Gregory Carroll

Stratingh Institute for Chemistry

University of Groningen

March 23, 2009

ACS National Meeting Salt Lake City

Light-driven Molecular Motors at

Interfaces

g.t.carroll@rug.nl

2

Rotary Motors

Can rotary motion at the molecular level to perform useful tasks?

3

Rotary Motors in Biology

ATP Synthase Bacterial Flagellar Motor

Rotor: 6000- 17 000 RPM

Alberts et al. Molecular Biology of the Cell

~100 r.p.s.

4

Designing a Molecular Rotor

( P , P ) - t r a n s

M e a x

M e a x

DEFINITION:

A rotary motor is a device that is able to convert

energy input into controlled,

directional, rotary motion in

a continuous fashion

REQUIREMENTS

• Controlled Motion

• Consumption of Energy

• Directional Movement

• Continuous Process

Structural Features

• Photo-isomerizable double-bond

• Two helical halves

• Two stereogenic centers on each half

cis

trans

5

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

6

Ideal Unidirectional Rotation

7

2nd Generation Motors

• 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

KEY FEATURES:

X

Y

Me

H

Desired Properties

• Ability to control speed

• Functionality for attachment to surface

8

Unidirectional Rotation

-150

-100

-50

0

+50

+100

+150

250 300 350 400 450

D

/nm

(2’R)-(M)-trans-1

(2’R)-(P)-cis-2

(2’R)-(M)-cis-2

(2’R)-(P)-trans-1

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

9

Increasing the Speed

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

S

S

M e a x

M e O

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

Michael M. Pollard, Martin Klok, Dirk Pijper and Ben L. Feringa Advanced Functional Materials 2007,17, 718-729.

10

Utilizing Motor to Perform Work

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

11

Surface-bound Motors

Azimuthal orientation Altitudinal orientation

G.S. Kottas, L.I. Clarke, D. Horinek, J. Michl , Chemical Reviews 2005, 105, 1281-1376

Need two-legged attachment to prevent

rotation around single bond.

12

Unidirectional rotation on Au nanoparticles

-38

-37.8

-37.6

-37.4

-37.2

-37

-36.8

-36.6

-36.4

0.0028 0.00285 0.0029 0.00295 0.003 0.00305 0.0031

1/T (K-1)

ln (

(k h

) /

(k B

T))

nanoparticles

parent motor

t1/2 = 198 h

t1/2 = 93 h

0 2 4 6 8 -20

-10

0

10

20

30

CD

(md

eg

)

hn>280 nm hn365 nm hn365 nm hn365 nm D D D D

CD signal at 280 nm

through 2 rotary cycles

13

Monolayer of Motors on Au Film

Au

Au

14

quartz

Thin gold surfaces

Au Vapour deposition

200 400 600 800 10000.0

0.2

0.4

0.6

ab

so

rba

nce

(a

.u.)

wavelength (nm)

5 nm gold

5 nm gold

quartz

quartz

OH OH OH OH OH OHO O

Si

NH2

O OSi

NH2

O OSi

NH2

O OSi

NH2

O OSi

NH2

O OSi

NH2

1) H2SO4 / H2O2

2)

O OSi

NH2

Transparent Gold Surface

15

Self-assembled monolayer of molecular motors

Dense SAM

Dilute SAM

No change upon irradiation

quartz quartz

5 nm gold 5 nm gold

10:1

Decanethiol:motor

SO

O

O

O

SS

S

OOO

O

SS

S

OO

OO

S S

S

O

O

OO

SS

SO

O

O

O

SS

S

O

O

OO

SS

S

OO

OO

SS

S

O OO

O

SS

Au Nanoparticles

16

Increasing the length of the legs

• Motors function with longer tethers to gold

surface, but suffer from some quenching by

the gold.

