Open Access Published by De Gruyter Open Access

Volume 6 Issue 3

September 2008

Issue of Open Chemistry

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Contents
Journal Overview

Open Access August 11, 2008

Molecular machines operated by light

Alberto Credi, Margherita Venturi

Page range: 325-339

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Abstract

The bottom-up construction and operation of machines and motors of molecular size is a topic of great interest in nanoscience, and a fascinating challenge of nanotechnology. Researchers in this field are stimulated and inspired by the outstanding progress of molecular biology that has begun to reveal the secrets of the natural nanomachines which constitute the material base of life. Like their macroscopic counterparts, nanoscale machines need energy to operate. Most molecular motors of the biological world are fueled by chemical reactions, but research in the last fifteen years has demonstrated that light energy can be used to power nanomachines by exploiting photochemical processes in appropriately designed artificial systems. As a matter of fact, light excitation exhibits several advantages with regard to the operation of the machine, and can also be used to monitor its state through spectroscopic methods. In this review we will illustrate the design principles at the basis of photochemically driven molecular machines, and we will describe a few examples based on rotaxane-type structures investigated in our laboratories.

Open Access August 11, 2008

Synthesis and structural peculiarities of gallium Complexes with novel paullone derivatives

Werner Ginzinger, Vladimir Arion, Gerald Giester, Markus Galanski, Bernhard Keppler

Page range: 340-346

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Abstract

9-Bromo-7,12-dihydroindolo[3,2-d][1]benzazepin-6-ylhydrazine was reacted with 2-acetylpyridine to give a Schiff base as a potential tridentate ligand. The reaction of this ligand with gallium chloride afforded complexes of 1:1 and 2:1 stoichiometry. The results of X-ray diffraction studies of the ligand and both gallium complexes are reported and compared with the data for a related gallium complex with a Schiff base obtained from 9-bromo-7,12-dihydroindolo[3,2-d][1]benzazepin-6-ylhydrazine and 2-hydroxybenzaldehyde.

Open Access August 11, 2008

Nuclear magnetic resonance spectroscopic studies of the trihexyl (tetradecyl) phosphonium chloride ionic liquid mixtures with water

Jerrod Dwan, Dan Durant, Khashayar Ghandi

Page range: 347-358

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Abstract

Tetra-alkyl Phosphonium ionic liquids are phosphonium salts with melting points near room temperature. We report the NMR studies of water-trihexyl (tetradecyl) phosphonium chloride ionic liquid mixtures. The proton chemical shifts were used to investigate the intermolecular interactions in mixtures of ionic liquids and water. The OH chemical shifts were found to decrease as the water concentration in the ionic liquid increased, and their rate of change with temperature decreased with water concentration. The CH2 and CH3 chemical shifts were found to move downfield with the increase in temperature, and moved further downfield as water concentration was decreased. The interface of experimental data and the results of quantum calculations suggest a significant binding of phosphonium cations to chloride anion and water molecules. As well, the analysis of the data suggests a possible transformation from cationchloride-water configuration at low water concentrations to cation-water-water at higher water concentrations.

Open Access August 11, 2008

Ugi products containing boronate esters

Francis Appoh, Marcy Manning, Teri Gullon, Margaret Hansen, Emily Bevans, Krista Hogan, Courtney Turner, Christopher Vogels, Andreas Decken, Stephen Westcott

Page range: 359-364

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Abstract

The Ugi reaction with formylphenylboronic acid derivatives as the carbonyl component proceeds to give the corresponding boron-containing dipeptide derivatives (Ugi products) in good yields.

Open Access August 11, 2008

Can N-heterocyclic germylenes behave as Lewis acids - is there another side to Meller germylenes?

Olaf Kühl

Page range: 365-372

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Abstract

N-Heterocyclic germylenes are known to exist in two structurally different forms, the planar Meller germylenes and the monoimino germylenes that feature an envelope structure. This essay reviews recent reports dealing with radical and cationic Meller type germylenes featuring the monoimino germylene structure, discusses their transformations and relationships, and asks the question whether indeed N-heterocyclic germylenes can be turned into Lewis acids.

