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Volume 11 Issue 11

November 2013

Issue of Open Chemistry

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Open Access August 25, 2013

A theoretical study of the limits of the acidity of carbon acids in phase transfer catalysis in water and in liquid ammonia

Ibon Alkorta, José Elguero, Roger Gallo

Page range: 1711-1722

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Abstract

The acidities of a large number of carbon acids have been theoretically calculated for the gas-phase and for DMSO solution. The gas-phase values, both ΔH and ΔG, are very well correlated with the available experimental data. From the calculated ΔG values in DMSO and the pKas in the same solvent, a homogeneous set of pK a (DMSO) values was devised that was used to generate pK a (water). These last pK as were used to establish the limits of the acidity of carbon acids for reactions under PTC conditions both alkylations and H/D exchange. A step further led to the pK as in liquid ammonia and from them to the virtual use of PTC using liquid ammonia instead of water.

Open Access August 25, 2013

Epoxy resin modified with amine as an effective complexing agent of metal cations

Joanna Kurczewska, Grzegorz Schroeder

Page range: 1723-1728

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Abstract

A simple synthesis of a material capable of metal cation removal is proposed. The material was a derivative of epoxy resin containing amine groups. It is insoluble in water and in this study it was characterized by elemental analysis and infrared spectroscopy. The sorbent obtained was tested for its ability to remove coper(II), cadmium(II) and lead(II) from water solutions. The tests were performed for different concentrations of metal ions (10–200 mg L−1) and at different pH (2.0–9.0). The effects of temperature and stirring time, as well as reusability of the sorbent were also studied in batch experiments. In the optimum conditions, the decrease in the cation concentration in aqueous solutions was observed in the order Cu>Pb>Cd but for each ion the decrease was at least 50% of the initial concentration. The sorbent has demonstrated high effectiveness in cation sorption and after regeneration it can be applied repeatedly in the process described.

Open Access August 25, 2013

Archaeometric investigations on naturally and thermally-aged iron-gall inks using different tannin sources

Antonio Costa, Nazareth Fonseca, Sheyla Carvalho, Fernanda Santos, Luana Barki, Denise Freitas, Marcelo Herbst, Márcia Lutterbach

Page range: 1729-1739

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Abstract

This paper investigates the behavior of paper strips containing iron-gall inks prepared with tannins from different sources, subjected to natural and thermally-induced aging. Results indicate that inks containing initial concentrations of ferrous sulphate ranging from 0.2 to 10.0 g are amenable to treatment with calcium phytate, and thata good correlation exists between the recovery of excess iron and the initial concentration. Infrared spectra showed an absorption band at 1,750 cm−1, typical of esther, solely in the samples prepared with a condensed tannin. The condensed nature of this tannin produced a different oxidation pattern, with iron removal inferior to those observed from inks produced with hydrolisable tannins. When tannic acid was used ferrous iron removals ranged from 0.050 to 1.800 g, decreasing to 0.5 g in the presence of copper; the same behavior was observed for the remaining hydrolisable tannins, with a lower recovery from the condensed tannin. The adopted natural aging procedure released a higher amount of ferrous iron compared to ASTM thermal aging. This was probably due to the marked effect of humidity, not considered in the thermal procedure. A series of archaeometric possibilities were used to help elucidate the degradation of cellulose strips impregnated with iron-gall inks.

Open Access August 25, 2013

Self-assembly of acetylcholinesterase on gold nanoparticles electrodeposited on graphite

Nina Dimcheva, Elena Horozova, Yavor Ivanov, Tzonka Godjevargova

Page range: 1740-1748

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Abstract

The immobilisation of AChE enzyme through chemisorption on Au-modified graphite was examined with view of its prospective application in the design of membraneless electrochemical biosensors for the assay of enzyme inhibitors. The developed immobilisation protocol has been based on a two-stage procedure, comprising i) electrodeposition of gold nanostructures on spectroscopic graphite; followed by ii) chemisorption of the enzyme onto gold nanoparticles. Both the coverage of the electrode surface with Au nanostructures and the conditions for enzyme immobilisation were optimised. The proposed electrode architecture together with the specific type of enzyme immobilisation allow for a long-term retaining of the enzyme catalytic activity. The extent of inhibition of the immobilised acetylcholinesterase enzyme by the organophosphorous compound monocrotophos has been found to depend linearly on its concentration over the range from 50 to 400 nmol mL−1 with sensitivity 77.2% inhibition per 1 µmol mL−1 of monocrotophos.

