Scholl reaction of hexaphenylbenzenes with hexakis-alkoxy substituents

The hexakis-alkoxy substituted hexa-peri-hexabenzocoronene (HBC) discotic core is desirable aiming at strong π–π interactions in columns, electronic tuning of the core and better processability. The feasibility of synthesising a new hexakis-alkoxy substituted HBC core is investigated and described in this report. Experimentally, it has been found that when two alkoxy substituents in a peripheral aromatic ring are placed meta to each other, the Scholl reaction results in fully cyclised HBC product. Surprisingly, when the alkoxy groups are ortho to each other, cyclodehydrogenation results in the formation of a partially fused product. This partially-fused ring formation happens under varying reaction conditions and irrespective of the differing alkyl chain lengths. Most plausibly, the considerable strain in the fully fused molecule from 1,2 isomer is the reason to cease the reaction at the partially fused stage. Further quantum-mechanical calculations at the B3LYP/6-31G(d) level of theory also support the hypothesis. The incorporation of two electron donating groups has also reduced the band gap compared to its mono alkoxy analogue. Reduced band gap values are promising feature of these molecules for finding future applications of discotic liquid crystals in organic electronics.     

Validated high-performance thin-layer chromatographic method for quantification of gallic acid and ellagic acid in fruits of Terminalia chebula,Phyllanthus emblica,and Quercus infectoria

A simple and rapid high-performance thin-layer chromatographic method for quantification of gallic acid and ellagic acid in dried fruits of Terminalia chebula, Phyllanthus emblica, and Quercus infectoria has been developed. The chromatographic development was carried out on precoated silica gel 60 F₂₅₄ plates in a mixture of toluene:ethyl acetate:chloroform:formic acid (4:8:1:3 v/v/v/v). The plate was scanned densitometrically at a wavelength of 280 nm. The retention factor value of gallic acid and ellagic acid was found to be 0.63 ± 0.2 and 0.53 ± 0.1, respectively. The developed method was validated in terms of linearity, precision, accuracy, sensitivity, robustness, specificity and stability as per the international conference of harmonization guidelines. The method showed good linear relationship over a range of 100–600 ng/band (gallic acid) and 100–500 ng/band (ellagic acid) with a regression coefficient (r²) of 0.997 (gallic acid) and 0.996 (ellagic acid). The method showed high accuracy (99.65%–100.85%). The percentage relative standard deviation of intra-day and inter-day precision studies was not more than 2%. The method is highly robust and has displayed high specificity. The developed method is new, simple, and accurate and can be successfully employed in routine analysis of raw materials and formulations containing gallic acid and ellagic acid.     

Utilization of Cheese Whey Using Synergistic Immobilization of β-Galactosidase and <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> Cells in Dual Matrices

Whey is a byproduct of the dairy industry, which has prospects of using as a source for production of various valuable compounds. The lactose present in whey is considered as an environmental pollutant and its utilization for enzyme and fuel production, may be effective for whey bioremediation. The dairy yeast Kluyveromyces marxianus have the ability to utilize lactose sharply as the major carbon source for the production of the enzyme. Five strains were tested for the production of the β-galactosidase using whey. The maximum β-galactosidase activity of 1.74 IU/mg dry weight was achieved in whey using K. marxianus MTCC 1389. The biocatalyst was further immobilized on chitosan macroparticles and exhibited excellent functional activity at 35 °C. Almost 89 % lactose hydrolysis was attained for concentrated whey (100 g/L) and retained 89 % catalytic activity after 15 cycles of reuse. Finally, β-galactosidase was immobilized on chitosan and Saccharomyces cerevisiae on calcium alginate, and both were used together for the production of ethanol from concentrated whey. Maximal ethanol titer of 28.9 g/L was achieved during fermentation at 35 °C. The conclusions generated by employing two different matrices will be beneficial for the future modeling using engineered S. cerevisiae in scale-up studies.     

Synthesis of 3,4-disubstituted 2H-benzopyrans through C-C bond formation via electrophilic cyclization

The electrophilic cyclization of substituted propargylic aryl ethers by I2, ICl, and PhSeBr produces 3,4-disubstituted 2H-benzopyrans in excellent yields. This methodology results in vinylic halides or selenides under mild reaction conditions and tolerates a variety of functional groups, including methoxy, alcohol, aldehyde, and nitro groups.     

