Titre : Photoactive Molecular Devices, Machines and Materials.

Cette conférence sera prononcée (en anglais) par le Professeur Alberto Credi, du département de chimie de l'Università di Bologna (Italy).

Résumé : Miniaturization has been an essential ingredient in the outstanding progress of information technology over the past fifty years. The next, perhaps ultimate, limit of miniaturization is that of molecules, which are the smallest entities with definite and programmable size, shape, and properties. Molecular-level systems that respond to external stimulation by changing some physical or chemical properties can be viewed as input-output devices and therefore may be useful for gathering, transferring, processing, and storing information. Some of these nanoscale devices can, in fact, perform logic operations of remarkable complexity. This research - although still far from being transferred into technology - is attracting interest, since the nanometer realm seems tobe out of reach for the 'top-down' techniques currently available to the microelectronics industry.

Among the examined systems are molecular switches, sensors, wires, plug/socket devices, extension cables, memories, and combinational and sequential logic circuits. These functionalities are implemented using a large variety of chemical species, from unsophisticated molecules to transition-metal complexes, supramolecular assemblies and molecule-nanocrystal hybrids. Particular attention is devoted to the concepts of logic superposition and reconfiguration, which can lead to a substantial degree of functional integration. We are also interested at developing strategies for the serial connection (cascading) of distinct molecular logic systems.

We are interested in the design, synthesis and study of multicomponent species (in most cases interlocked compounds such as rotaxanes, catenanes and related species) capable of performing mechanical motions of their molecular components in response to external stimulation (addition of chemical reactants, application of electric potentials, light irradiation). We have investigated examples of pH-driven and sunlight-powered molecular shuttles, molecular elevators, and catenane rotary devices. An important scientific objective of this research is to gain a deep understanding on the operating mechanisms of such systems, thereby learning how to design new prototypes with novel functionalities and/or improved performance. The final aim is the construction of mechanical nanodevices that can carry out useful functions such as memorizing/processing information in binary form, control of membrane permeability, uptake and release of other molecules, up to mechanical actuation on the micro- and macroscopic scales (molecular muscles).

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