Molybdenum blue

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 [Mo154O462H14(H2O)70]14−.

[4] The structure of the anion, PMoV4MoVI8O7−40, 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°).

This property is exploited as follows: The determination of phosphorus, arsenic, silicon and germanium are examples of the use of heteropoly-molybdenum blue in analytical chemistry.

A sample containing the phosphate is mixed with an acid solution of MoVI, for example ammonium molybdate, to produce PMo12O3−40, which has an α-Keggin structure.

Examples of procedures are: The comparison of the measured absorption against readings taken for analyses of standard solutions means that a detailed understanding of the structure of the blue complex was unnecessary.

By using an inexpensive and portable infrared Lightbox system, one can create uniform and repeatable lighting environments to take advantage of the peak absorbance of the molybdenum blue reaction in order to improve limit of detection of paper-based devices.

Finally the absorption of the hetero-poly molybdenum blue is measured using a colorimeter and compared to standards prepared from reacting sugar solutions of known concentration, to determine the amount of reducing-sugar present.

The spray reagent is prepared as follows: When applied to the TLC plate, compounds containing phosphate ester show up immediately as blue spots.

In between these extremes of pH, polymeric ions are produced which are mostly built from MoO6 octahedral units sharing corners and edges.

Examples include Mo7O6−24, Mo8O4−26 and Mo36O112(H2O)8−16, which contain the {(Mo)Mo5}-type unit comprising a central MoO7 pentagonal bipyramid sharing edges with five MoO6 octahedra.

[22] Further work by the same group then refined the initial findings and determined the structure of the wheel produced in molybdate solutions as [Mo154O462H14(H2O)70]14−.

[20] The Mo154-type cluster was then shown to be the basic structural type of molybdenum blue compounds obtained under slightly different conditions.