Effect of nickel sulphate hexahydrate addition on crystal growth,structural, optical and biological applications of glycine single crystals

In the present study, single crystals of α- and γ-glycine have been successfully grown in the presence of nickel sulphate hexahydrate as an additive for the first time by using slow solvent evaporation method. The analytical grade chemicals of glycine and nickel sulphate hexahydrate were taken in five different molar ratios: 1:0.2, 1:0.4, 1:0.6, 1:0.8 and 1:1 respectively to find out the α, and γ-polymorph of glycine. The lower molar proportion of nickel sulphate hexahydrate yield only α-polymorph whereas the higher molar proportion of nickel sulphate hexahydrate yields only γ-polymorph of glycine which was confirmed by powder XRD studies. UV–Visible–NIR transmittance spectra were recorded for the samples to analyze the transparency in visible and near infrared region (NIR). The optical band gap Eg was estimated for grown nickel sulphate hexahydrate (NSH) added glycine crystals using UV–Visible–Transmission study. Functional groups present in the sample were identified by FTIR spectroscopic analysis. The in vitro antimicrobial activities of the synthesized nickel sulphate added glycine single crystals were investigated against gram positive, gram negative bacterial strains using the agar disk diffusion method.     

Small-angle neutron scattering study of the effect of n -alkanols on interacting micelles

Small-angle neutron scattering cross-section distributions of sodium dodecyl sulphate (SDS) and dodecyl trimethyl ammonium bromide (DTAB), each 0·3 M in D₂O were obtained in the absence and presence of 0·1 M 1-pentanol, 1-hexanol, and 1-octanol at 25°C. The Hayter-Penfold type analysis was adopted. An ellipsoidal model with semiminor axis (a=16·5 ?) and semimajor axes (b=40·7 ? and 29·8 ?) for pure SDS and DTAB micelles has produced best fits. On increasing alkanol chain lengths an increase inb values was found. Micellar parameters like effective radius (R), (a, b), fraction of counterions per micelle, and intermicellar distances were obtained. Surfactant aggregation number, additive aggregation number intermicellar interaction potentials and values of Debye screening length were obtained for SDS and DTAB in the presence of alkanols. Implications of partitioning effect, surfactant ionicity and intermicellar potentials on the microstructures are rationalised.     

Theoretical studies on the carcinogenicity of polycyclic aromatic hydrocarbons

The distinct molecular regions of a set of 28 polycyclic aromatic hydrocarbons (PAHs) showing varying degrees of carcinogenic activity (CA) have been analyzed on the basis of their calculated molecular electrostatic potential (MESP) at B3LYP/6-31+G(d,p) level of theory. The MESP, being a property directly related to electron density, clearly distinguishes the electron dense centers in the molecule into K, L, M, and newly defined N regions. Further, a quantitative structure activity relationship (QSAR) model of carcinogenicity is developed using the volume of MESP lobes at the named regions for a set of 17 carcinogenic molecules with experimentally known CA index. The QSAR equation suggested that all the geometrical regions are significant in determining the carcinogenic property of PAHs. The model clearly showed that K and M regions have activating carcinogenic effect whereas L and N regions have deactivating carcinogenic effect. The CA showed considerable enhancement when any three distinct regions are present in a PAH. On the other hand, all the PAH systems with only one type of region are inactive irrespective of whether the region is activating or deactivating. Similarly, molecules showing the presence of two types of regions are either inactive or weakly active. The essential features of both the "K, L region" and the "bay region" theories of carcinogenesis are well evident in the new QSAR model, as the former theory works on the basis of activating K and deactivating L regions whereas the latter theory is related with the activating M region.     

Mössbauer study of Cd0.1Ni0.9Sn y Fe2−2y O4 ferrites

Mössbauer spectra of Cd_0.1Ni_0.9Sn_yFe_2?2yO₄ (y=0.0 to 0.5) ferrite system have been studied. The spectra suggest the existence of two hyperfine fields, one due to Fe³⁺ tetrahedral (A) site ions and the other due to Fe³⁺ octahedral (B) site ions. The variation of isomer shift, quadrupole interaction and internal magnetic fields of⁵⁷Fe³⁺ ions in both A and B sites have been determined as function of tin concentration. The systematic decrease in Curie temperature observed in the above system with tin concentration is explained on the basis of exchange interaction.     

ipso-nitration of arylboronic acids with chlorotrimethylsilane-nitrate salts

[reaction: see text] A mixture of nitrate salt and chlorotrimethylsilane is found to be an efficient regioselective nitrating agent for the ipso-nitration of arylboronic acids to produce the corresponding nitroarenes in moderate to excellent yields. High selectivity, simplicity, and convenience are the key features of the reaction.     

N‐(p‐Chloro­benzyl­idene)­phenyl­amine N‐oxide

The crystal structure of the title compound, C₁₃H₁₀ClNO, confirms that it exists as a nitro­ne. The geometry about C=N is Z. The relevant torsion angles indicate trans and cis conformations around the nitro­ne bond.     

Hydrophobic Interactions in Donor-Disulphide-Acceptor (DSSA) Probes Looking Beyond Fluorescence Resonance Energy Transfer Theory

Donor –linker –acceptor (DSSA) is a concept in fluorescence chemistry with acceptor being a fluorescent compound (FRET) or quencher. The DSSA probes used to measure thiol levels in vitro and in vivo. The reduction potential of these dyes are in the range of ?0.60 V, much lower than the best thiol reductant reported in literature, the DTT (?0.33 V). DSSA disulphide having an unusually low reduction potential compared to the typical thiol reductants is a puzzle. Secondly, DSSA probes have a cyclized rhodamine ring as acceptor which does not have any spectral overlap with fluorescein, but quenches its absorbance and fluorescence. To understand the structural features of DSSA probes, we have synthesized DSSANa and DSSAOr. The calculated reduction potential of these dyes suggest that DSSA probes have an alternate mechanism from the FRET based quenching, namely hydrophobic interaction or dye to dye quenching. The standard reduction potential change with increasing complexity and steric hindrance of the molecule is small, suggesting that ultra- low Eo’ has no contribution from the disulphide linker and is based on structural interactions between fluorescein and cyclized rhodamine. Our results help to understand the DSSA probe quenching mechanism and provide ways to design fluorescent probes.