Preparation,properties and reactivities of novel platinum compounds containing a thiomethoxymethyl group

Oxidative addition of ClCH₂SCH₃ to PtL₄ afforded trans-PtL₂(CH₂SCH₃)Cl (Ia, L = Ph₃P;Ib, L = MePh₂P). Treatment of I with NH₄PF₆ or Et₃OBF₄ in CH₂C1₂ gave ionic species, [PtL₂(CH₂SCH₃)]X (II, L = Ph₃P, MePh₂P, X = BF₄, PF₆), while similar treatment with MeSO₃F in benzene yielded a new type of stable dimethylsulfonium methylide—platinum complex, trans-[PtL₂(CH₂SMe₂)Cl] SO₃F (IIIa, L = Ph₃P; IIIb, L = MePh₂P). Action of H₂O₂ on Ia gave [Pt(Ph₃P)(μ-CH₂SCH₃)C1]₂ (IV) and its triphenylarsine analog, [Pt(Ph₃As)(μ-CH₂SCH₃)C1]₂ (V) was prepared in one step by oxidative addition of ClCH₂SCH₃ to Pt(AsPh₃)₄. The structural difference between [Pt(Ph₃P)(μ-CH₂SCH₃)C1]₂ and Pd(Ph₃P)- (CH₂SCH₃)C1 is discussed in terms of the difference in the ionization potential from d¹⁰ to d⁸ electronic state of metals.     

Synthesis and identification of an endogenous sperm activating and attracting factor isolated from eggs of the ascidian Ciona intestinalis; an example of nanomolar-level structure elucidation of novel natural compound

A sperm-activating and attracting factor (SAAF) was isolated from the eggs of the ascidian Ciona intestinalis, and its structure was deduced with only approximately 4 μg of the specimen. Based upon the proposed structure, two epimers were synthesized from chenodeoxycholic acid in 16 steps. Comparison between synthetic and natural compounds led to the unambiguous structure determination of SAAF to be (3R,4R,7R,25S)-3,4,7,26-tetrahydroxycholestane-3,26-disulfate. The synthetic pure specimen was also utilized to confirm that both sperm-activation and attraction were elicited by a single compound.     

Popolohuanone A and B. two new sesquiterpenoid aminoquinones from a pacific sponge dysidea sp

Popolohuanone-A ( ) and B ( ) are two new sponge metabolites of composition C₄₂H₅₇NO₃. Their structures, which were determined by spectral and chemical correlations, comprise two molecules of a benzenoid moiety each linked to a rearranged drimane sesquiterpene and connected by an amino function.     

Application of zone-melting technique to metal chelate systems-X Zone-refining of bis(acetylacetonato)beryllium(II), tris(acetylacetonato)aluminium(III) and bis(di-isovalerylmethanato)copper(II)

Bis(acetylacetonato)beryllium(II), tris(acetylacetonato)aluminium(III) and bis(di-isovaleryl-methanato)copper(II) were zone-refined. Also crude beryllium(II), aluminium(III) and copper(II) salts were purified by zone-melting the above-mentioned chelates, obtained by precipitation from aqueous methanol solutions. Some contaminants were excluded at the stage of chelate formation and the remainder were concentrated at the terminal end of a zone-refining column.     

Preparation and physical properties of amorphous V2O5 containing TiO2, Na2O or Li2O

V₂O₅ gels containing up to 18 mol% of TiO₂ were obtained through the simultaneous hydrolysis of alkoxides in ethanol solution. V₂O₅ gels containing Na₂O or Li₂O were obtained through the ion exchange method. The crystallization temperature, T_cr, of the gels increased and the H₂O content of the gels decreased by the addition of TiO₂ or Na₂O. These additives seem to stabilize the amorphous state of the gels. On the other hand, T_cr and the H₂O-content slightly varied with the addition of Li₂O. No ionic polarization was observed in coating films of the gels dried at temperatures below T_cr. The dc conductivity of the films was anisotropic, and increased with the addition of Li₂O or Na₂O. However, it decreased with increasing TiO₂ content. The fiber-like structure of gels was observed by TEM. The gels obtained from alkoxides were thin and short in comparison with the gels obtained through the ion exchange method.     

Epitaxial growth of GaAs and GaN by gas source molecular beam epitaxy using organic group V compounds

GaAs and GaN epilayers were grown on GaAs substrates by gas source molecular beam epitaxy technique using triethylarsine (TEAs) and diethylarsine (DEAsH) as As sources, and dimethylhydrazine (DMHy) as an N source. It was found that GaAs grows layer by layer even when organic arsine molecular sources are used. Cubic GaN was found to grow epitaxially on sufficiently nitrided surfaces of GaAs (001) substrates, in contrast with the growth of hexagonal GaN on GaAs (111) surfaces. It was also found that nitridation of GaAs surfaces does not occur when DEAsH and DMHy beams are supplied onto the GaAs substrates, simultaneously. Thus, GaN/GaAs multilayers were obtained only by intermittent supply of a DEAsH beam.     

Blends of organosilicon polymers with polystyrene and poly(2,6-dimethyl-1,4-phenylene oxide)

Blends of organosilicon polymers with polystyrene, PS, and poly(2,6-dimethyl-1,4-phenylene oxide), PPE, were investigated by transmission electron microscopy and differencial scanning calorimetry. Blends with poly(tetramethylsilphenylenesiloxane), PTMPS, showed a morphology characterized by globular domains dispersed in the organic matrix. An apparent homogeneous system was observed when poly(dimethylsilphenylene), PDSP, was mixed with PPE. A crystalline phase was found in samples with a higher PDSP content. The morphology of PS/PDSP blends with low PDSP content showed a dendritic phase dispersed in the PS-rich matrix. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 2609–2616, 1997     

Asymmetric Total Synthesis of Fredericamycin A

Seventeen years after the isolation of the promising antitumor antibiotic fredericamycin A, the first asymmetric total synthesis of this compound has been accomplished and thereby its absolute configuration established. The key feature is the regiocontrolled [4+2] cycloaddition of 3 to 2 , which was obtained by the stereospecific rearrangement of 1 . Cp = (−)‐camphanoyl.     

Preparation of hydrolyzed pH responsive ion track membrane

The porous copolymer films of N-methacryloyl-L -alanine methyl ester and diethyleneglycol-bis-allylcarbonate (diallyl oxydiethylene dicarbonate) were hydrolyzed with 1 M NaOH solution for 40 min at 25°C. The pores of the films showed pH response in diameter. The pore diameter of 3,7 μm in the buffer solution of pH 3 was closed completely at pH 5.     

Self-oscillating swelling and deswelling of polymer gels

Novel gel systems demonstrating rhythmically pulsatile mechanical motion similar to that of a heartbeat were developed. Self-oscillations of swelling and deswelling for the polymer hydrogels were realized by coupling pH and temperature sensitive hydrogels with a non-linear chemical reaction in the external solution media. The novel gel dynamics exhibiting cyclic and rhythmical oscillations may establish a new concept for functional materials that work under dynamic oscillating states.