Molecular Devices and Machines: Hybrid Organic-Inorganic Structures

Objective: In this review we present the general principles that are at the basis of the construction of artificial molecular devices and machines and the main characteristics of these systems with a special focus for the kind of energy inputs needed to make them work. Methodology: By the bottom-up (chemical) approach science and technology move from micro-to nano-world, and due to the nature of inputs (light and chemical) they move from electronics to photonics and chemionics. Furthermore the chemical molecule-by-molecule bottom-up approach offers unlimited opportunities for design and construction of nanoscale supramolecular structures, by combining the high precision of the chemical synthesis and scientists with a device driven-ingenuity. Furthermore, because the ability to perform specific functions as a response to external stimuli depends directly on the chemical nature and properties of the component units, in this review, we illustrate some examples of molecular devices and machines based on specific molecular units that have been developed in the research group of one of the authors. They are systems exhibiting pseudorotaxane, rotaxane, catenane and dendrimer structures that incorporate redox-and/or photoactive moieties. Conclusion: The future development of this kind of research will lead to more and more sophisticated artificial molecular devices and machines with better performances regarding their stability, switching, speed, and functions performed. We foresee that they will find useful applications in various fields, like energy conversion, sensoring, catalysis, and will give a great contribution in solving the present-day main problems regarding food, health, energy supply, and environment protection.