1. Study the state of counter-ions in polyoxometalate solutions
Tianbo Liu, Lehigh University (PRF46294-G3)
Large, hydrophilic, water soluble macroions such as some polyoxometalate ions
form clear “real solutions”, but the macroanions tend to further self-assemble into
unique hollow, spherical, single-layer, vesicle-like “blackberry” nanocapsules
(tens to hundreds nanometers in diameter). Amazingly, the blackberries are very
stable, robust in solution and show properties similar to biomembranes.
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2.5nm
It is very difficult for small ions to transport across the membrane of bilayer vesicles
formed by amphiphilic surfactants, due to the hydrophobic layer in the middle.
However, the blackberry membranes are highly porous, which allow small cations to
slowly permeate into the cavity inside blackberries.
This slow process can be monitored and controlled.
Meanwhile, anions cannot pass through the membrane.
The water inside the porous blackberry capsules is found to be more viscous than the bulk water.
Passive cation transportation
Publications: Mishra, P. P.; Pigga, J.; Liu, T. J. Am. Chem. Soc. 2008, 130, 1548.