Revisiting the reactivity of different carbon bases: A theoretical study

Quantum chemical calculations are performed on different carbon bases to understand the origin of their reactivity. Both carbon(0) and carbon(II) bases may show very high values of second proton affinity as well as bond dissociation energies for gem‐dimetallation. Thus, their distinction becomes blurred when subjected to electrophilic attack. However, unlike carbon(0) bases, carbon(II) bases are ambiphilic in nature owing to the presence of a σ symmetric lone pair and a vacant π orbital concentrated on the central carbon atom. Thus, they may show different reactivity when subjected to nucleophilic attack. This reactivity difference may be considered as another distinction between these two classes of compounds. © 2013 Wiley Periodicals, Inc.     

Basic Alumina‐Supported Synthesis of Aryl‐Heteroarylmethanes via Palladium Catalyzed Cross‐Coupling under Microwave Irradiation

A basic alumina‐supported microwave assisted simple methodology has been developed for the synthesis of aryl‐heteroaryl methanes (benzylated quinolones) via transition metal catalyzed cross‐coupling reaction of halo substituted polynuclear oxa‐aza quinolones with benzyl indium, an organometallic reagent easily derived from commercially available benzyl bromide.     

Metriplectic structure, Leibniz dynamics and dissipative systems

A metriplectic (or Leibniz) structure on a smooth manifold is a pair of skew-symmetric Poisson tensor P and symmetric metric tensor G. The dynamical system defined by the metriplectic structure can be expressed in terms of Leibniz bracket. This structure is used to model the geometry of the dissipative systems. The dynamics of purely dissipative systems are defined by the geometry induced on a phase space via a metric tensor. The notion of Leibniz brackets is extendable to infinite-dimensional spaces. We study metriplectic structure compatible with the Euler-Poincaré framework of the Burgers and Whitham-Burgers equations. This means metriplectic structure can be constructed via Euler-Poincaré formalism. We also study the Euler-Poincaré frame work of the Holm-Staley equation, and this exhibits different type of metriplectic structure. Finally we study the 2D Navier-Stokes using metriplectic techniques.     

WKB approximation in complex time

The WKB approximation to the one particle Schrödinger equation in time is used to obtain the wavefunction at a given point as a sum of semiclassical terms, each corresponding to a different classical trajectory (real or complex) but ending up at the same point. A method to find out reflection coefficient for processes involving one and two turning points is developed and it is shown that the semiclassical complex analysis reproduces exactly the reflection coefficient that is obtained through the exact solution of the problem. The connection between pair production and reflection amplitude is also shown. The pair production amplitude in a time dependent gravitational background is calculated and it is shown that the vacuum considered in complex trajectory WKB analysis refers to adiabatic vacuum.     

Bound states of the exponential cosine screened Coulomb potential

A generalized virial theorem and the Hellman-Feynman theorem have been used to calculate perturbatively the energy levels, expectation values of an arbitrary power of the position coordinates and normalization of the wave function. The method gives excellent results for low values of the screening parameter (λ ? λ_c/4).     

Particle Motion and Perturbed Dynamical System in Warped Product Spacetimes

In this paper we have used the dynamical systems analysis to study the dynamics of a five-dimensional universe in the form of a warped product spacetime with a spacelike dynamic extra dimension. We have decomposed the geodesic equations to get the motion along the extra dimension and have studied the associated dynamical system when the cross-diagonal element of the Einstein tensor vanishes, and also when it is non-vanishing. Introducing the concept of an energy function along the phase path in terms of the extra-dimensional coordinate, we have examined how the energy function depends on the warp factor. The energy function serves as a measure of the amount of perturbation of geodesic paths along the extra dimension in the region close to the brane. Then we studied the geodesic motion under a conventional metric perturbation in the form of homothetic motion and conformal motion and examined the nature of critical points for a Mashhoon-Wesson-type metric, for timelike and null geodesics when the cross-diagonal term of the Einstein tensor vanishes. Finally we investigated the motion for null and timelike geodesics under the condition when the cross-diagonal element of the Einstein tensor is non-vanishing and examined the effects of perturbation on the critical points of the dynamical system.     

One-pot synthesis of chromeno[2,3-b]isoindolo[1,2-e]pyrrole-12,13-dione derivatives by sequential reaction of ninhydrin, 2-aminochromen-4-ones and arylamines

Stirring an equimolar mixture of ninhydrin 1 and 2-aminochromen-4-ones 2 in CH₃COOH at room temperature produced 6a,11a-dihydroxy-6H-chromeno[2,3-b]indeno[2,1-d]pyrrole-11,12(6aH,11aH)-diones 3, which on heating with aromatic amines 6 in acetic acid produced 11b-hydroxy-7-N-arylimino-6H-chromeno[2,3-b]isoindolo[1,2-e]pyrrole-12,13(11bH)-diones 7.     

Synthesis and evaluation of urea and thiourea derivatives of oxazolidinones as antibacterial agents

Urea and thiourea derivatives of oxazolidinones were synthesized and their inhibitory activity (MIC) was determined on the bacterial strains which includes clinical isolates and quality control organisms. The structure activity relationships were studied and a 3D-QSAR model was built using Genetic Function Approximation. Interestingly found that electron withdrawing groups at the ortho position of the phenyl ring enhances the activity.