Classical chemical sciences
The metal(II) ion complexes of a tetradentate ligand (L), namely bis[O,O-2,4-O,O-6,7-(thiocyanatecarboxylic methylidene)]-L-ascorbic acid are synthesized and characterized by 1H,13C-NMR, elemental analysis (CHN), mass spectroscopy, UV-visible and Fourier Transform infrared (FTIR) methods. This ligand is prepared from the reaction of the L-ascorbic acid and two moles of trichloroacetic acid in basic medium (compound I) with two moles of potassium thiocyanate. The reaction of (L) in ethanol with MCl2.xH2O gave complexes with the general formula [M(L)Cl2] (where M= Ni(II), Cu(II) and Zn(II), respectively) characterized by FTIR, UV-Visible, molar conductance, atomic absorption, magnetic susceptibility. The analysis of IR, spectral data of all complexes indicated that (L) is bonded to metal(II) ions through the two nitrogen atoms of thiocyanate groups and two oxygen atoms of hydroxyl moieties. The synthesized complexes were proposed to be octahedral in geometry. Among these complexes, the Zn(II) complex demonstrated good antibacterial activity.
Keywords: Synthesis, tetradentate, thiocyanate, metal complexes, analysis
Indole and its various derivatives show diverse biological effects. In the present study, some novel indole derivatives like methyl-2-(1H-indole-3-yl)-ethanoate derivatives (D1-D5) have been synthesized. Three Schiff bases (D6-D8) have been synthesized by the reaction of (D5) with substituted benzaldehydes. Co(II), Cu(II) and Ni(II) complexes of the Schiff bases have been prepared. All the compounds have been characterized by elemental analysis, molar conductivity, magnetic moment effect and spectroscopic techniques. The compounds exhibited moderate to significant anti-bacterial and anti-fungal activities against E. coli, S. aurous, B. subtitles, P. aeruginosin, A. niger, A. flavours, R. stolonifera and C. Albicans
Keywords: Design, synthesis, biological evaluation triazole, indol
Schiff bases are a group of compounds prepared by the condensation of primary amines and active carbonyl compounds. The Schiff bases have a general structure RRʹC=N-Rʹʹ (where R, R’ and Rʹʹ are alkyl, cyclohexyl, hydroxyalky1, hydroxyary1, etc). Herein the different synthetic routes of Schiff Base complexes like, direct synthesis, in situ method, oxidation of coordinated secondary amine, amine exchange approach, metal exchange and ligand exchange reaction are reviewed. A concise survey of literature on the coordination modes of complexes of Schiff base ligands is also presented in this article. The coordination complexes have been successfully screened against different strains of bacteria where they depicted the potential antimicrobial behaviour.
Keywords: Schiff base, metal ion, dentation, synthesis, coordination
Stable 1-(N-alkoxy-N-alkoxycarbonyl)amino-4-dimethylaminopyridium salt, 1-(N-ethoxycarbonyl-N-isopropyloxy) amino-4-dimethyl-aminopyridinium chloride, has been synthesized for the first time. Its structure has been studied by XRD method.
Keywords: N-alkoxy-N-chlorocarbamates, 1-(N-alkoxy-N-alkoxycarbonyl)aminopyridinium salts, 1-(N-ethoxycarbonyl-N-isopropyloxy)amino-4-dimethylaminopyridinium chloride, synthesis, structure
Materials and environmental chemistry
The pure and copper doped zinc oxide Zn1-xCuxO (x=0,0.05,0.1) thick films were deposited on glass substrates by screen printing method from their nano powders, followed by sintering at 500 0C to obtain desired stoichiometry and better adherence of films. The structural and optical properties of the samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) with UV–visible spectroscopy and Raman spectroscopy. XRD patterns confirmed hexagonal wurtzite structure with minor detection of Cu and SEM micrographs revealed granular grains and porosity in films. The optical properties and the energy band gap of pure and Cu2+ions doped ZnO films were studied by UV–visible absorbance spectroscopy. As the doping concentration is increased, both the absorption edge and the reflectance edge is found to shift towards higher wavelengths (red shift) and the direct band gap decreased from 3.4 to 3.3 eV. The incorporation of copper in ZnO lattice is confirmed by Raman spectrum. The E2 (high) phonon and multiphoton modes are observed at 441 and 1132 cm-1 respectively in Raman spectra.
Keywords: Thick films; Screen printing; XRD; SEM; Raman analysis
Chemical and biological aspects of life
Carob (Ceratonia siliqua) is one of the important crops over western Asia and North Africa. Its nutritional value has been acknowledged for millennia but its medicinal properties were practically studied only in the last four decades, despite the fact that some of them were used in traditional medicines for centuries. Modern food industry is just starting to discover the great potential of this plant. Carob has outstanding antioxidant capacity along with other important medicinal activities. Some of these have been extensively studied and reported in the last decades, but very few review articles were published about this plant, that summarize and discuss the findings. In this comprehensive review article, we present these reports and discuss them with special attention to traditional medicine, modern research findings, natural products and recommendations for future research subjects.
Keywords: Carob, antimicrobial, antioxidant, chemical composition, polyphenols, nutritional value
Industrial and engineering chemistry
This study aimed at developing a laboratory scale packed bed reactor (PBR) and evaluating its performance in re-refining of used lubricating oils. Used and unused motor oil samples of two brands (Mobil Super SAE 20W-50 and Total Quartz 5000 SAE 20W-50) were used in this study. The sorbent materials were a blend of diatomaceous materials in the same mass ratio. The compound types of the oils eluted from the PBR and those of used and virgin oil samples were studied for comparison. FTIR spectroscopy was employed to observe the variations in the types and nature of functional groups present in the various oils as well as to estimate the oxidation products of the oils using peak area increase (PAI). The constituent organic compounds were also identified and quantified using GC-MS. The results revealed that some of the compounds exist in different isomeric forms in the oil samples. The similarity in the classes of compounds is affirmed by their very similar FTIR spectra. GC-MS results indicated that the used oils contained the highest number of compounds, followed by the treated oils and also indicated similar treatment effects on the brands of lubricating oil. The study concluded that the developed reactor is a viable and sustainable technique for re-refining of used lubricating oils.
Keywords: GC-MS, IR, lubricating oil, PBR, PAHs, re-refined
Theoretical and computational chemistry
In this work a new experimental approach to reveal and study the water intermediates with the gas species in condensed phase at ambient temperature by IR spectral technique is presented. It has been established that the complexes between water molecule and ammonia as well as carbon dioxide in KBr matrix can be formed. Ab initio calculations in terms of density functional theory (DFT) at B3LYP/6-311++G(2d,2p) level allowed us to conclude that this binding is accompanied by the hydrogen atom transfer from water to partner molecule.
Keywords: Water intermediates, ammonia, carbon dioxide, hydrogen bond, FTIR spectroscopy, DFT calculation