Molecular-Level Devices and Machines

The concept of a macroscopic device can be extended to themolecular level by designing and synthesizing (supra)molecular species capable of performing specific functions.Molecularlevel devices operate via electronic and/or nuclear rearrangements and, like macroscopic devices, need energy to operate and signals to communicatewith the operator. The energy needed to make the device work can be supplied as chemical energy, electrical energy, or light. Among the most useful techniques to monitor the operation of molecular-level devices are spectroscopy (particularly luminescence) and electrochemistry. Amolecular-level electronic set for energy and electron transfer (wires, switches, antennas, plug/ socket, and extension systems) and various kinds of molecular-level machines (tweezers, pyston/cylinder systems, shuttles, systems based on catenanes, rotary motors) have already been synthesized and studied. The extension of the concept of a device to the molecular level is of interest, not only for basic research, but also for the growth of nanoscience and the development of nanotechnology. Molecular-level devices should find applications in information storage, display, and processing; in the long run, they are expected to lead to the construction of molecular-based (chemical) computers.