Instantaneous and Reversible Gelation of Organically Grafted Polyoxometalate Complexes with Dicarboxylic Acids.
writer：Zhenfeng He, Huanbing Wang, Yinglin Wang, Haolong Li,* Lihua Bi, Lixin Wu,
keywords：polyoxometalate， supramolecularpolymer gel
source：期刊
specific source：Soft Matter, 2012, 8, 3315–3321.
Issue time：2012年
An organically pyridyl-grafted Anderson-type POM complex (TBA–Py–MnMo6) bearing counterions
of tetrabutylammonium (TBA) was found to form supramolecular gels instantaneously through mixing
with appropriate dicarboxylic acid additives in acetonitrile. In the gelation process, TBA–Py–MnMo6
was confirmed to self-assemble into supramolecular polymer chains through unidirectional hydrogen
bonding between the pyridyl groups of POMs and the carboxylic groups of dicarboxylic acids, which
drove the complexes into one-dimensional fibers. The fibers were demonstrated to further intertwine
together through the lateral hydrogen bonding between polymer chains under the support of excess
acid, forming three-dimensional networks. The distance between TBA–Py–MnMo6 units secluded by
dicarboxylic acid was proved to be a criterion for the formation of gels, which is related to the TBA
density along the supramolecular polymer chains and the solvent–fiber interfacial energy. The gelation
behaviour of the hybrid POM complex can be simply controlled through adjusting the length of
dicarboxylic acids. More interestingly, the POM hybrid gels exhibited a quick response to organic bases
and diacids reversibly.