Spin crossover-induced colossal positive and negative thermal expansion in a nanoporous coordination framework material.

ABSTRACT: External control over the mechanical function of materials is paramount in the development of nanoscale machines. Yet, exploiting changes in atomic behaviour to produce controlled scalable motion is a formidable challenge. Here, we present an ultra-flexible coordination framework material in which a cooperative electronic transition induces an extreme abrupt change in the crystal lattice conformation. This arises due to a change in the preferred coordination character of Fe(II) sites at different spin states, generating scissor-type flexing of the crystal lattice. Diluting the framework with transition-inactive Ni(II) sites disrupts long-range communication of spin state through the lattice, producing a more gradual transition and continuous lattice movement, thus generating colossal posit

SUBMITTER: Mullaney BR 

PROVIDER: S-EPMC5648752 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature