Accurately Tuning the Charge on Giant Polyoxometalate Type Keplerates through Stoichiometric Interaction with Cationic Surfactants

作者：Kistler Melissa L; Patel Komal G; Liu Tianbo^*

来源：Langmuir, 2009, 25(13): 7328-7334.

DOI：10.1021/la900394z

We report an approach of exploring the interaction between cationic surfactants and a type of structurally well-defined, spherical "Keplerate" polyoxometalate (POM) macroanionic molecular clusters, {Mo(72)V(30)}, in aqueous solution. The effectiveness of the interaction can be determined by monitoring the size change of the "blackberry" supromolecular structures formed by the self-assembly of {Mo(72)V(30)} macroions, which is determined by the effective charge density oil the macroions. Long-chain surfactants (CTAB and CTAT) can interact with {Mo(72)V(30)} macroions stoichiometrically and lower their charge density. Consequently, the blackberry size decreases continuously with increasing surfactant concentration in solution. On the other hand, for short-chain surfactants (e.g., OTAB), a larger fraction of surfactants exist as discrete chains in solution and do not strongly interact with the macroions. This approach shows that a controllable amount of suitable surfactants can accurately tune the charge on large molecular clusters.

• 出版日期2009-7-7