Thin Inorganic Ribbons Coil And Flex

If inorganic compounds could learn a trick or two about flexibility from biomolecules, they could be transformed into versatile building blocks for complex structures. Proteins and other long biomolecules gracefully bend, flex, and fold. That agility enables those compounds to assemble into a large variety of complex ordered structures. By contrast, inorganic wires, rods, and other elongated structures tend to be rigid, which limits the complexity and variety of structures they form. Researchers in China have now shown that indium sulfide, when prepared in ultrathin nanoribbon form, flexes and assembles in biomolecule-like ways. Tsinghua University chemists Peng-peng Wang, Xun Wang, and coworkers report that long InS ribbons just 9 Å thick are flexible enough to spontaneously coil into a variety of shapes including double-headed and S-shaped coils (J. Am. Chem. Soc., DOI: 10.1021/ja403065z). They also find that in response to the presence of alkylamines and other synthesis conditions, the coils adjust their shapes and spontaneously assemble into a variety of two- and three-dimensional ordered superlattices. Ultrathin nanocoils may lead to new insights into using flexible inorganic nanocrystals as building blocks for superstructures, the group predicts.