NMR study of O and N,O‐substituted 8‐quinolinol derivatives

The ¹H and ¹³C NMR spectral study of several biologically active derivatives of 8‐quinolinol have been made through extensive NMR studies including homodecoupling and 2D‐NMR experiments such as COSY‐45°, NOESY, and HeteroCOSY. Electron donating resonance and electron withdrawing inductive effect of several groups showed marked changes in chemical shifts of nuclei at the seventh positions of O‐substituted quinolinols (2–15). Although in N‐alkyl, 8‐alkoxyquinolinium halides (16–21), ring A rightly showed low frequency chemical shift values. Copyright © 2013 John Wiley & Sons, Ltd.     

Highly efficient silica gel-supported 1,2-diaminocyclohexane-Pd catalyst for Suzuki-Miyaura and Sonogashira coupling reactions

A palladium (Pd) catalyst was prepared by immobilization of a 1,2-diaminocyclohexane based Pd-complex onto amorphous silica gel and its applications as a heterogeneous catalyst for Suzuki-Miyaura and Sonogashira coupling reactions are described. The catalyst was highly efficient, reusable and air-stable. An erratum to this article is available at .     

Carbon dioxide sequestration and methane removal from exhaust gases using resorcinol–formaldehyde activated carbon xerogel

The world is faced with intrinsic environmental issues. Among these issues, the minimization of greenhouse gas emission to acceptable levels presents a high priority. This study seeks to help to reduce the greenhouse effect in sustainable manner. A resorcinol–formaldehyde xerogel was synthesized at specific conditions and used to prepare an activated carbon xerogel (RF-ACX). RF-ACX exhibited micropores in range of 1.2–1.4 nm, a surface area of 496 m²/g and a cumulative pore volume of 0.81 cm³/g. Scanning electron microscopy showed that it is made of microspherical particles with an almost uniform particle size of 1.3 ± 0.2 μm. Equilibrium and kinetic studies for the adsorption of CO₂, CH₄ and N₂ on RF-ACX were conducted at five temperatures (293, 303, 313, 323, and 333 K) and pressures of up to 1 MPa. The adsorption capacity on RF-ACX was highest for CO₂, followed by CH₄ and then N₂. Isosteric heats of adsorption and adsorption rates were investigated. The measured adsorption equilibria were fitted with the extended multisite Langmuir adsorption model and further used to predict adsorption equilibria of their corresponding binary systems.     

Exciton Migration in Conjugated Dendrimers: A Joint Experimental and Theoretical Study

We report a joint experimental and theoretical investigation of exciton diffusion in phenyl‐cored thiophene dendrimers. Experimental exciton diffusion lengths of the dendrimers vary between 8 and 17 nm, increasing with the size of the dendrimer. A theoretical methodology is developed to estimate exciton diffusion lengths for conjugated small molecules in a simulated amorphous film. The theoretical approach exploits Fermi’s Golden Rule to estimate the energy transfer rates for a large ensemble of bimolecular complexes in random relative orientations. Utilization of Poisson’s equation in the evaluation of the Coulomb integral leads to very efficient calculation of excitonic couplings between the donor and the acceptor chromophores. Electronic coupling calculations with delocalized transition densities revealed efficient coupling pathways in the bulk of the material, but do not result in strong couplings between the chromophores which are calculated for more localized transition densities. The molecular structures of dendrimers seem to be playing a significant role in the magnitude of electronic coupling between chromophores. Simulated diffusion lengths correlate well with the experimental data. The chemical structure of the chromophore, the shape of the transition densities and the exciton lifetime are found to be the most important factors in determining the size of the exciton diffusion length in amorphous films of conjugated materials.     

Phytochemical screening and biological activities of the oil components of Prunus domestica Linn

Phytochemical screening of three different oil fractions, obtained from n-hexane extract of Prunus domestica shoots were analyzed by GC and GC–MS. It resulted in the identification of 9, 16 and 24 compounds which representing 92.56%, 90.6% and 90.69% of these oil fractions, respectively. The main components identified from fraction 1, 2 and 3 were hentricontane (35.7%), ethyl hexadecanoate (21.7%) and linoleic acid (16.16%), respectively. Bioassay screening of oil showed moderate antibacterial activity against Salmonella group (Gram +ve and ?ve) by agar well diffusion method, moderate antifungal activity against Microsporum canis by agar tube dilution method and good antioxidant activity by DPPH radical scavenging method.     

Dependence of band offset and open-circuit voltage on the interfacial interaction between TiO2 and carboxylated polythiophenes

The interface of planar TiO(2)/polymer photovoltaic cells was modified with two carboxylated polythiophenes having different densities of carboxylic acid groups. Both of the interface modifiers increase the photocurrent of the cells but lower the open-circuit voltage. The work function of the TiO(2), measured using a Kelvin probe, increases with increasing density of carboxylic acid groups due to the formation of interfacial dipoles pointing toward the TiO(2) surface. The formation of interfacial dipoles results in a shift in the band offset at the TiO(2)/polymer interface, which explains the decrease in the open-circuit voltage. This work demonstrates that care must be taken when using carboxylic acid side groups to attach polymers to titania surfaces in photovoltaic cells. If the density of attachment groups is just enough to attach the polymer, then the benefits of the interface modifier can be realized without substantially decreasing the open-circuit voltage.     

Vanadium(III) Complexes of Oxygen Donor Ligands; Their Synthesis,Spectral Characterization and Antimicrobial Studies

A new series of vanadium(III) complexes with oxygen donor ligands have been synthesized and characterized on the basis of elemental analysis, conductance, infra‐red spectroscopy, electronic spectral data and mass spectrometry. Thermal stabilities of the complexes and their kinetics were studied through thermogravimetric analysis. Estimation of vanadium in the complexes is carried out by ICP‐AES. Biological activities of the complexes 2 – 5 , 7 and 8 have also been tested against various bacteria and fungi.     

Atomistic computer simulation studies of Sr2RuO4 and Ca2RuO4

Atomistic static computer simulation techniques have been applied to investigate the energetics of defects and dopants in Sr₂RuO₄ (SRO) and Ca₂RuO₄ (CRO). Interatomic potentials have been derived which reproduced the crystal structures of these systems. Solution energies are calculated for different dopant ions to ascertain the site occupied by the dopant ion in the host lattice. Monovalent and divalent ions are predicted to substitute preferentially at the alkaline-earth site in both the systems. Trivalent cations of smaller ionic radii substitute at the Ru sites while those having larger ionic radii prefer to substitute at the Sr or Ca sites in SRO or CRO systems, respectively. In addition, there is a possibility of self-compensation, where a trivalent cation can substitute at both Sr(Ca) and Ru sites. Tetravalent dopants are found to substitute at the ruthenium sites in both systems.