Advances in Chemistry The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Alternative Synthesis of 1,8-Difluoroanthracene via the Balz-Schiemann Reaction Tue, 03 May 2016 11:27:36 +0000 An alternative and improved method for the synthesis of 1,8-difluoroanthracene 5 is described. The precursor 1,8-difluoro-9,10-anthraquinone 4 was synthesized by precipitating the water-soluble 1,8-diazonium-9,10-anthraquinone fluoroborate 3 using isopropanol, before thermally decomposing it via the Balz-Schiemann reaction to yield 4 in the form of pure sublimed crystals. Compound 5 was later synthesized with 84% yield by reducing 4 in a Zn/NH4OH mixture. Using isopropanol to quantitatively precipitate water-soluble diazonium fluoroborate salts was also used to synthesize other fluoroanthraquinone derivatives with improved yields. Rabih O. Al-Kaysi Copyright © 2016 Rabih O. Al-Kaysi. All rights reserved. Antioxidants Activity and Color Evaluation of Date Fruit of Selected Cultivars Commercially Available in the United States Sun, 21 Jun 2015 10:04:20 +0000 Dates (Phoenix dactylifera L.) are nutrient-rich fruit consumed throughout the world, either directly or in several food products. Six commercially available date cultivars in the US were analyzed for total phenolics, antioxidant activity using ABTS, DPPH, FRAP, and ORAC assays, and instrumental color. Total phenolics content varied from 33 to 125 mg GAE/100 g dry weight, with the highest in Barni (Saudi Arabia). Antioxidant values as determined by the ABTS in Deglet Nour (Algeria), Deglet Nour (California), Deglet Noor (Tunisia), Shahia (Tunisia), Barni (Saudi Arabia), and Khudri (Saudi Arabia) were 1300, 1047, 796, 452, 776, and 341 μmol TE/g dry weight, respectively. Antioxidative properties as measure by DPPH, FRAP, and ORAC varied from 3.27 to 3.54, 3.29 to 5.22, and 189 to 243 μmol TE/g dry basis, respectively. Fruit and pulp color of Deglet Nour (Algeria) was lighter whereas pulp of Barni (Saudi Arabia) was the darkest. Antioxidant values varied with different techniques used and also followed a different pattern than that of phenolics content. Fahad Mohammed Al-Jasass, Muhammad Siddiq, and Dalbir S. Sogi Copyright © 2015 Fahad Mohammed Al-Jasass et al. All rights reserved. Telomerization of Vinyl Chloride with Chloroform Initiated by Ferrous Chloride-Dimethylacetamide under Ultrasonic Conditions Mon, 09 Mar 2015 11:28:08 +0000 Telomerization of vinyl chloride with chloroform was investigated using ferrous chloride-dimethylacetamide system, and 42.1% yield, more than four times the one reported before, was achieved. The addition of ultrasound further improved the reaction and yield was raised to 51.9% with trace byproducts at highly reduced reaction time and temperature. Ferrous chloride-dimethylacetamide under ultrasonic irradiation acts as a very efficient catalyst system for the 1 : 1 telomerization. Hua Qian and Hengdao Quan Copyright © 2015 Hua Qian and Hengdao Quan. All rights reserved. Anticancer Activities of Mononuclear Ruthenium(II) Coordination Complexes Thu, 19 Feb 2015 10:07:48 +0000 Ruthenium compounds are highly regarded as potential drug candidates. The compounds offer the potential of reduced toxicity and can be tolerated in vivo. The various oxidation states, different mechanism of action, and the ligand substitution kinetics of ruthenium compounds give them advantages over platinum-based complexes, thereby making them suitable for use in biological applications. Several studies have focused attention on the interaction between active ruthenium complexes and their possible biological targets. In this paper, we review several ruthenium compounds which reportedly possess promising cytotoxic profiles: from the discovery of highly active compounds imidazolium [trans-tetrachloro(dmso)(imidazole)ruthenate(III)] (NAMI-A), indazolium [trans-tetrachlorobis(1H-indazole)ruthenate(III)](KP1019), and sodium trans-[tetrachloridobis(1H-indazole)ruthenate(III)] (NKP-1339) to the recent work based on both inorganic and organometallic ruthenium(II) compounds. Half-sandwich organometallic ruthenium complexes offer the opportunity of derivatization at the arene moiety, while the three remaining coordination sites on the metal centre can be functionalised with various coordination groups of various monoligands. It is clear from the review that these mononuclear ruthenium(II) compounds represent a