Synthesis of Alkyl and Aryl Boronate Esters via CeO2-Catalyzed Borylation of Alkyl and Aryl Electrophiles Including Alkyl Chlorides.

A recyclable protocol using a CeO2-nanorod catalyst for borylation of alkyl halides with B2pin2 (pin = OCMe2CMe2O) is reported. A wide range of synthetically useful alkyl boronate esters are readily obtained from primary and secondary alkyl electrophiles, including unactivated alkyl chlorides, demonstrating broad utility and functional group tolerance. Preliminary investigation revealed an involvement of in situ formed catalytically active boryl species. The catalyst can be reused for up to six runs without appreciable loss in activity. In addition, we have demonstrated the use of this recyclable catalyst for the borylation of aryl halides with B2pin2, providing valuable aryl boronate esters under neat conditions.

Tuning the Surface Functionality of Fe3O4 for Sensitive and Selective Detection of Heavy Metal Ions.

The functionalization of materials for ultrasensitive detection of heavy metal ions (HMIs) in the environment is crucial. Herewith, we have functionalized inexpensive and environmentally friendly Fe3O4 nanoparticles with D-valine (Fe3O4-D-Val) by a simple co-precipitation synthetic approach characterized by XRD, FE-SEM, and FTIR spectroscopy. The Fe3O4-D-Val sensor was used for the ultrasensitive detection of Cd+2, Pb+2, and Cu+2 in water samples. This sensor shows a very low detection limit of 11.29, 4.59, and 20.07 nM for Cd+2, Pb+2, and Cu+2, respectively. The detection limits are much lower than the values suggested by the world health Organization. The real water samples were also analyzed using the developed sensor.

Recent advances in the chemistry of the phosphaethynolate and arsaethynolate anions.

Over the past decade, the reactivity of 2-phosphaethynolate (OCP-), a heavier analogue of the cyanate anion, has been the subject of momentous interest in the field of modern organometallic chemistry. It is used as a precursor to novel phosphorus-containing heterocycles and as a ligand in decarbonylative processes, serving as a synthetic equivalent of a phosphinidene derivative. This perspective aims to describe advances in the reactivities of phosphaethynolate and arsaethynolate anions (OCE-; E = P, As) with main-group element, transition metal, and f-block metal scaffolds. Further, the unique structures and bonding properties are discussed based on spectroscopic and theoretical studies.

Glucose oxidase mimicking half-sandwich nickel(II) complexes of coumarin substituted N-heterocyclic carbenes as novel molecular electrocatalysts for ultrasensitive and selective determination of glucose.

Glucose oxidase mimicking nickel-based porous structures with organic anchors are developed as cheap and reliable electrochemical sensors for the quantitative detection of glucose. A series of sterically and electronically modulated, air- and moisture-stable half-sandwich nickel(II) NHC complexes were prepared and characterized. Under the optimized electrocatalytic conditions, the nickel complex immobilized glassy carbon electrodes (GCEs) displayed high sensitivity (0.663, 1.280, 1.990 and 0.182 µA/µM) towards glucose detection, which is much higher than that of 3D porous nickel networks. The limit of detection of modified GCEs is found in the range 1.56-2.09 µM with much wider linear sensing range, and having a catalytic rate constant of 0.273 × 103 M-1s-1. Finally, the selectivity of the modified GCEs towards glucose in presence of other blood constituents was also evaluated.

Hydrogels of polyaniline with graphene oxide for highly sensitive electrochemical determination of lead ions.

Conducting polymers with graphene/graphene oxide hydrogels represent a unique class of electrode materials for sensors and energy storage applications. In this article, we report a facile in situ method for the polymerisation of aniline resulting in the decoration of 1D conducting polyaniline (PANI) nanofibers onto the surface of 2D graphene oxide (GO) nanosheets followed by hydrogel formation at elevated temperature. The synthesized nanomaterial exhibits significant properties for the highly sensitive electrochemical determination as well as removal of environmentally harmful lead (Pb2+) ions. The square wave anodic stripping voltammetry (SWASV) determination of Pb2+ ions showed good electroanalytical performance with two linear ranges in 0.2-250 nM (correlation coefficient = 0.996) and 250-3500 nM (correlation coefficient = 0.998). The developed protocol has shown a limit of detection (LOD) of about 0.04 nM, which is much lower than that of the World Health Organization (WHO) threshold limits. The prepared electrode showed an average of ∼99.4% removal of Pb2+ ions with a relative standard deviation (RSD) of 3.4%. Selectivity of the electrode towards Pb2+ ions were tested in presence of potential interferences such as Na+, K+, Ca2+, Mg2+, Cu2+, Cd2+, Hg2+, Zn2+, Co2+, Ni2+, Fe2+ and Fe3+ of similar and higher concentrations. The sensor showed good repeatability and reproducibility. The developed protocol was used to analyse samples from industrial effluents and natural water samples. The results obtained were correlated with atomic absorption spectroscopy (AAS).

Surface Passivation of MoO3 Nanorods by Atomic Layer Deposition toward High Rate Durable Li Ion Battery Anodes.

We demonstrate an effective strategy to overcome the degradation of MoO3 nanorod anodes in lithium (Li) ion batteries at high-rate cycling. This is achieved by conformal nanoscale surface passivation of the MoO3 nanorods by HfO2 using atomic layer deposition (ALD). At high current density such as 1500 mA/g, the specific capacity of HfO2-coated MoO3 electrodes is 68% higher than that of bare MoO3 electrodes after 50 charge/discharge cycles. After 50 charge/discharge cycles, HfO2-coated MoO3 electrodes exhibited specific capacity of 657 mAh/g; on the other hand, bare MoO3 showed only 460 mAh/g. Furthermore, we observed that HfO2-coated MoO3 electrodes tend to stabilize faster than bare MoO3 electrodes because nanoscale HfO2 layer prevents structural degradation of MoO3 nanorods. Additionally, the growth temperature of MoO3 nanorods and the effect of HfO2 layer thickness was studied and found to be important parameters for optimum battery performance. The growth temperature defines the microstructural features and HfO2 layer thickness defines the diffusion coefficient of Li-ions through the passivation layer to the active material. Furthermore, ex situ high resolution transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray diffraction were carried out to explain the capacity retention mechanism after HfO2 coating.

Electrochemical synthesis of thiol-monolayer-protected clusters of gold.

We have synthesized for the first time thiol-monolayer-protected gold nanoparticles (MPCs) by the process of electrochemical dissolution of gold in an ethanol-water mixture. The MPCs have been formed both with and without NaBH4 as a reducing agent. The well-dispersed thiol-capped MPCs were characterized by UV-visible absorption and transmission electron microscopy (TEM) studies.