Classical chemical sciences
This study is concerned with the synthesis and characterization derivatives of the mono/bis, syn and anti-y-lactams 2a-2i. These compounds were synthesized by reacting phenylsuccinic anhydride with the appropriate Schiff base (imines) 1a-1i in moderate yields (50-92 %). The structures of these y-lactams were established on the basis of the spectral data like IR, 1H-NMR,13C-NMR, HSQC 1H-13C-NMR, MS.
Keywords:y-Lactams, cycloaddition, phenylsuccinic anhydride, 13C NMR, HSQC 1H-13C-NMR
Sodium 3-(furan-2-yl)-3-oxoprop-1-en-1-olate was used as precursor for synthesis of some novel derivatives of various fused heterocyclic ring systems namely pyrazolo[1,5-a]pyrimidines, triazolo[1,5-a]pyrimidines, benzo[4,5]imidazo-[l,2-a]pyrimidines, pyrazolo[5,l-c]triazines, l,2,4-triazolo[4,3-c]triazines, benzo[4,5]imidazo[2,1-c]triazines. The structures of the newly synthesized compounds were established on the basis of their spectral data, elemental analyses and alternate synthetic routes wherever possible.
Keywords: Pyrazolo[1,5-a]pyrimidines, triazolo[1,5-a]pyrimidines, pyrazolo[5,l-c]triazines, l,2,4-triazolo[5,1-c]triazines, benzo[4,5]imidazo[2,1-c]triazines
The cloud point extraction (CPE) method was successfully employed for the separation and pre-concentration of trace amounts of palladium prior to its determination either by flame atomic absorption spectrometry (FAAS) or using visual spectrophotometry. Palladium(II) reacts with 2-Hydroxyimino-3-(2-hydrazonopyridyl)-butane (HHB) as chelating agent in the presence of p-octyl poly ethylene glycol phenyl ether (Triton X-100) as a nonionic surfactant giving a purple to pink surfactant rich phase chelate which could be used for CPE. The effects of experimental conditions such as pH, chelating agent and surfactant concentrations, equilibration temperature and time on CPE were studied. The performance characteristics of the method such as linearity, detection limit, pre-concentration and improvement factors were evaluated. Linearity was obeyed in the range of 0.5-15 and 0.4-18.0 ng mL-1 of Pd(II) with a detection limit of 0.08 and 0.035 ng mL-1 using FAAS and visual spectrometry, respectively. Validation of the method revealed good performance characteristics including good selectivity for Pd2+ over a wide variety of other diverse cations and anions, high reproducibility, low detection limit, acceptable accuracy and precision. The proposed method was successfully applied for the assessment of palladium (II) traces in water and food samples with satisfactory results.
Keywords: palladium; cloud point; spectrometry; pre-concentration
In the present study we have investigated the behaviour of 5-amino-3,4-diphenylthieno[2,3-c]pyridazine-6-carbonitrile towards the hydrazine hydrate which gives 5-amino-3,4-diphenylthieno[2,3-c]pyridazine-6-carboximidohydrazide which in turn was subjected to subsequent reactions with benzaldehyde, acetic anhydride, acetyl acetone, formic acid, maleic anhydride and phthalic anhydride. The new synthesized compounds were confirmed by their IR spectra, mass spectrum, 1H-NMR, and elemental analyses, and were screened for antimicrobial activity. Several compounds showed moderate to low activity against the examined microorganisms
Keywords: Pyridazine, thienopyridazine, pyrimidothienopyridazine, synthesis, antimicrobial activity
A family of novel 1,2,3-triazoles 3-7 were prepared by one pot reaction of 1,2,3-triazol-4-carbohydazides 1 with different reagents such as hydrazonoyl chlorides and methyl ketones. The novel compounds were evaluated for their antimicrobial activity. The results of antimicrobial screening showed that, compound 5 has the highest inhibitory effects on the growth of a wide range of the tested microbes due to the presence of sulphonyl moiety in its structure.
Keywords: 1,2,3-triazoles; hydrazones; hydrazonoyl chlorides; antimicrobial activity; MIC.
