Synthetic Molecular Motors

Gregory T. Carroll

University of Groningen

g.t.carroll@rug.nl

January 20, 2010

Dresden, Germany

2

Pertinent Questions Regarding

Nanomachines

1) What can be made that looks like a machine?

2) What can the thing we made do?

3) What would be a useful function and what do we need to make

to achieve it?

7) Do nanomachines need to be based on macroscopic machines?

5) How can we overcome Brownian motion?

9) What kind of physics will govern these machines?

4) How small can it be and still function?

6) What kind of energy should be used?

8) What kind of forces will result in locomotion?

3

From Macroscopic to Nanoscale Rotors

10 m 1 m 10 cm 1 cm

Chem. Comm. 2009, 1712-1714. Alberts et al. Molecular Biology of the Cell

Bacterial Flagellar Motor Synthetic Rotary Motor

100 nm 10 nm 1 nm

4

Components and Orientation of

Rotors

Chem. Rev. 2005, 105, 1281

Azimuthal orientation Altitudinal orientation

Rotor

Stator

Axle

Atomic Configuration

5

J. Org. Chem. 2003, 68, 8750–8766.

6

Synthetic Molecular Motors

• Molecular Rotors

• Rotary Motors

• Light-driven Rotary Motors

• Linear Motors

7

Molecular Rotary Motion

Free Motion Forced Motion

Triptycenes rotate in correlated fashion

8

Molecular Turnstile

J. Am Chem. Soc. 1995, 117, 10662

Rotation within a framework

9

Rotary Motion in Crystals

Crystalline molecular machines – possibility to gain high packing

density of multicomponent arrays of molecules that can act in

concert, transferring forces, motion and energy from one molecule

to another along the array

1) Rotary components

2) Free volume

3) Volume-conserving motions

4) Correlated Motions

5) Self-assembly

Acc. Chem. Res. 2006, 39, 413

J. Am. Chem. Soc. 2002, 124, 2398

Gyroscope and Compass-inspired

Molecules

10

Framework shields rotor from

intermolecular contacts within

crystal lattice and provides

free-volume needed for

unhindered rotation within

framework

Acc. Chem. Res. 2006, 39, 413

11

Attempted Molecular Ratchet

Journal of Organic Chemistry 1998, 63, 3655

2nd Law of Thermodynamics: It

is impossible for any device that

operates on a cycle to receive

heat from a single reservoir and

produce a net amount of work. ACS Nano 2009, 3, 1042

Feynman, Richard P. (1963). The Feynman Lectures on Physics, Vol. 1. Massachusetts, USA: Addison-Wesley. Chapter 46

12

Rolling Motions on Surfaces

13

Surface-attached Systems

Major Hurdle: Brownian Motion

Limit random motion – Confine motor at interface

Stable attachment to surface

Adsorption on surface

Long-term Goal: Show that movement of rotor

can affect motility of motor or molecule/material

in presence of motor

Interfacial Stir Bar

hn Crowd Surfing

Molecules

14

Surface attached rotors based on

thioethers

A. E. Baber, H. L. Tierney, E. C. H. Sykes ACS Nano, 2008, 2, 2385–2391

15

Donor-acceptor Surface-bound Rotor

J. Org. Chem. 2003, 68, 5091

Movement restricted by attachment to surface through a tripod

Can external electric stimuli induce rotation of the dipolar unit?

16

Surface-bound Altitudinal Rotor

X. Zheng, M. E. Mulcahy, D. Horinek, F. Galeotti, T. F. Magnera, J. Michl J. Am. Chem. Soc., 2004, 126, 4540

17

Controlled Rotary Motion – Rotary

Molecular Motors

DEFINITION:

