One goal of nanotechnology is to implement machine parts with atomically precise components. Adding to the list of mechanical components that have been demonstrated on the molecular scale, Taiwanese researchers have constructed a molecule in which exposure to light causes the molecule to change shape so that rotation of one part of the molecule with respect to another part can no longer occur. Excerpts from the Nanowerk Spotlight article written by Michael Berger “Molecular brakes for nanotechnology machines“:
The concept of a ‘machine’ — a mechanical or electrical device that transmits or modifies energy to perform a certain task — can be extended to the nano world as well. On the nanoscale, the nanomachine components would be molecular structures each designed to perform a specific task which, all taken together, would result in a complex function. Nanoscientists have already built molecular motors, wheels, and gears for powering nanomachines (see for instance: “Nanotechnology reinvents the wheel“). The ability to control nanoscale motors, more specifically, to control the motion of molecular components of such motors, doesn’t only involve acceleration and movement but, equally important, deceleration and stopping. So far, the development of a practical braking system for nanomotors remains a challenge. Researchers in Taiwan now have reported development of a light-driven molecular brake that could provide on-demand stopping power for futuristic nanotechnology machines.
…Dr. Jye-Shane Yang tells Nanowerk. “The key progress of our work is to use light as the control unit for ‘braking’ a rotary motion on the molecular scale.”
…Yang emphasizes that the stopping power of their light brake is of unprecedented range. The difference in rotation rates between brake-off and brake-on states could be as large as 1 billion-fold, i.e. nine orders of magnitude.
The Nanowerk article includes an animation illustrating how this molecular brake works and relates this accomplishment to previous molecular machine work. The research was published in Organic Letters (abstract).