Study of DNA Light Switch Ru(II) Complexes : Synthesis,Characterization, Photocleavage and Antimicrobial Activity

The three Ru(II) complexes of [Ru(phen)₂dppca]²⁺ (1) [Ru(bpy)₂dppca]²⁺ (2) and [Ru(dmb)₂dppca]²⁺ (3) (where phen = 1,10 phenanthroline, bpy = 2,2-bipyridine, dmb = 2 ,2-dimethyl 2′,2′-bipyridine and polypyridyl ligand containing a single carboxylate functionality dppca ligand (dipyridophenazine-11-carboxylic acid) have been synthesized and characterized. These complexes have been shown to act as promising calf thymus DNA intercalators and a new class of DNA light switches, as evidenced by UV-visible and luminescence titrations with Co²⁺ and EDTA, steady-state emission quenching by [Fe(CN)₆]⁴⁻ and KI, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments. The results suggest that 1, 2, and 3 complexes bind to CT-DNA through intercalation and follows the order 1 > 2 > 3. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR322 DNA.     

A numerical method for soluble surfactants on moving interfaces

We present a numerical method modeling soluble surfactants on deforming interfaces. The method uses an explicit Eulerian discretization of the interface allowing the use of standard finite difference schemes to solve coupled time-dependent differential equations for the concentration of surfactant on the interface and for the concentration of surfactant in the bulk. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Measurement of activity concentration of primordial radionuclides in soil samples from Thirthahalli taluk and the assessment of resulting radiation dose

The activity concentration of primordial radionuclides ²²⁶Ra, ²³²Th, and ⁴⁰K in soil samples of Thirthahalli taluk were measured systematically by using a low background HPGe detector coupled to 16 K MCA. The measured activity concentration of ²²⁶Ra lies between 5.1?±?0.2 and 79.5?±?1.7 Bq kg^?1with an average activity of 25.99 Bq kg^?1, ²³²Th ranges from 5.1?±?0.3 to 95.3?±?2.2 Bq kg^?1with an average activity of 33.60 Bq kg^?1and that of ⁴⁰K varies from 18.3?±?1.5 to 833.4?±?17.5 Bq kg^?1with an average activity of 175.52 Bq kg^?1. Higher concentration of these radionuclides were found in the soil samples where the regional geology is granites. The consequential gamma dose and the corresponding radiation hazard was also estimated and is found to be within the permissible limits. The possible radiological impact on the public was also determined and these results are presented in this paper.     

Polymer immobilized Fe(III) complex of 2-phenylbenzimidazole: An efficient catalyst for photodegradation of dyes under UV/Visible light irradiation

Fe(III) complex of 2-phenylbenzimidazole has been covalently anchored on polymer and characterized by elemental analysis, FT-IR, far-IR, BET surface area measurements, UV–Vis/DRS spectroscopy, thermo-gravimetric analysis and magnetic moment measurements by VSM which confirmed an octahedral environment around Fe(III) in the bound complex. The photocatalytic performance of this complex was evaluated in the photodegradation of dyes in presence of H₂O₂ as an oxidizing agent. Suitable reaction conditions have been optimized by considering the effects of various reaction parameters such as pH, oxidants, concentration of dye, H₂O₂ and catalyst for the maximum degradation of dye. The photodegradation was found to be 100% with complete mineralization in 150?min. The comparison of photocatalytic efficiency of the catalyst under visible light, sunlight and dark conditions are accomplished. Comparison between catalytic activity of the polymer-supported complex and unbound complex demonstrated that the polymer-supported complex was more active. Photocatalytic performance of PS-Fe(III)PBMZL was also compared with commercial TiO₂ (P25). This heterogeneous complex retained its activity up to 8 runs. A tentative mechanism has been proposed.     

Modeling the effect of non-cytolytic immune response on viral infection dynamics in the presence of humoral immunity

Nonlinear Dynamics - In this paper, a mathematical model describing the viral infection dynamics with non-cytolytic effect of humoral immune response is presented and analyzed. The effect of...