We intend to develop a new method, which uses light excitation to promote large conformational changes in suitable molecules (photoisomerizable or photochromic species) for controlling optically the motion and positioning of individual molecules with nanometric precision. To achieve this goal we adopt a strongly interdisciplinary approach in which physicists and chemists will collaborate together on 3 major themes: 1) movement of molecules and material in films and on surfaces; 2) transport of ions or of molecules in organized structures; 3) conduction across molecular wires containing a photoswitchable unit. The light induced movements will produce new interesting properties in the materials or open new technology for the construction of photo-gated devices.
Understanding and controlling the movements of molecules on a surface or in organized matrices for the development of nanometric scale devices represents one of the ultimate goals of nanotechnology. We intend to show that under proper light excitation (wavelength, intensity gradient, polarization), using new photoactive compounds we can achieve the following objectives:1. Transport of ions or molecules in organized structures; 2. Light control of individual molecule motion at the nanometric scale; 3. Nanosized electronic device fabrication by light controlled positioning and self-assembly of molecules between electrodes.
Work will centre around the development of: a) junctions in which photoactive groups are responsible for different electrical conduction upon light excitation; b) light active systems able to orient and self assemble in order to form a bridge between two electrodes.
DESCRIPTION OF WORK
The project involves highly interdisciplinary research that will be carried out in a collaborative effort by all the teams involved. An important step will be the synthesis of specific molecules containing the photoactive groups. We intend to focus on azobenzene derivatives, but additional photochromic compounds will be considered that are known to undergo reversible conformational changes upon light excitation. In order to study the movement and positioning of molecules inside a matrix or on a surface we plan to attach a fluorescent dye to the photoisomerizable unit. This will make possible the detection of the displacement of the whole molecule. Under non-uniform NFO excitation the photoisomerizable molecules will move, and the distribution of fluorescent molecules in the matrix will no longer be uniform. From the distribution of fluorescence intensity we will deduce the distances and speed of molecular transport. The aim of our project is to develop a new technology of non-contact manipulation of (individual) molecules, which should permit the displacement, and positioning of (individual) functional species inside a matrix or in organized monolayers. The external input we wish to use is light and it will represent the fuel that the molecules (machines) will use for their movement. In this project we intend to achieve light controlled vectorial transport for information and electronic applications. Finally such photoinduced changes in conformation can be useful for the construction of a nanosized electronic device which uses light controlled positioning and self-assembly of molecules between electrodes.
We intend to develop:
a) photoswitchable junctions in which photoactive groups are responsible for different electrical conduction upon light excitation;
b) light active systems able to orient and self assemble in order to form a bridge between two metallic electrodes.
Funding SchemeCSC - Cost-sharing contracts
75794 Paris Cedex 16
75794 Paris Cedex 16
CA 90024 Los Angeles