STUDIA CHEMIA - Issue no.2 / 2018 - Table of contents

Indolizines represent a class of heteroaromatic compounds (of pharmacological importance) containing two condensed (5- and 6-memebered) rings bridged by a nitrogen atom, showing a variety of biological activities. An attempt was made to deposit indolizines on the cube rhombellane homeomorphs surface as possible nano-drug complexes, since rhombellane homeomorphs may be bound in a protein as the active pocket and further may be used in personalized medicine. In the present study, a molecular docking analysis of two indolizine derivatives on some cube rhombellane homeomorphs was carried out for the first time.

Keywords: binding energy, indolizine, molecular docking, nanostructure, cube rhombellane homeomorph

The present paper focuses on the connection amongst the structure of 25 liquid crystals in the benzylideneaniline class and some of their physico-chemical properties. Simple and multiple correlations between transition temperatures and 34 calculated molecular descriptors (25 topological indices and 12 Van der Waals parameters), for each compound, were made. Simple and multiple correlations amongst topological indices and Van der Waals parameters, respectively, observing the variations taking place, are presented.

Keywords: liquid crystals, benzylideneaniline, topological indices, Van de Waals parameters

In this research work, we presented the results of theoretical calculations for the change of thermodynamic properties such as enthalpy ΔH, entropy ΔS, heat capacity ΔCp, and Gibbs free energy ΔG, for pure water, pure ethanol and interaction of mixture (50% water + 50% ethanol) and binary mixture of (water + ethanol) under thermal equilibrium condition at T = (273.15, 283.15, 293.15, 298.15, 305.15, 311.15, 320.15, 333.15) K and at atmospheric pressure. This theoretical calculation was done using Molecular Dynamic (MD) simulation. The results show that the values of ΔH and ΔS increase and also value of ΔCp decreases by temperature growth. The obtained value of change of Gibbs free energy for interaction of mixture (50% water + 50% ethanol) shows that this interaction is possible at T = (298.15, 311.15, 320.15, 333.15) K. Also, it showed that the self-diffusion coefficient and the mutual diffusion coefficients increase by increasing temperature.

Keywords: water, ethanol, mixture, interaction, thermodynamic properties, temperature, MD simulation

The research was conducted in order to evaluate the microwave effect on fatty acids profile and quality parameters of safflower and rapeseed oils. To simulate conventional times used in microwave domestic cooking, different exposure times were tested: 1, 3, and 5, respectively. After 5 minutes of microwave exposure, the peroxide index showed a significant increase for both types of oil (P≤0.05). Rapeseed fatty acids profile was rich in olei (C18:1), vaccenic (C18:1i), linoleic (C18:2), palmitic (C16:0) and linolenic (C18:2) fatty acids, followed by miristic (C17:0) and stearic (C18:0) acids. Microwave heating inflicted changes in fatty acids profile of both oils, the most affected fraction was the polyunsaturated fatty acids, directly related with their higher number of double bonds, with higher susceptibility to oxidation. Microwave heating exerted more aggressive effects on safflower oil, and rapeseed oil can be exposed for 5 minutes without negative effects.

Keywords: fatty acids profile, microwave heating, peroxide index, iodine index

The aim of this study is to investigate the hot air drying kinetics of sugar beet pulp, without and with dolomite addition, in order to establish the drying mechanism. The influence of temperature and dolomite addition on the drying rates is observed. The drying constant rates and the activation energies for different working conditions are determined. The obtained results show that the drying took place in falling rate period. The obtained activation energy values correspond to the mechanism mass transfer at low amount of dolomite addition and combined mechanism, mass transformation (evaporation process) – mass transfer, at higher amount.

Keywords: sugar beet pulp, hot air drying, dolomite, constant rate, activation energy

Thermal degradation of commercial polystyrene was investigated by XRD and FT-IR metods. The samples were heated 30 minutes at temperatures 140ºC, 200ºC, 250ºC, 300ºC and 350ºC and then brought back to room temperature. XRD investigation denotes structural modification for samples heated above 200ºC. This modification is confirmed by FT-IR measurments. Some vibration bands are affected by thermal degradation at temperatures higher than 200ºC. Both FT-IR and XRD methods reveal modification of microscopic structure of the polystyrene submitted to thermal degradation.

