Cu(OAc)2 entrapped on ethylene glycol-modified melamine–formaldehyde polymer as an efficient heterogeneous catalyst for Suzuki–Miyaura coupling reactions

Research on Chemical Intermediates - This work is described as an environmental friendly approach for Cu(OAc)2 entrapped on ethylene glycol-modified melamine–formaldehyde-based polymeric...     

Shock Processing of Amino Acids Leading to Complex Structures—Implications to the Origin of Life

The building blocks of life, amino acids, are believed to have been synthesized in the extreme conditions that prevail in space, starting from simple molecules containing hydrogen, carbon, oxygen and nitrogen. However, the fate and role of amino acids when they are subjected to similar processes largely remain unexplored. Here we report, for the first time, that shock processed amino acids tend to form complex agglomerate structures. Such structures are formed on timescales of about 2 ms due to impact induced shock heating and subsequent cooling. This discovery suggests that the building blocks of life could have self-assembled not just on Earth but on other planetary bodies as a result of impact events. Our study also provides further experimental evidence for the ‘threads’ observed in meteorites being due to assemblages of (bio)molecules arising from impact-induced shocks.     

Pre- and post-breakdown electrical studies in ultrathin Al2O3 films by conductive atomic force microscopy

The loss of local dielectric integrity in ultrathin Al₂O₃ films grown by atomic layer deposition is investigated using conducting atomic force microscopy. I–V spectra acquired at different regions of the samples by constant and ramping voltage stress are analyzed for their pre- and post-breakdown signatures. Based on these observations, the thickness dependent dielectric reliability and failure mechanism are discussed. Our results show that remarkable enhancement in breakdown electric field as high as 130 MV/cm is observed for ultrathin films of thickness less than 1 nm.     

Eco-friendly synthesis of ZnO nanorods using Cycas pschannae plant extract with excellent photocatalytic,antioxidant, and anticancer nanomedicine for lung cancer treatment

The tunable ZnO nanorods (NRs) are produced due to the phytochemicals present in Cycas pschannae leaves which act as reducing and stabilizing agents. The confirmations of the ZnO NRs were validated using different characterization techniques: X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer, Emmett and Teller (BET), scanning electron microscopy–Energy Dispersive X-Ray Analysis (EDX), UV–visible spectroscopy, Raman spectroscopy, and transmission electron microscopy. The ZnO NRs show unique surface area and low particle size. Photocatalytic activity was measured and found to be 50.75% at low concentrations and 78.33% at high concentrations. The antioxidant activity of the ZnO NRs also showed promising results for their use in free radical scavenging. In vitro toxicity studies using zebrafish embryos was performed to evaluate the toxic nature of it and the obtained result confirmed its non-toxic nature. In addition, ZnO anticancer potential was verified using the A549 lung cancer cell line. Cytotoxic assessments of ZnO NRs were performed via 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and neutral red uptake assays to examine the cell death cycle on the A549 lung cancer cell. Dose-dependent apoptosis and necrosis were confirmed by Lactate dehydrogenase (LDH) assay. It was also confirmed that ZnO NRs induce Reactive oxygen species (ROS) and apoptosis inside cancer (A549) cells via different intrinsic gene expression. Thus, based on this research it is evident that an effective ecofriendly, nontoxic potential anticancer drug can be synthesized using C. pschannae leaf extract.     

Polyol technique synthesis of Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> coated on LiFePO<Subscript>4</Subscript> cathode materials for Li-ion storage

A novel approach has been made to tailor Niobium pentoxide (Nb₂O₅) as a coating material on the surface of lithium iron phosphate (LiFePO₄) via a facile polyol technique. The coating content was optimized at 1 wt%. The superficial coating demonstrated superior discharge capacity than the pristine LiFePO₄. However, increasing the coating content further would result in a capacity loss. This may be due to the electrochemical inactiveness that increases with the content of the coating material, and 1 wt% of Nb₂O₅-coated LiFePO₄ sample exhibits initial discharge capacity of 163 mAh g^?1 at a current of 0.1 C and retains a stable discharge capacity of 143 mAh g^?1 up to 400 cycles at 1 C rate with a coulombic efficiency of 98%.

Open image in new window

Graphical abstract ?