Open Access August 11, 2008

Gas-phase synthesis of inorganic fullerene-like structures and inorganic nanotubes

F. Deepak, Reshef Tenne

Page range: 373-389

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Abstract

Following the discovery of fullerenes (C60) and carbon nanotubes, it was shown that nanoparticles of inorganic layered compounds, like WS2 and MoS2, are unstable in the planar form and they form closed cage structures with polyhedral or nanotubular shapes. Although initially the method of synthesis for the formation of such closed caged structures and nanotubes involved starting from the respective oxides, it is now well established that the gas-phase synthetic route (using metal chlorides, carbonyls etc) provides an alternative which is suitable for the synthesis of very many closed caged structures and nanotubes hitherto unknown. Various issues with this method of synthesis, including its fundamentals, mechanism, and the properties of the inorganic fullerene-like structures produced are reviewed, together with some possible applications.

Open Access August 11, 2008

Synthesis of Xenbucin using Suzuki reaction catalyzed by Pd/C in water

Noora Kuuloja, Tuula Kylmälä, Youjun Xu, Robert Franzén

Page range: 390-392

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Abstract

Xenbucin 1, an analgesic drug, was synthesized in 4 steps using two different routes. The biaryl fragment could successfully be produced via a Pd/C catalysed Suzuki coupling in water using sodium tetraphenylborate as a phenylation reagent. Overall yields of the routes were 36% and 59%, respectively.

Open Access August 11, 2008

Solid-state linear polarized IR-spectroscopy of croconic and rhodizonic acids

Tsonko Kolev, Bojidarka Koleva, Michael Spiteller

Page range: 393-399

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Abstract

The applications of linear-polarized IR-spectroscopy to oriented colloid suspensions in a nematic host are demonstrated with croconic and rhodizonic acids. The experimental IR vibrational assignments of the solid-state of both neutral compounds are presented. Assignments are supported by theoretical quantum chemical calculations and vibrational analysis at the DFT level of theoretical approximation with the 6-311++G** basis set.

Open Access August 11, 2008

A G2(MP2) theoretical study of substituent effects on H3BNHnCl3−n (n= 3-0) donor-acceptor complexes

Hafid Anane, Soufiane Houssame, Abdelali Guerraze, Abdeladim Guermoune, Abderrahim Boutalib, Abedellah Jarid, Ignacio Nebot-Gil, Francisco Tomás

Page range: 400-403

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Abstract

The complexation energies of H3BNHnCl3−n (n= 3-0) complexes and the proton affinities of NHnCl3−n compounds have been computed at the G2(MP2) level of theory. G2(MP2) results show that the successive chlorine substitution on the ammonia decreases both the basicity of the NHnCl3−n ligands and the stability of H3BNHnCl3−n complexes. The findings are interpreted in terms of the rehybridisation of the nitrogen lone-pair orbital. The NBO partitioning scheme shows that the variation of the N-H and N-Cl bond lengths, upon complexation, is due to variation of “s” character in these bonds.

Open Access August 11, 2008

Efficient synthesis of diarylidene octahydroacridines by one-pot multi-component tandem reactions

Qi-Fang Wang, Chao-Guo Yan

Page range: 404-409

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Abstract

A one-pot multi-component reaction is developed for the efficient synthesis of 4,5-dibenzylidene octahydroacridines in high yields. The reaction is performed by the tandem reaction of three molar equivalent aromatic aldehydes with two molar equivalent 4-alkylcyclohexanone in the system of NH4OAc/HOAc under microwave irradiation.

Open Access August 11, 2008

Determination of phenolic acids by capillary zone electrophoresis and HPLC

František Kvasnička, Jana Čopíková, Rudolf Ševčík, Jana Krátká, Andrej Syntytsia, Michal Voldřich

Page range: 410-418

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Abstract

Selected phenolic acids are determined by capillary zone electrophoresis and HPLC, each using UV detection. The optimised CZE background electrolyte contained 50 mM acetic acid, 95 mM 6-aminocaproic acid, 0.1% polyacrylamide, 1% polyvinylpyrrolidone, and 10% methanol. Twelve phenolic acids (gallic, p-hydroxybenzoic, 3,4-dihydroxybenzoic, vanillic, syringic, o-coumaric, p-coumaric, caffeic, sinapic, ferulic, salicylic and chlorogenic) were separated within 10 minutes. Chromatographic separation of these phenolic acids was carried out on an Eclipse XBD C8 column using a mobile phase gradient (acetonitrile / methanol / water / 0.1% phosphoric acid); all were separated within 25 minutes. Electrophoretic and chromatographic determinations of ferulic and chlorogenic acids were compared on barley, malt, and potato samples. The methods’ characteristics were: linearity (1–20 mg ml and 0.2–4 mg ml−1), accuracy (recovery 94 ± 5% and 96 ± 4%), intra-assay repeatability (4.1% and 3.5%), and detection limit (0.2 and 0.02 mg ml−1).