Keywords: thermal degradation, commercial polystyrene, FT-IR, XRD

Bonding of current adhesives to dentin is usually through the formation of the interfacial hybrid layer between adhesives and dentin. Intertubular and intra-tubular resin infiltration leads to an increase of the quality regarding the dentinal adhesion. The aim of this study is in vitro testing of new experimental adhesives in comparison with commercial adhesive, regarding sorption and solubility as well as to investigate molecular chemical features of the adhesive/dentin interfaces. We used 4 experimental adhesives systems A1, A2, A3, A4 and IBond® (Heraeus) as reference material. Organic phase adhesive system consists of a mixture of monomers. As filler for these systems, besides hydroxyapatite, we used TiO2 nanoparticles. FTIR spectroscopy was used to investigate molecular chemical features of the adhesive/dentin interfaces. The obtained data show the main advantages and disadvantages of the tested adhesive systems. The best values of water sorption and solubility both in water and artificial saliva present A2 and A3 adhesives.

Keywords: FTIR spectroscopy, TiO2, dental adhesives, sorption, solubility

The present study consisted in the determination of lead concentrations in soil samples and sterile material dumped collected from the Almașu Mare mining area. The lead concentration in the samples collected were determined by atomic adsorption spectrometry (AAS). In spite of the fact that all mines from area are nowadays inactive, the results of the chemical analysis showed that the soils in the area are still highly polluted with lead, except at the base of the “Radeș” dump, where the lead concentrations were below the intervention thresholds.

Keywords: mining area, “Radeş” dump, lead concentration

The main purpose of this research is in vitro biocompatibility testing of a polylactic acid polymer (PLA) synthesized by the condensation of lactic acid separated from whey (Zonar). The experimental PLA obtained was characterized by: Scanning Electron Microscopy which pointed a homogeneous microstructure of the polymer without a separation phase and differential scanning calorimetry (DSC) analysis which indicated a melting point of 1740C of the biomaterial. The cytotoxicity test for experimentally obtained polymer was performed according to ISO 10 993 -123. Six solutions of different concentrations were prepared (30 mg/ml, 20 mg/ml, 10 mg/ml, 5 mg/ml, 2.5 mg/ml and 1.25 mg/ml) and were tested on a fibroblast culture at 48 hours using MTT cell viability and proliferation assay. At 48h the obtained polylactic polymer showed good compatibility with an IC 50 of 64.82 mg/ml. The results showed that the cytotoxicity level can be influenced by the period of time in which the extract acts on the cell culture.

Keywords: whey, polylactic acid, cytotoxicity, biocompatibility, eco-friendly

The synthesis and characterization of new palladium and ruthenium derivatives using the bis-sulfone 1,3-bis{(4-methylphenyl)sulfonyl}-5-tert-butylbenzene ligand is presented. The new compounds were characterized in solution by multinuclear NMR spectroscopy and for the palladium derivative the molecular structure in solid state was also determined by single crystal X-ray diffraction. The work was completed with a DFT study in order to better understand the electronic effect in the stabilization of the new complexes containing bis-sulfone ligand.

Keywords: bis-sulfone, palladium and ruthenium derivatives, NBO analysis

New 2-(2-(10H-phenothiazin-3yl)vinyl)-3H-indolium cationic dyes were successfully prepared by Knoevenagel condensation of 1,2,3,3-tetramethyl- 3H-indolium iodide with 10-methyl-10H-phenothiazine-3-carbaldehyde and 10H-phenothiazine-3-carbaldehyde respectively. Their optical properties were emphasized by UV-Vis absorption spectroscopy. The position of their characteristic intramolecular charge transfer absorption maxima is situated in the visible range (550-630 nm), exhibiting solvatochromism induced by solvent polarity. Experimental evidences of linear optical properties were completed by a theoretical DFT computational study.

