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Introduction: Comprising of a unique combination of bioactive polyphenol compounds, grapes are shown to have a beneficial effect on the skin as well as the whole body. They exhibit high antioxidative and antiradical activity through mechanisms of heavy metals chelation, scavenging reactive oxygen species, inhibiting lipid peroxidation, and preserving the integrity of the cell membranes. In the winemaking industry, after crushing and pressing, grape pomace (stems, seeds, pulp, and skin) is removed as a by-product. This valuable source of bioactive compounds is often treated as animal food, compost, raw material in the brewery, but unfortunately mostly disposed of as unusable waste. Aim: The aim of this study was to compare redox properties of absolute EtOH, 50% EtOH, and H2 O grape wine skin extracts in a way of scavenging DPPH radicals, showing that biowaste obtained from grape wineskins could be used as an immense source of bioactive compounds with high antiradical activity. Material and Methods: Electron Paramagnetic Resonance (EPR) spectroscopy was used to detect the activity of grape skin extracts toward DPPH radicals and UHPLC-DAD MS/MS analysis to separate, identify and quantify their active components. Results: The results show that Cabernet Sauvignon and Pinot Blanc grape skin extracts have unexpectedly large potential to remove DPPH radicals from the system. Having in mind the concentration of redox-active components obtained by UHPLC-DAD MS/MS analysis and presented EPR results, there is strong evidence that primarily quercetin 3-O-glucoside, as well as kaempferol 3-O-glucoside, isorhamnetin 3-O-glucoside, kaempferol 7-O-glucoside supplemented with catechin and rutin are responsible for the antioxidative capacity of extracts. Conclusions: This study demonstrates that extracts obtained from grape skins, initially intended as biowaste, exhibit high antiradical activity. The largest quantity of the most redox-active components could be found in 50% EtOH extracts, which we propose to be the starting material for making potent redox-active cosmetic products and dietary supplements.

Durability and cost of Proton Exchange Membrane fuel cells (PEMFCs) are two major factors delaying their commercialization. Cost is associated with the price of the catalysts, while durability is associated with degradation and poisoning of the catalysts, primarily by CO. This motivated us to develop tungsten-carbide-oxide (WxCyOz) as a new non-carbon based catalyst support for Pt–Ru–based anode PEMFC catalyst. The aim was to improve performance and obtain higher CO tolerance compared to commercial catalysts. The performance of obtained PtRu/WxCyOz catalysts was investigated using cyclic voltammetry, linear scan voltammetry and rotating disk electrode voltammetry. Particular attention was given to the analysis of CO poisoning, to better understand how WxCyOz species can contribute to the CO tolerance of PtRu/WxCyOz. Improved oxidation of COads at low potentials (E < 0.5 V vs. RHE) was ascribed to OH provided by the oxide phase at the interfacial region between the support and the PtRu particles. On the other hand, at high potentials (E > 0.5 V vs. RHE) CO removal proceeds dominantly via OH provided from the oxidized metal sites. The obtained catalyst with the best performance (30% PtRu/WxCyOz) was tested as an anode catalyst in PEM fuel cell. When using synthetic reformate as a fuel in PEMFC, there is a significant power drop of 35.3 % for the commercial 30% PtRu/C catalyst, while for the PtRu/WxCyOz anode catalyst this drop is around 16 %.

Coordination effects have been considered through the most common interactions in the crystal structures of fluoro compounds (C-H/F and F/F interactions). The supramolecular profile of these effects is based on quantum-chemical calculations for the assessment of the interaction strength and electrostatic potential maps, which provide a qualitative insight into the examined effect. Coordination of aliphatic fluorides leads to an increase of the negative potential of the F atoms, and, hence, an increase in the hydrogen-bonding acceptor ability (strengthening of C-H/F interactions) and a weakening of the F/F interactions, due to an increase in repulsive interactions between the F atoms. There is no significant change in the potential of the F atoms due to coordination of C6-aromatic fluorides, as in the case of aliphatic ones. This results in slight changes in the strengths of the C-H/F and F/F interactions (coupled with parallel interaction at large offsets, PILO), in a noticeable enhancement of stacking interactions, as well as in a significant enhancement of interactions involving the π-system (F/πand C-H/πinteractions). It has also been shown that a decrease in the charge of the metal ions leads to a decrease in the negative potential of the F atom and also that the nature of the metal ion has a significant influence on the value of the potential of the F atoms. Supplementary material: [https://vinar.vin.bg.ac.rs/handle/123456789/9996]