strongly emerging field of research that will soon culminate into several ruthenium based antitumor agents. William M. Motswainyana and Peter A. Ajibade Copyright © 2015 William M. Motswainyana and Peter A. Ajibade. All rights reserved. Synthesis and Structural Studies of a New Complex of Di[hexabromobismuthate (III)] 2,5-Propylaminepyrazinium [C10H28N4]Bi2Br10 Thu, 12 Feb 2015 07:08:31 +0000 A new organic-inorganic hybrid material, [C10H28N4]Bi2Br10, has been synthesized and characterized. The compound crystallizes in monoclinic P21/c space group with a = 11.410(4) Å, b = 11.284(4) Å, c = 12.599(3) Å, β = 115.93(2)°, and V = 1458.8(8) Å3. The structure consists of discrete dinuclear [Bi2Br10]4− anions and [C10H28N4]4+ cations. It consists of a 0-D anion built up of edge-sharing bioctahedron. The crystal net contains N–H⋯Br hydrogen bonds. The differential scanning calorimetry (DSC) reveals an irreversible phase transition at −17°C. The frontier molecular orbital and the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) calculation allow the classification of the material as an insulator. Mohamed El Mehdi Touati and Habib Boughzala Copyright © 2015 Mohamed El Mehdi Touati and Habib Boughzala. All rights reserved. Optical Breakdown in Liquid Suspensions and Its Analytical Applications Tue, 10 Feb 2015 12:45:27 +0000 Micro- and nanoparticles persist in all environmental aquatic systems and their identification and quantification are of considerable importance. Therefore, the application of Laser-induced breakdown to aquatic particles is of interest. Since direct application of this method to water samples is difficult, further understanding of the breakdown is needed. We describe several optical techniques for investigation of laser breakdown in water, including Mach-Zehnder interferometry, shadow, and Schlieren diagnostic. They allow for studying the time dependent structure and physical properties of the breakdown at high temporal and spatial resolutions. Monitoring the formation of microbubbles, their expansion, and the evolution of the associated shockwaves are described. The new understanding is that the plasma column in liquids has a discrete nature, which lasts up to 100 ns. Controlling the generation of nanoparticles in the irradiated liquids is discussed. It is shown that multivariate analysis of laser-induced breakdown spectroscopy allows for differentiation between various groups of suspended particulates. Tatiana Kovalchuk-Kogan, Valery Bulatov, and Israel Schechter Copyright © 2015 Tatiana Kovalchuk-Kogan et al. All rights reserved. Zr(IV), La(III), and Ce(IV) Chelates with 2-[(4-[(Z)-1-(2-Hydroxyphenyl)ethylidene]aminobutyl)-ethanimidoyl]phenol: Synthesis, Spectroscopic Characterization, and Antimicrobial Studies Sun, 01 Feb 2015 14:25:00 +0000 La(III), Zr(IV), and Ce(IV) chelates of 2-[(4-[(Z)-1-(2-hydroxyphenyl)ethylidene]aminobutyl)-ethanimidoyl]phenol were synthesized and characterized by using several physical techniques. The Schiff base was obtained by refluxing of o-hydroxyacetophenone with 1,4-butanediamine in 2 : 1 molar ratio. The CHN elemental analysis results showed the formation of the Schiff base and the chelates has been found to be in 1 : 1 [M : L] ratio. The molar conductance measurements revealed that all the chelates are nonelectrolytes. Structural elucidations of the ligand and its chelates were based on compatible analytical and spectroscopic evidences. The infrared spectral data revealed that the Schiff base coordinates to the metal ions through active sites which are –OH and –C=N groups. According to the electronic spectral data, an octahedral geometry was proposed for the chelates. The synthesized ligand and its metal chelates were screened for their antimicrobial activity against two Gram negative (Escherichia coli, Salmonella kentucky) and two Gram positive (Lactobacillus fermentum, Streptococcus faecalis) bacterial strains, unicellular fungi (Fusarium solani), and filamentous fungi (Aspergillus niger). The activity data showed that the metal chelates have antibacterial and antifungal activity more than the parent Schiff base ligand against one or more bacterial or fungi species. The results also indicated that the metal chelates are higher sensitive antimicrobial agents as compared to the Schiff base ligand. M. M. El-ajaily, H. A. Abdullah, Ahmed Al-janga, E. E. Saad, and A. A. Maihub Copyright © 2015 M. M. El-ajaily et al. All rights reserved. Synthesis, Characterization, and Antihypertensive Evaluation of Some Novel 2,2,8,8-Tetramethyl-2,3,7,8-tetrahydro-4,6-diamino-3,7-dihydroxy-6,7-epoxy-benzo-[1,2-b:5,4-b′]dipyran Derivatives Thu, 29 Jan 2015 14:31:38 +0000 A series of 2,2,8,8-tetramethyl-2,3,7,8-tetrahydro-4,6-diamino-3,7-dihydroxy-6,7-epoxy-benzo-[1,2-b:5,4-b′]dipyran derivatives 7a–e and 8a–e were synthesized from resorcinol. All the synthesized compounds were characterized by FTIR, mass spectra, and 1H NMR. These compounds were evaluated for antihypertensive activity using Wister Albino Rat model. Direct antihypertensive activity was performed using the instrument BIOPAC System MP-36 Santa Barbara, California, for recording blood pressure response. Among the title compounds, compounds 7b, 7c, and 7d showed potent antihypertensive activity and other compounds were also found to exert low and moderate antihypertensive activity. The relaxant potency in rat aorta and trachea was used for biological characterization of the benzopyrans. Structure-activity relationships study was investigated around position-4 of the benzopyran nucleus. Pankaj Dwivedi, Kuldipsinh P. Barot, Shailesh Jain, and Manjunath D. Ghate Copyright © 2015 Pankaj Dwivedi et al. All rights reserved. Effect of C–O Bonding on the Stability and Energetics of High-Energy Nitrogen-Carbon Molecules N10C2 and N16C2 Thu, 25 Dec 2014 00:10:12 +0000 Molecules consisting of nitrogen have been the subject of much attention due to their potential as high-energy materials. Complex molecules consisting entirely of nitrogen can be subject to rapid decomposition, and therefore other atoms are incorporated into the structure to enhance stability. Previous studies have explored the incorporation of carbon atoms into otherwise all-nitrogen cages molecules. The current study involves two such cages, N10C2 and N16C2, whose structures are derived from N12 and N18, respectively. The N10C2 and N16C2 cages in this study are modified by bonding groups O3 and CO3 to determine the effect on the relative energies between the isomers and on the thermodynamic energy release properties. Energetic trends for N10C2 and N16C2 are calculated and discussed. Douglas L. Strout Copyright © 2014 Douglas L. Strout. All rights reserved. A Review on Current Status of Stability and Knowledge on Liquid Electrolyte-Based Dye-Sensitized Solar Cells Thu, 27 Nov 2014 08:52:37 +0000 The purpose of this review is to gather the current background in materials development and provide the reader with an accurate image of today’s knowledge regarding the stability of dye-sensitized solar cells. This contribution highlights the literature from the 1970s to the present day on nanostructured TiO2, dye, Pt counter electrode, and liquid electrolyte for which this review is focused on. Frédéric Sauvage Copyright © 2014 Frédéric Sauvage. All rights reserved. Conical Intersections Leading to Chemical Reactions in the Gas and Liquid Phases Sun, 16 Nov 2014 07:39:41 +0000 The current status of the role of conical intersections (CoIns) in molecular photochemistry is reviewed with a special emphasis on the procedures used to locate them. Due to space limitations, the extensive literature of the subject is given by referring the reader to representative references, whereas the author group’s work is described in detail. The basic properties of CoIns are outlined and contrasted with those of transition states in thermal reactions. Location of CoIns using the method of Longuet-Higgins sign-inverting loops is described in detail. The concept of “anchors”—valence bond structures that represent stable molecules and other stationary points on the potential energy surface—is introduced and its use in constructing loops is described. The authors’ work in the field is outlined by discussing some specific examples in detail. Mathematical aspects and details are left out. The main significance of the method is that it explains a large body of photochemical reactions (for instance, ultrafast ones) and is particularly suitable for practicing chemists, using concepts such as reaction coordinates and transition states in the search. Yehuda Haas Copyright © 2014 Yehuda Haas. All rights reserved. Speeds of Sound and Excess Molar Volume for Binary Mixture of 1,4-Dioxane with 1-Heptanol at Five Temperatures Wed, 05 Nov 2014 10:42:45 +0000 Speed