Keywords: 10H-phenothiazine, indolium salts, cyanine dyes

Four varietal wines Fetească Neagră, Merlot, Cabernet Sauvignon and Pinot Noir from Romania were submitted to a liquid-liquid extraction with dichloromethane and analysed by gas chromatography-mass spectrometry (GC–MS). A total of 29 volatile compounds were identified and quantified over two periods of ageing. Wines were differentiated by a number of compounds, such as esters, higher alcohols, and lactones. During wine ageing, all chemicals changed in the volatile composition. Most of alcohols and acids (hexanoic and octanoic acids) increased during ageing, while the esters, except ethyl lactate and diethyl succinate, were found in lower concentrations as ageing time increased. Considering all the volatile compounds detected, esters and higher alcohols are the main contributors for Romanian red wines.

Keywords: GC-MS, volatile compounds, red wine, liquid-liquid extraction

The pigments composition of sweet cherry leaves (Prunus avium L.) were identified for the first time under condition of Cluj-Napoca city. Five cherry tree varieties (Merchant, Early Red, Lapins, Burlat, Kordia) have been selected in autumn of 2016 in order to identify and quantify the major pigments in these types of leaves. Five carotenoids (lutein, β- carotene, zeaxanthin, cis-β-caroten, α-carotene) and one major anthocyanin (cyanidin-3-glucoside) were found in cherry leaves. The main carotenoids identified in all cultivars were lutein (340.55 μg/g), followed by β-carotene (147.06 μg/g). Early Red cultivar had the highest content of cyanidin-3- glucoside (17.96 mg/100g), followed by Kordia variety (11.46 mg/100g). Cyanidin-3-glucoside is responsible for red coloration of the leaves, meanwhile lutein, β-carotene, zeaxanthin, cis-β-carotene and α-carotene are providing yellow to orange colours of the leaves. The coloration of sweet cherry leaves, given by the accumulation of anthocyanin and carotenoids in autumn, makes this species suitable for ornamental use in urban design.

Keywords: anthocyanin, carotenoids, HPLC

Thermal methods have an important applicability in the pharmaceutical field, such as raw material control, purity determination, thermal stability determination, substance compatibility, qualitative and quantitative analysis of drugs, etc. Data on substance stability are obtained from the analysis of thermal decomposition determinations that occur both under isothermal conditions and under non-isothermal conditions. Thermogravimetry and derived thermogravimetry (TG / DTG) and differential scanning calorimetry (DSC) that are used to study the compatibility of the active substances and excipients have become increasingly important, because identify possible interactions between these components of the drugs. These thermoanalytic techniques have been used to study the behavior of a Nigella sativa semen glycerin macerate. To obtain tinctures and glycerin macerates, the European Pharmacopoeia methodology was followed. The thermoanalytic curves were recorded in a dynamic atmosphere of nitrogen and air (20 ml / min). The sample heating rate was 10 ° C / min. Thermal TG / DTG and DSC methods were applied in the temperature range of 25-1000 ° C.

Keywords: Nigella sativa semen, thermogravimetry, differential scanning calorimetry

Polyethylenimine (PEI) represents the most extensively used non-viral vector for gene delivery. The complexation between nucleic acids and PEI chains is intimately related to electrostatic interactions of the positively charged amine groups with the negatively charged phosphate groups. All-atom molecular dynamics simulations of alternatively protonated PEI chains, DNA and, respectively, polyplexes thereof in solution were performed. Our results reveal an increase in gyration radius of solvated PEI chains in the presence of DNA. In order to understand the major changes in DNA properties, the impact of PEI chains on the ionic environment of DNA is described in detail. In addition, the amine-phosphate contact analysis provides valuable insight into the formation mechanism of PEI/DNA complexes.

Keywords: polyethlenimine, cationic polymers, molecular dynamics simulations, PEI/DNA polyplexes, gene delivery systems.