Many researchers predict that complementary metal oxide semi-conductor (CMOS) technology runs into significant physical and economic limitations shortly after 2010.
This is because the insulating oxide layer of the transistor materials has become so thin, between 1.5 and 2.0 nm, representing 3 to 4 atomic layers of oxide, that quantum mechanical tunneling of electrons has become possible. The tunneling process does not appear to damage the oxide, but the resulting gate leakage can cause circuit failures. Even if circuit techniques can be designed to deal with this leakage, the amount of power consumed will become unacceptably large. By using specifically designed conducting molecules it could be possible to construct better and cheaper transistors than with CMOS. Breakthrough products of the bottom up approach, such as organic light-emitting diodes and organic field effect-transistors, show that molecular electronics is an actively emerging technology with immense promise for innovative, convenient and high-performance electronics.
In our research, metal-coordinated polyisocyanides will be investigated as a new class of building blocks for (semi-)conducting materials. These polymers are exceptionally rigid nanowires, as stiff as DNA, which can be as long as 20 μm
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The wires contain α-diimines, which can coordinate to metals such as rhodium, iridium etc. It is expected that coordination of these metals to the polyisocyanides converts the polymers into conducting wires.
The organization of functional outer units into a well-defined array, as a result of the presence of an internal H-bonding network between the side-chains of the polymers, is expected to optimize electron conducting properties of the materials.
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Instead of polyisocyanides, also the polyguanidine of Novak could be used. Polyguanidine are also stable helices in solutions and are made by a polymerization reaction of carbodiimides. The polymerization of carbodiimides by the titanium half-metallocenes are living, reversible polymerizations with large, negative ΔSpolym values and comparatively small ΔHpolym. Hence, they have relatively low ceiling temperatures, Tc. Therefore, carbodiimide polymerizations are carried out at room temperature and at the highest possible monomer concentrations.
Coordination of the metals to the polyguanidine could give a six-membered ring instead of the five-membered ring of the polyisocyanide.
Nolte group for physical-organic and supramolecular chemistry
