Phosphotungstic acid

About: Phosphotungstic acid is a research topic. Over the lifetime, 1925 publications have been published within this topic receiving 38059 citations. The topic is also known as: Phosphowolframic acid.

Solubilization, purification and functionalization of carbon nanotubes using polyoxometalate.

Abstract: In this work, we developed a convenient and efficient method for solubilization, purification and functionalization of carbon nanotubes (CNTs) using a versatile reagent (phosphotungstic acid (HPW)). Because HPW can spontaneously attach to graphite walls as polyanions and provide static repulsion, CNT aggregates were divided into individual and small bundles of CNTs and turned into a stable solution by sonication in the presence of HPW. Amorphous carbon impurities and metal catalysts in the raw CNTs were removed by centrifugation and filtration. Finally, purified CNTs with a yield of 82 wt% were obtained. Using HPW on graphite walls as an electrostatic and acid anchor, positively charged titania nanoparticles and albumin molecules were successfully assembled around CNTs without altering their delocalized π-electron system. The versatility of this simple approach could be extended beyond inorganic nanoparticles and proteins, to other systems with desired properties.

Weak charge-transfer polyoxoanion salts: the reaction of quinolin-8-ol (Hquin) with phosphotungstic acid and the crystal and molecular structure of [H2quin]3[PW12O40]·4EtOH·2H2O

Abstract: Different solvated charge-transfer salts between quinolin-8-ol (Hquin) and phosphotungstic acid have been synthesized and characterized. Spectroscopic data support the presence of a sizeable electronic interaction between electron-rich aromatic organics and the inorganic acid, both in the solid state and in solution, provided that a large excess of the organic is present. This interaction is responsible for the formation of photosensitive compounds and provides a rationale for the subsequent facile photo-oxidation of the organic substrate. The crystal and molecular structure of [H2quin]3[PW12O40]·4EtOH·2H2O has been solved by the heavy-atom method and refined to a final R= 0.083, for 4 902 reflections with I 3σ(I): triclinic space group P; with a= 11.721(3), b= 12.818(3), c= 12.878(3)A, α= 89.20(2), β= 104.10(2), γ= 117.30(2)°, and Z= 1. The anion structure consists of an α-Keggin-type molecule in two-fold disorder. The 8-hydroxyquinolinium moieties (three per [PW12O40]3–) are stacked approximately along the x direction, with alternative interplanar spacings of 3.25 and 3.57 A. The crystal structure determination reveals the absence of any substantial, direct interaction between the organic cations and the phosphototungstate anions. Therefore no clear structural basis for the electronic interaction noted above can be given.