Molecular-level devices

In everyday life we make extensive use of macroscopic devices. A macroscopic device is an assembly of components designed to achieve a specific function. Each component of the device performs a simple act, while the entire device performs a more complex function, characteristic of the assembly. For example, the function performed by a hairdryer (production of hot wind) is the result of acts performed by a switch, a heater, and a fan, suitably connected by electric wires and assembled in an appropriate framework. The concept of device can be extended to the molecular level. A molecular–level device can be defined as an assembly of a discrete number of molecular components (that is, a supramolecular structure) designed to achieve a specific function. Each molecular component performs a single act, while the entire supramolecular structure performs a more complex function, which results from the cooperation of the various molecular components. The extension of the concept of 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 [4]. Looking at supramolecular chemistry from the viewpoint of functions with references to devices of the macroscopic world is a very interesting exercise that helps the development of chemistry by introducing new concepts.