Open Access Published by De Gruyter Open Access

Volume 12 Issue 3

March 2014

Issue of Open Chemistry

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Contents
Journal Overview

Open Access December 21, 2013

Crystallographic and structural characterization of heterometallic platinum complexes Part V. Heteropentanuclear complexes

Milan Melník, Peter Mikuš, Clive Holloway

Page range: 283-306

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Abstract

This review classifies and analyzes over eighty heteropentanuclear Pt complexes. There are eight types of metal combinations: Pt4M, Pt3M2, Pt2M3, PtM4, Pt3MM′, Pt2M2M′, PtM2M′2 and PtM3M′. The five metal atoms are in a wide variety of arrangements: trigonal-bipyramidal (most common), square-pyramidal, spike-triangular, butterfly, cubane, linear and one unique. Platinum bonds to a variety of triad partner metal atoms, soft, through borderline to hard. The shortest Pt-M bond distances for non-transition and transition M are 2.406(4) Å (M = Ge) and 2.30(1) Å (M = Co). The shortest Pt-Pt bond distance is 2.580(1) Å. Several relationships between the structural parameters were found and are discussed. Several complexes exist in two isomeric forms and others contain two crystallographically independent molecules. Both the isomers as well as independent molecules are examples of distortion isomerism.

Open Access December 21, 2013

Spectroscopic route to monitoring individual surfactant ions and micelles in aqueous solution: A case study

Junfeng Geng, Brian Johnson, Andrew Wheatley, Jack Luo

Page range: 307-311

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Abstract

Using a very popular and commonly used surfactant sodium dodecylbenzene sulfonate (SDBS, C18H29SO3Na) for a case study, we report a new method of monitoring different forms of surfactant molecules in aqueous solution and measuring their critical micelle concentration (CMC) by ultraviolet-visible (UV-Vis) spectroscopy. The forms of SDBS micelles are also investigated by synthesizing and characterizing NiB nanoparticles using the micelles as molecular templates. In addition, the observed shifts of UV-Vis bands are analysed from the viewpoint of the electrons locations and distributions within the molecules and the possible overlap of their electronic orbitals between neighbouring molecules in each micelle.

Open Access December 21, 2013

Agglomeration of ZnS nanoparticles without capping additives at different temperatures

Petr Praus, Richard Dvorský, Petr Kovář, Ladislav Svoboda

Page range: 312-317

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Abstract

ZnS nanoparticles were precipitated in diluted aqueous solutions of zinc and sulphide ions without capping additives at a temperature interval of 0.5–20°C. ZnS nanoparticles were arranged in large flocs that were disaggregated into smaller agglomerates with hydrodynamic sizes of 70–150 nm depending on temperature. A linear relationship between hydrodynamic radius (R a) and temperature (T) was theoretically derived as R a =652 - 2.11 T. The radii of 1.9–2.2 nm of individual ZnS nanoparticles were calculated on the basis of gap energies estimated from their UV absorption spectra. Low zeta potentials of these dispersions of −5.0 mV to −6.3 mV did not depend on temperature. Interactions between individual ZnS nanoparticles were modelled in the Material Studio environment. Water molecules were found to stabilize ZnS nanoparticles via electrostatic interactions.

Open Access December 21, 2013

Thermodynamic investigation of the binary and ternary complexes involving 1-aminocyclopropane carboxylic acid with reference to plant hormone

Mohamed Shoukry, Safaa Hassan

Page range: 318-324

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Abstract

Complex formation equilibria of 1-aminocyclopropane carboxylic acid (ACC) and 3,3-bis(1-methylimidazol-2-yl) propionic acid (BIMP) with metal ions Cu2+, Ni2+, Co2+, Zn2+, Mn2+ and Fe2+ were investigated. ACC forms 1:1 and 1:2 complexes in addition to the hydrolysed form of the 1:1 complex, except in the case of Mn2+ and Fe2+, where the hydrolysed complex is not formed. BIMP forms 1:1 and 1:2 complexes in addition to the hydrolsed form of the 1:1 complex in the case of Mn2+ and Cu2+, however the hydrolysed complex is not detected for Ni2+, Co2+, Zn2+ and Fe2+. The concentration distribution diagrams of the complexes were determined. The Fe2+-complex with BIMP is exothermic and the thermodynamic parameters were calculated. The effect of organic solvent on the acid dissociation constants of 1-aminocyclopropane carboxylic acid (ACC) and 3,3-bis(1-methylimidazol-2-yl) propionic acid (BIMP) and the formation constants of Fe2+ complexes were investigated. Fe2+ forms a mixed-ligand complex with ACC and BIMP with stoichiometric coefficients 1:1:1. The formation constant was determined. The ternary complex is enhanced by back donation from the negatively charged 1-aminocyclopropane carboxylate to the π-system of BIMP. From the concentration distribution diagram, the ternary complex prevails in the physiological pH range.