A rotary motor is a device that is able to convert

energy input into controlled,

directional, rotary motion in

a continuous fashion

Energy

• Photons

• oxidation/reduction

• Chemicals

REQUIREMENTS

• Controlled Motion

• Directional Movement

• Continuous Process

• Consumption of Energy

Electrical or Photocontrol of the Rotary

Motion of a Metallacarborane

18

M. Frederick Hawthorne, et al. Science 303, 1849 (2004)

19

Chemical Motor - 120º Rotation

Kelly, T. R. et al. Nature, 1999, 401, 150-152

O

H O

N C O

O

N

O O O O

H O

N H 2 N

O O

O

O

H O

N H 2

O

H O

N C O

C O C l 2

N a B H ( O E t ) 3

20

Chemical Rotor - 360º Rotation

Science, 2005, 80, 310

21

Catenanes

Leigh, D.A., Wong, J.K.Y., Dehez, F., Zerbetto F. Nature, 2003, 424, 174

22

Three Rings

Leigh, D.A., Wong, J.K.Y., Dehez, F., Zerbetto F. Nature, 2003, 424, 174

23

Catenane Motor

Leigh, D.A., Wong, J.K.Y., Dehez, F., Zerbetto F. Nature, 2003, 424, 174

24

Chemically Propelled Rotation

2 um long

500 nm long

H2O2 O2 + H2O

Si Wafer

S. Fournier-Bidoz, A.C. Arsenault, I. Manners, G.A. Ozin Chem. Commun. 2005, 441

25

Molecular Rotary Motors Based on

Photo-active Overcrowded Alkenes

( P , P ) - t r a n s

M e a x

M e a x

Structural Features

• Photo-isomerizable double-bond

• Two helical halves

• Two stereogenic centers on each half

cis

trans

26

Rotary Cycle

( P , P ) - t r a n s

M e a x

M e a x

( M , M ) - c i s

M e e q M e e q

> 2 8 0 n m

M e e q

M e e q

( M , M ) - t r a n s

> 2 8 0 n m

N. Koumura, R.W.J. Zijlstra, R.A. van Delden, N. Harada, B.L. Feringa, Nature 1999, 401, 152

D 6 0 o C

T1/2 (4th Step) = 233 h at 20° C

M e a x M e a x

( P , P ) - c i s

2 0 o C

T1/2 (2nd Step) = 32 min. at 20° C

27

Ideal Unidirectional Rotation

28

2nd Generation

KEY FEATURES:

X

Y

Me

H

Desired Properties

• Ability to control speed

• Functionality for attachment to surface

• Symmetric tri-cyclic lower half

• Unidirectional rotation controlled by a single stereogenic center

• The energy barriers for the thermal steps can be adjusted (X,Y)

• Distinct chemical functionalities can be introduced into the upper and lower

halves, allowing for attachment to surface and modification of properties

29

Rotary Cycle

S

S

M e a x

M e O

H g - l a m p , 3 6 5 n m

5 ~ 1 0 ° C

S

S

M e O

6 0 ° C

S

S

M e O

S

S

M e O

M e e q

M e a x M e e q

6 0 ° C

H g - l a m p , 3 6 5 n m

5 ~ 1 0 ° C

( 2 ' R ) - ( M ) - t r a n s - 1 ( 2 ' R ) - ( P ) - c i s - 2

( 2 ' R ) - ( P ) - t r a n s - 1 ( 2 ' R ) - ( M ) - c i s - 2

r a t i o 1 4 : 8 6

r a t i o 8 9 : 1 1

T1/2 = 233 h at 20° C

(2’R)-(M)-trans-1

(2’R)-(P)-cis-2

(2’R)-(M)-cis-2

(2’R)-(P)-trans-1

-150

-100

-50

0

+50

+100

+150

250 300 350 400 450

De

l /nm

30

Increasing the Speed of Rotation

hn hn

D

Ene

rgy

Rotation step

stable trans stable trans stable cis

unstable

trans

D

unstable cis

Size of bridging rings

Size of substituent

at stereocenter

T1/2 = 5.74 x 10-3 s at 20° C T1/2 = 3.2 min. at 20° C T1/2 = 233 h at 20° C

Michael M. Pollard, Martin Klok, Dirk Pijper and Ben L. Feringa

Advanced Functional Materials 2007,17, 718-729.

