Unidirectional molecular motor on a gold surface
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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

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
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


Protein motor in nature

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


Unidirectional molecular motor
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


Structure of molecular motor
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.


Rotation of the molecular motor

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


Rotation of the molecular motor1

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


Rotation of the molecular motor2

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


Rotation of the molecular motor3

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


Photochemical process

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.


Thermal process

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.


Unidirectionality
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.


Coclusion
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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