Open Access December 21, 2013

Determination of vitamin B6 (pyridoxine hydrochloride) based on a novel BZ oscillating reaction system catalyzed by a macrocyclic complex

Qingling Zeng, Lulu Chen, Xianyi Song, Gang Hu, Lin Hu

Page range: 325-331

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Abstract

This paper reports a new method for determination of VB6 (pyridoxine hydrochloride) by its perturbation effects on a novel Belousov-Zhabotinskii (BZ) oscillating system. This novel BZ system, in which malic acid serves as the substrate, contains an enzyme-like complex, macrocyclic complex {[CuL](ClO4)2}, as catalyst. The ligand L in the complex is 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene. Results show that the addition of pyridoxine hydrochloride can perturb the oscillation amplitude and period, and the change of the oscillation amplitude is linearly proportional to the concentration of pyridoxine hydrochloride in the range of 5×10−7−2.5×10−4 M. The obtained RSD with seven samples is 3.073%. An assay of pharmaceutical tablets of vitamin B6 was evaluated. Some foreign ions were studied with respect to their possible influence on the determination of pyridoxine hydrochloride. The factors which influence this reaction include the concentration of reactant, the temperature of the reaction, property of catalyst, etc. Furthermore, the possible reaction mechanism has been proposed using the Field-Körös-Noyes (FKN) model.

Open Access December 21, 2013

The exploration of interaction studies of smaller size, mostly ignored yet intrinsically inestimable molecules towards BSA; An example of STD and DOSY NMR

Sheraz Tanoli, Nazish Tanoli, Saman Usmani, Zaheer-Ul-Haq, Antonio Ferreira

Page range: 332-340

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Abstract

Larger size or novel structure molecules are always appreciated by all fields of experimental and computational science. Conversely, molecules with smaller size and simple structures are usually ignored with no explanation as to why. However, the vast majority of more diminutive molecules behave as a cornerstone in the synthesis of a bigger structural framework. Subsequently, we planned to uncover the interactions of small molecules towards macromolecules, and successfully presented the binding results of 2-aminopyridine and Isovanillin towards BSA through NMR techniques. STD epitope mapping and also the DOSY results provided evidence that Isovanillin remained closer to the binding cavity of protein. Titration experiments afforded 584 µM (0.584mM) and 487 µM (0.487 mM) dissociation constants for isovanillin and 2-aminopyridine respectively. Furthermore, changes in diffusion coefficient (with and without protein addition in DOSY spectra) were found to be 0.081 log (m2 s−1) and 0.096 log (m2 s−1) points for isovanillin and 2-aminopyridine respectively. Docking studies exhibit that these molecules can tie to site 1 (sub-area IIA) through the pi-pi interaction and hydrogen bonding with Trp213. Our results demonstrated that both compounds could be utilized as part of a transporter in the circulatory system and their extension-inspired compounds may be utilized in new drug design.

Open Access December 21, 2013

A low-cost automated flow analyzer based on low temperature co-fired ceramic and LED photometer for ascorbic acid determination

Osmundo Pessoa-Neto, Vagner Santos, Fernando Vicentini, Willian Suarez, Julián Alonso-Chamarro, Orlando Fatibello-Filho, Ronaldo Faria

Page range: 341-347

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Abstract

An automated flow analyzer based on low temperature co-fired ceramic (LTCC), a solid-phase reactor (SPR) and a low-cost photometer was designed for ascorbic acid (AA) determination in pharmaceutical formulations. It consists of a peristaltic pump, three-way solenoid valves, SPR to chemically convert Cu(II) into Cu(I), and a LTCC device for mixing the liberated copper with bathocuproine and detection. The flow cell in the LTCC employed an ultrabright LED — photodiode photometer. The analyzer successfully determined AA in pharmaceutical formulations. The analytical curve from 8.5×10−6 to 7.0×10−4 M gave a detection limit of 7.0×10−7 M and a RSD of 2.1% for a 2.0×10−4 M AA solution (n = 10). A high sampling frequency of 102 h−1 and low reagent and sample consumption (150 µL) resulted.