of sound and density data for dilute liquid solutions of cyclic ether 1,4-dioxane with 1-heptanol was obtained using the Anton-Paar DSA 5000 at five temperatures   = (298.15, 303.15, 308.15, 313.15, and 318.15) K at atmospheric pressure. The excess parameters were calculated from experimental data and fitted with a Redlich-Kister polynomial function and concluded the presence of weak molecular interactions. Anil Kumar Koneti and Srinivasu Chintalapati Copyright © 2014 Anil Kumar Koneti and Srinivasu Chintalapati. All rights reserved. Adsorption Studies of Lead by Enteromorpha Algae and Its Silicates Bonded Material Wed, 05 Nov 2014 00:00:00 +0000 Lead adsorption by green Enteromorpha algae was studied. Adsorption capacity was 83.8 mg/g at pH 3.0 with algae (E) and 1433.5 mg/g for silicates modified algae (EM). FTIR and thermal analysis of algae materials were studied. Thomas and Yoon-Nelson column model were best for adsorbent (E) and algae after reflux (ER) and Yan model for (EM) with capacity 76.2, 71.1, and 982.5 mg/g, respectively. (ER) and (EM) show less swelling and better flow rate control than (E). Nonlinear methods are more appropriate technique. Error function calculations proved valuable for predicting the best adsorption isotherms, kinetics, and column models. Hassan H. Hammud, Ali El-Shaar, Essam Khamis, and El-Sayed Mansour Copyright © 2014 Hassan H. Hammud et al. All rights reserved. Ionic Liquids: Synthesis and Applications in Catalysis Wed, 29 Oct 2014 00:00:00 +0000 Ionic liquids have emerged as an environmentally friendly alternative to the volatile organic solvents. Being designer solvents, they can be modulated to suit the reaction conditions, therefore earning the name “task specific ionic liquids.” Though primarily used as solvents, they are now finding applications in various fields like catalysis, electrochemistry, spectroscopy, and material science to mention a few. The present review is aimed at exploring the applications of ionic liquids in catalysis as acid, base, and organocatalysts and as soluble supports for catalysts. Rajni Ratti Copyright © 2014 Rajni Ratti. All rights reserved. Complex Molecules at Liquid Interfaces: Insights from Molecular Simulation Tue, 28 Oct 2014 12:02:58 +0000 The behaviour of complex molecules, such as nanoparticles, polymers, and proteins, at liquid interfaces is of increasing importance in a number of areas of science and technology. It has long been recognised that solid particles adhere to liquid interfaces, which provides a convenient method for the preparation of nanoparticle structures or to modify interfacial properties. The adhesion of proteins at liquid interfaces is important in many biological processes and in a number of materials applications of biomolecules. While the reduced dimensions of these particles make experimental investigation challenging, molecular simulations provide a natural means for the study of these systems. In this paper I will give an overview of some recent work using molecular simulation to investigate the behaviour of complex molecules at liquid interfaces, focusing on the relationship between interfacial adsorption and molecular structure, and outline some avenues for future research. David L. Cheung Copyright © 2014 David L. Cheung. All rights reserved. Structural Conformational Study of Eugenol Derivatives Using Semiempirical Methods Mon, 20 Oct 2014 00:00:00 +0000 We investigated the conformational structure of eugenol and eugenyl acetate under torsional angle effect by performing semiempirical calculations using AM1 and PM3 methods. From these calculations, we have evaluated the strain energy of conformational interconversion. To provide a better estimate of stable conformations, we have plotted the strain energy versus dihedral angle. So, we have determined five geometries of eugenol (three energy minima and two transition states) and three geometries of eugenyl acetate (two energy minima and one transition state). From the molecular orbital calculations, we deduce that the optimized trans form by AM1 method is more reactive than under PM3 method. We can conclude that both methods are efficient. The AM1 method allows us to determine the reactivity and PM3 method to verify the stability. Radia Mahboub Copyright © 2014 Radia Mahboub. All rights reserved. Space Group Approximation of a Molecular Crystal by Classifying Molecules for Their