Classical chemical sciences
A C60 fullerene/tetracene adduct was synthesized and studied by electronic absorption spectroscopy and FT-IR spectroscopy. Essentially the mono-adduct was obtained as suggested by the spectroscopic analysis and by the thermogravimetric analysis (TGA). The stability and the retro Diels-Alder reaction of the C60/tetracene adduct was studied by TGA, differential thermogravimetric analysis (DTG) and by differential scanning calorimetry (DSC). It was found that the adduct is stable above 300°C and decomposes at 323-390 °C according to the DSC analysis. The decomposition involves the release of tetracene and the restoration of C60 in high yields. However, part of the C60 is lost as amorphous carbon in the retro Diels-Alder reaction.
Keywords: fullerene C60; tetracene or naphthacene; Diels-Alder adduct; retro Diels-Alder; spectroscopy; thermal stability
A series of monoazo disperse dyes based on 5,6-diphenyl-2,3-dihydro-3-oxopyridazine-4-carbohydrazide was prepared by reacting with azobenzeneacetylacetone, ethyl azobenzeneacetoacetate, and azobenzenemalononitrile derivatives. The dyeing performance of these dyes was assessed on polyester fabrics. The dyes were found to give yellow to brown color shades on dyeing with good depth levelness on fabrics. The dye bath exhaustion, fixation and fastness properties of the dye were also determined.
Keywords: 5,6-diphenyl-2,3-dihydro-3-oxopyridazine-4-carbohydrazide; disperse dyes; dyeing; fixation; fastness
Analysis of the nature of intermolecular interactions is of utmost importance in the field of crystal engineering to facilitate the design of new materials with desirable properties. A better understanding of these interactions and their influence on the crystal packing can be obtained by evaluating the energetics associated with these interactions. In this regard, we have identified from the literature a series of 3-acetyl coumarin derivatives and calculated the lattice energy of these crystal structures by using PIXELC module in Coulomb London Pauli (CLP) package. The lattice energy of all the compouds have been partitioned into corresponding coulombic, polarization, dispersion and repulsion contributions. The important packing motifs have been extracted from the crystal packing for a complete understanding of the nature of intermolecular interactions with quantitative inputs from an evaluation of the interaction energy calculated from Pixel. It is found that most stabilizing molecular pair in most of the structures involve bifurcated C-H…O hydrogen bonding. The weak interactions like C-H…O, π…π and C-H…X ( Cl or Br) also play an important role in the stabilization of the crystal packing.
Keywords: Coumarins; PIXEL; hydrogen bonding; intermolecular interactions; lattice energy
A preparation of new series of 2'-hydrazinocholest-6-eno[4,5-d]thiazoles 4-6 from 5α-cholestan-6-ones 1-3 are herein reported. After characterization by IR, 1H NMR, 13C NMR, MS and analytical data, the synthesized compounds 4-6 were tested for anticancer activity in vitro against the human cancer cell lines A549, HepG2, HeLa, SW480 and HL-60 by MTT assay during which compounds 4-6 showed significant anticancer behaviour. The gel electrophoresis pattern demonstrated that the compound 4 alone or in presence of Cu(II) causes the nicking of super coiled pBR322. Further the compound 4 is also able to generate reactive oxygen species (hydroxyl radical) in a dose dependent manner, which correlates its ability to cause DNA breakage in cancer cells. The genotoxicity of the compounds was studied by comet assay involving potential apoptotic degradation of DNA and was analyzed by agarose gel electrophoresis and visualized by ethidium bromide staining.