M e a x

M e O

( 2 ' R ) - ( M ) - t r a n s - 1

S

S

31

A Cholesteric (Chiral) LC Chiral Dopant:

R. Eelkema, B. L. Feringa et al., Nature 2006, 440, 163.

ee.concHTP

1p

pitch (p)

32 32

(P,P)-trans (M,M)-cis

MeeqMeeq

Meax

Meax

Meax Meax

Meeq

Meeq

> 280 nm

> 380 nm

> 280 nm

> 380 nm

D 60oC 20oC

t0

t180 sec

R.A. van Delden, N. Koumura, N. Harada, B.L. Feringa, Proc. Nat. Acad. Sci. 2002, 99, 4945.

6.16 weight % in E7

HTPE7

69.4 mm-1

-5.0 mm-1 12.5 mm-1

Color Tuning

By Molecular Rotation in an LC

33

Macroscopic Visualisation of

Rotation

hn

(P,P)-trans

(P,P)-cis

(M,M)-trans

E7

34

Rotating Microscale Objects

Rienk Eelkema, et. al. Nature 2006, 440, 163

Texture rotation Rotation of Micro-rod

35

Surface attachment - Azimuthal

D

hn

D

hn

S

OO

OO

SS

S

OO

OO

SS

S

OO

OO

SS

S

OO

OO

SS

quartz quartz

Gold

quartz quartz

Gold

quartz quartz

Gold

quartz quartz

Gold

hn

hn

D D

( ) 9

( ) 9

( ) 9

( ) 9

( ) 9

( ) 9

( ) 9

( ) 9

CD

(m

deg

)

l (nm)

-3

-2

-1

0

1

2

320280240200

36

Surface Attachment - Azimuthal

SiO O Si O

O

O

O

O

N

N

N

N

NN

SiO O Si O

O

O

O

O

N

N

N

N

NN

D

365 nm

300 400 500

0,000

0,005

0,010

Ab

s

nm

Stable, -20C

30 min irr, 365nm

Therm Conv

hn

hn

D D

1.6x10-3

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0.0

Ab

so

rba

nce

at 43

9 n

m

40003000200010000

Time (s)

28 C 40 C

37

Visualization of Rotary Motion

H. Noji, R. Yasuda, M. Yoshida, K. Kinosita Jr. Nature, 1997, 386, 299-302

Group Fluorescent

Group

38

Molecular Motor with Extended Arm

Me

OPr

OPr

MeO2C CO2Me

N

O OEt2N

O

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

39

39

Length of Arm

Dye for visualization with wide-field

fluorescence imaging

Two alkyne moieties for attachment of

the motor ‘stator’ to the surface

40

Fluorescence on Surface

O

O

O

O

O

O

N

OPr

OPr

OEt2N

8

NN

N NN

N

O

SiO

Si

OO O

10 10

Fluorescence Wide-field Microscopy

41

Towards a Nanocar?

Organic Letters 2006, 8, 1713-1716

42

Linear Motors

Rotaxanes and Catenanes

Molecular components that move along pre-defined tracks

A.M. Brouwer, C. Frochot, F.G. Gatti, D.A. Leigh, L. Mottier, F. Paolucci, S. Roffia, G.W.H. Wurpel Science 2001, 291, 2124.

43

Molecular Shuttle

A.M. Brouwer, C. Frochot, F.G. Gatti, D.A. Leigh, L. Mottier, F. Paolucci, S. Roffia, G.W.H. Wurpel Science 2001, 291, 2124.

44

Molecular Elevator

J.D. Badjic, V. Balzani, A. Credi, S. Silvi, J.F. Stoddart Science 2004, 303, 1845.

45

Molecular Muscle

Angew. Chem. Int. Ed. 2000, 39, 3284

46

Contraction

A nanomechanical device based on

linear molecular motors

47

Huang et al., Appl. Phys. Lett., Vol. 85, No. 22, 29 November 2004

48

Combining Rotary and Linear Motion

Angew. Chem. Int. Ed. In Press