Polymer-based, highly porous nanocomposites with functionalized ligands attached to the core structure are extremely efficient in the detection, removal and recovery of metals through the process of sorption. Quantumchemical models could be helpful for sorption process analyses. The sorption of Cu(II) ions by amino-functionalized chelating macroporous copolymers poly(GMA-co-EGDMA)-amine and sorption selectivity of the subject copolymers, ethylenediamine (en), diethylenetriamine (dien) and triethylenetetramine (trien), were successfully modelled by quantum chemical calculations. Considering the crystal structures from CSD and experimental conditions during the formation of metal complexes, the most frequent mononuclear complexes are those with the tetradentate teta ligand, while binuclear complexes are formed when the metal ion is in large excess. Although the en-copolymer was the most effective functionalized one, higher maximum sorption capacities (Qmax) were observed for the dien- and trien-copolymers, due to their abilities to form binuclear complexes. The enthalpy term has the greatest contribution to the total Gibbs energy change of reaction for the formation of mononuclear Cu(II) complexes (ΔGaq), while the solvation energy of the reaction has the greatest contribution in the formation of binuclear complexes. The results of the study indicate that small amines with the ability to form binuclear complex are the best choice for functionalization of the considered copolymer. [Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. OI 172043, Grant no. 172023 and Grant no. III 43009]

Semiconducting composites of nanostructured and granular polyaniline (PANI) with FeZSM-5 zeolite were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in water, without added acid and in an aqueous H2SO4 solution, in the presence of FeZSM-5, by using initial weight ratios aniline/FeZSM-5 of 1/1 and 1/5. These novel composite materials, in their as-synthesized (protonated) and deprotonated forms, were characterized by elemental, thermogravimetric and differential thermal analysis, scanning electron microscopy, FTIR and Raman spectroscopy, X-ray powder diffraction and conductivity measurements. The catalytic activity of the PANI/FeZSM-5 composites towards the oxidation of herbicide glyphosate with hydrogen peroxide has been investigated. A significant improvement of the catalytic activity of PANI/FeZSM-5 composites compared to that of pure PANI and FeZSM-5 was observed, manifested by the almost one order of magnitude more efficient oxidative degradation of glyphosate with hydrogen peroxide. The maximum of oxidized/decomposed amount of glyphosate was achieved in the presence of PANI/FeZSM-5 composite synthesized using an initial aniline/FeZSM-5 = 1/5 wt ratio. It has been shown that the method of synthesis and interactions between PANI and zeolite in this complex composite system, leading to more efficient electron transfer and hydrogen peroxide decomposition, are crucial for the catalytic properties of tested PANI/FeZSM-5 materials. It is shown that new PANI/FeZSM-5 composites present advanced catalyst materials for enhanced green catalytic degradation of pesticide/herbicide pollutants in environmental remediation systems.

Thiosemicarbazides are an important class of compounds with pronounced biological activities. In this contribution, the crystallographic structure of (E)-2-(2,5-dimethoxybenzylidene)hydrazinecarbothioamide (DBH) was described, and further spectroscopic studies (IR, Raman, 1H, and 13C NMR) studies were performed. Several density functional theory functionals (B3LYP, CAM-B3LYP, APFD, PBEPBE, M05-2X, and M06-2X) in conjunction with 6-311++G(d,p) were applied for the optimization of the structure. The highest resemblance to the crystallographic structure was obtained for structure optimized at M05-2X/6-311++G(d,p) level of theory. This structure was further used for the prediction of IR, Raman, and NMR spectra. The detailed vibrational and NMR analysis, with the most prominent bands assigned, proved that the experimental and theoretical spectra match well and that the obtained level of theory was suitable for the description of structure. Special emphasis was put on the analysis of dimers of DBH and water/DMSO-DBH structures to examine specific interactions. Natural Bond Orbital (NBO) and Quantum Atoms in Molecules (QTAIM) theories were applied for the quantification of the strength of these interactions. The most active positions were outlined through the calculation of the Fukui functions. A molecular docking study of DBH was performed towards Polo-like Kinase 1 (PLK1) to investigate the potential antitumor activity and the results were compared to volasertib. Specific interactions and binding affinities of monomers and dimers of DBH were discussed.