Keywords: Thiazole; 5α-iodocholestan-6-one; MTT assay; pBR322; Comet assay
The transition metal (II) complexes were formed by the reaction of Co(II), Ni(II), Zn(II), Fe(II) and Cu(II) nitrates with the Schiff base ligands. The complexes were characterized using infrared (FT-IR), electronic spectral (UV), elemental analysis, melting points and XRD analysis etc. The transition metal(II) complexes were screened for antibacterial and antifungal activities. Antibacterial activity against four bacteria such as Escherichia coli, Salmonella typhi, Staphylococcus aureus and Bacillus subtilis bacterial strains by the agar-cup method. Antifungal activity was studied against four bacteria Aspergillus Niger, Penicillium Chrysogenum, fusarium moneliforme and aspergillus flavus bacterial strains by the poison plate method. The complexes were found to exhibit higher to moderate activity against some bacterial species.
Keywords: Antibacterial activity; antifungal activity; metal complex; Schiff bases; FT-IR and UV-VIS spectral data
The oxidative deoximination of several aldo- and keto-oximes by bis[dipyridinesilver(I)] dichromate (BDSD), in dimethylsulphoxide (DMSO), exhibited a first order dependence on BDSD. A Michaelis-Menten type kinetics was observed with respect to oximes. The oxidation of ketoximes is slower than that of aldoximes. The rates of oxidation of aldoximes correlated well in terms of Pavelich-Taft dual substituent-parameter equation. The low positive value of polar reaction constant indicated a nucleophilic attack by a chromate-oxygen on the carbon. The reaction is subject to steric hindrance by the alkyl groups. The reaction of acetaldoxime has been studied in nineteen different organic solvents. The solvent effect has been analysed by multiparametric equations. A mechanism involving the formation of a cyclic intermediate, in the rate-determining step is suggested.
Keywords: carbonyl compounds; bis[dipyridinesilver(I)] dichromate, kinetics; mechanism; oxidation; oximes
As a part of our structural studies of 1,8-dibenzoylnaphthalene compounds, one of the highly congested aromatic-rings-accumulated molecules, 2,7-dibenzyloxy-1,8-bis(4-fluorobenzoyl)naphthalene is designed and determined the crystal structure by X-ray crystallography. Through comparison of the single molecular structure and the molecular packing structure with the homologues bearing alkoxy/aryloxy groups (methoxy, ethoxy, butoxy, and phenoxy groups) at the 2,7-positions, the contribution of the non-bonding molecular interactions to stabilization of the molecular packing is estimated. As a common feature of single molecular structure in the series of the compounds, two aroyl groups are attached to the naphthalene ring in a nearly perpendicular fashion. In the crystal packing of these compounds, aromatic hydrogen interacts with carbonyl oxygen to stabilize the spatial organization of non-coplanarly accumulated aromatic rings replacing π …π stacking interaction of benzene rings. Especially, intermolecular (Ar)C–H…O=C interactions between the benzene rings of the aroyl groups and the carbonyl groups of the neighbouring molecules are influential. The pile superposing the naphthalene ring planes constructed mainly by this intermolecular interaction probably plays the most important role for stabilizing the crystal structure of these compounds. In addition to the (Ar)C–H…O=C interactions, butoxy-, phenoxy- and benzyloxy-bearing compounds have intermolecular (sp3)C–H…π interactions between the methylene moieties (benzene rings for phenoxy-bearing homologue) of the 2,7-substituents and the aromatic rings of the neighbouring molecules (aromatic ring: the naphthalene ring for butoxy-bearing homologue; the benzene rings for phenoxy-bearing homologue; the benzene ring of the benzyloxy group for benzyloxy-bearing homologue). Furthermore, the effective contribution of (Ar)C– H…O=C interaction depends on the kind of the 2,7-substituents. The existence of intermolecular (sp3)C–H…π interactions by 2,7- substituents is plausible to weaken the contribution of intermolecular (Ar)C–H…O=C interactions to the molecular packing. The stability of the molecular accumulation in the crystal is rationally interpreted from the viewpoint of the complementary combination of (Ar)C–H…O=C and (sp3)C–H…π interactions. The order of the total stability of the crystals of these compounds estimated on the basis of melting point and density is in good agreement of the number of these superior interactions, (Ar)C–H…O=C and (sp3)C–H…π interactions.
