Final Report Summary - FOSIMEL (Aromatic Foldamers for Single Molecule Electronics)
Over the last decade molecular devices consisting of single molecules have attracted strong interest due to the miniaturisation needs in electronic materials. Indeed, the Moore's law that predicted in 1968 a doubling of devices per chip every 18-24 months proved to be true, but the top down approach of miniaturisation of silicon based devices is now reaching its limit. An alternative is the use of molecules to process some inherent function, then to assemble them with other components to build electronic devices; this approach is known as the bottom-up approach. Among the devices needed to achieve molecular scale electronics, wires are the simplest, and as such are particularly suited to the development of new technologies and also to fundamental understanding. An increasing number of molecules have shown interesting properties for electronic applications. Among the most studied are conjugated molecules or polymers, carbon nanotubes, DNA and, more recently, metallo-organic assemblies.
Recent results demonstrate that short aromatic oligomers that adopt stable helical conformation in solution and known as foldamers, developed by the host, showed the unusual ability to transport electrons very rapidly (in the fs range) with remarkably low attenuation factors upon excitation by light. This preliminary study initiated the proposed project to explore the potential of this class of foldamers to be used as molecular wires, and which represents the first step toward their use in a new field of electronic materials.
The main objectives of the project were to investigate on the photoinduced charge transfer properties as a function of foldamer length; to assess whether there is a difference between charge transfer in the excited state and conductance in the ground state; and to investigate the effect of metal doping on electron transfer and conductance.
These objectives all involved a massive effort in the organic synthesis of modified helical oligomers of very high length and containing a new type of side chains. The synthesis (Task 1) proved to be a serious time limiting factor of the project and investigations of the conducting properties had to be postponed.
The main results were: the optimization of synthetic protocols to produce multiturn helical foldamers on a large (>10g), by far the largest described to date in this field (manuscript submitted); the introduction of new side chains at the periphery of the helices that allow to dissolve them in a wide variety of solvents and investigate the solvent dependence of their conformational stability (publication and cover picture of Chem. Commun.); the optimization of protocols for metal doping; the optimization of protocols for the synthesis of the longest foldamers described to date (64 units, manuscript in preparation); the development of a living polymerization procedure investigations on the deposition of helical foldamers on surfaces by atomic force microscopy.
Continuation of the project in the return phase in China and through collaborative work with the European host is on going and expected to bring significant progress towards the initial objectives concerning the potential of helical foldamers as wires for single molecule electronics. The long term collaborations which have been established between several the European host and the Chinese host of the return phase has already resulted in further exchanges of early stage and experienced researchers.
Recent results demonstrate that short aromatic oligomers that adopt stable helical conformation in solution and known as foldamers, developed by the host, showed the unusual ability to transport electrons very rapidly (in the fs range) with remarkably low attenuation factors upon excitation by light. This preliminary study initiated the proposed project to explore the potential of this class of foldamers to be used as molecular wires, and which represents the first step toward their use in a new field of electronic materials.
The main objectives of the project were to investigate on the photoinduced charge transfer properties as a function of foldamer length; to assess whether there is a difference between charge transfer in the excited state and conductance in the ground state; and to investigate the effect of metal doping on electron transfer and conductance.
These objectives all involved a massive effort in the organic synthesis of modified helical oligomers of very high length and containing a new type of side chains. The synthesis (Task 1) proved to be a serious time limiting factor of the project and investigations of the conducting properties had to be postponed.
The main results were: the optimization of synthetic protocols to produce multiturn helical foldamers on a large (>10g), by far the largest described to date in this field (manuscript submitted); the introduction of new side chains at the periphery of the helices that allow to dissolve them in a wide variety of solvents and investigate the solvent dependence of their conformational stability (publication and cover picture of Chem. Commun.); the optimization of protocols for metal doping; the optimization of protocols for the synthesis of the longest foldamers described to date (64 units, manuscript in preparation); the development of a living polymerization procedure investigations on the deposition of helical foldamers on surfaces by atomic force microscopy.
Continuation of the project in the return phase in China and through collaborative work with the European host is on going and expected to bring significant progress towards the initial objectives concerning the potential of helical foldamers as wires for single molecule electronics. The long term collaborations which have been established between several the European host and the Chinese host of the return phase has already resulted in further exchanges of early stage and experienced researchers.