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Hein A Tsolakidou A Iliopoulos I Mommsen H Buxeda i Garrigós J Montana G Kilikoglou V 《The Analyst》2002,127(4):542-553
Chemical analysis is a well-established procedure for the provenancing of archaeological ceramics. Various analytical techniques are routinely used and large amounts of data have been accumulated so far in data banks. However, in order to exchange results obtained by different laboratories, the respective analytical procedures need to be tested in terms of their inter-comparability. In this study, the schemes of analysis used in four laboratories that are involved in archaeological pottery studies on a routine basis were compared. The techniques investigated were neutron activation analysis (NAA), X-ray fluorescence analysis (XRF), inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). For this comparison series of measurements on different geological standard reference materials (SRM) were carried out and the results were statistically evaluated. An attempt was also made towards the establishment of calibration factors between pairs of analytical setups in order to smooth the systematic differences among the results. 相似文献
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Balamurugan V Hundal MS Mukherjee R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(7):1683-1690
Using a group of six neutral M(II)Cl(2)-containing coordination compounds as building blocks, the first systematic investigation of C-H...Cl hydrogen-bonding interactions was performed. Single-crystal X-ray structural analyses of four new compounds (pseudo-tetrahedral Co(II) and Zn(II); distorted trigonal bipyramidal Zn(II)) authenticate the metal coordination geometry. To provide a unified view of the presence of noncovalent interactions in this class of compounds, we have re-examined the packing diagram of two previously reported compounds (a distorted square-pyramidal Cu(II) complex and a trans-octahedral Co(II) complex). The organic ligands of our choice comprise bidentate/tridentate pyrazolylmethylpyridines and an unsymmetrical tridentate pyridylalkylamine. This systematic investigation has allowed us to demonstrate the existence of versatile C-H...Cl(2)M interactions and to report the successful application of such units as inorganic supramolecular synthons. Additional noncovalent interactions such as C-H...O and O-H...Cl hydrogen bonding and pi-pi stacking interactions have also been identified. Formation of novel supramolecular architectures has been revealed: 2D lamellar (p-cyclophane) and 3D lamellar, 3D "stitched staircase" (due to additional hydrogen-bonding interactions by water tetramers, with an average O-O bond length in the tetramer unit of 2.926 A, acting as "molecular clips" between staircases), 3D linked ladder, and single-stranded 1D helix. 相似文献
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Age K. Smilde Piet Hein van der Graaf Durk A. Doornbos Ton Steerneman Anita Sleurink 《Analytica chimica acta》1990
When retention measurements are available for a set of solutes on different stationary phases, with varying mobile phase compositions, the resulting data set can be represented by a three-way array. Models that describe the systematic variation in this training set sufficiently, can be used to calibrate a new stationary phase. Two models are tested for this purpose: three-way partial least squares and parallel factor analysis. 相似文献