Keywords: Non-coplanarly aromatic-rings-accumulating molecules, Crystal structure, Spatial organization, Non-bonding molecular interactions, C–H…O=C interaction, C–H…π interaction
A new and general method for preparation of C-benzotriazolated nitrones is reported. The reactivity of C-benzotriazolated nitrones is applied for reaction with Reformatsky reagent in the absence of Lewis acid to produce 2,3-Disubstituted isoxazol-5-ones in good yields.
Keywords: Synthesis, Diaryl(heteroaryl) nitrones, C-benzotriazolated nitrones, isoxazol-5-ones, Reformatsky reagent
Materials and environmental chemistry
Triarylmethane dyes have been identified as one of the toxic dyes. The presence of triarylmethane dyes in water act as pollutant and cause hazardous effect on natural resources, aquatic life as well as to human being. Triarylmethane dyes are extensively used for wool, silk, cotton, leather and paper industries. In the present work, natural sand has been utilised as an adsorbent for developing methodology for the removal of these dyes, which does not easily biodegrades in aqueous medium. The adsorption efficiency of natural sand was tested by using Victoria Blue (VB) as model dye. The adsorpion behaviour as a function of the pH of the aqueous dye solution, the contact time, initial concentration of the dye and the amount of adsorbent was studied. All studies were performed at room temperature (298 K). It was observed that under optimized conditions, 91 % of VB can be removed from aqueous media. The adsorption data was fitted well by the Langmuir and Freundlich adsorption isotherm; pseudo-second-order and intraparticle diffusion models were also applied.
Keywords: Victoria blue; natural sand, adsorption isotherm and kinetics
Water quality around the cities is a global concern owing to the impact of the population density and industrial activities. Assessment of the Caledon River (Mohokare), which flows along the periphery Maseru City, was carried out using a number of physico-chemical properties. The data obtained shed considerable light to the effect of the textile industry on the water quality. There was generally much higher increase in most parameters up to 900% at sampling site where textile effluents joins the river water (Tikoe-Thetsanae) compared to ‘Maliemere (a sampling site upstream of the city). There was however a slight decrease in other parameters (dissolved oxygen, pH) while other parameters (silicates, nitrates and phosphates) did not seem to change or follow any particular pattern. Principal component analysis indicated conductivity, turbidity and total dissolved solids as the most prominent variants accounting for major difference in the PC1 in agreement with the comparison of relative amounts as a percentage of the ‘Maliemere sampling site. The major contributor along the PC2 was found to be the silicates. However, only the concentrations of phosphates were above the maximum contaminant level (0.74 compared to 0.1 mg L-1 respectively) at all sampling points. Hence it is concluded that the water quality assessment shows a detrimental impact on the quality of the water.
Keywords: water pollution, physico-chemical properties, principal component analysis, Caledon River, Maseru
The dyeing and printing of cotton and synthetic fabrics constitute highly specialized industries at Pali. Pollution of surface water stream has always implicit effect on groundwater quality and river Bandi is no more an exception. The primary and foremost cause is the release of untreated effluents in the river by the industries at Pali city. The sodium salts of chloride carbonate, bicarbonate and sulphate are the major pollutants which have increased significantly in polluted groundwaters besides dyes and organic substances. The application of polluted groundwater (salinity >8000 μS cm-1 and SAR >30) in agriculture fields has reduced the yields of crops considerably. The majority of well waters (67.92 %) are characterized (Group V classes) with very high to excessive salinity and sodium hazard (C5S3, C5S4 and C5S5).