Open Access December 21, 2013

Solvent extraction with organophosphorus extractants in environmental samples: determination of cadmium(II) in natural water

Victoria Mánuel, Juan Pinto, Carolina Mendiguchía, Carlos Moreno

Page range: 348-353

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Abstract

In this work, Cd(II) extraction in natural waters by organophosphorus extractants as organic phase, as well as its back-extraction in an acidic media, has been studied. Cadmium extraction behavior at natural waters’ pH conditions (values in the range 7–8) was studied with two different extractants and co-ions, obtaining the highest extraction efficiency when using 0.1M Cyanex 272 in kerosene as organic phase and 0.1 M NO3 − as co-ion. Once they were selected, the effect on the extraction efficiency of sample pH, buffer concentration, extraction time, Cyanex 272 concentration as well as back-extractant concentration, was studied. The presence of the main inorganic and organic ligands in the sample was also studied, observing that extraction efficiency was affected most significantly when chlorides were present, with a decrease of about 14%, proving negligible for the others. Under the selected conditions, spiked real samples were successfully analyzed.

Open Access December 21, 2013

Solid contact Zn2+ -selective electrode with low detection limit and stable and reversible potential

Cecylia Wardak

Page range: 354-364

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Abstract

A new solid contact Zn2+ polyvinylchloride membrane sensor with 2-(2-Hydroxy-1-naphthylazo)-1,3,4 -thiadiazole as an ionophore has been prepared. For the electrode construction, ionic liquids, alkylmethylimidazolium chlorides are used as transducer media and as a lipophilic ionic membrane component. The addition of ionic liquid to the membrane phase was found to reduce membrane resistance and determine the potential of an internal reference Ag/AgCl electrode. The electrode with the membrane composition: ionophore: PVC: o-NPOE: ionic liquid in the percentage ratio of (wt.) 1:30:66:3, respectively, exhibited the best performance, having a slope of 29.8 mV decade−1 in the concentration range 3×10−7–1×10−1 M. The detection limit is 6.9×10−8 M. It has a fast response time of 5–7 s and exhibits stable and reproducible potential. It has a fast response time of 5–7 s and exhibits stable and reproducible potential, which does not depend on pH in the range 3.8–8.0. The proposed sensor shows a good and satisfactory selectivity towards Zn2+ ion in comparison with other cations including alkali, alkaline earth, transition and heavy metal ions. It was successfully applied for direct determination of zinc ions in tap water and as an indicator electrode in potentiometric titration of Zn2+ ions with EDTA.

Open Access December 21, 2013

QSAR of caffeines by similarity cluster prediction

Teodora Harsa, Alexandra Harsa, Beata Szefler

Page range: 365-376

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Abstract

A novel QSAR approach based on correlation weighting and alignment over a hypermolecule that mimics the investigated correlational space was performed on a set of 40 caffeines downloaded from the PubChem database. The best models describing log P and LD50 values of this set of caffeine derivatives were validated against the external test set and in a new predictive model by using clusters of similarity.

Open Access December 21, 2013

Effect of extraction conditions of paprika oleoresins on their free radical scavenging and anticancer activity

Vesna Šaponjac, Dragana Četojević-Simin, Gordana Ćetković, Jasna Čanadanović-Brunet, Sonja Djilas, Anamarija Mandić, Aleksandra Tepić

Page range: 377-385

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Abstract

Ground spice paprika was extracted with hexane, by conventional Soxhlet procedure (SX oleoresin), and with supercritical carbon dioxide at three different pressures — 20, 30 and 40 MPa (SF20, SF30 and SF40 oleoresins). The effect of extraction method and conditions on the colour intesity of paprika oleoresins, content of α-tocopherol, as well as antioxidant and antiproliferative activity was examined. Hexane showed highest selectivity for paprika pigments (886.02 ASTA), while α-tocopherol showed highest solubility (3846.9 mg kg−1) in supercritical carbon dioxide at 20 MPa. All paprika oleoresins exhibited good superoxide anion radical scavenging activity SF30 being the best superoxide anion radical scavenger. Cell growth activity was evaluated in vitro in human cell lines:cervix epitheloid carcinoma (HeLa), breast adenocarcinoma (MCF7) and colon adenocarcinoma (HT-29). The highest antiproliferative activity was exhibited by SX in MCF7 cell line (IC50=14.28 mg mL−1). Extract SF40 produced significant and selective antiproliferative action towards HeLa cell line. These results suggest that paprika oleoresins, due to high antiradical and tumor cell-inhibiting activity, can be regarded as functional food ingredients.