With regard to the harmful effects of heavy metals on human health and the environment, the demand for synthesis and investigation of macromolecules with large capacity of harmful substances sorption is ever greater. Quantum-chemical methods may be applied in structural modeling, prediction, and characterization of such molecules and reactions. Sorption of metal ions (Cu2+, Cd2+, Co2+, and Ni2+) to triethylenetetramine-functionalized copolymer poly(GMA-co-EGDMA)-teta was successfully modeled by quantum chemical calculations, at the B3LYP//6–311++G**/lanl2dz level. Optimized structures of metal complexes were used for calculation of real binding energy of metal ion within the complex (ΔEr). Solvent and hydrolyzation effects were essential for obtaining the objective values. Solvent effect was included in ΔEr by using the total solvation energy for reaction of formation of tetaOH complex (ΔEs1, the first approach) or by using dehydration energy of free metal ion (ΔEs2, the second approach). Experimental results were confirmed in our theoretical analyses (using the second approach).

Polymerizations of aniline were conducted in the mixtures of water and polar organic solvents (50 vol.%): acetone, acetonitrile, dimethylsulfoxide and ethanol, by using ammonium peroxydisulphate as an oxidant, without added acid. Course of reactions was followed by recording the temperature and pH changes of the reaction systems. The influence of the organic co-solvents and the reaction time on the molecular structure, molecular weights, morphology and properties of synthesized polyaniline (PANI) samples was studied by elemental analysis, laser desorption ionization mass spectrometry (LDI-MS), gelpermeation chromatography (GPC), FTIR, Raman and UV vis spectroscopies, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrical conductivity measurements. The results were compared with those obtained for PANI prepared under the same reaction conditions in water without a co-solvent. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3422]

The current study reports the synthesis and characterization of tungstophosphoric acid and its acid silver salt supported on mesoporous molecular sieve SBA-15 and TiO2. Because silver salts are partially insoluble, the SBA-15 and TiO2 supported silver acid salts were prepared by two step sequential impregnations. The synthesized catalysts were characterized by various physicochemical methods such as Fourier transform infrared and Raman spectroscopy, differential thermal analysis, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and nitrogen physisorption at -196 degrees C. It is observed that both active phases keep their Keggin-type structure after being supported on the supports while their specific surface area is considerably increased by deposition on mesoporous substrates. The results also indicated that the synthesized catalysts retained the morphology specific for each of the supports, while their thermal stability is increased in comparison with their active phases. The catalytic activity of the prepared catalysts was probed for the vapor phase dehydration of ethanol at 300 degrees C. Results revealed that all the catalysts show considerably improved catalytic activity in comparison to the bulk active phases.

Recent advances in synthesis, characterization and application of the selected conducting/semiconducting and redox-active oligomers and polymers of arylamines are reviewed. A brief historical background of the selected topics is given. The overview of the preparation, structure and properties of polyaniline, substituted polyanilines, especially those obtained by the oxidative polymerization of p-substituted anilines, poly(1-aminonaphthalene) and its derivatives, carbocyclic and heterocyclic polyaryldiamines such as poly(p-phenylenediamine) and polydiaminoacridines, is presented. The mechanism of formation of polyaniline nanostructures is discussed. Recent approaches to the preparation of one-dimensional polyaniline nanostructures are concisely reviewed, with special attention paid to the template-free falling-pH method. Current and potential future applications of oligo/polyarylamines are briefly discussed. [Projekat Ministarstva nauke Republike Srbije, br. OI 172043]

The oxidation of aniline with ammonium peroxydisulfate in water without added acid was studied in dilute reaction media. The new nanostructured nonconducting polyaniline sulfate/hydrogen sulfate, synthesized by dilute dopant-free template-free falling-pH method, consists of network of nanorods and nanogranules. The molecular structure of polyaniline, investigated by the elemental analysis, FTIR, Raman, UV–Vis and EPR spectroscopies, was found to be significantly different in comparison with the structure of the nanostructured PANI sulfate/hydrogen sulfate prepared by dopant-free template-free falling-pH method in concentrated aqueous aniline solutions. The mechanism of the formation of nanostructured polyaniline under dopant-free template-free dilute reaction conditions is discussed.