Open Access August 11, 2008

Kinetic studies for the esterification of acetic acid with epichlorohydrin over an anion exchange resin catalyst

Emil Muresan, Spiridon Oprea, Vasile Hulea, Theodor Malutan, Mihai Vata

Page range: 419-428

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Abstract

The kinetics of the esterification reaction between acetic acid and epichlorohydrin catalysed by Purolite A-520E strong basic anion exchange resin was studied. The effects of certain parameters such as stirring speed, particle diameter, temperature, catalyst amount and molar ratio between reactants were experimentally determined. It was found that the overall reaction rate is intrinsically kinetically controlled. The partial orders of reaction with respect to catalyst, acetic acid and epichlorohydrin were determined. A reaction mechanism is proposed. Based on chromatographic data and taking into account the partial orders of reaction, a more detailed kinetic model is suggested.

Open Access August 11, 2008

Novel pH responsive luminescent poly(oxyethylene phosphate) tris(β-diketonate) europium (III) complexes

Stanislav Stanimirov, Ivan Petkov

Page range: 429-437

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Abstract

The paper reports on the dependence of the absorbance and luminescent intensity from pH of novel poly(oxyethylene phosphate) tris(β-diketonate) europium (III) complexes. The photophysical data obtained allow some preliminary assumptions about the nature of this phenomenon. Increase in luminescent efficiency is a consequence of enhanced efficiency of energy transfer caused by structural changes in complexes after water deprotonation. Remarkable change has been observed in photophysical properties of the polymer complexes by studying the fluorescent emission and excitation spectra and absorption recorded at various pH both in solution and in the solid state. Some of the complexes derivative of the dibenzoylmethane (DBM) show more than hundred times increase in the luminescence after alkalization. The pH value, at which the maximum luminescent efficiency appears, depends on the type of the fourth ligand. The difference between luminescent efficiency of the complexes in alkaline and neutral environment depends on the β-diketonate ligands and on polymer type as well.

Open Access August 11, 2008

Thermodynamic and kinetic properties of scandium (I) ion reacting with SCO in gas phase

Ping Yin, Rongjun Qu, Hou Chen, Yuan Tian, Gui Yin, Chongrong Bao

Page range: 438-442

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Abstract

Theoretical studies on the thermodynamic and kinetic properties of the reactions of scandium (I) ion with the sulfur-transfer reagent SCO via the C-O bond activation pathway have been carried out over the temperature range of 200-1200 K using the DFT/B3LYP method, general statistical thermodynamics, and Eyring transition state theory with Wigner correction. The relevant reactions include reaction 1 1Sc+ + SCO → 1IM1 → 1TS1 → 1IM2 (Step 1) → 1TS2 → 1IM3 → 1ScO+ + 1CS (Step 2), and reaction 2 3Sc+ + SCO → 3IM1 → CP → 1IM2 → 1TS2 → 1IM3 → 1ScO+ +1CS in which the spin multiplicity changes from the triplet state to the singlet state in the crossing region. It was concluded that the order of the equilibrium constants (K) and the reaction rate constants (k) are consistent with that of their corresponding exoergic energies, ΔE, and reaction barriers, respectively. Step 2 of reaction 1 is both thermodynamically and kinetically favored over the whole temperature range. Moreover, both Reaction 1 and reaction 2 are exothermic and spontaneous processes in which their entropy increases, and the magnitudes of their thermodynamic values all decrease with increasing temperature.

Open Access August 11, 2008

2-(benzimidazol-2-yl)-3-hydroxychromone derivatives: spectroscopic properties and a possibile alternative intramolecular proton phototransfer

D. Svechkarev, G. Karpushina, L. Lukatskaya, A. Doroshenko

Page range: 443-449

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Abstract

Three 2-(benzimidazol-2-yl)-3-hydroxychromone derivatives were synthesized. Their spectroscopic and fluorescent properties, due to excited state intramolecular proton transfer (ESIPT) from OH to carbonyl, were studied. Theoretical possibility of an alternative intramolecular H-bonding and experimental evidence for such behavior are discussed.

