Chemists at the University of Bologna, in collaboration with researchers at the University of California, have developed Sunny, a clean, nano-sized motor that works with sunlight. This system, which transforms solar energy into mechanical energy, is composed of two molecules, one ring-shaped, which slides along a six-nanometer axis formed by the second molecule. When a photon strikes the ring, it changes shape and moves along the axis by transferring an electron. The displacement of this "molecular piston" is reversed thanks to the energy provided by another photon. The cycle of this engine is performed in less than one thousandth of a second, the equivalent of 60 000 rpm for a combustion engine.
To exploit the mechanical power generated by this device on a macroscopic scale, scientists are trying to synchronize the operation of millions of such nanomotors. Another application of this system is to build the memory of a "chemical computer", the conductivity of the ring-shaped molecule being modified by the inciding photons.

Source: ADIT