Open Access August 25, 2013

Separation of trace amounts palladium by SiO2/TiO2/Ce nanoparticles prior to flame atomic absorption spectrometry determination in anodic slime and wastewater samples

Sayed Mohammadi, Hooshang Hamidian, Zahra Moeinadini

Page range: 1749-1756

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Abstract

In the present work, a new SiO2/TiO2/Ce, nanoparticle was synthesed using sol-gel method and evaluated as an adsorbent for preconcentration trace amounts of Pd(II) ions. The characterization of the nanoparticles has been studied by transmission electron microscope and X-ray diffraction. The preconcentration method is based on palladium adsorption onto the surface of nanoparticle at pH 8.5. The main factors affecting Pd(II) adsorption, such as pH of sample solution, concentration and volume of eluent, sample volume, interfering of the coexisting ions and flow rate of sample and eluent were investigated and optimized. At optimum conditions, linearity was maintained between 4.0 to 1000.0 ng mL−1. Detection limit based on 3Sb/m was 2.3 ng mL−1. Seven replicate determinations of a solution containing of 12.5 µg palladium gave a relative standard deviation ±1.7%. According to the Langmuir linear model, the maximum adsorption capacity of palladium was found to be 34.5 mg g−1. Finally, the feasibility of the proposed method for Pd(II) determination was assessed by analysis of certified reference materials, anodic slime and wastewater samples and satisfactory results were obtained.

Open Access August 25, 2013

Synthesis of new (arylcarbonyloxy)aminopropanol derivatives and the determination of their physico-chemical properties

Jan Tengler, Iva Kapustíková, Ondřej Stropnický, Petr Mokrý, Michal Oravec, Jozef Csöllei, Josef Jampílek

Page range: 1757-1767

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Abstract

Eight hydrochlorides of 3-{2-[(2/4-fluorophenoxy)-ethylamino]}-2-hydroxypropyl-4-alkoxybenzoates and four hydrochlorides of 3-tert-butylamino-2-hydroxypropyl-4-butoxybenzoates were prepared as potential antagonists of the β1-adrenergic receptor (beta-blockers). A multistep synthesis of these compounds is described as well as their detailed analytical characterization. The pharmacokinetic properties of these weak base compounds are significantly influenced by their acid-base dissociation constant, pK a. The knowledge of this value is crucial for new drug development. This paper is aimed at developing a methodology that utilizes pH-dependent 1H NMR spectroscopy for its routine analysis. The selected predicted physico-chemical parameters of the new (arylcarbonyloxy)aminopropanols (i.e., aryloxyaminopropanol derivatives) were compared with the model drugs esmolol and flestolol.

Open Access August 25, 2013

Preparation and conductivities of polyacrylic acid/polyvinylimidazole grafted and ungrafted iron oxide nanocomposite polymer electrolytes

Mehmet Senel, Hüseyin Kavas, Mehmet Tutgun, Abdulhadi Baykal

Page range: 1768-1779

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Abstract

Nanocomposites of Polyacrylic acid/polyvinylimidazole (PAA/PVI) with grafted and ungrafted iron oxide nanoparticles were prepared by a Reflux method. The Fe3O4 nanoparticles with 10 nm average diameter were synthesized by controlled co-precipitation and silanization of Si-PVI on Fe3O4 was used to obtain the grafted ones. Grafting becomes important at composites of less PVI that cause drastic decreases in AC conductivity. The content of PVI has important effects on the conductivity mechanism of these composites. The effect of grafting and Polyacrylic acid/polyvinylimidazole molar ratio on the conduction mechanism were studied. The conduction mechanism of iron oxide nanocomposites can be adjusted by changing molar ratio of Polyacrylic acid/polyvinylimidazole and grafting of Fe3O4NPs.