Open Access August 11, 2008

Consequence of hydrogen atom abstraction from 5’-hydroxyl group of 2’-deoxyadenosine. Theoretical quantum mechanics study

Bolesław Karwowski

Page range: 450-455

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Abstract

Reactive oxygen species (ROS) may generate different nucleoside/nucleotide radicals in a cell environment. In this study, the possibility of cyclic-2’-deoxyadenosines formation by a rearrangement of their free radicals was investigated. It seems that for cyclic-nucleosides formation, adoption of an O4’-exo conformation by the sugar moiety is necessary. However, this is the energetically unfavoured form of the 2-deoxyribose ring. Moreover, the creation of a O5’, C8 bond in purine deoxy-nucleosides/nucleotides leads to the termination of the DNA elongation process.

Open Access August 11, 2008

Sol-gel preparation and characterization of non-substituted and Sr-substituted lanthanum cobaltates

Sigute Cizauskaite, Aivaras Kareiva

Page range: 456-464

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Abstract

This paper reports on the results concerning the sol-gel preparation and characterization of Sr-substituted perovskite lanthanum cobaltates La1−xSrxCoO3−δ (x = 0.0, 0.25, 0.5 and 0.75). The metal ions, generated by dissolving starting materials in diluted acetic acid were complexed by 1,2-ethanediol to obtain the precursors for the non-substituted and Sr-substituted LaCoO3. The influence of the synthesis temperature, heating time and the amount of substituent on the phase purity of La1−xSrxCoO3−δ were investigated. The phase transformations, composition and micro-structural features in the gels and polycrystalline samples were studied by thermal analysis (TG/DTA), infrared spectroscopy (IR), powder X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM).

Open Access August 11, 2008

2-pyrrolidone - capped Mn3O4 nanocrystals

Tevhide Özkaya, Abdulhadi Baykal, Muhammet Toprak

Page range: 465-469

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Abstract

Water-soluble Mn3O4 nanocrystals have been prepared through thermal decomposition in a high temperature boiling solvent, 2-pyrrolidone. The final product was characterized with XRD, SEM, TEM, FTIR and Zeta Potential measurements. Average crystallite size was calculated as ∼15 nm using XRD peak broadening. TEM analysis revealed spherical nanoparticles with an average diameter of 14±0.4 nm. FTIR analysis indicated that 2-pyrrolidone coordinates with the Mn3O4 nanocrystals only via O from the carbonyl group, thus confining their growth and protecting their surfaces from interaction with neighboring particles.

Open Access August 11, 2008

Palladium(0)-catalyzed amination of allylic natural terpenic functionalized olefins

Soufiane Houssame, Hafid Anane, Larbi Firdoussi, Abdellah Karim

Page range: 470-476

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Abstract

The palladium(0) catalyzed amination of allylic acetates and carbonates derivatives from terpenic olefins was carried out under mild conditions. The reaction offers a very good method for the preparation of allylic amines and thus to provide a useful entry to new functionalized terpenic olefin products. The mechanism involving a formation of p-allyl-palladium intermediate complex is in good agreement with the results obtained with the optically active substrates, as well as via an analysis of the observed regio-and stereoselectivity.

Open Access August 11, 2008

Synthesis and monolayer film of a series of new twin-tailed gemini cationic surfactants at the air/water interface

Zhi Chen, Yujun Feng, Dongliang Zhou, Puxin Zhu, Dacheng Wu

Page range: 477-481

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Abstract

A series of new dimeric surfactants, twin-tailed gemini surfactants, 2(12)-s-2(12), were successfully prepared and characterized, and their monolayer films investigated by the measurement of surface pressure-area (π-A) and surface pressure-time (π-t) isotherms at the air/water interface by a Langmuir film balance. Compared to their monomeric counterparts, their collapse pressure (γcollapse) is smaller, whilst all the molecular area parameters are larger. The limited area (Alimited) and the initial area (Ainitial) of these twin-tailed gemini surfactants change with increasing spacer length s, and the surface pressure decreases with increasing time. It was also found that the higher the initial surface pressure, the larger the attenuation.