A copper (II) catalyzed Baeyer-Villiger reaction of 2-butanone in the presence of oxygen and 2-amino-5-nitropyridine produced crystals of bis(2-amino-5-nitropyridine)tetraacetatedicopper(II) dehydrate, (1). 1 and its anhydrous form, (bis-2-amino-5- nitropyridine)tetraacetatedicopper(II), (2), were then synthesized directly from Cu(CH3COO)2·H2O and 2-amino-5-nitropyridine. Crystals of both compounds were grown using slow evaporation, and characterized using IR, combustion analysis, X-ray powder diffraction, single crystal X-ray diffraction, and temperature-dependent magnetic susceptibility measurements. 1 and 2 are both monoclinic and crystallize in the space groups P21/c and C2/m, respectively. 2 exhibits 2-fold disorder in the 2-amino-5-nitropyridine molecule that arises due to symmetry. Both compounds pack in sheets of isolated dimers, and exhibit strong antiferromagnetic interactions within the dimers (J = - 442(5) and -471(5) K for 1 and 2 respectively).
Keywords: use the Keywords style for the list of keywords, separating with a comma each items
Steroidal spiroazetidinone derivatives (3, 10-12) were obtained by the multi-step reactions of ketosteroids. It involved Staudinger keteneimine [2+2] cycloaddition reaction of steroidal iminophenylcholest-5-enes (2, 7-9). The structural assignment of the products was confirmed on the basis of IR, 1H NMR, 13C NMR, MS and analytical data. The synthesized compounds were screened for in vitro antimicrobial activity against different bacterial and fungal strains by agar diffusion method and in vitro antioxidant activity by using DPPH method. Docking studies were performed to investigate the hypothetical binding mode of the steroidal spiroazetidinones. The results suggest that steroidal bearing a core spiroazetidinone scaffold would be potent phramacological agents.
Keywords: Spiroazetidinone; Staudinger reaction; Antimicrobial; Antioxidant; Docking
The title compound 5'-chloro-5,5''-difluoro-1H,1''H-[3,3':3',3''-terindol]-2'(1'H)-one synthesized via one-pot multicomponent reaction (MCR) at room temperature using commercially available sulfamic acid as inexpensive and environmentally benign organo-catalyst. It crystallizes in the monoclinic space group P21 with the unit-cell parameters: a= 10.193(5), b= 9.012(5), c= 13.406(5) A, ß = 102.767(5)o and Z = 2. The crystal structure was solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R-value of 0.0390 for 1972 observed reflections. The molecules within the unit cell are stabilized by N-H..O and C-H..F type of hydrogen bonding. The sulphur atom of DMSO solvent molecule is found disordered over two set of sites S100 and S200 with occupancy ratio 0.70:0.30.
Keywords: Crystal structure, Direct methods, Hydrogen bond
Materials and environmental chemistry
InP/Ga2O3 core-shell nanowires were grown on Si substrate at 400 oC in the hydrazine (N2H4) vapor diluted with 3 mol. % H2O. The crystalline InP and solid Ga served as source materials for the growth of nanowires. According to TEM and EDX data the nanowires consisted of InP core with wurtzite-type structure and an amorphous Ga2O3 shell. The minimum diameter of NWs was 14 nm, while the maximum lengths reached several micrometers. The twinned planes appeared in WZ InP core at increased nanowire diameters. Based on the obtained results and possible chemical reactions, the following mechanism was proposed for the growth of core-shell nanowires: pyrolytic decomposition of hydrazine caused the appearance of intermediate NH2, NH and H species in the vapor. At elevated temperatures the crystalline InP source was also dissociated to In and phosphorus precursors. At source temperatures close to 600 oC, due to the interaction of In and Ga sources with water molecules and hydrazine decomposition products the volatile Ga2O and In2O were formed. These molecules reached the Si substrate which was heated to 400 oC. The final chemical reaction involved Ga2O3, In2O3 and phosphorus precursors. As a result of a spontaneous reaction the Ga2O3 and InP phases were produced and segregated. The InP crystallized as a core while Ga2O3 created the amorphous shell, because the growth temperature was insufficient for its crystallization.
Keywords: core-shell nanowire, indium phosphide, gallium(III) oxide
Preparation of silver nanoparticles in silver nitrate solution using tannin as a reductant and sodium carbonate-as a solution stabilizer was performed. Spectrophotometric and electron-microscopic methods were used to investigate the process of synthesis of silver nanoparticles. The effect of microwave power on the formation of nanoparticles was analyzed.
