MEDIA/NANO: molecular wheels discovered at IBM

Alexander 'Sasha' Chislenko (
Thu, 30 Jul 1998 17:37:27 -0400

                 IBM scientists help discover "molecular
                 wheels" -- a breakthrough for designing
                 nanoscale devices 

                 On July 24, IBM scientists
                 and a team of international
                 collaborators reported the
                 discovery of "molecular
                 wheels": propeller-shaped
                 molecules that rotate rapidly
                 in a bearing-like structure
                 formed by surrounding
                 molecules. The scientists
                 believe this unexpected
                 phenomenon shows great
                 promise for the development of molecular mechanical devices
                 and further demonstrates the validity of using single molecules to
                 perform the various functions required in such devices. 

                 In a paper published in Science, IBM's Zurich Research
                 Laboratory, together with colleagues at the French National
                 Center for Scientific Research (CNRS) in Toulouse, and the Riso
                 National Laboratory in Roskilde, Denmark, report their design of
                 the propeller-shaped molecules which can switch between two
                 states -- rotating and immobilized, and the high-speed molecular
                 rotation which they observed by using a scanning tunneling
                 microscope (STM). 

                 "Our discovery of the molecular wheel came about from recent
                 molecular switch experiments in which we were investigating a
                 reversible change in the shape of specifically designed molecules
                 triggered by a voltage pulse from the STM tip," said James
                 Gimzweski, who leads the nano-engineering effort at IBM's Zurich
                 Research Laboratory. "We believe that compared to other
                 proposed or synthetic molecular mechanisms, the molecular
                 wheel, which works in a dry state and appears to be wearless, is
                 advantageous for creating gears and motors at the nanoscale

                 In viewing the
                 STM images, the
                 found a ring-like
                 object instead of
                 the molecule that
                 had been there.
                 The object, now
                 in a slightly
                 different position,
                 shifted by just
                 one-fourth of a
                 nanometer. It evidently jumped into a tiny space left vacant by an
                 irregularity in the molecular layer and thus escaped the
                 immobilizing grip of four molecules that surrounded it closely on
                 one side. An adjacent molecule on the other side confined its
                 further lateral motion and, in effect, contributed to forming a
                 bearing for rotation of the central molecule. This rotation was
                 responsible for the blurred, ring-like appearance of the molecule
                 in the STM image. Researchers at CNRS calculated the behavior
                 of the molecular wheel. Such wheels may someday become the
                 smallest conceivable components of molecular engines. 

Alexander Chislenko <> Extropy Online <>