Probing helix formation in chains of vertexlinked octahedra

The rational design of crystal structures based on the chemical nature of molecular components, a longstanding and exciting research topic in organic solid state chemistry, is an emerging theme of crystal engineering in inorganic solid state chemistry. In particular, noncentrosymmetric structures, or those lacking inversion symmetry, are important for future technologies that are based on piezoelectricity, pyroelectricity, ferroelectricity and second harmonic generation (SHG). Materials that exhibit these properties provide a large and new class of solids for studies in basic science associated with the noncentrosymmetric (chiral, polar, or chiral-polar) space groups. Structures comprised of vertex-linked octahedra are common in inorganic solids. The subject of our Highlight is the rational synthesis of linear, zigzag or helical chains when two vertices of an octahedron, which are either adjacent (cis) or opposite (trans), are linked.