Open Access August 25, 2013

Effects of mechanical activation on structure and photocatalytic properties of ZnO powders

Maria Gancheva, Reni Iordanova, Yanko Dimitriev, Georgi Avdeev, Tzvetoslav Iliev

Page range: 1780-1785

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Abstract

Zinc oxide (ZnO) was mechanically activated in air using a planetary ball mill using varying milling speeds and time. The obtained samples were analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and UV-Vis diffusion reflectance spectroscopy. The photocatalytic activity of the mechanically treated ZnO powders were investigated in the reaction of Malachite Green (MG) degradation in aqueous solution under UV-light irradiation. A decrease in the crystallite size (from 90 to 10 nm) accompanied by an increase of microstrains and lattice parameters were established applying different milling speeds. The agglomeration of the particles was observed by SEM analysis. The absorption spectra of the initial and mechanically activated ZnO samples show shifting of the band position from 360 to 330 nm, which can be related to decrease in the crystalline size. The ZnO powders activated at lower milling speeds (for shorter time intervals) exhibit highest photocatalytic activity.

Open Access August 25, 2013

Chemical modification and characterization of poly(ethylene terephthalate) surfaces for collagen immobilization

Mioara Drobota, Zdenka Persin, Lidija Zemljic, Tamiselvan Mohan, Karin Stana-Kleinschek, Ales Doliska, Matej Bracic, Volker Ribitsch, Valeria Harabagiu, Sergiu Coseri

Page range: 1786-1798

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Abstract

The functionalization of poly(ethylene terephthalate) (PET) surface films by reactions with multifunctional amines such as triethylenetetramine (TETA), and tetraethylenepentamine (TEPA) was investigated. For the functionalization of PET films surface we used a new way of treatment, a “sandwich model”. Physical-chemical properties of functionalized PET films were analysed. Qualitative and quantitative determination of the introduced amine groups were examined by means of Fourier Transform Infrared Attenuated Total Reflexion (FTIR — ATR), X-ray photoelectron spectroscopy (XPS), and potentiometric titration. Gained wetting properties were determined by using contact angle measurements and thoroughly analysed by acid-base approach. In addition, surface topography was investigated by atomic force microscopy (AFM). The amount of the introduced amino groups after TETA incorporation has been found to be two times higher as compared to TEPA. Wetting properties were significantly improved after aminolysis. Surface free energy was higher for PET — TETA treated film than that observed for PET — TEPA treated which is in accordance with titration results. The collagen immobilization onto PET treated films was evidenced by using AFM and subsequently by using XPS.

Open Access August 25, 2013

Oligomers-model building in protonation equilibria of sitagliptin

Milan Meloun, Zuzana Ferenčíková, Irena Niesnerová, Tomáš Pekárek

Page range: 1799-1807

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Abstract

Mixed protonation constants of sitagliptin phosphate at various ionic strengths I (mol kg−1) in range 0.01 and 0.50 and at 298.15 K are determined using FBSTAC4 and HYPERQUAD nonlinear regression analyses of the potentiometric titration curve. At a low concentration c L = 1.1 mmol kg−1 the monomers L, LH, LH2, LH3 and LH4 dominate, while for a concentration range from c L = 13.7 to 24.7 mmol kg−1 dimers L2H2, L2H3, L2H4 and L2H are mainly present. The regression programme has almost no influence on the precision of the protonation constants. The accuracy of the protonation constants log βqr depends on the accuracy of the group parameters. As two group parameters c L,0, c H,T are ill-conditioned in a model, their determination is therefore uncertain: both can significantly cause a systematic error in the estimated common parameters log10βqr . Fitness tests using regression diagnostics have proven the reliability of the parameter estimates.

