Water- and Temperature-Triggered Reversible Structural Transformation of Tetranuclear Cobalt(II) Cores Sandwiched by Polyoxometalates.

Although stimuli-responsive structural transformations of inorganic materials have attracted considerable attention because of their potential use as functional switchable materials, multinuclear metal cores frequently suffer from unexpected dissociation of metal cations and/or irreversible transformations into infinite structures. In this study, we describe the successful demonstration of the water- and temperature-triggered reversible structural transformation between cubane- and planar-type tetranuclear Co(II) cores sandwiched by polyoxometalates. The arrangements and coordination geometries of the Co(II) cations were interconverted by simple hydration and dehydration, resulting in the manipulation of the magnetic and optical properties of these compounds. Moreover, this system showed unique thermochromism through temperature-dependent reversible structural interconversion.
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