tautomeric equilibrium. Linear free energy relationships (LFERs) were applied to the substituent-induced NMR chemical shifts (SCS) using SSP (single substituent parameter) and DSP (dual substituent parameter) model. Theoretical calculations and obtained correlations gave insight into the influence of molecular conformation on the transmission of substituent electronic effects, as well as on different solvent-solute interactions, and the state of tautomeric equilibrium.