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The design and synthesis of molecules containing both a substrate-binding cavity and a nearby catalytically active metal center is a useful approach to the development of synthetic systems that function according to the principles of enzymes. To this end the receptor molecule 2a, derived from diphenylglycoluril, was functionalized with triaryl phosphite ligands to give the receptor ligand 2d. Exchange reactions of 2d with (diketonate)Rh(CO)(2), (diketone = acetylacetone, dibenzoylmethane, or dipivaloylmethane) led to the formation of the metallohosts 3a-c, respectively. The properties and conformational behavior of these metal complexes were studied by NMR techniques. Reaction of compounds 3 with H(2) in the presence of a small excess of additional triphenyl phosphite yields the rhodium(I) hydride complex 5. The metallohosts are capable of binding dihydroxybenzene guests in their cavities by hydrogen bonding and pi-pi stacking interactions. On binding a substrate the conformational behavior of hosts 3a-c was affected considerably. 相似文献
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V. Balamurugan Jhumpa Mukherjee Maninder Singh Hundal Rabindranath Mukherjee 《Structural chemistry》2007,18(2):133-144
New MnII/CuII/ZnII complexes [(L1)MnCl2] (1), [(L2)CuCl2]·0.5H2O (2) and [(L2)ZnCl(H2O)][ClO4] (3), containing (2-pyridyl)alkylamine ligands, N-methyl-N,N-bis(2-pyridylmethyl)amine (L1) and methyl[2-(2-pyridyl)ethyl](2-pyridylmethyl)amine (L2), have been prepared and characterized, including X-ray crystallography. The most striking feature of the structures of these
complexes is the formation of molecular ladder and lamellar topology through the crystal packing arrangement, determined by
both strong O–H···Cl and weak (however, multiple) C–H···Cl hydrogen-bonding interactions, to maintain the neutral/cationic
metal-ligand coordination units linked to each other. In 3, additional secondary interactions are observed involving coordinated solvent and the counter-ion. The results presented
here demonstrate that (i) the choice of organic ligands to provide flexibility and inherent potential to participate in hydrogen-bonding
interactions, (ii) the coordination geometry preferences of metal ions, (iii) the number of metal-bound chloride ion and (iv)
the presence of solvent/counter-anion have a great influence on supramolecular network topology. 相似文献
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K. Diemert G. Hein A. Janssen W. Kuchen 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):339-356
Abstract Aminophosphine des Typs Rn P(NR′2)3-n (n= 2, 1, 0; R = Ph, c-Hex, (-)Men, t-Bu; R′= Me, Et, n-Bu) reagieren mit 2, 4-Bis(aryl)-1, 3, 2, 4-dithiadiphosphetan-2, 4-disulfiden (ArPS2)2(Ar: Ph, 4-Methoxyphenyl = An, Naphthyl, Thienyl) unter formaler Insertion monomerer {ArPS2)-Einheiten in eine oder in zwei der λ3-P—N-Bindung zu chiralen Organophosphorverbindungen Ar(R′2N)P(S)—S—PRn (NR′2)2-n(n = 2, 1, 0) und [Ar(R′2N)P(S)—]2PR2(NR′2)1-n (n = 1.0). In diesen werden bei Raumtemperatur bevorzugt die λ3—P—N—und λ3—P—S-Bindungen durch H2O oder Methanol unter Bildung von Produktgemischen solvolysiert. Mit Chlorwasserstoff bildet sich aus An(Et2N)P(S)—S—PPh(NEt2) das An(Et2 N)P(S)—S—PPh(C1). Addition von Schwefel führt zu Ar(R′2N)P(S)—S—P(S)Rn (NR′)2-n (n=2, 1). Die Stereoisomerenbildung der neuen Verbindungen wird besprochen und ihre Struktur sowie die Zusammensetzung der Reaktionsmischungen aus den 31P-Spektren hergeleitet. Aminophosphines Rn P(NR′2)3-n (n = 2, 1, 0; R = Ph. c-Hex, (-)Men, t-Bu; R′= Me, Et, n-Bu) react with 2, 4-Bis(aryl)-1, 3, 2, 4-dithiadiphosphetane-2, 4-disulfides (ArPS2)2 (Ar: Ph, 4-Methoxyphenyl = An, Naphthyl, Thienyl) under formal insertion of monomeric {ArPS2)-units in one or in two of the λ3-P—N-bonds to yield chiral organophosphorus compounds Ar(R′2N)P(S)—S—]2PRn (NR′2)2 (n = 2, 1, 0) and [Ar(R′2N)P(S)—S—]2 PR2 (NR′2)2-n (n = 1, 0). At room temperature chiefly the A—P—N and A3—P—S-bonds in these products are solvolyzed by H, O or methanol with formation of mixtures of compounds. With hydrogen chloride An(Et2N)P(S)—S—PPh(NEt2) is converted into An(Et2N)P(S)—S—PPh(Cl). Addition of sulfur yields Ar(R′2N)P(S)—S P(S)Rn (NR′2)2-n (n = 2, 1). Stereoisomerism of the new compounds is discussed and their structures as well as the composition of reaction mixtures are deduced from “P-NMR-spectra”. 相似文献