Abstract

We often think of crystal structures as essentially rigid—but in many cases parts of the structure have considerable freedom of movement, and may even undergo outright chemical reaction, within the crystal lattice. I will discuss two families of materials in which substantial atomic motion gives rise to unusual, useful properties. First, in frameworks of d10 metals connected by cyanide bridges, the motion of the cyanide ligands gives rise to anomalous thermal expansion behaviour; I show that this can easily be tuned by altering the composition of the material. Second, ruthenium-sulfur dioxide complexes undergo photoinduced linkage isomerism, which leads to properties potentially useful in holographic data storage. I demonstrate the powerful influence of the local crystal structure over the structural changes observed.