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Light-Driven Molecular Motors

Light-Driven Molecular Motors. Symposium ‘Transport on the Edge’. Friday, June 18, 2004. Eek Huisman Supervisor: Dr. R. A. van Delden. ?. What is a (molecular) motor?. Oxford English Dictionary: ‘A machine or mechanical agency which imparts motion’. A molecular motor should 1 :

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Light-Driven Molecular Motors

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  1. Light-Driven Molecular Motors Symposium ‘Transport on the Edge’ Friday, June 18, 2004 Eek Huisman Supervisor: Dr. R. A. van Delden

  2. ?

  3. What is a (molecular) motor?

  4. Oxford English Dictionary: ‘A machine or mechanical agency which imparts motion’

  5. A molecular motor should1: • overcome Brownian motion • be unidirectional • perform the same cycle of movements a large number of times • convert energy into work 1 B. L. Feringa, N. Koumura, R. A. van Delden and M. K. J. ter Wiel, Appl. Phys. A. 75, 301 (2002)

  6. Are there any fundamental differences between macroscopic and molecular motors?

  7. M=4 . 10-25 kg v=1 .102m/s M=400kg Msol=4 . 10-26 kg v=3 .10-12m/s vsol=3 .102m/s Thermal Motion Thermal energy at roomtemperature ~kbT = 4 . 10-21 J Thermal energy ~

  8. BROWNIAN STORM

  9. HOW TO CONTROL MOLECULAR MOTION?

  10. How to control molecular motion? I) Energy input: • Light • Chemicals • Electro chemicals II) Proper molecular geometry III) Mechanism that ensures unidirectional motion

  11. Energy input: light

  12. hv hv Energy input: light Cis-trans isomerization + + A B A+ B- A* B + Charge transfer

  13. Molecular Geometries Rotaxanes Catenanes Others

  14. 3 EXAMPLES

  15. Example 1: A linear motor 2 • [2]-rotaxane: thread and ring • Two stations: change of affinity upon charge transfer (triplet excited state!) • Hydrogen bonds 2 A. M. Brouwer, C. Frochot, F. G. Gatti, D. A. Leigh, L. Mottier, F. Paolucci, S. Roffia and G. W. H. Wurpel, Science291, 2124 (2001)

  16. Example 2: A rotary catenane motor 3 • [3]-catenane: 1 static ring, 2 gliding rings • Static ring: 4 stations • 2 stations susceptible to cis-trans isomerization: A and B (A’, B’) • 2 other stations C and D • affinity with the gliding rings: A>B>C>D>A’>B’ • Hydrogen bonds 3 D. A. Leigh, J. K. Y. Wong, F. Dehez and F. Zerdetto, Nature424, 174 (2003)

  17. affinity with the gliding rings A>B>C>D>A’>B’

  18. Example 3: A rotary motor with a rigid axis4 • Sterically overcrowded alkene • Cis-trans isomerization causes rotation • Isomerization is followed by a an irreversible thermal step • Steric hindrance of methyl group is crucial 4 N. Koumura, R. W. J. Zijlstra, R. A. van Delden, N. Harada and B. L. Feringa, nature401, 152 (1999)

  19. 2 De 2 1 De 1 4 4 3 3 Studium Generale Lezing 30-10-2002

  20. Overview

  21. WHAT CAN WE DO WITH MOLECULAR MOTORS?

  22. Applications Molecular muscle Modification of surfaces Color change of LCD Logic gates and switches

  23. 2 meter 0.000000002 meter

  24. ‘I have no doubt that it is possible to give a new direction to technological development, a direction that shall lead it back to the real needs of man, and that also means: to the actual size of man. Man is small, and, therefore, small is beautiful.’ Ernst Friedrich Schumacher (1911–1977), economist

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