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In 1910 the first deliberately targeted search for a new chemotherapeutic agent came to fruition when Paul Ehrlich introduced Salvarsan for the treatment of syphilis. This thesis presents a detailed review of the history and literature leading up to and following on from Ehrlich’s discovery and thoroughly investigates the chemistry of Salvarsan and related species. A series of arylarsonic acids was prepared and fully characterised by electrospray mass spectrometry, NMR and X-ray crystallography for six examples. A detailed analysis of the hydrogen bonding in crystals of these molecules showed that they adopt several characteristic motifs which govern the packing in the crystals. Two of the examples containing NH2 groups crystallised as zwitterions while one NH2 containing example containing other bulky groups was is its molecular form....
The title compound, [As₄O₄(C₆H₄NO₃)₄], has an eight-membered As₄O₄ ring with a slightly twisted boat-chair conformation. The aryl groups complete the threefold coordination for each As atom. Each OH group forms a strong intramolecular O-H⋯O hydrogen bond to the adjacent NO₂ group, with only weak C-H⋯O, O⋯As [3.036 (6)-3.184 (6) Å] and O⋯O [2.921 (10)-2.930 (10) Å] interactions between tetramers.
The complexes [CpCo{P(OR′)2O}3]SnR3 − nCln [R′ = Me, Et; R = Ph, Me] are readily prepared from the corresponding organotin chloride and the sodium salt of the Kläui ligands. The X-ray crystal structures of the full series are reported for R = Ph, n = 0-3, and these show that they are all six-coordinate, including the Ph3Sn derivative which is the first example of a SnC3O3 coordination sphere. 1H, 13C, 31P and 119Sn NMR spectra are reported, and interpreted in terms of significant second-order effects and fluxional processes.
Ehrlich introduced in 1910 the compound 3-amino-4-hydroxyphenylarsenic(I) [Salvarsan, arsphenamine, Ehrlich 606,] as a remedy for syphilis, a disease caused by the spirochaete bacterium Treponema pallidum. His methodical search for a specific curative for an identified disease can be regarded as the introduction of targeted chemotherapy.
Full NMR and ESI-MS spectra, and differential scanning calorimeter data are presented for 15 substituted phenylarsonic acids, including two new fluoro-substituted examples. X-ray crystal structure determinations of five examples (phenylarsonic acid and the 4-fluoro-, 4-fluoro-3-nitro-, 3-amino-4-hydroxy- and 3-amino-4-methoxy-substituted derivatives) were determined and the H-bonding crystal-packing patterns analysed.
PhGeCl₃ reacts with Na{[OP(OEt)₂]₃CoCp} to give the six-coordinate complex PhCl₂Ge{[OP(OEt)₂]₃CoCp}, characterised spectroscopically and by an X-ray crystal structure determination which showed a firmly-attached tridentate ligand [Ge–O 1.973(2) Å].
Uranium isotope (235U, 236U, 238U) ratios were determined for microscopic uranium-oxide grains using laser-ablation multi-collector inductively-coupled-plasma mass-spectrometry (LA-MC-ICP-MS). The grains were retrieved from contaminated soil and dust samples. The analytical technique utilised is rapid, requires minimal sample preparation, and is well suited for nuclear forensic applications. Precision and accuracy were assessed by replicate analyses of natural uraninite grains: relative uncertainty for 235U/238U is 0.2 % (2σ), and the mean is in agreement with the natural ratio. A total of 115 uranium-oxide grains were analysed from environmental samples (soils and dusts); all of these were depleted uranium (DU) from a factory that produced uranium articles. Knowledge of the range of isotope ratios from particles of this controversial ...
Potassium isotopic (K-41/K-39) compositions are notoriously difficult to measure. TIMS measurements are hindered by variable fractionation patterns throughout individual runs and too few isotopes to apply an internal spike method for instrumental mass fractionation corrections. Internal fractionation corrections via the K-40/K-39 ratio can provide precise values but assume identical K-40/K-39 ratios (e.g. 0.05% (1sigma) in [1]); this is appropriate in some cases (e.g. identifying excess K-41) but not others (e.g., determining mass fractionation effects and metrologically traceable isotopic abundances). SIMS analyses have yielded measurements with 0.25% precisions (1sigma) [2]. ICP-MS analyses are significantly affected by interferences from molecular species such as Ar-38H(+) and Ar-40H(+) and instrument mass bias. Single collector ICP...
Organo-tin compounds have wide applications as pesticides and as intermediates for organic synthesis.?? They are invariably Sn(IV) derivatives and are generally four-coordinate.?? The mixed organo/chioro compounds of the type RnSnCI4-n do however have the ability to expand their coordination numbers to five or six. This depends critically on the substituents - with four organic groups, R???Sn, there is no tendency at all to coordinate extra ligands, while at the other extreme SnCl??? readily forms six-coordinate [SnC1???L???] complexes since the electronegative halo groups increase the Lewis acidity of the tin centre.
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