Electric Potentials and Roughness on Their Inertial Ellipsoid Surface Thu, 16 Oct 2014 11:44:42 +0000 In order to predict the most probable space group where a molecule crystallizes, it is assumed that molecular shape and electric potential distribution on the molecular surface are the main factors or predictors. However, to compare and classify molecules by these two factors seems to be very difficult for in general such different objects. Thus, in order to compare molecules, they are reduced to their inertial ellipsoid in which surface 26 equally spaced points were chosen where a roughness factor and an electric potential due to all atomic charges of the whole molecule are calculated. By this procedure, different molecules encoded by these two predictor vectors can be compared and classified, showing that molecules that crystallize in the same space group have more similar predictor vectors. This result opens the possibility to predict the more probable spatial group associated with a molecule. Jose Fayos Copyright © 2014 Jose Fayos. All rights reserved. Cobalt(II) Chloride Hexahydrate as an Efficient and Inexpensive Catalyst for the Preparation of Biscoumarin Derivatives Sun, 12 Oct 2014 08:01:39 +0000 Cobalt(II) chloride hexahydrate (CoCl2·6H2O) has been found to be an efficient catalyst for the one-pot synthesis of biscoumarin derivatives through a combination of aromatic aldehydes and 4-hydroxycoumarin in aqueous media at 70°C. Several types of aromatic aldehyde, containing electron-withdrawing groups as well as electron-donating groups, were used in the reaction and in all cases the desired products were synthesized successfully. The present approach offers remarkable advantages such as short reaction times, excellent yields, straightforward procedure, easy purification, environment friendliness, and low catalyst loading. Mohammad Reza Nazarifar Copyright © 2014 Mohammad Reza Nazarifar. All rights reserved. The Inhibition Effect of Potassium Iodide on the Corrosion of Pure Iron in Sulphuric Acid Wed, 24 Sep 2014 07:21:13 +0000 The use of inorganic inhibitors as an alternative to organic compounds is based on the possibility of degradation of organic compounds with time and temperature. The inhibition effect of potassium iodide on the corrosion of pure iron in 0.5 M H2SO4 has been studied by weight loss. It has been observed from the results that the inhibition efficiency (IE%) of KI increases from 82.17% to 97.51% with the increase in inhibitor concentration from 1·10−4 to 2·10−3 M. The apparent activation energy () and the equilibrium constant of adsorption () were calculated. The adsorption of the inhibitor on the pure iron surface is in agreement with Langmuir adsorption isotherm. Tarik Attar, Lahcène Larabi, and Yahia Harek Copyright © 2014 Tarik Attar et al. All rights reserved. Detection and Estimation of alpha-Amyrin, beta-Sitosterol, Lupeol, and n-Triacontane in Two Medicinal Plants by High Performance Thin Layer Chromatography Mon, 22 Sep 2014 05:53:30 +0000 A normal phase high performance thin layer chromatography (HPTLC) method has been developed and validated for simultaneous estimation of four components, namely, alpha-amyrin, beta-sitosterol, lupeol, and n-triacontane from two medicinally important plants, Leptadenia reticulata Wight & Arn. and Pluchea lanceolata (DC.) CB. Clarke. In Ayurveda, both plants have been reported to possess immunomodulatory activity. Chromatographic separation of the four components from the methanolic extracts of whole plant powders of Leptadenia reticulata Wight & Arn. and Pluchea lanceolata (DC.) CB. Clarke. was performed on TLC aluminium plates precoated with silica gel using a suitable mobile phase. The densitometric scanning was done after derivatization at λ = 580 nm for α-amyrin, β-sitosterol, and lupeol, and at 366 nm for n-triacontane. The developed HPTLC method has been validated and used for simultaneous quantitation of the four components from the methanolic extracts of whole plant powders of Leptadenia reticulata Wight & Arn. and Pluchea lanceolata (DC.) CB. Clarke. The developed HPTLC method is simple, rapid, and precise and can be used for routine quality control. Saikat S. Mallick and Vidya V. Dighe Copyright © 2014 Saikat S. Mallick and Vidya V. Dighe. All rights reserved. Increasing the Stability of Metal-Organic Frameworks Thu, 18 Sep 2014 09:03:51 +0000 Metal-organic