摘要:

Abstracto‐Cyclohexadiamine (the base component of tetraplatin) adducts of Ph2Sn(OCOCH3)2, nBu2Sn(OCOH3)2, (PhCH2)2Sn(OCOCH3)2, PhSn(OCOCF3)3, BuSn(OCOCH3)3and Sn(OCOCH3)4have been synthesized and characterized by elemental analysis and spectroscopy. The compounds appear to be the first such adducts in their clas

ISSN:0268-2605    

DOI:10.1002/aoc.590080502

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractTitanocene dichloride (1) and its bis(trifluoromethyl) (2) and bis(N,N‐dimethylamino) (3) derivatives have been compared as catalysts for ethylene and propylene polymerizations using both methylaluminoxane (MAO) and triphenylcarbenium tetrakis(pentafluorophenyl)borate (4)/triisobutylaluminum (TIBA) as cocatalysts. The differences between the activities of the three ‘free’ titanocenium ions and theMwof the polyolefins produced by them may be attributable to the relative stabilities of the intermediate olefin–titanocenium π‐complexes. Interaction of either the neutral MAO or its anion with the titanocenium species may be responsible for the significantly lower catalytic efficiencies when the precursors were activated by MAO than by the 4/T

ISSN:0268-2605    

DOI:10.1002/aoc.590080503

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe effect of aryltin compounds (Ar4Sn and Ar3SnCl) on the growth ofCeratocystis ulmi, the causative agent of Dutch elm disease, was studied in shake culture. In all cases, the triaryltins were more effective than the tetra‐aryltins as inhibitors ofC. ulmi in vitro.Furthermore, substitution on the phenyl ring at themeta‐ andpara‐ positions in the triaryltins did not have a major effect on the biocidal activity for the substituted triaryltins. Quantitative structure–activity relationships (QSARs) gave support to the idea that the species responsible for the inhibition of the fungus is the triaryltin cation. The QSARs further suggest that the interaction of the triaryltin cation with the fungal cell wall ofC. ulmiis by a non‐specific

ISSN:0268-2605    

DOI:10.1002/aoc.590080504

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractTwo simple sample preparation methods for the speciation analysis of triphenyltin and butyltin compounds in marine biotissues, using tetramethylammonium hydroxide (TMAH) solubilization and enzymic hydrolysis, have been developed and compared with conventional acid digestion. Derivatization was carried outin situusing sodium tetraethylborate (NaBEt4) without prior separation of the analytes from the tissue matrix. Separation and detection was performed using capillary gas chromatography (GC) coupled to microwave‐induced plasma atomic emission spectrometry (MIP AE) allowing detection limits of 2 ng g−1(as tin) to be reached. The accuracy of the presented methods was demonstrated by the analysis of a fish reference material (NIES No. 11). the necessity for sample clean‐up is discussed and examples of the analysis of mussel tissue are

ISSN:0268-2605    

DOI:10.1002/aoc.590080505

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

Abstract1H spin–echo NMR spectroscopy of intact cells ofC. roseusfacilitates monitoring changes inside the cells on treatment with arsenicals. Thisin situdetection method is non‐invasive and non‐destructive in comparison to other available biochemical methods. Short term uptake of the arsinicals, methylarsinate MMA and dimethylarsenate DMA, byC. roseuscells that have reached stationary phase in 1‐B5 medium, is followed by using NMR spectroscopy, and in particular, the Carr–Purcell–Meiboom–Gill pulse sequence. An increase in the peak height of the methylarsenic resonance over a period of 11 h is indicative of uptake of each arsenical. However, there is no evidence of any biotransformation products in the1H NMR spectra. The accumulation site of DMA is probably the vacuole as is seen from the change in the chemical shift of DMA as it moves into a compartment of lower pH. Biochemical changes associated with the presence of arsenicals are evident in the1H NMR spectra ofC. roseuscells isolated at different stages in the growth cycle. Although uptake has been demonstrated by other analytical techniques, the resonances corresponding to both MMA and DMA are not observed in the1H NMR spectra of cells growing in media containing each arsenical. The association of these arsenicals with large biomolecules in the cell may account for these absences. In this event, the spins–spin relaxation time of the arsenic species would shorten and the signals would not be seen in the spin–echo NMR spectrum. In cells growing in the presence of MMA, a new resonance is observed at a chemical shift position 2.2 ppm after 15 days of growth. The shift in position of the resonance, from 1.75 ppm expected at physiological pH, may indicate an altered environment around the arsenic species such as high intr

ISSN:0268-2605    

DOI:10.1002/aoc.590080506

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractThe metal complexes and salts of amine carboxyboranes were shown to be potent anti‐inflammatory agents in rodents at 8 mg kg−1. They were effective in blocking induced edema, pleurisy and endotoxic shock while blocking both local and central pain processes. The ability of the agents to function as anti‐inflammatory agents is multi‐fold. First, lysosomal enzymes of specific cells, e.g. macrophages, were inhibited with IC50values in the range of 10−6M. Collagenase I and II activities were inhibited with IC50values approximately equal to 10−4M. The anti‐inflammatory activity of these agents at the molecular levels appears to be due to inhibition of the release of TNFα and Il‐1 from macrophages which indirectly control chemotaxic migration of white blood cells as indicated by the suppression of PMN and macrophage invasion into sponges implanted subcutaneously (SC) in mice. Furthermore, in these invading cells, the agents' blockage of TNFα and Il‐1 or Il‐2 release down‐regulates prostaglandin and leukotriene enzymatic synthetic rates and, consequently, their release, resulting in a reduction of t

ISSN:0268-2605    

DOI:10.1002/aoc.590080507

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

AbstractNew germa‐ and silathiazolidines or germa‐ and siladithioacetals withN‐allyl‐substituted cysteamine and methylcysteamine ligands have been synthesized and their pharmacological properties (toxicity, radioprotective activity) have been studied. A notable decrease in the toxicity and a rather large increase in the radioprotective activity of these new organometallic derivatives compared toN‐allyl‐substituted cysteamine and methylcysteamine we

ISSN:0268-2605    

DOI:10.1002/aoc.590080508

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

摘要:

Abstract[Me2SiNBFN(SiMe3)2]3(1) is synthesized in the reaction of trilithiated hexamethylcyclotrisilazane with F2BN(SiMe3)2. The mono‐ and dilithium derivatives of the six‐membered ring (Me2SiNH)2Me2SiNSiFMe2react with the F2B‐substituted cyclotrisilazane F2B(NSiMe2)3(SiFMe2)2in the molar ratio 1:1 or 1:2 to give the BF‐coupled rings 2 and 3. The crystal structure analysis of 1 and 3 and pyrolysis of 1 and 3 with formation of silicon boron carbonitride and its crystallisation to composite powders at very high temperatures are r

ISSN:0268-2605    

DOI:10.1002/aoc.590080509

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

ISSN:0268-2605    

DOI:10.1002/aoc.590080511

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY

ISSN:0268-2605    

DOI:10.1002/aoc.590080501

出版商:John Wiley&Sons, Ltd.    

年代:1994

数据来源: WILEY