Selective Oxidation of Alcohols with a New Reagent: Iron(III) Nitrate Supported on Aluminum Silicate

A selective and effective oxidation of alcohols, except aliphatic alcohols, such as 1‐hexanol or 1‐octyl alcohol, to the corresponding aldehydes and ketones using a new reagent, iron(III) nitrate supported on aluminum silicate, under heterogeneous conditions with reflux with 85–98% yield is described.     

Quartz Crystal Microbalance Biosensor for Saxitoxin Based on Immobilized Sodium Channel Receptors

This work explored the possibility of coupling the toxin receptor-binding principle with the piezoelectric transduction principle. The sensing component of the saxitoxin biosensor involves a piezoelectric quartz crystal that was coated with sodium channel receptors. The sodium channel receptors were isolated from the electroplax organ of Electrophorus electricus. Binding of the sodium channel extracts to the quartz crystal was facilitated by pre-coating the gold electrode with a hydrophobic self-assembled monolayer of dodecanethiol. The instrumentation system consisted of a flow cell that held the quartz crystal, an oscillator circuit, an injection port, and a frequency counter that was connected to a personal computer. The various immobilization and measurement parameters were optimized. Binding of saxitoxin standards with the immobilized sodium channels was monitored through the decrease in the crystal oscillation frequency readings (ΔF) upon the introduction of saxitoxin into the flow cell. A calibration curve for saxitoxin was constructed by plotting the ΔF values vs. saxitoxin concentrations in the range from 0.1 to 2.0 μg/mL. A correlation coefficient of 0.9653 was obtained. The saxitoxin biosensor developed has the potential to be applied to the rapid screening of total paralytic shellfish poisoning toxins.     

Syntheses and structures of M–Na (M=Zn,Mn) coordination polymers in which ligands and Na ions exhibit complex coordination modes

The novel heteronuclear complexes [Na₂Zn(dipic)₂(H₂O)] _n (1) and [Na₂Mn(dipic)₂(H₂O)₂] _n (2) (H₂dipic?=?pyridine-2,6-dicarboxylic acid) were synthesized and characterized by single-crystal X-ray diffraction, analysis, IR spectroscopy and thermogravimetric analysis. Complex 1 consists of infinite 2D double layers, which are further attached into a 3D network through π–π stacking. All sodium ions are 3-coordinate. Complex 2 has an intricate 3D structure, in which two sodium ions are differently involved in forming polymeric coordination units, and are 3- and 7-coordinate, respectively. Dipic anions act as multidentate ligands showing novel and unprecedented bridging coordination modes. One ligand coordinates to three metal ions and with five bonds; the other coordinates five metal ions with nine bonds.     

Effect of K4FE(CN)6 and K3FE(CN)6 on TICT Dual Fluorescence of Sodium p-Dimethylaminobenzoate in Cetyltrimethylammonium Chloride Micelle. Identification of the Magenetic Effect in TICT Process

Comparison of the effects of K₄Fe(CN)₆ and K₃Fe(CN)₆ on TICT dual fluorescence of sodium p-dimethylaminobenzoate (SDMAB) in cetyltrimethyl ammonium chloride (CTAC) micelle yields a conclusion that the presence of a magnetic effect un favors the TICT process, which is verified by inserting the sample in a stationary magnetic field of 100G in which a decrease in the relative quantum yield of TICT state is observed.     

Evolution and properties of antiphase boundaries in silicate minerals

Experimental and observational evidence is reviewed for the mechanisms and kinetics of antiphase domain coarsening in silicate minerals. The expected rate law has the form (domain size)ⁿ ≈ annealing time, but the ideal value of n=2 has been observed in only one of three cases. Values of n≈8 or 10 are interpreted as implying adsorption of impurity atoms onto the antiphase boundaries. Diffusion of these impurities can then provide the rate determining step for boundary migration. Local ordering at the boundaries can also provide some stabilising influence, though this does not appear to affect the coarsening rate law. If the stabilisation is sufficient it might result in the development of an incommensurate superstructure, either as a stable phase or as a metastable phase under non-equilibrium conditions. The effective width of these boundaries appears to be ～ 25°, or approximately two unit cells, and their maximum effective interaction length appears to be ～ 4 times this width.     

