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翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Molybdenum blue ： ウィキペディア英語版 Molybdenum blue Molybdenum blue is a term applied to: *reduced heteropolymolybdate complexes, polyoxometalates containing Mo(V), Mo(VI), and a hetero atom such as phosphorus or silicon *reduced isopolymolybdate complexes, polyoxometalates containing Mo(V), Mo(VI) formed when solutions of Mo(VI) are reduced *a blue pigment containing molybdenum(VI) oxide The "heteropoly-molybdenum blues", are used extensively in analytical chemistry and as catalysts. The formation of "isopoly-molybdenum blues" which are intense blue has been used as a sensitive test for reducing reagents. They have recently been shown to contain very large anionic species based on the so-called "big wheel" containing 154 Mo atoms, with a formula ()14−.〔''From Scheele and Berzelius to Müller: polyoxometalates (POMs) revisited and the "missing link" between the bottom up and top down approaches'' P. Gouzerh, M. Che; L’Actualité Chimique, 2006, 298, 9〕 The molybdenum blue pigment is historically documented〔''A Dictionary of Arts, Manufactures, and Mines: Containing a Clear Exposition of Their Principles'', Andrew Ure, Published 1844, D. Appleton & Co.〕 but may not be in use today. ==Heteropoly-molybdenum blues== The first heteropoly molybdate and first heteropolymetallate, yellow ammonium phosphomolybdate, (NH4)3PMo12O40 was discovered by Berzelius in 1826.〔Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4〕 The phosphorus atom in the anion is termed the hetero-atom, other hetero-atoms are silicon and arsenic. The heteropoly-molybdenum blues have structures based on the Keggin structure. The blue colour arises because the near-colourless anion, such as the phosphomolybdate anion, PMo12O403−, can accept more electrons (i.e. be reduced) to form an intensely coloured mixed-valence complex. This can occur in one electron or two electron steps.〔 The reduction process is reversible and the structure of the anion is essentially unchanged.〔 : PMoVI12O403− + 4e (unicode:⇌) PMoV4MoVI8O407− The structure of the anion, PMoV4MoVI8O407−, has been determined in the solid state and is a β-isomer (i.e. with one of the four groups of edge-shared octahedra on the α-Keggin ion rotated through 60 degrees).〔''Structure of a heteropoly blue. The four electron reduced beta-12-molybdophosphate anion'', JN Barrows, G. B. Jameson, M. T. Pope, J. Am. Chem. Soc., 1985, 107, 1771〕 Similar structures have been found with silicon, germanium or arsenic hetero-atoms.〔 The intense blue colour of the reduced anion is the basis for the use of heteropoly-molybdenum blues in quantitative and qualitative analytical techniques. This property is exploited as follows: *the sample to be analysed is reacted to produce the reduced blue heteropoly-molybdate in order to: * *detect the presence of a hetero atom in e.g. a spot test * * measure the amount of a hetero atom present in the sample colorimetrically *the sample is added to a solution of the near colourless, un-reduced complex in order to: * *detect the presence of a reducing compound e.g. a reducing sugar such as glucose * *measure the amount of a reducing compound in a two step procedure 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Molybdenum blue」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.