Classical and Advanced Chemical Sciences
A simple, highly efficient and eco-friendly protocol for the synthesis of bioactive 2,4,5-trisubstituted-1H-imidazoles via one-pot three component condensation of benzil, aromatic aldehydes and ammonium acetate under solvent free conditions has been achieved utilizing the novel Bronsted acidic ionic liquid, (L-pyrrolidine-2-carboxylic acid sulfate) as catalyst. The distinguishing features of this methodology are excellent yields in shorter reaction time, cleaner reaction profile, and environmentally friendly nature, use of non-toxic, easily synthesizable, inexpensive catalyst.
Keywords: Eco-friendly, imidazole, ionic liquid, three-component reaction
Materials and Environmental Chemistry
A solid contact biosensor for Acetylcholine (ACh) based on host-guest interactions and potentiometric transduction has been designed and characterized. The biomimetic man-tailored host was synthesized using methacrylic acid as a functional monomer, ethylene glycol di-methacrylate as a crosslinker in the presence of benzoyl peroxide as an initiator. The imprinted beads were dispersed in 2-nitrophenyloctyl ether and entrapped in a poly(vinyl chloride) matrix. Slopes and detection limits are 55.2-59.6 mV decade-1 and 0.65-1.31 μg mL-1, respectively. Significantly, improved accuracy, precision, good reproducibility, long-term stability, selectivity and sensitivity were offered by these simple and cost-effective potentiometric biosensors. A tubular version was further developed and coupled to a flow injection system for acetylcholine determination. This simple and inexpensive flow injection analysis manifold, with a good potentiometric detector, enabled the analysis of ∼30 samples h-1 without requiring pretreatment procedures. An average recovery of 98.3 % and a mean standard deviation of 1.1% were obtained. The sensors were used to follow up the decrease of a fixed concentration of ACh+ substrate as a function of acetylcholinesterase (AChE) activity under optimized conditions of pH and temperature. A linear relationship between the hydrolysis initial rate of ACh+ substrate and enzyme activity hold 0.01- 5.0 IU L-1 of AChE enzyme.
Keywords: Acetylcholine, acetylcholinesterase enzyme assay, molecular imprinted polymers, potentiometry, flow injection analysis
The use of biomass and other solid material as a source of energy is associated with some deleterious effects consequent to incomplete combustion associated with poor ventilation leading to production of a number of chemical compounds that are known or suspected to be a health threat. This study reports the screening of the formation of the polycyclic hydrocarbons during pyrolysis of the fuel materials, namely, coal, dung and wood, commonly used as fuel in rural areas in Lesotho, under poor aeration using a simple in-house pyrolysis unit The method demonstrated sufficient linearity for the standards with correlation coefficient, R2 ≥ 0.9884 and repeatability (%RSD ≤ 15 %) of the real samples used, coal demonstrated production of naphthalene and pyrene, while from the cake dung formation of naphthalene was detected. Despite not being extensive, the results form a basis for a more rigorous study including employing more identification tools, such as mass spectrometry that enables identification and a better detection of low levels of the analytes.
Keywords: Biomass fuel, cake dung, incomplete burning, polycyclic aromatic hydrocarbons, pyrolysis
Nanostructured Al2O3 in 60-80 nm diameter has been deposited on carbon steel substrates, by cathodic electrophoretic deposition (EPD), in ethanol with poly(acrylic acid) (PAA) as charging agent, as a protective coating against corrosion for carbon steel (C.S.) in seawater environment. Potentiodynamic polarization measurements performed on the Al2O3 coated carbon steel coated by Al2O3in 3.5 % NaCl at temperature range 298-328 K and the result showed that using PAA charging agent lead to increase the corrosion resistance.
Keywords: Alumina, carbon steel, AFM, nanoparticle, polyacrylic acid, corrosion
Chemical and Biological Aspects of Life
The article describes the findings of a comparative study of the sugar-acid index, content of free organic, ascorbic, and hydroxycinnamic acids, dry, tanning, and pectic substances, soluble sugars, and the main groups of bioflavonoids in fruit of six newly introduced Oxycoccus macrocarpus (Аit.) Рers. cultivars in Belarus — Stevens (st), Bain Favorite, Holliston, Hollister Red, Stankovich, and WSU 108. It is established that the Hollister Red cultivar has the highest integrated level of nutritive and vitamin value of fruit based upon the combination of properties analyzed, from 1.8 to 11 times the level observed in the other cultivars, whereas the WSU 108 and especially the Bain Favorite cultivars have the lowest levels.
Keywords: Oxycoccus macrocarpus, cranberry, cultivar, fruit, biochemical composition, organic acids, carbohydrates, bioflavonoids
The genus micromeria is one of the most widespread plant families in the "old world". Its subspecies, especially Micromeria fruticosa, have been used by humans for thousands of years. The plant(s), its extracts and its chemical ingredients are reviewed in this article for their reported medicinal/biological activities. In addition, the traditional medicine and ethnobotanical uses are briefly presented.
Keywords: micomeria, micromeria fruticosa, essential oil, plant extracts, medicinal activities
Theoretical and Computational Chemistry
The high acidity of Meldrum’s acid, barbituric and tetronic acids in comparison to their acyclic analogues was explained by density functional theory and calculations and by natural bond orbital analysis. The present study shows that cyclic β-dicarbonyl compounds are remarkably stabilized by intramolecular donor-acceptor interactions and this effect is absent in their acyclic analogues.
Keywords: Meldrum’s acid, barbituric acid, tetronic acid, carbon acidity donor-acceptor interactions, DFT calculations, NBO analysis
The notion of spatial-energy parameter (P-parameter) is introduced based on the modified Lagrangian equation for relative motion of two interacting material points, which is a complex characteristic of important atomic values. Wave properties of P-parameter are found, its wave equation having a formal analogy with the equation of Ψ-function is given. In the systems in which the interactions proceed along the potential gradient (positive performance) the resulting potential energy is found based on the principle of adding reciprocals of the corresponding energies of subsystems. Some correlations of P-parameter values with Lagrangian and Hamiltonian functions are obtained.
Keywords: Spatial-energy parameter, wave functions, electron density, structural interactions