Open Access August 25, 2013

Polymer conjugates with potential biological activity based on new derivatives of 2-mercaptobenzoxazole-synthesis and characterization

Rǎdiţa Aparaschivei, Valeriu Şunel, Mihaela Holban, Marcel Popa, Jacques Desbrieres

Page range: 1808-1815

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Abstract

New potentially biologically active compounds derived from 2-mercapto-benzoxazole were synthesized and coupled on polymeric support of poly (maleic anhydride-alt-vinyl acetate) for the preparation of polymer-drug conjugates with controlled drug release. All compounds were characterized by elemental and spectroscopy (FT-IR, 1H-NMR) analysis. The toxicological tests recommend the products for further laboratory screening.

Open Access August 25, 2013

Ionic liquids based on 2-chloroethyltrimethylammonium chloride (CCC) as plant growth regulators

Tadeusz Praczyk, Katarzyna Zakrocka, Danuta Wyrzykowska, Michał Niemczak, Juliusz Pernak

Page range: 1816-1821

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Abstract

Plant growth regulator — 2-chloroethyltrimethylammonium chloride (CCC) was converted into ionic liquid in the metathesis reaction. New forms of CCC as ILs were stable in air as well in contact with water and organic solvents. The biological action of the cation (CCC) in ILs was preserved. Type of anion determined hydrophobicity and hydrophilicity of the whole molecule and it also influenced the biological activity of the plant growth regulator. All of the investigated salts retarded growth of winter wheat stems and most of them increased yield at the same time, when compared to control and standard 2-chloroethyltrimethylammonium chloride.

Open Access August 25, 2013

Molecular structures of metalmacrocyclic chelates of 3d-elements formed at template synthesis in the ion M(II)- thiooxamide-guanidine-formaldehyde quaternary systems

Oleg Mikhailov, Denis Chachkov, Olga Grigorieva

Page range: 1822-1829

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Abstract

Using density functional theory (DFT) at the OPBE/TZP level, the calculation of the geometric parameters of the molecular structures of M(II) (5456)macrotetracyclic complexes with a tetradentate macrocyclic ligand with (NNNN)-coordination of donor centers, resulting from template reactions in M(II)- thiooxamide- guanidine-formaldehyde quaternary systems, where M= Mn, Fe, Co, Ni, Cu, Zn was performed. The calculation of the molecular structure of this “template” ligand itself was also carried out. The values of the bond lengths, bond and torsion angles in the resulting complexes are presented. The values of the standard enthalpy, entropy and Gibbs free energy of formation of these compounds were also calculated.

Open Access August 25, 2013

Flow-injection spectrophotometric determination of dipyrone in pharmaceutical formulations using a solid-phase reactor with copper(II) phosphate

Viviane Bonifácio, Orlando Filho, Luiz Marcolino-Júnior

Page range: 1830-1836

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Abstract

In this work, a flow-injection spectrophotometric method for dipyrone determination in pharmaceutical formulations was developed. Dipyrone sample solutions were injected into a carrier stream of deionized water and the reaction was carried out in a solid-phase reactor (12 cm, 2.0 mm i.d.) packed with Cu3(PO4)2(s) entrapped in a matrix of polyester resin. The Cu(II) ions were released from the solid phase reactor by the formation of Cu(II)-(dipyrone)n complex. When the complex is released, it reacts with 0.02% m/v alizarin red S in deionized water to produce a Cu(VABO3)3 complex whose absorbance was monitored at 540 nm. The calibration graph was linear over the range 5.0×10−5–4.0×10−4 mol L−1 with a detection limit of 2.0×10−5 mol L−1 and relative standard deviation for 10 successive determinations of 1.5% (2.0×10−4 mol L−1 dipyrone solution). The calculated sample throughput was 60 h−1. The column was stable for at least 8 h of continuous use (500 injections) at 25°C. Pharmaceutical formulations were analyzed and the results from an official procedure measurement were compared with those from the proposed FIA method in order to validate the latter method.