Keywords: silver nanoparticle, tannin, silver nitrate, sodium carbonate, microwave irradiation
New chemical synthesis methods for producing nano-sized iron oxides particles and producing biocompatible polymer coated nanoparticles in the solution has been investigated. A new particle processing device for making high performance nanomaterials as well as their applications in medicine has been developed by applying electrohydraulic technique for nanohomoganization. Biomedical application requires the biocompatible super paramagnetic iron oxide nanoparticles (SPIONs), which are stable and well dispersed in water at physiological pH or in physiological salinity. In order to obtain biocompatible SPIONs, particles of 10-15 nm size have been synthesized and these SPIONs have been coated with ascorbic acid. Vibrating Sample Magnetometer studies (VSM) were carried out to study the effect of phase transformations on the magnetic properties of the nanoparticles. The samples were analyzed by VSM at room temperatures to find the saturation magnetization. The ascorbic acid coated iron oxide nanoparticles were found to be well dispersed in water as they have a hydrophilic outer surface containing hydroxyl and amine groups. This hydrophilic outer surface is likely to enhance their bioactivity. Therefore they may become a very good drug carrier for biomedical applications.
Keywords: Nanoparticles, iron oxides, electrohydraulic technique, ascorbic acid, biomedical applications
The results of applied investigations carried out by some groups of Georgian scientists in the field of nanobiotechnology using different physical and chemical methods are presented. A number of new strains of the terrestrial actinomycetes isolated from soils and rocks of Georgia as well as the blue-green alga Spirulina platensis were used as the templates for production the noble metal nanoparticles on examples of silver and gold. A variety of spectral and analytical methods was applied to determine optimal conditions of synthesis and characterize the synthesized nanoparticles. The features of the used research methods and some results obtained with them are detail described. The advantages of each method and their ability to characterize the process of synthesis of nanoparticles are shown.
Keywords: microbial synthesis, nanoparticle, gold, silver, nanotechnology, biotechnology
Organically modified clay mineral was prepared by exchanging hexadecyltrimethylammonium bromide (HDTMA) onto kaolinite clay mineral. The prepared organoclay was characterized using FTIR, XRD and TGA for assigning the surface groups, layer spacing and thermal stability. The adsorption efficiency of the produced organoclay towards hydrocarbons that likely to be present in oily wastewaters and oil spills (gasoline and kerosene) was studied. Different process parameters as contact time, adsorbent dose and HDTMA concentration were studied. The obtained results clarified that the adsorption capacity of the prepared organoclay was potentially enhanced than that of unmodified clay. The batch adsorption capacity was found to be more than 5 g g-1 and 7 g g-1 with respect to kerosene and gasoline, respectively after 24 h of contact.
Keywords: Organoclay, Adsorption, Petroleum, Hydrocarbon
Globally there is a large population of people suffering with diabetes. A large percentage of these patients develop foot ulcers at some point that heal very slowly and can worsen very rapidly. The use of silver nanoparticles in silver release dressings and in management of infected wounds is important, as several pathogenic bacteria have developed resistance against various antibiotics. Such dressings vary in technological nature of their silver content and release. Use of silver dressings in recent times has a considerable challenge of lacking cost effectiveness. In-vitro susceptibility of microorganisms causing foot ulcers to a silver nanocomposite of Polyvinyl alcohol (PVA) and Melamine formaldehyde (MFR) resin both as films and coatings is being reported. AgNP solution was prepared by colloidal route and characterised. MFR was prepared and reacted with PVA and AgNP solution to obtain PVA-MFR composite and PVA-MFR-Ag composite. The antimicrobial composites were casted into films, also soaked into polyvinyl foam, and coated on Whatman paper. Antimicrobial efficacy of such prepared dressing materials was tested. They are stable and do not lose their antimicrobial activity with time. Tissues from the wounds of five diabetic patients with deep foot infections were collected to isolate and identify the microorganism responsible for causing foot ulcers in the diabetic patients. Their sensitivity towards various antibiotics was studied. Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa and Enterobacter cloacae species isolated from wound samples, though were found resistant to many antibiotics are sensitive to PVA-MFR-Ag films. These silver composites can be cost effective for the reason that efficacy of nanosilver is superimposed on antimicrobial activity of cheaper PVA-MFR composite. Thus, AgNP immobilised on antimicrobial PVA-MFR, could probably be a promising wound dressing in diabetic foot disease management.
