Acidity Measurements on a Heteropolyacid Hydrate in Acetic Acid Solution: A Case of Three Hydrons Ionizing Independently, Rather Than Consecutively

A new mixed-matrix membrane for DMFCs

“…Earlier investigations showed that protons in PTA dissociate independently in solutions with acidic sites bearing the same strength. 23 However, PTA super acid is highly soluble in water when incorporated with CS to form a mixed-matrix membrane. PTA also has the tendency to leach out from the membrane, which limits its long-term use in DMFCs.…”

Probing surface acidity, basicity, and dipolarity/polarizability of 12-tungstophosphoric acid by means of solvatochromic dyes

“…Heteropolyacids have been widely used in homogeneous and heterogeneous catalytic systems as well as photocatalysts. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] They and related compounds have attracted increasing interest in catalysis owing to their ability to catalyze both acidic and redox processes. [18][19][20][21][22] The acidic strength of heteropolyacids in solution has been studied by conductivity, 23 UV/vis spectroscopy of Hammett (H 0 ) indicators, 24 NMR spectroscopy, 25 and 13 C NMR chemical shift of mesityl oxide as a probe.…”

“…[18][19][20][21][22] The acidic strength of heteropolyacids in solution has been studied by conductivity, 23 UV/vis spectroscopy of Hammett (H 0 ) indicators, 24 NMR spectroscopy, 25 and 13 C NMR chemical shift of mesityl oxide as a probe. 8 IR spectroscopy of adsorbed bases (e.g. NH 3 , pyridine), 5,26,27 TPD (temperature programmed desorption) of NH 3 or pyridine, 5,28 and microcalorimetry of adsorbed ammonia 29 have been used to investigate the acidity of these solid catalysts.…”

Can Polyoxometalates Be Considered as Superchaotropic Ions?

“…23,24 Similar to other heteropolyacids, 12tungstophosphoric acid (H 3 PW 12 O 40 ) is an extremely strong acid; thus, complete deprotonation of the anionic cluster will occur, even at very acidic conditions. 25 The results obtained with PW 3− are compared with those obtained in the presence of the tetraphenyl anion, Ph 4 B − , a large hydrophobic anion (radii ca. 0.5 nm) with four phenyl rings bonded to a central boron atom (Figure 3a), 13 and with the archetypical chaotropic (SCN − ) and kosmotropic (citrate 3− ) anions.…”