frameworks (MOFs) are a new category of advanced porous materials undergoing study by many researchers for their vast variety of both novel structures and potentially useful properties arising from them. Their high porosities, tunable structures, and convenient process of introducing both customizable functional groups and unsaturated metal centers have afforded excellent gas sorption and separation ability, catalytic activity, luminescent properties, and more. However, the robustness and reactivity of a given framework are largely dependent on its metal-ligand interactions, where the metal-containing clusters are often vulnerable to ligand substitution by water or other nucleophiles, meaning that the frameworks may collapse upon exposure even to moist air. Other frameworks may collapse upon thermal or vacuum treatment or simply over time. This instability limits the practical uses of many MOFs. In order to further enhance the stability of the framework, many different approaches, such as the utilization of high-valence metal ions or nitrogen-donor ligands, were recently investigated. This review details the efforts of both our research group and others to synthesize MOFs possessing drastically increased chemical and thermal stability, in addition to exemplary performance for catalysis, gas sorption, and separation. Mathieu Bosch, Muwei Zhang, and Hong-Cai Zhou Copyright © 2014 Mathieu Bosch et al. All rights reserved. Determination of Tannins of Three Common Acacia Species of Sudan Wed, 17 Sep 2014 06:13:40 +0000 The objective of this study is to analyze and compare tannins of three common Acacia species of Sudan, since vegetable tannins are important in leather industry. Acacia nilotica and Acacia seyal samples were collected from Sunt Forest in Khartoum State, while Acacia senegal samples were collected from the Debabat Forest in South Kordofan State. Bark samples from bulk collections of the three Acacia species were extracted with boiled deionized water. The amount of tannins present in these bulk samples was determined by Folin-Denis method for total phenolic materials, followed by precipitation with hide-powder. The difference between the amount of phenolic materials present before and after addition of hide-powder represents the amount of tannins present. The percentage of tannins in the leaves, bark, and mature and immature fruits of collections of individuals of Acacia species was estimated; mature and immature fruits of Acacia nilotica contain tannins (22.15% and 22.10%, resp.). The leaves of Acacia nilotica and Acacia seyal contain tannins (11.80% and 6.30%, resp.). The barks of Acacia seyal, Acacia nilotica, and Acacia senegal contain tannins (12.15%, 10.47%, and 3.49%, resp.). Isam Eldin Hussein Elgailani and Christina Yacoub Ishak Copyright © 2014 Isam Eldin Hussein Elgailani and Christina Yacoub Ishak. All rights reserved. Allotropic Carbon Nanoforms as Advanced Metal-Free Catalysts or as Supports Mon, 15 Sep 2014 08:17:34 +0000 This perspective paper summarizes the use of three nanostructured carbon allotropes as metal-free catalysts (“carbocatalysts”) or as supports of metal nanoparticles. After an introductory section commenting the interest of developing metal-free catalysts and main features of carbon nanoforms, the main body of this paper is focused on exemplifying the opportunities that carbon nanotubes, graphene, and diamond nanoparticles offer to develop advanced catalysts having active sites based on carbon in the absence of transition metals or as large area supports with special morphology and unique properties. The final section provides my personal view on future developments in this field. Hermenegildo Garcia Copyright © 2014 Hermenegildo Garcia. All rights reserved. Separation and Characterization of Synthetic Polyelectrolytes and Polysaccharides with Capillary Electrophoresis Sun, 14 Sep 2014 09:12:49 +0000 The development of macromolecular engineering and the need for renewable and sustainable polymer sources make polymeric materials progressively more sophisticated but also increasingly complex to characterize. Size-exclusion chromatography (SEC or GPC) has a monopoly in the separation and characterization of polymers, but it faces a number of proven, though regularly ignored, limitations for the characterization of a number of complex samples such as polyelectrolytes and polysaccharides. Free solution capillary