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Unidirectional Molecular Motor on a Gold Surface.

Unidirectional Molecular Motor on a Gold Surface. van Delden, R. A.; ter Wiel, M. K. J.; Pollard, M. M.; Vicario, J.; Koumura, N.; Feringa, B. L. Nature , 2005 , 437 , 1337. Tomoki KATO Tobe Lab. Contents. Introduction Protein Motor in Nature Unidirectional Molecular Motor

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Unidirectional Molecular Motor on a Gold Surface.

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  1. Unidirectional Molecular Motor on a Gold Surface. van Delden, R. A.; ter Wiel, M. K. J.; Pollard, M. M.; Vicario, J.; Koumura, N.; Feringa, B. L. Nature, 2005, 437, 1337. Tomoki KATO Tobe Lab.

  2. Contents • Introduction Protein Motor in Nature Unidirectional Molecular Motor Structure of Motor Molecule • Results and Discussion Rotation of the Molecular Motor Photochemical Process Thermal Process Unidirectionality • Conclusion

  3. ATP synthesis by ATP synthetic enzyme H+ H+ H+ ADP + Pi ATP Current of electron ATP synthetic enzyme Electron transferring protein Protein Motor in Nature

  4. Unidirectional Molecular Motor Harada, N.; Feringa, B. L. et.al. Nature 1999, 401, 152-155. Feringa, B. L. et.al. J. Am. Chem. Soc. 2002. 124, 5037–-5051. Kelly, T. R. et.al. Nature 1999, 401, 150-152. Chemical rotation Photo – induced rotation Rotation of C – C double bond by photoirradiation hn

  5. Structure of Molecular Motor Au (2’R) - (M) – 1 (2’R) - (M) – 2 (2’R) - (M) – 1 - Au : Meax • The motor molecule is a light – driven molecular capable of repetitive unidirectional rotation mounted on the surface of gold nanoparticles. • The motor design uses a chiral helical alkene with an upper half that serves as a propeller and connected throw a carbon – carbon double bond (the rotation axis) to a lower that half that serves as a stator. • The stator carries two thiol – functionalized ‘legs’, which then bind the entire motor molecule to a gold surface.

  6. Au Au Au Au Rotation of the Molecular Motor hn (2’R) - (M) – 1 - Au : Meax (2’R) - (P) – 1 - Au : Meeq Photochemical Process D D hn (2’R) - (P) – 1 - Au : Meeq (2’R) - (M) – 1 - Au : Meax

  7. Au Au Au Au Rotation of the Molecular Motor hn (2’R) - (M) – 1 - Au : Meax (2’R) - (P) – 1 - Au : Meeq Thermal Process D D hn (2’R) - (P) – 1 - Au : Meeq (2’R) - (M) – 1 - Au : Meax

  8. Au Au Au Au Rotation of the Molecular Motor hn (2’R) - (M) – 1 - Au : Meax (2’R) - (P) – 1 - Au : Meeq Photochemical Process D D hn (2’R) - (P) – 1 - Au : Meeq (2’R) - (M) – 1 - Au : Meax

  9. Au Au Au Au Rotation of the Molecular Motor hn (2’R) - (M) – 1 - Au : Meax (2’R) - (P) – 1 - Au : Meeq Thermal Process D D hn (2’R) - (P) – 1 - Au : Meeq (2’R) - (M) – 1 - Au : Meax

  10. Au Au Photochemical Process hn (365 nm) (2’R) - (M) – 1 - Au : Meax (2’R) - (P) – 1 - Au : Meeq CD and UV spectra of 1-Au and 2. CD (a) and UV/Vis (b) spectra of pure (2’R) – (M) – 1 – Au (solid black line), PSS≧280nm (dashed black) and PSS365nm (dotted black) samples (all spectra has adjusted for molar concentration of chromophores), and CD (a) and UV/Vis (b) spectrum of (2’R) – (M) – 2 (solid grey) in toluene. After heating of the PSS samoles (T＞50 ºC), the original spectra of (2’R) – (M) – 2 were obtained.

  11. Au Au Thermal Process 50 ˚C (2’R) - (P) – 1 - Au : Meeq (2’R) - (M) – 1 - Au : Meax Following two full turns by CD spectroscopy. Schematic representation of the unidirectional rotation of 1 (as viewed along the rotation axis) and two full four-stage 360°rotary cycles followed by CD spectroscopy. The change in CD intensity (mdeg) at 290nm (solid line) and 320 nm (dashed) at each photochemical (hn ≧ 280 nm and hn ＝ 365nm) and thermal (D353K) isomerization step is shown. CD and UV spectra of 1-Au and 2. CD (a) and UV/Vis (b) spectra of pure (2’R) – (M) – 1 – Au (solid black line), PSS≧280nm (dashed black) and PSS365nm (dotted black) samples (all spectra has adjusted for molar concentration of chromophores), and CD (a) and UV/Vis (b) spectrum of (2’R) – (M) – 2 (solid grey) in toluene. After heating of the PSS samoles (T＞50 ºC), the original spectra of (2’R) – (M) – 2 were obtained.

  12. Unidirectionality Confirmation of unidirectional rotation on the nanoparticle using NMR spectroscopy. a, Photochemical and thermal isomerization of 13C isotope labelled motor 4 on gold (4-Au) and structures of major isomers of 4-Au. Cleaved motor probably exists as a mixture of free thiol (R . H) and disulphide (R . S-Motor). b, Key signals (ArH) in the 1H NMR of stable-cis-4 in solution (top panel), after irradiation of stable-cis-4-Au and core etching (middle panel) and after irradiation of stable-cis-4-Au, heating, then etching (bottom panel). c, Key signals (-O13CH2[CH2]7) in the 13C NMR of stable-cis-4 in solution (top panel), after irradiation of stable-cis-4- Au and core etching, and subsequent heating (middle panel), and after irradiation of stable-cis-4-Au, heating, then etching (bottom panel). The conversion of stable isomer 4-Au to unstable isomer 4-Au (evaluated by 1H NMR) matched the final conversion of stable-cis-4-Au to stable-trans-4-Au evaluated by 13C NMR. In both cases, NMR analysis was performed after detachment.

  13. Coclusion • The combined results (from CD studies of optically active (2’R) – (M) – 1 – Au, and NMR studies of 13C isotopically labelled 4 – Au, with distinct legs) provide compelling evidence for the unidirectionality of the rotary process on the surface.

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