The present study characterizes using molecular dynamics simulations the behavior of the GAA (1186-1188) hairpin triloops with their closing c-g base pairs in large ribonucleoligand complexes (PDB IDs: 1njn, 1nwy, 1jzx). The relative energies of the motifs in the complexes with respect to that in the reference structure (unbound form of rRNA; PDB ID: 1njp) display the trends that agree with those of the conformational parameters reported in a previous study1 utilizing the de novo pseudotorsional (?,?) approach. The RNA regions around the actual RNA-ligand contacts, which experience the most substantial conformational changes upon formation of the complexes were identified. The thermodynamic parameters, based on a two-state conformational model of RNA sequences containing 15, 21 and 27 nucleotides in the immediate vicinity of the particular binding sites, were evaluated. From a more structural standpoint, the strain of a triloop, being far from the specific contacts and interacting primarily with other parts of the ribosome, was established as a structural feature which conforms to the trend of the average values of the thermodynamic variables corresponding to the three motifs defined by the 15-, 21- and 27-nucleotide sequences. From a more functional standpoint, RNA-ligand recognition is suggested to be presumably dictated by the types of ligands in the complexes.

Many properties of cytochromes and model systems depend on orientations of axial ligands. In this work, we elucidated the role of porphyrin substituents on orientation of axial ligands in model systems of cytochromes. The orientations of axially coordinated imidazoles and pyridines in crystal structures of model systems of cytochromes were analyzed and data were compared with previous quantum-chemical calculations. The results show that eight ethyl groups on porphyrin ring strongly favor parallel orientation, hence, in all these complexes axial ligands, pyridines or imidazoles, are mutually parallel. Four phenyl or mesityl groups at meso-carbons also favor parallel orientation but less strongly. Hence, in most of the bis-imidazole complexes the orientation is parallel, while in bis-pyridine complexes the orientation of pyridines depends on oxidation state of Fe. In bis-pyridine Fe(II) complexes orientation is parallel, in Fe(III) it is orthogonal. This analysis is in agreement with previous quantum-chemical calculations. (C) 2005 Elsevier Inc. All rights reserved.

Polyaniline (PANI) was synthesized by the oxidation of aniline with ammonium peroxydisulfate (APS) as an oxidant in an immiscible organic/aqueous biphasic system, without added acid. An organic phase contained aniline dissolved in chloroform, while the oxidant was dissolved in water. The produced PANIs have conductivities in the range 0.008-0.1 S cm(-1). Their nanogranular morphology was confirmed by scanning electron microscopy (SEM). Molecular structure of synthesized PANIs was investigated by FTIR, Raman, and UV-Vis spectroscopies, and elemental analysis. The influence of mechanical stirring and reaction time on the yield of polymerization, structure, and properties of synthesized PANIs was studied. The differences in the molecular structure, morphology, and conductivity between PANI prepared by dopant-free interfacial polymerization and PAN1 prepared by corresponding polymerization in monophasic aqueous system are discussed. The results are also compared with the literature data on the interfacial polymerizations of aniline with APS in the presence of acids. (C) 2014 Elsevier B.V. All rights reserved.

Nanostructured polyaniline (PANI) was synthesised by the oxidation of aniline in a water/ isopropanol (propan-2-ol, IPA) (50 vol. %) mixture, without added acid, using ammonium peroxydisulfate (APS) as an oxidant. Influence of the IPA co-solvent and the reaction time on the molecular structure, morphology and properties of synthesised PANI samples was studied by FTIR, Raman, and UV-VIS spectroscopies, scanning and transmission electron microscopies (SEM and TEM), and conductivity measurements. The course of the reaction was followed by monitoring changes in the temperature and acidity of the reaction medium. The results were compared with those obtained for PANI prepared in water without IPA under the same reaction conditions. The importance of the solvation effects, dielectric constant of the solvent, and the enthalpy of mixing of IPA with water on the course of the polymerisation reaction and on the properties of polymeric products in the water/IPA medium in comparison with those in water was pointed out.