Classical and advanced chemical sciences
Eco-friendly, one-pot three-component syntheses of 2-(1H-benzo[d]imidazole-2-yl)-N-arylbenzamideshave been developed by combining Phthaloyl dichloride with anilinesand o-phenylenediamine in glycerol without any external catalyst. These reactions involve easy workup, provide excellent yields and use glycerol as solvent at 100 oC for 60-90 min which are the merits of this preparation.
Keywords: Green synthesis; 2-(1H-benzo[d]imidazole-2-yl)-N-arylbenzamides; glycerol; one-pot synthesis; anilines; ophenylenediamine (OPDA); phthaldichloride
Materials and environmental chemistry
A comparative study using two different thiocyanate electrode designs was conducted; a solid type electrode (type A) and conventional liquid inner contact electrode (type B). The fabrication of these electrodes was based on Al (III) [4-(2-Pyridylazo) resorcinol] (Al/PAR) and Mg (II) phthalocyanine (MgPC) complexes as a charged carrier, aliquate 336S and TDMAC as ion exchangers in plasticized poly (vinyl chloride) membrane. Electrodes type (A) revealed significantly enhanced response towards SCN- ions with displayed near-Nernstian slope of -53.7 - -55.8 mV decade-1 over the concentration range 5.0x10-6-1.0x10-2 mol L-1 and a detection limit of 0.4-3.7 μg mL-1. Type (B) sensors revealed near-Nernstian potential response to SCN- with a slope of -45.9 - -62.4 mV decade-1 over a linear range of 5.0x10-5- 1.0x10-2 mol L-1 and a detection limit of 0.12-0.3 μg mL-1. Membrane sensors based on (Al/PAR) and (MgPC) using the so called "fixed interference method" (FIM) exhibited a good selectivity over different anions which differ significantly from the classical Hofmeister series. All sensors were integrated in a flow system for continuous monitoring of thiocyanate under hydrodynamic mode of operation. The sensors revealed a frequency of ~ 54 samples h-1. Application of the proposed sensors for SCN- determination in biological fluid samples such as saliva collected from some non-smoker and smoker donors. Determination of cyanide content in electroplating wastewater samples after its conversion into thiocyanate was also applied. The results obtained from the proposed sensors were agreed with that obtained using the standard methods of thiocyanate and cyanide analysis
Keywords: Potentiometry, conventional sensors, solid state; thiocyanate, flow injection analysis, biological fluids
Chemical and biological aspects of life
The foliose lichen, Parmotrema melanothrix has been chemically screened for the first time and isolated the depside atranorin (1) in significant quantity (2 %) along with methyl 2,4-dihydroxy-3,6-dimethylbenzoate (2) and methyl 3-formyl-2,4-dihydroxy-6-methylbenzoate (3). In view of its abundance, interesting structural features and significant biological profile, atranorin was subjected to chemical modification and synthesised five diverse analogues in very good yields (70~93%). The synthesised analogues along with the three isolated compounds were evaluated for their cytotoxic potential against a panel of six human cancer cell lines using MTT assay. Among the tested compounds, 1a showed enhanced activity than the parent compound (1) against almost all the tested cell lines. Significantly, 1a showed highest activity (IC50 = 15.19 μM) against prostate cancer cell line (DU145). The results indicate that complete protection of the phenolic hydroxyls in atranorin as acetates enhances the cytotoxicity, especially against DU 145.
Keywords: Lichen, Parmotrema melanothrix, atranorin, cytotoxicity, MTT assay
Three different extracts (aqueous, ethanolic and ethyl acetate) of Carthamus tenuis and Cephalaria jopprnsis were prepared and tested for total phenolic content (TPC), antioxidant capacity and antifungal activity. Results for C. tenuis are meaningfully different of known findings. As for C. joppensis, the medicinal and biological properties of this plant were never published before. For each plant, TPC was highest in aqueous extracts and these had highest antioxidant capacity. Ethanolic extracts of both plants had strongest activity against Rhizopus stolonifer (black mold).
Keywords: Carthamus tenuis, Cephalaria joppensis, total phenolic content, antioxidant, antifungal, Rhizopus stolonifer
To search for natural materials that protect human skin from damage caused by ultraviolet-B (UV-B) irradiation, we prepared water extracts of the following four dry berries: lowbush blueberry (LBB) (Vaccinium angustifolium L.), highbush blueberry (HBB) (Vaccinium corymbosum L.), cranberry (CB) (Vaccinium macrocarpon Ait.) and grape (Vitis vinifera L.). Normal human epidermal keratinocytes (NHEKs) were pretreated with each of the extracts and then subjected to transient UV-B irradiation (15.0 W m-2) for 80 s. The results showed that pretreatment of NHEKs with LBB extract significantly attenuated UV-B-induced damage. The concentrations of proanthocyanidins, total flavonoids and total polyphenols in LBB extract were higher than those in the other three berry extracts. Therefore, these compounds might mediate the protection of NHEKs from UV-B-induced damage
Keywords: flavonoids, normal human epidermal keratinocytes (NHEKs), polyphenols, proanthocyanidins, ultraviolet-B (UV-B)
Theoretical and computational chemistry
The concept of retardation is usually applied successfully for the description of transport in two-phase systems of different kind with one moving and one stagnant phase. It simplifies understanding the multitude of processes in the two phases. Retardation factors can be derived from measurements and also mathematically from basic transport equations in the single phases, and thus form a link between practice and theory. The author recently presented a generalization of the theoretical derivations for systems with two moving and/or diffusive phases, in which so called R-factors were introduced. Like retardation factors, R-factors reduce the complexity of the description of a two-phase system. Here conditions are examined in detail under which the generalized R-factor approach is applicable. A demonstration example shows steady states depending on phase dependent reaction rates. A final example application demonstrates how the approach works interpreting real world data.
Keywords: Two-phase; biogeochemistry; retardation; porous media; sediment chemistry
The dynamics of a polaron on a one-dimensional harmonic lattice in an applied constant electric field has been considered. The calculations were performed with parameters close to those of polyacetylene and DNA. The polaron in a constant field goes to a stationary state, characterized by a constant profile and velocity. In this case, the energy got by the polaron from the electric field is transformed into longitudinal coherent lattice vibrations. For several thousand lattice sites, these oscillations have constant frequency and wave number, and these values depend weakly on the electric field.
Keywords: Polaron, charge transfer, electron-lattice interaction, electron-phonon interaction, SSH