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Shiv Nadar University

(SoNS) School of Natural Sciences

Potassium tert-butoxide acts as a nucleophilic oxygen source during the hydration of nitriles to give the corresponding amides under anhydrous conditions. The reaction proceeds smoothly for a broad range of substrates under mild conditions, providing an efficient and economically affordable synthetic route to the amides in excellent yields. This protocol does not need any transition-metal catalyst or any special experimental setup and is easily scalable to bulk scale synthesis. A single-electron-transfer radical mechanism as well as an ionic mechanism have been proposed for the hydration process.

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Chemistry

Journal of Organic Chemistry

Transition-metal-free hydration of nitriles using potassium tert -butoxide under anhydrous conditions

Selective oxidation of alcohol to its corresponding carbonyl compound is an important chemical process in biological as well as industrial reactions. The heme containing enzyme CytP450 has been known to selectively oxidize alcohols to their corresponding carbonyl compounds. The mechanism of this reaction, which involves high-valent FeIV(O)-porphyrin•+ intermediate with alcohol, has been well-studied extensively both with the native enzyme and with model complexes. In this paper, we report for the first time the mechanistic insight of alcohol oxidation with FeV(O) complex of biuret TAML (bTAML), which is isoelectronic with FeIV(O)-porphyrin•+ intermediate form in CytP450. The oxidations displayed saturation kinetics, which allowed us to determine both the binding constants and first-order rate constants for the reaction. The K and k values observed for the oxidation of benzyl alcohol by FeV(O) at room temperature (K = 300 M-1, k = 0.35 s-1) is very similar to that obtained by CytP450 compound I at -50 °C (K = 214 M-1, k = 0.48 s-1). Thermodynamic parameters determined from van't Hoff's plot (ΔH∼ -4 kcal/mol) suggest hydrogen bonding interaction between substrate and bTAML ligand framework of the FeV(O) complex. Analysis of H/D KIE (kH/kD ∼ 19 at 303 K), Hammett correlation and linearity in Bell-Evans-Polyanski plot points to the C-H abstraction as the rate determination step. Finally, experiments using FeV(O18) for benzyl alcohol oxidation and use of the "radical clock" cyclobutanol as a substrate shows the absence of a rebound mechanism as is observed for CytP450. Instead, an ET/PT process is proposed after C-H abstraction leading to formation of the aldehyde, similar to what has been proposed for the heme and nonheme model compounds. © 2015 American Chemical Society.

Inorganic Chemistry

Mechanism of Alcohol Oxidation by FeV(O) at Room Temperature

Gold nanoparticles (Au NPs) were synthesized using Au containing CTAB gel as a precursor. The effect of concentration of NaBH4 on the structural, optical, catalytic and electrochemical properties of the Au NPs was also investigated. With the increase of NaBH4 concentration from 0.1 to 0.15 M, an increase in the particle size and change in the morphology from spherical to elliptical was observed. Absorption and emission properties of the Au NPs were also probed using UV–Vis and photoluminescence spectroscopy respectively. Synthesized Au NPs samples were explored as catalyst for the reduction of 4-nitrophenol to 4-aminophenol. Catalytic activity of Au NPs samples prepared using 0.1 and 0.15 M concentration of NaBH4 were also compared. It was found that Au NPs prepared using lower concentration of NaBH4 (Au-0.1) exhibits better catalytic activity compared to the other Au NPs sample (Au-0.15). Synthesized Au NPs were also utilized as electrode material for the detection of Pb2+ ions, results show that Au NPs modified glassy carbon electrode can detect very low concentration of Pb2+ ions (2 µM). Au-0.1 sample exhibited better electrochemical performance compared to the Au-0.15 sample. © 2015, Springer Science+Business Media New York.

Physics

Journal of Materials Science: Materials in Electronics

Optical, structural, catalytic and electrochemical properties of the Au nanoparticles synthesized using CTAB based gels

Let F and G be two bounded operators on two Hilbert spaces. Let their numerical radii be no greater than one. This note investigates when there is a Γ-contraction (S, P) such that F is the fundamental operator of (S, P) and G is the fundamental operator of (S*, P*). Theorem 1 puts a necessary condition on F and G for them to be the fundamental operators of (S, P) and (S*, P*) respectively. Theorem 2 shows that this necessary condition is also sufficient provided we restrict our attention to a certain special case. The general case is investigated in Theorem 3. Some of the results obtained for Γ-contractions are then applied to tetrablock contractions to figure out when two pairs (F1, F2) and (G1, G2) acting on two Hilbert spaces can be fundamental operators of a tetrablock contraction (A, B, P) and its adjoint (A*, B*, P*) respectively. This is the content of Theorem 3. © 2015 Elsevier Inc.

