Poly(isocyanidcs), ( R N = C < ) n, can be prepared from isocyanidcs, R N += C " , by the catalytic action of nickel(II) compounds. The main chain of these polymers is a rigid helix. This helical conformation results from a restricted rotation around the single bonds that connect the main-chain carbon atoms. Polymerization of achiral isocyanides generally gives a racemic mixture of leftand righ...

The asymmetric syntheses of two new spirolactones prepared in optically pure form from L-3-nitrotyrosine are described. The key step, an oxidative spiroannulation, was carried out on the optically active phenols 11a and 11b and afforded the new spirolactones 5a and 5b in 85% and 83% yields, respectively, as mixtures (3:1 dr) of diastereomers. The major diastereomers from these mixtures could be...

A successful observation and analysis of the Zeeman effect on the lambda approximately 1.54 microm photoluminescence band in Er-doped crystalline MBE-grown silicon are presented. The symmetry of the dominant optically active centers is conclusively established as orthorhombic I(C(2v)) with g axially approximately 18.39 and g radially approximately 0. In this way the long standing puzzle as rega...

A series of optically active, tartaric acid-based, monodisperse dendrimers 1 4 was prepared. The central core and branching junctures of these dendritic compounds were made up from phloroglucinol units and the surface sectors used were 4-tert-butylphenoxy moieties. The optically active elements, which were derivatives of either (D)or (L)-tartaric acid, served as the chiral linker branches of th...

The synthetic route for a uterine relaxant, bis(2-[[(2S)-2-([(2R)-2-hydroxy-2-[4-hydroxy-3-(2-hydroxyethyl)-phenyl]ethyl]amino)-1,2,3,4-tetrahydronaphthalen-7-yl]oxy]-N,N-dimethylacetamide) sulfate (KUR-1246), was established by the coupling of optically active components, the bromohydrin 14 and the amine 24. We now describe the practical synthesis of these two optically active components. Brom...

2014 A study has been made of the use of optically active additives in twisted nematic devices to remove areas of reverse twist, the results obtained depending on the chirality of the additives and the director alignment on the two containing surfaces. Under certain conditions degeneracy of the field induced reorientation of the director produces a patched appearance even in the absence of reve...

The first method for the synthesis of optically active calix[4]arenes that are chiral as a result of substitution on the methylene bridges is described. The key step in the synthesis involves the reaction of a biscarbene complex with a diyne, which generates two of the benzene rings and the macrocyclic ring of the calix in a single transformation. The utility of this triple annulation process i...

The accumulation of heavy metals in the human body and/or in the environment can be highly deleterious for mankind, and currently, considerable efforts have been made to develop reliable and sensitive techniques for their detection. Among the detection methods, chemical sensors appear as a promising technology, with emphasis on systems employing optically active nanofibers. Such nanofibers can ...

(wherein R' and Rare the same or different and each repre sent a hydrogen atom or an alkyl group, or form an alkylene group by binding to each other at the ends thereof; R and R are the same or different and each represent a hydrogen atom or an alkyl group, or form an alkylene group by binding to each other at the ends thereof; A represents a single bond or a methylene group; and X represents a...