Acid-base properties of 1-acyl-5-hydroxypyrazolidines in a hydrogen bond

In solutions, 1-acyl-5-hydroxypyrazolidines form only intermolecular hydrogen bonds in which the proton acceptor is the oxygen atom of the hydroxyl group. These compounds are similar to phenols with respect to the acidity in a hydrogen bond.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 936–939, July, 1989.     

Autocomplexes of Anthraquinone Derivatives with a One-Membered NH Bridge

A number of aminonitroanthraquinone autocomplexes with a one-membered NH bridge were synthesized from 1,5-dinitroanthraquinone and substituted aromatic amines. Intramolecular charge transfer in the products was studied by spectral methods.     

Stereochemical Features of the Condensation of Lithiated (<Emphasis Type="Italic">S</Emphasis>)-<Emphasis Type="Italic">N,N</Emphasis>-Dimethyl-1-phenylethylamine with <Emphasis Type="Italic">o</Emphasis>-Methoxybenzophenones

The condensation of lithiated (S)-N,N-dimethyl-1-phenylethylamine with o-methoxybenzophenones occurs in a nonstereoselective fashion due to possible coordination of lithium not only at the carbonyl group but also at the oxygen atom of the ortho-methoxy group.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 567–570.Original Russian Text Copyright © 2005 by Dem’yanovich, Shishkina, Gritsyuk, Potekhin, Chesnova, Ashkinadze.     

Hysteretic microwave cyclotron resonance of a laterally confined 2 DEG

A hysteretic cyclotron resonance (CR) is discovered in a laterally confined high mobility two-dimensional electron gas (2DEG) in GaAs/AlGaAs heterostructures. The hysteresis and switching phenomena are observed in microwave radiation (36 GHz) transmission at temperature 1.8–25 K. It is found that the hysteresis is accompanied by long-lived, microwave-induced changes of the 2DEG density. These density changes is attributed to a modification of electron vertical transport processes in heterostructures under the microwave heating of the 2DEG. A phenomenological model based on the 2DEG density-dependent CR, describes reasonably the main experimental findings.