Synthesis of 3‐imidazolylazole derivatives from a new nitrile oxide

The synthesis of a series of 3‐Imidazolylazole derivatives using cycloaddition reactions of a useful new nitrile oxide is described.     

Analysis of iron state in some Argentinian soils by dissolution methods and Mössbauer spectroscopy

Bahia Blanca (Argentina) soils, in particular entisols, are studied by Mössbauer spectroscopy. X-ray diffraction and scanning electron microscopy are used to characterize the samples. Samples were treated with different chemical iron extraction methods, in order to determine relative Fe_o and Fe_d fractions. The Fe_o/Fe_d ratios are obtained and the relative effect of iron extraction treatment on spectra components are determined. In addition, the effect of extraction procedures, dithionite-citrate-bicarbonate and oxalate, in the residual soil fraction are analyzed.     

Scleroglucan: a versatile polysaccharide for modified drug delivery

Scleroglucan is a natural polysaccharide, produced by fungi of the genus Sclerotium, that has been extensively studied for various commercial applications (secondary oil recovery, ceramic glazes, food, paints, etc.) and also shows several interesting pharmacological properties. This review focuses its attention on the use of scleroglucan, and some derivatives, in the field of pharmaceutics and in particular for the formulation of modified-release dosage forms. The reported investigations refer mainly to the following topics: natural scleroglucan suitable for the preparation of sustained release tablets and ocular formulations; oxidized and crosslinked scleroglucan used as a matrix for dosage forms sensitive to environmental conditions; co-crosslinked scleroglucan/gellan whose delivery rate can be affected by calcium ions. Furthermore, a novel hydrogel obtained with this polysaccharide and borate ions is described, and the particular structure of this hydrogel network has been interpreted in terms of conformational analysis and molecular dynamics. Profound attention is devoted to the mechanisms involved in drug release from the tested dosage forms that depend, according to the specific preparation, on swelling and/or diffusion. Experimental data are also discussed on the basis of a mathematical approach that allows a better understanding of the behavior of the tested polymeric materials.     

Molecular determinants for drug—receptor interactions: Part 2. An ab initio molecular orbital and dipole moment study of the novel nootropic agent piracetam (2-oxopyrrolidin-1-ylacetamide)

From the ab initio molecular energies of the possible conformers and from a classical dipole moment analysis of 2-oxopyrrolidin-1-ylacetamide (υ = 4.02 D in dioxan at 30.0°C), the preferred conformation in solution of this novel nootropic agent has been determined. The exocyclic NCH₂ bond is rotated in one sense by 90° and the exocyclic CH₂C bond rotated in the same sense by 120° from the “planar” (OO)-cis conformation. The structures of the two enantiomers in solution differ from that of the crystalline molecule.     

High-throughput assay of rotenone in olive oil using atmospheric pressure chemical ionization tandem mass spectrometry

A high-throughput method is presented for the determination of rotenone in contaminated matrices. The procedure involves atmospheric pressure chemical ionization tandem mass spectrometry with a triple-quadrupole instrument and the use as internal standard of a cycloadduct derivative of rotenone itself. The method was applied to the evaluation of the decay of rotenone in olives and olive oil at various times after exposure to the contaminant.     

Design and synthesis of chemiluminescent probes for the detection of cholinesterase activity

Acetylcholinesterase is one of the most widely used and studied enzymes. Not only does this enzyme regulate neurotransmission (and thus play a key role in neurodegenerative processes) but it is also a prime target for pest control agents and warfare agents. Above all, due to its particularly high turnover rate, acetylcholinesterase is among the most efficient reporter enzymes yet described (for use as enzymatic tracer in immunoassays, for instance). However, its activity is detected through a colorimetric reagent, the Ellman reagent, which displays low detection limits and is often subject to background perturbations. In the course of our search for a more sensitive detection assay, we describe here a first-generation 1,2-dioxetane chemiluminescent probe, based on chemically induced electron exchange luminescence, which has an approximately 10 times lower detection limit than the Ellman colorimetric assay (2.5 x 10(-19) mol for Electrophorus electricus AChE in its tetrameric form).     

Branched Polyethylenes by Cationic Benzyl Zirconium Heteroscorpionate Complexes: Role of the Borate Anion

Summary: A comparative study of the performances of (bpzmp)ZrBz₃ ( 1 ) and (hppzm)ZrBz₃ ( 2 ) activated with B(C₆F₅)₃ or [Ph₃C][B(C₆F₅)₄] in ethylene polymerisation pointed out that the steric properties of the metal complex and the boron activator affect the productivity of the catalyst and, more remarkably, the microstructure of the polyethylenes produced. A polymerisation mechanism accounting for these results has been proposed.

Structure of two heteroscorpionate zirconium complexes (bpzmp)ZrBz₃ ( 1 ) and (hppzm)ZrBz₃ ( 2 ).     

Relation between molecular and atomic correlation energies via overlap population

A relationship is explored between correlation energies of light diatomic molecules, both hetero and homo, correlation energies of the constituent atoms and the overlap population S. While S is quantitatively sensitive to the choice of basis set, it is demonstrated that the general trends revealed are largely independent of such a choice. A weak residual dependence on molecular chemical potential is also indicated by the present study.