electrophoresis (CE), or capillary zone electrophoresis, allows usually more robust separations than SEC due to the absence of a stationary phase. It is, for example, not necessary to filter the samples for analysis with CE. CE is mostly limited to polymers that are charged or can be charged, but in the case of polyelectrolytes it has similarities with liquid chromatography in the critical conditions: it does not separate a charged homopolymer by molar mass. It can thus characterize the topology of a branched polymer, such as poly(acrylic acid), or the purity or composition of copolymers, either natural ones such as pectin, chitosan, and gellan gum or synthetic ones. Joel J. Thevarajah, Marianne Gaborieau, and Patrice Castignolles Copyright © 2014 Joel J. Thevarajah et al. All rights reserved. Synthesis and Characterization of Novel Processable and Flexible Polyimides Containing 3,6-Di(4-carboxyphenyl)pyromellitic Dianhydride Wed, 10 Sep 2014 07:25:43 +0000 A series of six novel polyimides containing 3,6-di(4-carboxyphenyl)pyromellitic dianhydride were synthesized via two steps condensation method. Aromatic diamines monomers, 4-(4-aminophenoxy)-N-(4-(4-aminophenoxy)benzylidene)-3-chloroaniline (DA1), 4-(4-amino-3-methylphenoxy)-N-(4-(4-amino-3-methylphenoxy)benzylidene)-3-chloroaniline (DA2), 4-(4-amino-2-methylphenoxy)-N-(4-(4-amino-2-methylphenoxy)benzylidene)-3-chloroaniline (DA3) 4-(4-aminophenoxy)-N-(4-(4-aminophenoxy)benzylidene)-2-methylaniline (DA4), 4-(4-amino-3-methylphenoxy)-N-(4-(4-amino-3-methylphenoxy)benzylidene)-2-methylaniline (DA5), and 4-(4-amino-2-methylphenoxy)-N-(4-(4-amino-2-methylphenoxy)benzylidene)-2-methylaniline (DA6) were prepared and used to synthesize new polyimides by reaction with resynthesized 3,6-di(4-carboxyphenyl)pyromellitic dianhydride by using two-step condensation method. The inherent viscosities of polyimides range from 0.68–1.04 dL gm−1 and were soluble in polar solvents. Polyimides have excellent thermal stability by showing 10% weight loss temperature was above 450°C. Their glass transition temperatures lie in the range of 250–335°C. Wide-angle X-ray diffractometer investigations revealed the amorphous nature of polyimides. Therefore, these polymers can be a potential candidate as processable high performance polymeric materials. Muhammad Kaleem Khosa, Muhammad Asghar Jamal, Rubbia Iqbal, and Mazhar Hamid Copyright © 2014 Muhammad Kaleem Khosa et al. All rights reserved. Theoretical Simulations of Reactive and Nonreactive Scattering of Light Diatomic Molecules from Metal Surfaces: Past, Present, and Future Wed, 10 Sep 2014 06:10:32 +0000 In everyday life we are surrounded by surfaces and, therefore, by phenomena involving molecule-surface interactions. Furthermore, the processes of heterogeneous catalysis, which are governed by molecule-surface interactions, are of huge practical importance, because the production of most synthetic compounds involves catalytic processes, which explains the tremendous effort that surface science scientists have invested to understand the basic principles underlying elementary interactions between light molecules and surfaces. This effort was recognized in 2007 with the Nobel prize in chemistry awarded to Gerhard Ertl. Here we revise some of the most relevant studies performed so far in this field. We also point out the major challenges that the surface science community may face in this field in the years to come. C. Díaz Copyright © 2014 C. Díaz. All rights reserved. Synthesis and Antimicrobial Activity of Some Novel Heterocyclic Candidates via Michael Addition Involving 4-(4-Acetamidophenyl)-4-oxobut-2-enoic Acid Wed, 10 Sep 2014 00:00:00 +0000 This paper discusses the utility of 4-(4-acetamidophenyl)-4-oxobut-2-enoic acid as a key starting material for the preparation of a novel series of pyridazinones, thiazoles derivatives, and other heterocycles via interaction with nitrogen, sulfur, and carbon nucleophiles under Michael addition conditions and studies the antimicrobial activities of some of these compounds. Maher A. EL-Hashash, A. Essawy, and Ahmed Sobhy Fawzy Copyright © 2014 Maher A. EL-Hashash et al. All rights reserved. Quantum Calculation for Musk Molecules Infrared Spectra towards the Understanding of Odor Sun, 07 Sep 2014 10:51:18 +0000 It is not clear so far how humans can recognize odor. One of the theories regarding structure-odor relationship