Open Access August 25, 2013

Differential pulse adsorptive stripping voltammetric determination of methotrexate using a functionalized carbon nanotubes-modified glassy carbon electrode

Geiser Oliveira, Bruno Janegitz, Valtencir Zucolotto, Orlando Fatibello-Filho

Page range: 1837-1843

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Abstract

A glassy carbon electrode (GC) containing multiwalled functionalized carbon nanotubes (MWCNTs) immobilized within a dihexadecylhydrogenphosphate film (DHP) is proposed as a nanostructured platform for determination of methotrexate (MTX) concentration (a drug used in cancer treatment) using differential pulse adsorptive stripping voltammetry (DPAdSV). The voltammograms for a MTX solution using MWCNTs-DHP/GC electrode presented an oxidation peak potential at 0.98 V vs. Ag/AgCl (3.0 mol L−1 KCl) in a 0.1 mol L−1 sulphuric acid. The apparent heterogeneous electron transfer rate constant of 0.46 s−1 was calculated. The recovery area of 2.62×10−9 mol cm2 was also obtained. Under the optimal experimental conditions, the analytical curve was linear in the MTX concentration range from 5.0×10−8 to 5.0×10−6 mol L−1, with a detection limit of 3.3×10−8 mol L−1. The MWCNTs-DHP/GC electrode can be easily prepared and was applied for the determination of MTX in pharmaceutical formulations, with results similar to those obtained using a high-performance liquid chromatography comparative method.

Open Access August 25, 2013

New 5-bromo-2-hydroxybenzaldehyde S-ethylisothiosemicarbazone and its mixed-ligand Cu(II) complex with imidazole: synthesis, characterization and DFT calculation

Reza Takjoo, Alireza Akbari, Mehdi Ahmadi, Hadi Rudbari, Giuseppe Bruno

Page range: 1844-1851

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Abstract

A new Schiff base ligand of 5-bromo-2-hydroxybenzaldehyde S-ethyl-isothiosemicarbazone (H2L) was synthesized and its mixed-ligand Cu(II) complex was also prepared by reaction of Cu(NO3)2·3H2O with H2L and imidazole. Their structures were fully characterized by elemental analysis, FT-IR, molar conductivity and UV-Vis methods. The analytical data suggest that the metal, H2L and imidazole ratios in the Schiff base complex are 1:1:1. Single crystal diffraction was also used to better understand the molecular structure of the Cu(II) complex. The results of physico-chemical analyses of the Schiff base complex reveal the coordination geometry around the central atom is square planar. The H2L ligand (NNO donor) is coordinated to the metal center as a tridentate bionegatively agent. Another position of the square planar geometry is occupied by the imidazole ligand. Furthermore, computational studies of the new complex were performed by carrying out DFT calculations. Geometry optimization and natural band analysis of the complex is discussed in further detail.

Open Access August 25, 2013

Extractants selection for hyphenated electrothermal atomic absorption method

Antonina Alemasova, Natalya Alemasova, Alexander Pupyshev

Page range: 1852-1859

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Abstract

The theoretical approach for extractants selection during hyphenated atomic absorption determination of highly volatile metals (Pb, Cd), hydride- (Sb, Bi) and carbide-forming (Cr) metals using thermodynamic modelling was proposed. The calculated parameter — maximum pyrolysis temperature — can be used for selection of the extractants and chemical modifiers. Using this approach the antimony extract with Brilliant green was modified for which the 1.8-fold sensitivity and 2.6-fold repeatability decreasing while extract sampling in graphite furnace was observed. A chemical modifier — mixture of hydrazine nitrate with the palladium(II) complex with Xylenol orange — was theoretically selected and experimentally tested, which allowed to enhance the maximum pyrolysis temperature on 200°C, to eliminate extract matrix influence. Using this modifier two-fold increasing in sensitivity and 3-fold decreasing in relative standard deviation was achieved while extraction atomic absorption determination.

