Escher goes chemical

In his 1948 wood engraving Stars, M. C. Escher celebrated geometric symmetry in a composition of polyhedrons, including a cuboctahedron, in which an octahedron infiltrates a cube. Now chemists from the University of Science & Technology of China's Hefei National Laboratory for Physical Science at the Microscale and the Max Planck Institute of Colloids & Interfaces, Potsdam, Germany, have made micrometer-scale cuboctahedral structures (Chem. Mater., DOI: 10.1021/cm060956u). Each copper sulfide cuboctahedron consists of four intersecting hexagonal flakes, each about 2 μm across (shown). To make the Escherian crystals, the researchers prepared an ethylene glycol solution of Cu(NO₃)₂ and elemental sulfur, which they autoclaved at 140 °C for a day. After they collected the resulting black solid by centrifugation, scanning electron microscope imagery gave Shu-Hong Yu and his coworkers a most welcome surprise. "It is appealing that a synthetic technique as simple as the one presented here can produce such beautiful objects that even a skilled craftsman cannot touch on the microscale level," the researchers note. Building blocks for larger structures and encapsulating agents for other materials are among the structures' potential uses, they suggest.