is vibrational theory, which claims that odors can be recognized by their modes of vibration. In this sense, this paper brings a novel comparison made between musky and nonmusky molecules, as to check the existence of correlation between their modes on the infrared spectra and odor. For this purpose, sixteen musky odorants were chosen, as well as seven other molecules that are structurally similar to them, but with no musk odor. All of them were submitted to solid theoretical methodology (using molecular mechanics/molecular dynamics and Neglect of Diatomic Differential Overlap Austin Model 1 methods to optimize geometries) as to achieve density functional theory spectra information, with both Gradient Corrected Functional Perdew-Wang generalized-gradient approximation (GGA/PW91) and hybrid Becke, three-parameter, Lee-Yang-Parr (B3LYP) functional. For a proper analysis over spectral data, a mathematical method was designed, generating weighted averages for theoretical frequencies and computing deviations from these averages. It was then devised that musky odorants satisfied demands of the vibrational theory, while nonmusk compounds belonging either to nitro group or to acyclic group failed to fulfill the same criteria. Elaine Rose Maia, Daniela Regina Bazuchi Magalhães, Dan A. Lerner, Dorothée Berthomieu, and Jean-Marie Bernassau Copyright © 2014 Elaine Rose Maia et al. All rights reserved. Mycotoxin Analysis: New Proposals for Sample Treatment Sun, 07 Sep 2014 07:25:25 +0000 Mycotoxins are toxic secondary metabolites produced by different fungi, with different chemical structures. Mycotoxins contaminate food, feed, or raw materials used in their production and cause diseases and disorders in humans and livestock. Because of their great variety of toxic effects and their extreme heat resistance, the presence of mycotoxins in food and feed is considered a high risk to human and animal health. In order to ensure food quality and health consumers, European legislation has set maximum contents of some mycotoxins in different matrices. However, there are still some food commodities susceptible to fungal contamination, which were not contemplated in this legislation. In this context, we have developed new analytical techniques for the multiclass determination of mycotoxins in a great variety of food commodities (some of them scarcely studied), such as cereals, pseudocereals, cereal syrups, nuts, edible seeds, and botanicals. Considering the latest technical developments, ultrahigh performance liquid chromatography coupled to tandem mass spectrometry has been chosen as an efficient, fast, and selective powerful analytical technique. In addition, alternative sample treatments based on emerging methodologies, such as dispersive liquid-liquid microextraction and QuEChERS, have been developed, which allow an increased efficiency and sample throughput, as well as reducing contaminant waste. Natalia Arroyo-Manzanares, José F. Huertas-Pérez, Ana M. García-Campaña, and Laura Gámiz-Gracia Copyright © 2014 Natalia Arroyo-Manzanares et al. All rights reserved. New Strategy for the Cleaning of Paper Artworks: A Smart Combination of Gels and Biosensors Tue, 02 Sep 2014 05:30:43 +0000 In this work an outlook on the design and application, in the cultural heritage field, of new tools for diagnostic and cleaning use, based on biocompatible hydrogels and electrochemical sensors, is reported. The use of hydrogels is intriguing because it does not require liquid treatment that could induce damage on artworks, while electrochemical biosensors not only are easy to prepare, but also can be selective for a specific compound and therefore are suitable for monitoring the cleaning process. In the field of restoration of paper artworks, more efforts have to be done in order to know how to perform the best way for an effective restoration. Rigid Gellan gel, made up of Gellan gum and calcium acetate, was proposed as a paper cleaning treatment, and selective biosensors for substances to be removed from this gel have been obtained by choosing the appropriate enzymes to be immobilized. Using this approach, it is possible to know when the cleanup process will be completed, avoiding lengthy and sometimes unnecessary cleaning material applications. Laura Micheli, Claudia Mazzuca, Eleonora Cervelli, and Antonio Palleschi Copyright © 2014 Laura Micheli et al. All rights reserved.