Open Access August 25, 2013

Dispersive evaluation and surface chemistry of advanced, multifunctional silica/lignin hybrid biomaterials

Magdalena Nowacka, Łukasz Klapiszewski, Małgorzata Norman, Teofil Jesionowski

Page range: 1860-1873

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Abstract

Advanced silica/lignin hybrid biomaterials were obtained using hydrated or fumed silicas (Aerosil®200) and Kraft lignin as precursors, which is a cheap and biodegradable natural polymer. To extend the possible range of applications, the silicas were first modified with N-2-(aminoethyl)-3-aminopropyltrimethoxsysilane, and then with Kraft lignin, which had been oxidized with sodium periodate. The SiO2/lignin hybrids and precursors were characterised by means of determination of their physicochemical and dispersive-morphological properties. The effectiveness of silica binding to lignin was verified by FT-IR spectroscopy. The zeta potential value provides relevant information regarding interactions between colloid particles. Measurement of the zeta potential values enabled an indirect assessment of stability for the studied hybrid systems. Determination of zeta potential and density of surface charge also permitted the quantitative analysis of changes in surface charge, and indirectly confirmed the effectiveness of the proposed method for synthesis of SiO2/lignin hybrid materials. A particularly attractive feature for practical use is their stability, especially electrokinetic stability. It is expected that silica/lignin hybrids will find a wide range of applications (polymer fillers, biosorbents, electrochemical sensors), as they combine the unique properties of silica with the specific structural features of lignin. This makes these hybrids biomaterials advanced and multifunctional.

Open Access August 25, 2013

Erratum to: “In vitro biological activity comparison of some hydroxyapatite-based composite materials using simulated body fluid”

Melinda Czikó, Erzsébet-Sára Bogya, Réka Barabás, Liliana Bizo, Răzvan Stefan

Page range: 1874-1874

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Abstract

The original version of the article was published in Cent. Eur. J. Chem. 11(10) (2013) pp. 1583–1598. Unfortunately, the original version of this article contains a mistake in the affiliation section. The affiliation for Răzvan Stefan is Veterinary Medicine Faculty, University of Agricultural Science and Veterinary Medicine, RO-400372 Cluj Napoca, Romania.

About this journal

Open Chemistry is a peer-reviewed, open access journal that publishes original research, reviews, and communications in the fields of chemistry in an ongoing way. Our central goal is to provide a hub for researchers working across all subjects to present their discoveries, and to be a forum for the discussion of the important issues in the field.

There are no submission charges. In order to sustain the production of our fully-refereed open access journal, each article accepted for publication in Open Chemistry is subject to Article Processing Charges (APC).

Special/Topical Issues:

Advanced Nanomaterials for Energy, Environmental and Biological Applications
Submission deadline: 30.09.2023

Marine Environmental Sciences and significance of the multidiscplinary approaches for assessing pollutions, remedies, and predictions
Submission deadline: 30.09.2023

Energy conversion and energy storage reactions
Submission deadline: 30.09.2023

Recent Trends in Green Chemistry
Submission deadline: 30.09.2023
Therapeutic Potentials of Natural Compounds Targeting Malaria
Submission deadline: 30.09.2023
Advancements at the Nexus of Mathematics, Artificial Intelligence, and IoT in Medicinal Chemistry and Healthcare
Submission deadline: 30 June 2024

You are also welcome to submit your Special Issue proposal by contacting Managing Editor at openchemistry@degruyter.com

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Catalysis Conferences
Submission deadline: 30.09.2023
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Euro-Mediterranean Conference for Environmental Integration 2023
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CFP Applied Biochemistry and Biotechnology 2023
Submission deadline: 30.11.2023
World Chemistry Forum 2024
Date: 1.02 - 3.02.2024
2nd International Summit on Biopolymers and Polymer Science
Date: 10-12.06.2024
4th Edition of the International Conference on Green Chemistry and Renewable Energy
Date: 17-19.06.2024
11th International Conference on Materials Research and Nanotechnology
Date: 1.07 – 2.07.2024
2nd Global Summit on Advanced Materials and Sustainable Energy (GAMSE24)
Submission Deadline: 31.07.2024
European Congress of Applied Chemistry (ECAC24)
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