Keywords: Wound dressings; Nanosilver; Antimicrobial; diabetic ulcers; Polyvinyl alcohol-Melamine formaldehyde resin
In the present work, synthesis of silver nanoparticles has been done using a particular variety of medicinal plant extract. Silver nanoparticles have unique optical, electrical, and thermal properties that play an indispensable role in drug delivery, diagnostics, imaging, sensing, gene delivery, artificial implants and tissue engineering. . We used an environmentally friendly extracellular biosynthetic technique for the production of the AgNPs. The reducing agents used to produce the nanoparticles were from aqueous extracts made from the leaves of Ficus microcarpa. We have synthesized silver nano particles by adding the 80 ml of 1 mM silver nitrate solution into the plant extract and characterized by UV-Vis absorption spectroscopy, Infra-red spectroscopy. The UV-Visible spectrum showed a peak at 451 nm corresponding to the Plasmon absorbance of the AgNPs. Moreover, use of plant extracts also reduces the cost of microorganism isolation and culture media enhancing the cost competitive feasibility over nanoparticle synthesis by microorganisms. The antibacterial efficacy also determined by disc diffusion method with Bacillus cereus, Escherchia coli, Klebsiella pneumonia, Staphylococcus aureus and it showed that high level of inhibition. Further, efficient antimicrobial activity of the synthesized silver nanoparticles proves the application potential of green synthesis in the area of nano-medicine
Keywords: Plant extracts, Ficus microcarpa, silver nanoparticle synthesis and antibacterial activity
It was shown for the first time, that after IR heating of polyphenoxazine in the presence of cobalt(II) acetate Co(CH3CO2)2∙4H2O in the inert atmosphere at the temperature of 450–650 °C, the growth of the polymer chain via the condensation reaction of phenoxazine olygomers happens simultaneously with the dehydrogenation of phenyleneamine structures with the formation of conjugated C=N bonds. Hydrogen emitted during these processes contributes to the reduction of Co2+ to Co0. As a result the nanostructured composite material in which Co nanoparticles are dispersed into the polymer matrix is formed. According to TEM Co nanoparticles have size 4 d 14 nm. The investigation of magnetic and thermal properties of Co/polyphenoxazine nanocomposite has shown that the obtained nanomaterial is superparamagnetic and thermally stable.
Keywords: polymers with a polyconjugated system; polyphenoxazine; IR heating; Co nanoparticles; metal-polymer nanocomposite; hybrid magnetic nanomaterial.
The main research was the multielementary analyses of some environmental toxic elements downstream the river Lumbardhi Deçan (Kosovo), where they end up as natural and anthropogenic recipients. We used ICP/MS as method for the analysis. Results of some toxic elements are as: Cu (4.3-12.6 µg dm-3), Zn (8.8-65.7 µg dm-3), Pb (1.44-8.85 µg dm-3), Cd (0.02-0.15 µg dm-3), Mn (7.6-48.8 µg dm-3), As (0.46-0.68 µg dm-3), Cr (0.3-1.1 µg dm-3), Fe (30-760 µg dm-3), Ni (0.6-3.4 µg dm-3), Sb (0.06-0.33 µg dm-3), Al (112-659 µg dm-3). Also some physico-chemical parameters are determined: air temperature, water temperature, pH, electrical conductivity (EC), total hardness, sulphates, phosphates, nitrites, ammonium, dissolved oxygen and BOD5. Results obtained by the box plot method showed the regions with determined anomalous element concentration values in the water of Lumbardhi Deçan. Even that in Kosovo we don’t have yet any legislative convent for allowed concentrations of toxic metals for natural water resources, the results from this study are a small contribution to gain a clear overview of the statement in this field of environmental quality assurance.
Keywords: Water, ICP/MS, pollution assessment, Lumbardhi River
The results of direct synthesis of boron nitride from boron powders of mean sizes of 0.05, 0.20, and 2.00 µm in nitrogen flow with impurity of H2O in a xenon high-flux optical furnace are presented. Formation of equiaxed, plate-like powders and film-like structures of different sizes was observed. The presence of moisture contributes to the formation of large film-like structures in BN powders from nanosized boron. Carbon impurity in boron powder of mean size of 0.20 µm facilitates formation equiaxed nanosized powders of the smallest mean size. High-temperature gradients in a xenon high-flux optical furnace results in the appearance of vibrations of w-BN at 1097-1107 cm-1 in the FTIR spectra besides the h-BN vibrations of BN powders produced. The presence of moisture in nitrogen flow promotes formation of new BN structures and other compounds as well. Vibrations belong to B-O-H bonds (1184-1193 cm-1), N-B-O and B-O-B linkages (1107– 924 and ~ 700 cm-1, respectively), and tetrahedral BO4 units in B2O3 could be detected in the FT-IR spectra of BN powders produced and XRD studies confirmed that the produced BN powders contains significant amount of sassolite (H3BO3, boric acid) as well.
Keywords: Boron nitride; moisture; structure; concentrated light heating; Fourier Transform Infrared Spectroscopy
Chemical and biological aspects of life
The analysis of algebraic equations for the dependence of the initial velocities of inhibited (seven equations) and activated (seven equations) enzymatic reactions on concentrations of inhibitors (i) and activators (a) is intended to take into account the sources of errors (Corrections 1–8) in using Dixon plots for calculation of constants of inhibition and characteristics of types of inhibition (and activation) of the enzymes.
