An overview of a series of tetrachalcogenafulvalene derivatives and their charge transfer complexes is presented in connection with the molecular designing of molecular conductors of one component (molecular fastener and chalcogen-chalcogen chain compound), organic metals, organic superconductors, complex isomerization, and other functional molecular assembly.
Recent developments in the chemistry of various types of Fe-S clusters involved in biologically important metalloenzymes, e. g. aconitase, hydrogenase, nitrogenase and their model complexes, are reviewed. In particular, the magnetic interaction between the Fe-S clusters and the active site is emphasized. Importance of the Fe-S clusters in the redox reactions via multielectron transfer is demonstrated.
Fluoropolymers have become indispensable materials not only in the chemical industries as the pipe laying, the packing, the gasket etc. of the chemical plants, but also in the electrical industries as the electric line, the cable and so on, as a result of the application of their excellent heat resistance, chemical resistance and electric insulation. In addition to these characteristics, they have many other highly functional ones such as surface activity, piezoelectricity, low refractive index, sensitivity to high energy ray, selective transmission and biocompatibility which are described here from the viewpoint of principles and applications.
Currently biologically interesting organic sulfur compounds are classified into seven categolies : naturally occurring bio-active compounds, antihypertensive ACE inhibitors, sulfonamides, psychotropic agents, antianginal agents, antiulcer agents and β -lactam antibiotics. The activities of the representative compounds in each part are commmented briefly from the standpoint of the interaction between sulfur and the animal body.
More than 20 % of about 300 active ingredients of pesticides registered in Japan are phosphorus compounds. Although they are mainly insecticides including acaricides, organophosphorus fungicides and herbicides have recently been developed. Moreover, nematicides, rodenticides, plant growth regulators, insect chemosterilants, and insecticide synergists are also known. Majority of organophosphorus pesticides are P (V) oxyacid derivatives, carrying a phosphoryl or thiophosphoryl group. Phosphonium salts and trivalent phosphorus compounds are rather rare as pesticides. The role of phosphorus moiety in pesticides is 1) the principal in phosphorylation, 2) a leaving group in alkylation, 3) a carrier for other active moiety, and 4) an analogous group for the carboxyl group. In order to display a certain pesticidal activity, the compound should have a structure suitable for selectivity or affinity to the target organism and biomacromolecule.
Heteromacrocycles have been widely employed because of the unique property of forming stable complexes with a variety of molecules. Recently, new compounds have been designed to construct a rigid complex-forming cavity, such as cavitand, spherand, cryptophane, calixarene, and cucurbitril, whose syntheses and complex-forming properties are briefly discussed in this article. Moreover, the recent developments in utilization of crown ether-type heteromacrocycles have revealed the great ability to enhance selectivity in organic and asymmetric sythesis. Biomimetic chemistry are also developed by the use of the heteromacrocycles as enzyme mimics, realizing biomimetic reactions, such as acyl transfer, hydrogen transfer, and peptide synthesis.
In this review, recent advances of multinuclear NMR spectroscopy as applied to organic chemical problems have been described. In view of the rapid progress in the structure determination of organic molecules by means of a combination of SCM NMR instruments and 2D techniques, a compilation of chemical shifts data are not very useful for this purpose. Hence, this review puts some stress on the more sophisticated application of multinuclear NMR, for instance, the use of relaxation time in organic chemistry. After a brief introduction, the chemical shifts, the relaxation times and lanthanide induced shifts for such nuclei as 14N, 15N, 17O, 31P and 33S are described. It is pointed out that the advantage of multinuclear NMR is a direct observation of the heteroatoms which is often a very good indicator of the physical/chemical properties of heteroatom compounds.
This review deals with the synthesis and reactions of phosphine-boranes. Phosphine-boranes exhibit unique chemical properties and possess potential utility as the reagents in organic synthesis. Useful organophosphorus compounds such as optically pure phosphine ligands are synthesized via phosphine-boranes.
Synthetically interesting organic transformations involving tellurium are reviewed with an emphasis on reactions recently appeared in the literature. Included are oxidation and reduction with tellurium-based reagents, tellurium-mediated carbon-carbon bond formation, telluronium ylides and tellurilimines, elimination of tellurium moiety leading to olefins, oxytelluration, hydrogenolysis and halogenolysis of tellurium-containing compounds.