Keywords: Groundwater; electrical conductivity; sodium adsorption ratio; residual sodium carbonate; irrigation water quality
Batch adsorption studies were carried out to investigate the adsorption behaviour of textile dye- Reactive red 2 (RR2) from aqueous solution onto montmorillonite (Mt) clay and organophilic Mt clays. The monovalent organic cations- cetyltrimethylammonium (CTA+) and cetylpyridinium (CP+) were exchanged for the metal cations in montmorillonite clay to prepare the organophilic Mt clays- CTA–Mt and CP-Mt. The synthesis of these organophilic clays was confirmed by X-Ray diffraction (XRD), Fourier Transformed Infra Red (FTIR), specific surface area (BET ) and zeta potential techniques. The adsorption affinity of Mt, CTA-Mt and CP-Mt for RR2 was investigated as a function of pH of the aqueous dye solution, contact time, initial dye concentration and adsorbent dosage. The adsorption data obtained was fitted to the Langmuir, Freundlich and Temkin adsorption models and it was found that Langmuir adsorption isotherm yielded the most favourable representation of the adsorption behaviour of RR2. The adsorption kinetics of RR2 has been studied in terms of pseudo-firstorder, pseudo-second-order and intraparticle diffusion processes. It was found that the pseudo-second-order mechanism is predominant in the present adsorption system suggesting chemisorption of the dye.
Keywords: adsorption; adsorption kinetics; cation exchange; montmorillonite; organophilic clays; zeta potential
Chemical and biological aspects of life
The climatic conditions of some regions of Hungary provide great opportunity for apricot cultivation. A majority of apricot fruit is harvested in the northern part of the country. The most important traditional cultivars include ‘Gönci magyar kajszi’, ‘Ceglédi óriás’ and ‘Bergeron’. The element content of six different apricot cultivars (‘Goldrich’, ‘Ceglédi óriás’, ‘Aurora’, ‘Gönci Magyar kajszi’, ‘Magyar kajszi C.235’ and ‘Orange Red’) was examined in this study. The total element content was measured by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Selenium content was determined by polarography. From geographical point of view there is a wide variation in the selenium content of fruits. Apricot cultivars show great variations in element contents. It was determined that apricot contains a low quantity from most elements and daily requirements may not be covered by consumption of 300 g fresh apricot. Although they might be good sources of some essential elements. On the basis of RDA and DRI each examined apricot cultivar proved to be a good source of potassium; ‘Gönci Magyar kajszi’ and ‘Ceglédi óriás’ for manganese, ‘Aurora’ for manganese, potassium and copper. ‘Aurora’ fruits contain the most appreciable element concentrations (Ca, Fe, K, Mg, Na and S). An excellent content of potassium (ranged from 2127 to 4175 mg kg-1 fresh weight) was observed in fruits of all tested cultivars. Although non-essential elements such as B and Al were also present in multiple DRI quantities in samples.
Keywords: mineral elements, apricots, inductively coupled plasma optical emission spectrometry
Acalypha wilkesiana var. lace-acalypha (Muell & Arg.) is a cultivated ornamental plant used in folkloric medicine for the treatment of fever, bacterial, skin fungal infections, wounds, tumors, inflammations and gastro-intestinal troubles. Silica gel column chromatography of the butanol fraction gave two polyphenolic compounds, designated as compounds 1 [m.p. 148-150 0C; Rf 0.67; [n]20 D 1.4118 ] and 2 [m.p. 130-132 0C; Rf 0.46; [n]20 D 1.4079]. The structures of 1 and 2 have been established to be ethyl 3, 4, 5-trihydroxybenzoate (ethyl gallate) and 1, 2, 3-benzenetriol (pyrogallol or fouramine brown) respectively using the 1H NMR, 13C NMR, MS and IR spectral techniques. Both polyphenols were strongly bacteriostatic against against B. subtilis, S. aureus, E. coli, Ps. aeriginosa and S. typhi. Furthermore, 2 was more suppressive of the bacterial strains than 1. However, neither gave any anticandidal activity. The crude extract and butanol fraction demonstrated comparatively weaker antimicrobial activities than the two isolated compounds. The results of the antimicrobial screening have lent scientific credence to the traditional uses of the plant.