Keywords: Dixon plots; correction; enzyme; inhibition; activation
Industrial and engineering chemistry, biotechnology
Transportation biofuel ethanol was produced from xylose and corn fiber hydrolyzate (CFH) in a batch reactor employing Escherichia coli FBR5. This strain was previously developed in our laboratory to use cellulosic sugars. The culture can produce up to 49.32 g L-1 ethanol from approximately 125 g L-1 xylose. Use of commercial nutrient sources such as corn steep liquor (CSL) and soy peptone (SP) was also studied and SP was found to be superior than CSL. SP at a concentration of 15 g L-1 resulted in the production of 42.2 g L-1 ethanol with ethanol yield and productivity of 0.49 and 0.74 g L-1 h-1, respectively. Corn fiber (CF) was pretreated with dilute H2SO4 and hydrolyzed using commercial cellulases. Employing CFH as a sole substrate, the culture produced 35.33 g L-1 ethanol with a productivity and yield of 1.01 g L-1 h-1 and 0.54, respectively, leaving behind no residual sugars in the medium. This productivity is 40 % higher than when using xylose as the carbon source in the control experiment.
Keywords: Corn fiber, corn fiber hydrolyzate, ethanol, productivity, yield, Escherichia coli FBR5
Theoretical and computational chemistry
Boron nitride shell structures of chemical composition BNx with boron excess (x 1) contaminated with carbon are synthesized in the process of melting of a boron-rich material in a boron nitride crucible with the nitrogen source in the form of high-purity pressed boron nitride rods, which held up the crucible. The obtained material is found to be conductive despite the fact that all the boron nitrides of stoichiometric chemical composition BN are insulators. “Metallic” boron nitride is modelled as a mixture of structural modifications of semiconducting boron and boron carbide heavily doped with nitrogen. First principle calculations performed within the quasi-classical approximation prove that nitrogen impurities, accommodated in large crystallographic voids characteristic of all-boron and boron-rich crystalline lattices, create donor electron-states inside the conduction band and then lead to the local “metallization” of chemical bonds in these initially covalently bonded structures.
Keywords: boron nitride, non-stoichiometric chemical composition, metallization by doping.
As science advances, its laws become fewer but of greater scope. In this respect the Periodic Law, which is the basis of the Periodic Table, represents a major step in the progress of chemistry — it affords the natural classification of the elements. The Periodic Table was developed by chemists more than one hundred years ago as a correlation for the properties of the elements. With the discovery of the internal structure of the atom, it became recognized by physicists as a natural law. When the crystalline structure of solids was studied, the nature of the chemical bonds was understood, and the theory of metals was put forward, it became an essential tool not only for chemists and physicists, but for metallurgists as well. Of the 87 naturally occurring elements, 63, i.e., about three fourth are described as metals, 16 as nonmetals, and 9 as metalloids. Chemists should abandon numbering the groups in the Periodic Table and to give descriptive names instead.
Keywords: metals; nonmetals; metalloids; typical metals; less-typical metals; transition metals; inner transition metals; lanthanides; actinides
The donor numbers (DN) of a series of 20 phosphoramides with general structure (R2N)(X2N)(Y2N)P=O (with R,X and Y alkyl radicals, nitrogen-heterocycles or hydrogen atoms) were revised on the basis of a series of rather simple considerations. It is shown that all the phosphoramides considered even after the revision are characterized by high DN. In a scale of 163 different type of solvent molecules, the phosphoramides are all collocated with their DN above 35 kcal mol-1 till 50 kcal mol-1. The extremely high DN value reported previously for (tris(1-aziridinyl)phosphine oxide (TEPA), is now revised to 50 kcal mol-1. The highest DN values in the phosphoramides considered in this investigation were those of TEPA, (NHEt)3P=O and (pyrrolidino)3P=O.
Keywords: Gutmann donicity, solvent donor numbers, phosphoramides, (tris(1-aziridinyl)phosphine oxide, electron pair donors
Complete thermodynamic analysis of the system Ti-B-O-C at atmospheric pressure and in a vacuum for the following structures: 1.TiO2 - 38.14 wt.%; B2O3 - 33.25 wt.%; C - 28.61 wt.%. 2. TiO2 - 49.07 wt. %; B2O3 - 21.40 wt.%; C - 29.53 wt. %. The basic results for all structures are presented in the form of diagrams (dependence of the contents of components on temperature range 700-1800 K)
Keywords: Full thermodynamic analysis, vacuum, oxide, carbothermal reduction