Mathematics

Fulltext

Journal of Mathematical Analysis and Applications

Admissible fundamental operators

In this paper, we study the multi-objective flexible linear programming (MOFLP) problems (or fuzzy multi-objective linear programming problems) in the heterogeneous bipolar framework. Bipolarity allows us to distinguish between the negative and the positive preferences. Negative preferences denote what is unacceptable while positive preferences are less restrictive and express what is desirable. This viewpoint enables us to handle fuzzy sets representing constraints and objective functions separately and combine them in distinct ways. In this paper, a solution concept of Pareto-optimality for MOFLP problems is defined and an approach is proposed to single out such a solution for MOFLP with highest possible degree of feasibility. © 2014 Taylor & Francis.

International Journal of General Systems

Computing a Pareto-optimal solution for multi-objective flexible linear programming in a bipolar framework

We investigate bicomplex Hamiltonian systems in the framework of an analogous version of the Schrodinger equation. Since in such a setting three different types of conjugates of bicomplex numbers appear, each is found to define, in a natural way, a separate class of time reversal operator. However, the induced parity (P)-time (T)-symmetric models turn out to be mutually incompatible, except for two of them which could be chosen uniquely. The latter models are then explored by working within an extended phase space. Applications to the problems of harmonic oscillator, inverted oscillator and isotonic oscillator are considered and many new interesting properties are uncovered for the new types of PT symmetries. © 2015 IOP Publishing Ltd.

Journal of Physics A: Mathematical and Theoretical

Bicomplex hamiltonian systems in quantum mechanics

We examine the analytical structure of the nonlinear Liénard oscillator and show that it is a bi-Hamiltonian system depending upon the choice of the coupling parameters. While one has been recently studied in the context of a quantized momentum-dependent mass system, the other Hamiltonian also reflects a similar feature in the mass function and also depicts an isotonic character. We solve for such a Hamiltonian and give the complete solution in terms of a confluent hypergeometric function. © 2015 AIP Publishing LLC.

Journal of Mathematical Physics

On quantized Liénard oscillator and momentum dependent mass

We derive a one-step extension of the well known Swanson oscillator that describes a specific type of pseudo-Hermitian quadratic Hamiltonian connected to an extended harmonic oscillator model. Our analysis is based on the use of the techniques of supersymmetric quantum mechanics and addresses various representations of the ladder operators starting from a seed solution of the harmonic oscillator expressed in terms of a pseudo-Hermite polynomial. The role of the resulting chain of Hamiltonians related to similarity transformation is then exploited. In the second part we write down a two dimensional generalization of the Swanson Hamiltonian and establish superintegrability of such a system. © 2015 Elsevier B.V. All rights reserved.

Physics Letters, Section A: General, Atomic and Solid State Physics

New 1-step extension of the Swanson oscillator and superintegrability of its two-dimensional generalization

Examination of protein structure at the subatomic level is required to improve the understanding of enzymatic function. For this purpose, X-ray diffraction data have been collected at 100K from cholesterol oxidase crystals using synchrotron radiation to an optical resolution of 0.94Å. After refinement using the spherical atom model, nonmodelled bonding peaks were detected in the Fourier residual electron density on some of the individual bonds. Well defined bond density was observed in the peptide plane after averaging maps on the residues with the lowest thermal motion. The multipolar electron density of the protein-cofactor complex was modelled by transfer of the ELMAM2 charge-density database, and the topology of the intermolecular interactions between the protein and the flavin adenine dinucleotide (FAD) cofactor was subsequently investigated. Taking advantage of the high resolution of the structure, the stereochemistry of main-chain bond lengths and of C=O⋯H - N hydrogen bonds was analyzed with respect to the different secondary-structure elements.

Acta Crystallographica Section D: Biological Crystallography

Cholesterol oxidase: Ultrahigh-resolution crystal structure and multipolar atom model-based analysis

Diketopyrrolopyrole-naphthalene polymer (PDPP-TNT), a donor-acceptor co-polymer, has shown versatile behavior demonstrating high performances in organic field-effect transistors (OFETs) and organic photovoltaic (OPV) devices. In this paper we report investigation of charge carrier dynamics in PDPP-TNT, and [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) bulk-heterojunction based inverted OPV devices using current density-voltage (J-V) characteristics, space charge limited current (SCLC) measurements, capacitance-voltage (C-V) characteristics, and impedance spectroscopy (IS). OPV devices in inverted architecture, ITO/ZnO/PDPP-TNT:PC71BM/MoO3/Ag, are processed and characterized at room conditions. The power conversion efficiency (PCE) of these devices are measured ∼3.8\%, with reasonably good fill-factor 54.6\%. The analysis of impedance spectra exhibits electron's mobility ∼2 × 10-3 cm2V-1s-1, and lifetime in the range of 0.03-0.23 ms. SCLC measurements give hole mobility of 1.12 × 10-5 cm2V-1s-1, and electron mobility of 8.7 × 10-4 cm2V-1s-1. © 2015 Author(s).

AIP Advances

Charge transport studies in donor-acceptor block copolymer PDPP-TNT and PC71BM based inverted organic photovoltaic devices processed in room conditions