Nanocrystalline films of Au-Ag, Au-Cu, and Au-Ag-Cu alloys formed at the organic-aqueous interface

By the reaction of the appropriate organometallic precursors and tetrakishydroxymethyl phosphonium chloride (THPC) at the toluene-water interface, we have prepared nanocrystalline films of Au-Ag and Au-Cu alloys with a range of compositions. The films have been characterized by X-ray diffraction, electron microscopy, optical spectroscopy, and other techniques, besides compositional analysis. The particle size of the nanocrystals in the films varies with the composition. The surface plasmon band of the alloy films as well as of the organosols obtained by the disintegration of the films by the addition of an alkanethiol show the expected composition dependence. It has been possible to prepare the nanocrystalline films of a ternary Au-Ag-Cu alloy.     

A Comparative Study of Glycosyl Thioimidates as Building Blocks for Chemical Glycosylation

Our results indicate that the reactivity and the activation profile of thioimidate glycosyl donors vary significantly depending on the endocyclic heteroatom (N,O,S). Reactivity diminishes in accordance with the following sequence: O > S > N; and this trend stands for a majority of promoters tested. Acyclic glycosyl thioimidates were found to be generally less reactive than the respective cyclic counterparts. The difference in the reactivity was confirmed in direct competition experiments. These findings made possible a two-step one-pot selective activation using thioimidates as the anomeric leaving group of the glycosyl donor and temporary masking group of the glycosyl acceptor.

Supplemental materials are available for this article. Go to the publisher's online edition of Journal of Carbohydrate Chemistry to view the supplemental file.     

Lithiation of 2-Methyl-2-Phenyl-1,3-Dioxolane with Sutyllithium

In lithiation of acetophenone ketal by butyllithium in diethyl ether, both aromatic lithiation and ketal ring cleavage are observed.     

Facile Synthesis of Isodamascone and Its Analogs

Synthesis of isodamascone and its analogs, the commercially important aroma compounds, have been accomplished from the readily available 1,5,5‐trimethyl‐2‐cyclohexen‐1‐ol via a short, facile, and simple sequence of reactions in excellent yield.     

The unravelling of metabolic dysfunctions linked to metal-associated diseases by blue native polyacrylamide gel electrophoresis

Gel electrophoresis is routinely used to separate and analyse macromolecules in biological systems. Although many of these electrophoretic techniques necessitate the denaturing of the analytes prior to their analysis, blue native polyacrylamide gel electrophoresis (BN-PAGE) permits the investigation of proteins/enzymes and their supramolecular structures such as the metabolon in native form. This attribute renders this analytical tool conducive to deciphering the metabolic perturbations invoked by metal toxicity. In this review, we elaborate on how BN-PAGE has led to the discovery of the dysfunctional metabolic pathways associated with disorders such as Alzheimer’s disease, Parkinson’s disease, and obesity that have been observed as a consequence of exposure to various metal toxicants.     

Oxidative Intramolecular 1,2-Amino-Oxygenation of Alkynes under AuI/AuIII Catalysis: Discovery of a Pyridinium-Oxazole Dyad as an Ionic Fluorophore

Oxidative intramolecular 1,2-amino-oxygenation reactions, combining gold(I)/gold(III) catalysis, is reported. The reaction provides efficient access to a structurally unique ionic pyridinium-oxazole dyad with tunable emission wavelengths. The application of these fluorophores as potential biomarkers has been investigated.     

Stereoselective synthesis of (S)-dapoxetine: a chiral auxiliary mediated approach

An imidazolidin-2-one chiral auxiliary mediated acetate aldol reaction was explored in the enantioselective synthesis of (S)-dapoxetine (SSRI). The diastereoselective aldol adduct was transformed to highly enantiopure (S)-dapoxetine with overall good yield.     

Sensitivity Analysis of Contact Type Vibration Measuring Sensors

With the Internet of Things (IoT) era dawning in, we are surrounded by a plethora of sensors. The present paper focuses on MEMS-based vibration measuring accelerometers, which are ubiquitously present in smartphones, tablets, smartwatches/bands, etc. These contact type vibration sensors have the unique advantage of being very small, low cost, low power, less weighing, and easily accommodatable in electronics. However, the accuracy of these sensors needs to be quantified with respect to more accurate sensors. With this objective, the paper presents a comparison of the relative sensitivity of a MEMS-based accelerometer (MPU 6050), a Geophone, and a sensor from Xiaomi Y2 smartphone with respect to a more standard Piezoelectric ICP based accelerometer, when all sensors are tested on a shaker table. Data are measured with harmonic excitation over a frequency range of 2–184 Hz. The relative sensitivity of MPU 6050 was 90% accurate in the frequency range 18–116 Hz for RMS measurements. Other sensors such as the one used in the Xiaomi Y2 smartphone and the Geophone were less accurate. The relative sensitivity measured in this work can be used to obtain sensitivity and hence more accurate data from these low-cost accelerometers.