Computed positron lifetimes in vacancies and vacancy-iron clusters in gold

Annihilation characteristics are calculated for positrons trapped in clean and impurity decorated vacancy clusters in Au. The positron lifetime depends strongly on the structure of the clusters. In a strongly relaxed vacancy cluster, the lifetime can become smaller than the lifetime in a single vacancy. The substitution of some neighbour atoms of a vacancy cluster by Fe atoms has only a minor effect on the positron lifetimes.     

NEW APPROACHES TO THE SYNTHESIS OF ORGANOPHOSPHORUS COMPOUNDS

Abstract

The past two decades have brought us a snowballing development of organophosphorus chemistry. Indeed organophosphorus compounds have found wide practical application (in agriculture, petroleum industry, as drugs, etc.) and continue to afford promising objects for the study of theoretical matters such as tautomerism, ambiphilicity, ambidenticity, and other problems of organic chemistry. On the other hand, however impressive this progress may be, the search for new methods of synthesis, improving the known methods and forecasting new types of organophosphorus compounds remain as challenging problems as before.     

Sodium Alginate and Poly(ethylene glycol) Blends: Thermal and Morphological Behaviors

Sodium alginate (SA) was blended with varying amounts of poly(ethylene glycol) (PEG) viz., 10, 20, 30, 40 and 50 wt % by using water as a solvent. The obtained SA/PEG blends have been characterized for thermal behavior by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and surface morphology by scanning electron microscopic (SEM) methods. DSC analysis indicates the increase in glass transition temperature (T_g) of the blends with an increase in PEG content in the blend, which is due to chain entanglement. TGA results reveal the enhancement of thermal stability of SA/PEG blends in terms of the onset of degradation and percentage of weight loss. SEM photomicrographs shows the two phase morphology. This result indicates the immiscible nature of the SA/PEG blends.     

Cross‐linked Multilayer Polymer‐Clay Nanocomposites and Permeability Properties

Abstract

Electrostatically layered aluminosilicate nanocomposites have been prepared by the sequential deposition of poly(allylamine hydrochloride)/poly(acrylic acid)/poly(allylamine hydrochloride)/saponite (PAH/PAA/PAH/saponite)₁₀ on poly(ethylene terephtalate) (PET) film. Exfoliated saponite nanoplatelets were obtained by extensive shaking, sonication, and centrifugation of a water suspension. To minimize permeability and improve the mechanical integrity, cross‐linking of composite films was carried out at different temperatures. The formation of amide linkage induced through heating was observed by Fourier Transform Infrared (FT‐IR) and x‐ray photoelectron spectroscopy (XPS). The cross‐linking of nanocomposites (PAH/PAA/PAH/saponite)₁₀ showed 60% decrease in permeability of oxygen when compared with the pristine PET substrate film. In contrast, water permeability of the nanocomposite membrane was not affected by heating temperature and deposition cycles.     

Room Temperature Phosphorescence of 1-Bromo-4-(bromoacetyl)naphthalene Induced by Sodium Deoxycholate

Sodium deoxycholate (NaDOC) can induce 1-bromo-4-(bromoacetyl)naphthalene (BBAN) to undergo strong room temperature phosphorescence (RTP) without the removal of dissolved oxygen from the solution. RTP spectra, phosphorescence polarization and ¹³C NMR results, along with the molecular modeling calculations, supported the conclusion that BBAN molecule was combined in a sandwich with two NaDOC molecules by a “back-to-back” hydrophobic interaction arising from the apolar faces of the NaDOC molecules, which provided BBAN with a rigid enough microenvironment to produce RTP.