     

Synthesis,Structure, and Highly Efficient Copper‐Catalyzed Aziridination with a Tetraaza‐Bispidine Ligand

The distorted trigonal‐bipyramidal Cu^II complex [Cu(L¹)(NCCH₃)]²⁺ of the novel tetradentate bispidine‐derived ligand L¹ with four tertiary amine donors (L¹=1,5‐diphenyl‐3‐methyl‐7‐(1,4,6‐trimethyl‐1,4‐diazacycloheptane‐6‐yl)diazabicyclo[3.3.1]nonane‐9‐one) is a very efficient catalyst for the aziridination of olefins in the presence of a nitrene source. In agreement with the experimental data (in situ spectroscopy, product distribution, and its dependence on the geometry of the substrate and of the nitrene source), a theoretical analysis based on DFT calculations indicates that the active catalyst has the Cu center in its +II oxidation state, that electron transfer is not involved, and that the conversion of the olefin to an aziridine is a stepwise process involving a radical intermediate. The striking change of efficiency and reaction mechanism between classical copper–bispidine complexes and the novel L¹‐based catalyst is primarily attributed to the structural variation, enforced by the ligand architecture.     

Amino-functionalized MIL-101(Fe) metal-organic framework as a viable fluorescent probe for nitroaromatic compounds

Microchimica Acta - A highly luminescent iron(III)-based amino-functionalized metal-organic framework (MOF) of type NH2-MIL-101(Fe) was synthesized by a solvothermal method. Its structure and...     

Synthesis and electrochemical characterization of olivine-type lithium iron phosphate cathode materials via different techniques

High-potential, eco-friendly LiFePO₄ cathode materials were synthesized by polyol, hydrothermal, and solid-state reaction methods. The polyol technique was carried out without any special atmosphere and postheat treatment. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectrometry (XPS), and charge-discharge and cyclic voltammetry tests. The LiFePO₄ prepared via polyol technique exhibits good electrochemical performance than other method samples do.

Open image in new window

Graphical abstract?

     

Effect of solvent volume on the physical properties of sprayed fluorine‐doped zinc oxide thin films

Fluorine‐doped zinc oxide (FZO) films were deposited from aged starting solutions having different solvent volumes (10, 20, 30, 40 and 50 ml) using a simplified spray pyrolysis technique. The electrical studies showed that the resistivity is minimum (4.68 × 10^–2 Ω cm) for lowest solvent volume (10 ml) and the value progressively increased with the increase in the solvent volume indicating that the fluorine incorporation increases with solvent volume. The systematic study clearly showed that the spray flux rate plays a crucial role in determining the electrical, optical, surface and structural properties of the FZO films. The optical transparency is found to be gradually increased (from 85 to 95%) as the volume of the solvent increases. The scanning electron microscope images depicted that the decrease in the spray flux rate caused an enhancement in the grain size. The X‐ray diffraction profile clearly showed that all the films have preferential orientation along the (002) plane with hexagonal wurtzite structure. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The mechanism of the (bispidine)copper(II)-catalyzed aziridination of styrene: a combined experimental and theoretical study

Experimental and DFT-based computational results on the aziridination mechanism and the catalytic activity of (bispidine)copper(I) and -copper(II) complexes are reported and discussed (bispidine=tetra- or pentadentate 3,7-diazabicyclo[3.1.1]nonane derivative with two or three aromatic N donors in addition to the two tertiary amines). There is a correlation between the redox potential of the copper(II/I) couple and the activity of the catalyst. The most active catalyst studied, which has the most positive redox potential among all (bispidine)copper(II) complexes, performs 180 turnovers in 30 min. A detailed hybrid density functional theory (DFT) study provides insight into the structure, spin state, and stability of reactive intermediates and transition states, the oxidation state of the copper center, and the denticity of the nitrene source. Among the possible pathways for the formation of the aziridine product, the stepwise formation of the two N-C bonds is shown to be preferred, which also follows from experimental results. Although the triplet state of the catalytically active copper nitrene is lowest in energy, the two possible spin states of the radical intermediate are practically degenerate, and there is a spin crossover at this stage because the triplet energy barrier to the singlet product is exceedingly high.