Bis-4,4′-biphenyl Ring Embedded Octaphyrin with Three Distinct Conformational Structures

Three distinct conformational structures of carbaoctaphyrins were prepared by incorporating bis-4,4'-biphenyl units in the macrocyclic core. The free-base form adopts a figure-eight conformation, whereas the protonation triggers a conformational change with a pyrrole ring inversion and acquires an open-framework structure. The insertion of bis-Rh^I metal ion in the macrocyclic core affords a singly twisted conformational structure. Furthermore, the local aromaticity in the bis-4,4'-biphenyl ring dominates the overall macrocyclic aromaticity in all three forms, and thus adopts nonaromatic characteristics. These results are supported by spectral as well as theoretical studies, and they are unambiguously confirmed by X-ray crystal analyses.     

HPTLC analysis of Scoparia dulcis Linn (Scrophulariaceae) and its larvicidal potential against dengue vector Aedes aegypti

This study evaluates the larvicidal activity of Scoparia dulcis aqueous extract against dengue vector and determines its major chemical components. The extract was tested at various concentrations ranging from 0.1 to 2 mg/mL against Aedes aegypti larvae. The extracts displayed significant larvicidal efficacy against Ae. aegypt species after 24 h exposure revealing LC₅₀ of 3.3835 (mg/mL) and LC₉₀ of 5.7578 (mg/mL). Finger printing profile carried out by CAMAG automatic TLC sample applicator programmed through WIN CATS software revealed peaks with different R_f values for three different volumes injected: 16, 15 and 18 peaks were spotted for 3, 6 and 9 μL, respectively. Ascending order of R_f values was also ascertained for each peak recorded. This study clearly signifies that S. dulcis extract contains numerous compounds that are known to have larvicidal properties which clearly substantiates its efficacy on Ae. aegypti larvae.     

Rheological and anti-microbial study of silica and silver nanoparticles-reinforced k-carrageenan/hydroxyethyl cellulose composites for food packaging applications

Cellulose - Sustainable food packaging films were developed using a combination of k-Carrageenan (k-C), hydroxyl ethyl cellulose (HEC), silicon dioxide (SiO2), and silver (Ag) nanoparticles. The...     

Correction to: Effects of environmental factors on key kinetic parameters relevant to pitting corrosion

Journal of Solid State Electrochemistry -     

Characterization of a Polymer-Bound Palladium Acetate Catalyst and Studies on the Selective Hydrogenation of Dienes and Alkynes

Abstract

Palladium(II) acetate has been anchored onto a copolymer support containing pyridyl and carboxyl groups. XPS studies showed the Pd 3d binding energies for the recovered catalyst to be less by 1 eV after being used in hydrogenation studies. However, x-ray studies and a chemical test based on KCN treatment failed to reveal any palladium oxide or palladium metal formation in the recovered catalyst. It is presumed that an acetate ligand is lost during hydrogenation, which could be the reason for the lowering of the palladium 3d binding energies in the recovered catalyst. Results of investigations of the hydrogenation of olefins and selectivity of the catalyst toward the hydrogenation of dienes and alkynes are presented. The loss of palladium due to leaching under the reaction conditions employed was found to be very low (<1%/cycle).     

meta-Nitration of Arenes Bearing ortho/para Directing Group(s) Using C−H Borylation

Herein, we report the meta-nitration of arenes bearing ortho/para directing group(s) using the iridium-catalyzed C−H borylation reaction followed by a newly developed copper(II)-catalyzed transformation of the crude aryl pinacol boronate esters into the corresponding nitroarenes in a one-pot fashion. This protocol allows the synthesis of meta-nitrated arenes that are tedious to prepare or require multistep synthesis using the existing methods. The reaction tolerates a wide array of ortho/para-directing groups, such as −F, −Cl, −Br, −CH₃, −Et, −iPr −OCH₃, and −OCF₃. It also provides regioselective access to the nitro derivatives of π-electron-deficient heterocycles, such as pyridine and quinoline derivatives. The application of this method is demonstrated in the late-stage modification of complex molecules and also in the gram-scale preparation of an intermediate en route to the FDA-approved drug Nilotinib. Finally, we have shown that the nitro product obtained by this strategy can also be directly converted to the aniline or hindered amine through Baran's amination protocol.     

A unified approach to the integrals of Mellin–Barnes–Hecke type

In this paper, we provide a unified approach to a family of integrals of Mellin–Barnes type using distribution theory and Fourier transforms. Interesting features arise in many of the cases which call for the application of pull-backs of distributions via smooth submersive maps defined by Hörmander. We derive by this method the integrals of Hecke and Sonine related to various types of Bessel functions which have found applications in analytic and algebraic number theory.     

Sulfur Transfer Reactions of Tetrathiomolybdate in Water: Synthesis of Alkyl Disulfides from Alkyl Halides

Abstract: Reaction of a number of alkyl halides with tetrathiomolybdate in water as the solvent affords the corresponding disulfides in good yields.