Open Access December 21, 2013

Lead and cadmium atomic absorption determination in solid carbonized food samples using flame-furnace atomizer

Kostyantyn Lugovyy, Olexander Buhay, Antonina Alemasova

Page range: 386-390

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Abstract

Direct atomic absorption solid sampling analysis using flame-furnace atomizer enables a significant decrease in the analysis duration, to avoid sample pollution and to exclude toxic reagents. The selection of the chemical modifiers decreasing the detection limit and improving the results repeatability is based on the analyte’s free atoms formation mechanism. The developed kinetic approach has allowed to determine pre-exponential factors k0 and apparent activation energies Ea of atomization processes for Pb(II) and Cd(II) compounds and to propose effective chemical modifiers sodium N,N-diethyldithiocarbamate and urea for food samples. The express and precision technique for lead and cadmium determination in food, using proposed chemical modifiers and carbonization techniques was developed.

Open Access December 21, 2013

Numerical study of the laminar flame propagation in ethane-air mixtures

Venera Giurcan, Domnina Razus, Maria Mitu, Dumitru Oancea

Page range: 391-402

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Abstract

The structure of premixed free one-dimensional laminar ethane-air flames was investigated by means of numerical simulations performed with a detailed mechanism (GRI-Mech version 3.0) by means of COSILAB package. The work provides data on ethane-air mixtures with a wide range of concentrations ([C2H6] = 3.0–9.5 vol.%) at initial temperatures between 300 and 550 K and initial pressures between 1 and 10 bar. The simulations deliver the laminar burning velocities and the profiles of temperature, chemical species concentrations and heat release rate across the flame front. The predicted burning velocities match well the burning velocities measured in various conditions, reported in literature. The influence of initial concentration, pressure and temperature of ethane-air mixtures on maximum flame temperature, heat release rate, flame thickness and peak concentrations of main reaction intermediates is examined and discussed.

Open Access December 21, 2013

Spectral properties and photophysical behaviour of water soluble cationic Mg(II) and Al(III) phthalocyanines

Mopelola Idowu, Yasin Arslanoğlu, Tebello Nyokong

Page range: 403-415

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Abstract

Peripherally and non-peripherally tetrasubstituted-[(N-methyl-2-pyridylthio)]phthalocyaninato magnesium (II) (5 and 6) and chloro aluminium (III) (7 and 8) tetraiodide have been synthesized and characterized. The photophysical properties of the complexes in dimethyl sulfoxide (DMSO) and aqueous medium in the presence and absence of cremophore EL have been studied. These complexes show high solubility in aqueous medium though they were aggregated. The triplet state quantum yields (FT) and the triplet lifetimes (tT) were found to be higher in DMSO with ΦT ranging from 0.32 to 0.51, while tT ranged from 282 to 622 ms in DMSO, compared to aqueous medium (pH 7.4 buffer) where ΦT ranged from 0.15 to 0.19 and tT from 26 to 35 ms. Addition of cremophore EL in aqueous solution resulted in partial disaggregation and increased photoactivity. The fluorescence lifetimes of the complexes showed strong dependence on their immediate environment. The ionic magnesium(II) and aluminium(III) phthalocyanines strongly bind to bovine serum albumin (BSA).

Open Access December 21, 2013

Enantioselective Michael additions of aldehydes to nitroalkenes catalyzed with ionically tagged organocatalyst

Radovan Šebesta, Attila Latika

Page range: 416-425

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Abstract

Enantioselective organocatalytic Michael additions affords useful building blocks for many biologically and medicinally relevant compounds. Ionically-tagged diphenylprolinol silyl ether efficiently catalyzes several Michael additions of aldehydes to nitroalkenes in ionic liquids. The Michael additions work well in ionic liquids; yields up to 95% and enantioselectivities up to 95% ee were achieved. Furthermore, in some cases, the catalytic system was reusable.

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:

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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Submission deadline: 30.09.2023
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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
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Date: 17-19.06.2024
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Date: 1.07 – 2.07.2024
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European Congress of Applied Chemistry (ECAC24)
Submission Deadline: 31.07.2024