Keywords: Polyphenols; ethyl gallate; pyrogallol; bacteriostatic; A. wilkesiana var. lace-acalypha
We present the potential role of aptamers in elucidating the function of hypothetical proteins, as well as the possibilities provided by bioinformatics for establishing a benchmark for aptamer-protein prediction methods. With these future perspectives, the role of hypothetical proteins as target molecules for diagnostics and therapies could prove to be very useful in development of medical technology.
Keywords: Aptamers, hypothetical proteins, pull down assay, in silico studies
The analysis of algebraic forms of corrected equations for the calculation of constants of enzyme inhibition (Ki) and activation (Ka) have shown that the secondary intersects coordinates (1/ V'; i) may be use for calculation only KIIIi constants of noncompetitive enzyme inhibition. A few examples of application of corrected coordinates are given in the present research article.
Keywords: noncompetitive enzyme inhibition; corrected coordinates for calculation of enzyme inhibition and enzyme activation constants; secondary coordinates of intersects
The inhibition of mineralisation of urinary stone forming minerals by glycolic acid has been investigated. The inhibition efficiency of different concentration was studied. Increased intake of glycolic acid would be helpful in urinary stone prophylaxis. Glycolic acid acts as ‘protecting agent’. It has been suggested that ‘proteceting agents’ perhaps withdraw the metal cation from solution, and thus increase the degree of ‘supersaturation and it is to be expected that their addition to solution containing such ions would cause a reduction in the rate of crystal growth. Crystal growth is a very complex process since both the surface and the super saturation varies continuously throughout the period of the growth.
Keywords: urinary stone; urolithiasis; flow static and dynamic models; in vitro inhibition; glycolic acid
Industrial and engineering chemistry, biotechnology
The production of hydrogen from CH4:CO2:H2S (70 % : 30 % : 1000 ppm) mixture, simulating dry biogas in a DBD reactor, supplied with nanosecond negative pulses, is presented. We have found that sulphur produced from H2S during the process changes the electrical parameters of the reactor with a RVC electrode. As a result, the production of syngas and the selectivity of methane conversion into hydrogen, decreases. Due to changed electrical parameters of the reactors, radicals formed from methane recombine into C2 and C3 hydrocarbons more efficiently, resulting in lower production of hydrogen. Major by-product of the methane processing is propane, concentration of which is comparable to hydrogen.
Keywords: hydrogen; biomethane; dielectric barrier discharge; plasma; hydrogen sulphide
The recent focus of research with electrohydraulic discharges is on bacteria and microorganism inactivation. The processes and main biocidal effects in which this occurs are not fully understood. In this paper a study of energy emission from electrohydraulic spark discharge is presented. The spark discharge was generated in a cylindrical reactor 25 mm in diameter made of PTFE between a stainless steel hollow needle electrode and a steel rod electrode. Distilled water was used and the flow was 30 ml/min. The gap between the electrodes was 3 mm. Spark discharge energy was measured to be 1.2-1.4 J. Measurements show that over 50% of this energy is used for heating of the reactor and electrodes, and about 2% for acoustic waves. The rest of the discharge energy, i.e. ~0.54 J, is distributed among UV/Vis radiation, production of primary active species and ultrasonic.
Keywords: spark discharge, electrohydraulic discharge, energy emission
Theoretical and biological aspects of life
New complexone derivatives of 8-hydroxyquinoline (quinolinol) were synthesized by the Mannich reaction from secondary and primary amines. Our syntheses were carried out either at room temperature, at reflux or under microwave irradiation, in good yields. The use of the 7-(dioctylamino) methyl) quinolin-8-ol (3f) as new extractant for the uptake and removal of UO2 2+ was investigated. Conditions for an effective sorption were optimized. The total sorption capacity was 102 (mg.g-1) under optimum experimental conditions.
Keywords: Multicomponent Mannich reactions; microwave irradiation; 7-(alkylaminomethyl)quinolin-8-ol type complexones; uranylion extraction; 7-(dioctylaminomethyl)quinolin-8-ol.