1. Molecular Computing by Jason Bryant and Richard Overstreet

2. Why do we need smaller computers? Increased Complexity=Increased Computing Power To achieve this complexity, the components of a computer must be made smaller. There are both practical and scientific limitations on current silicon-based technology (Moore ’ s Law) One solution lies in molecular switches

3. What is a molecular switch? The use of molecules to construct electronic components that perform the same function as a macroscopic counterpart. Wires, logic gates, memory circuits, etc.

4. What kind of molecule do we need? What do we need it to do? Ideally, transmit or store electrons Need an empty low energy orbital Can create a "pi-conjugated system"

5. Pi Conjugated system These pi bonds act as wires by allowing the passage of electrons www.d.umn.edu/~pkiprof/chemweb/ Overlap/overlap2.html

6. Benefits of the Molecular Switch Obvious size advantage High current flow generates little heat Self-Assembly=Cheap, identical production in mass quantities High potential circuit density Non-volatile RAM

7. Need more than just wires Need Transistors Exploiting the pi orbital overlap Now we have the concepts, how do we use it?

8. Mark Reed and James Tour Base molecule was the Benzine Ring http://www.sciam.com/2000/0600issue/0600reed.html

9. Properties of Benzine Dithol Allowed for trapping of electrons Varying voltage controlled conductive and nonconductive state http://www.sciam.com/2000/0600issue/0600reed.html

10. How could they turn it on and off? Addition of NO2 and NH2 to the center ring created asymmetry that allows for twisting with applied voltage. http://www.sciam.com/2000/0600issue/0600reed.html

11. So how did they build it? Self assembly Need to be able to attach to metal surfaces Addition of thiols. http://www.sciam.com/2000/0600issue/0600reed.html

12. Self Assembly Process http://www.sciam.com/2000/0600issue/0600reed.html

13. Help from Photolithography For now, help from current semiconductor technology Creates selected regions for self assembly Now we have something resembling current computer architecture

14. Hurdles The Molecular Transistor- under development Connecting molecular switches Logic Gates

15. Notes Mark A. Reed and James M. Tour “ Computing with Molecules ” Scientific American June 2000 http://www.sciam.com/2000/0600issue/0600reed.html http://www.sciam.com/2000/0600issue/0600reed.html Ben Feringa, editor. Molecular Switches (Wiley-VCH: New York) 2001 David Rotman “ Molecular Computing ” Technology Review May/June 2000 University of Minnesota Inorganic Chemistry Website www.d.umn.edu/~pkiprof/chemweb/ Overlap/overlap2.html 2001 www.d.umn.edu/~pkiprof/chemweb/ Overlap/overlap2.html