Open Access August 11, 2008

Preparation and characterization of alumina-zirconia composite material with different acid ratios by the sol-gel method

Ozgecan Ergu, Metin Gürü, Canan Cabbar

Page range: 482-487

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Abstract

Alumina-zirconia composite materials were produced with different acid ratios by the sol-gel method using aluminum isopropoxide and zirconium chloride. The composites were produced by changing acid/alkoxside ratio in alumina. The composite materials were calcinated at 600°C, 900°C and 1300°C. The effects of acid concentration and calcination temperature on the surface area and pore radius were determined from the nitrogen adsorption isotherm at 77 K. The density of the composites was also measured. The minimum density of produced material was recorded as 1.35 g cm−3 at an acid/alkoxside ratio of 0.2. The highest specific surface area and pore diameter of the lightest material are 191.86 m2 g−1 and 18.4 Ǻ, respectively. Although pore diameter and specific surface area are not changed at any of the experimental temperatures which were tested by decreasing acid/alkoxside ratio, the density is slightly increased. However, it was observed that the calcination temperature significantly affects the surface area and density of the material.

Open Access August 11, 2008

Combination of cloud point extraction and flame atomic absorption spectrometry for preconcentration and determination of trace iron in environmental and biological samples

Mehrorang Ghaedi, Ardeshir Shokrollahi, Raziyeh Mehrnoosh, Omid Hossaini, Mustafa Soylak

Page range: 488-496

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Abstract

In the presented work, the conditions for cloud point extraction of iron from aqueous solutions using 7-iodo-8-hydroxyquinolin-5-sulphonic acid (Ferron) was investigated and optimized. The procedure is based on the separation of its ferron complex into the micellar media by adding the surfactant Triton X-114. After phase separation, the surfactant-rich phase was dissolved with 1.0 M HNO3 in methanol. Iron was determined by flame atomic absorption spectrometry. Optimization of the pH, ligand and surfactant quantities, incubation time, temperature, viscosity, sample volume, and interfering ions were investigated. The effects of the matrix ions were also examined. The detection limits for three times the standard deviations of the blank for iron was 0.4 ng m L-1, enrichment factor of 19.6 and preconcentration factor of 30 could be achieved. The validity of cloud point extraction was checked by employing real samples including soil, blood, spinach, milk, meat, liver and orange juice samples using the standard addition method, which gave satisfactory results.In the presented work, the conditions for cloud point extraction of iron from aqueous solutions using 7-iodo-8-hydroxyquinolin-5-sulphonic acid (Ferron) was investigated and optimized. The procedure is based on the separation of its ferron complex into the micellar media by adding the surfactant Triton X-114. After phase separation, the surfactant-rich phase was dissolved with 1.0 M HNO3 in methanol. Iron was determined by flame atomic absorption spectrometry. Optimization of the pH, ligand and surfactant quantities, incubation time, temperature, viscosity, sample volume, and interfering ions were investigated. The effects of the matrix ions were also examined. The detection limits for three times the standard deviations of the blank for iron was 0.4 ng m L−1, enrichment factor of 19.6 and preconcentration factor of 30 could be achieved. The validity of cloud point extraction was checked by employing real samples including soil, blood, spinach, milk, meat, liver and orange juice samples using the standard addition method, which gave satisfactory results.

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.

Aims and Scope

Open Chemistry aims to publish high quality research in the following areas:

Biological Chemistry/Biochemistry including bioanalytical chemistry, biochemistry and biological chemistry, biophysics and chemical physics in biology

Analytical Chemistry including electrochemistry, environmental chemistry, spectroscopy
Physical Chemistry including catalysis, chemical kinetics and reactivity, chemical physics, computational chemistry, chemometrics and QSAR, hydrogen technologies, hydrogen storage, nanochemistry, photochemistry, physical chemistry and physical organic chemistry, radiochemistry and nuclear chemistry, supramolecular chemistry, surface chemistry and colloids, theoretical chemistry, thermodynamics
Inorganic Chemistry including coordination chemistry, crystallography, materials and solid- state chemistry
Organic Chemistry including macromolecules and polymers, natural product chemistry, organic chemistry, organometallic chemistry, phytochemistry
Interference with other sciences including clinical chemistry, marine chemistry, medicinal chemistry, pharmaceutical chemistry

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In order to sustain the publishing process, each article accepted for publication in Open Chemistry is subject to an Article Processing Charge of €1200. This fee is used to cover the costs of the peer-review process, professional typesetting and copyediting, as well as online hosting, long-term preservation, and extensive promotion to potential readers. There is no submission fee. Information regarding payment of the charge will be provided following acceptance for publication. For more information please go to Article Processing Charges

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