• Results in longer irradiation times

9 9 9 9

9 9 9 9

17

Grafting Motor to Quartz

M. M. Pollard, M. Lubonska, P. Rudolf, B.L. Feringa, Angewandte Chemie Int. Ed. 2007, 46, 1278-1280

18

Molecular motors function on quartz

on surface

in solution

in solution

on surface

D

19

Altitudinal Motor on Surface

XX

• Store for extended periods without degradation or polymerization

• Motor should be stable for complete characterization prior to surface modification

• Reliable and reproducible surface modification

• Monolayer

New Strategy for Functionalization of Quartz, SiO2/Si and mica

• Difficulty introducing acid chloride into legs of some motors

• Acid chloride moisture sensitive and therefore characterization prior to surface

modification is limited

• amino silane surfaces not easy to control

Limitations of Previous Method

20

Interfacial 1,3 Dipolar Cycloaddition

H R2

Cu-cat. N NNR1

R2H

NR1 N N

T. Lummerstorfer, H. Hoffmann

Journal of Physical Chemistry B 2004, 108, 3963-3966

R R'

Hartmuth C. Kolb, M. G. Finn, and K. Barry Sharpless

Angewandte Chemie International Edition 2001, 40, 2004-2021

Mixed monolayers on Au Monolayers on SiO2/Si wafer

Magnetic Nanoparticles

J. P. Collman, N. K. Devaraj,

C. E. D. Chidsey Langmuir 2004, 20, 1051-1053

M. A. White, J. A. Johnson, J. T. Koberstein, N. J. Turro

Journal of the American Chemical Society 2006, 128, 11356-11357

21

Solution-phase

365 nm

OR

OR

OR

OR

DO

O

O

O

stable unstable stable

t1/2 = 1.5 min (20oC)

D‡G° = 83.5 kJ/mol

R = (CH2)2OCH2CCH

300 400 500

0,0

0,1

0,2

0,3

0,4

0,5

Ab

so

rba

nc

e (

a.u

.)

Wavelenght (nm)

Stable, MeOH, -20C

60 min irrad, 365nm

300 400 500

-50

0

50

100

D

Wavelenght (nm)

Stable, MeOH, -20C

90 min irrad, 365 nm

UV-Vis Absorbance

CD

3:1 ratio at

photostationary state

G. London, G. T. Carroll, T. Fernández Landaluce, M. M. Pollard,

P. Rudolf and B. L. Feringa, Chemical Communications, 2009, 1712

22

Azide-SAM Formation

SiO O Si O Si O

N3 N3 N3SiO O Si O Si O

OH OH OH

SiO

OO

11CH2

Br

SiO

OO

11CH2

N3

NaN3

Cyclohexane/THF

H2O/H+

H2O Contact Angle: 73±3

Ellipsometric Thickness: 0.7 ±0.1 nm

Method 2 (Self-assembly in toluene) Method 1 (Hydrolysis in THF,

Self-assembly in cyclohexane)

H2O Contact Angle: 82±1

Ellipsometric Thickness: 1.8 ±0.1 nm

CH2

ATR IR

cm-1

1.5

1.0

0.5

x1

0-3

3000 2900 2800 2700 2600

1.5

1.0

0.5

x1

0-3

2200 2150 2100 2050 2000

Ab

s

390392394396398400402404406408410 In

ten

sit

y (

Arb

. U

nit

s)

Binding Energy (eV)

N1s

X-ray Photo-electron Spectroscopy (XPS)

Azide 2095 cm-1

No photochemical degradation after 24 hrs irradiation

90%

23

Motor-monolayer formation

800

600

400

200

x1

0-6

2120 2100 2080 2060

Azide, 2095 cm-1 FT-IR

H2O Contact Angle decreases: 67±2º

Ellipsometric thickness increases: 2.9 ±0.1 nm

390392394396398400402404406408410

Motor monolayer

Azide monolayerXPS

In

ten

sit

y (

Arb

. U

nit

s)

Binding Energy (eV)

XPS

Azide

Triazole

No Cu or Na found in XPS survey

nm

8

6

4

2

0

x10

-3

460440420400380360340320300

Unmodified Quartz

Without Copper

Ab

so

rba

nce

Motor

SiO O Si O Si O

OO

OO

N3 N3 N3

SiO O Si O

O

O

O

O

N

N

N

N

NN

CuSO4*5H2O (2 %)Na-ascorbate (10%)

DMF, rt, 12h

2% Cu(SO4)

10% NaAsc DMF

24

Rotary Motion on Surface

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

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

28⁰C

40⁰C

Thermal step affected by confinement in monolayer

Two processes occurring?

T1/2 1st step: 3 minutes

T1/2 2nd step: 21 minutes

Decay at 439 nm

25

SEM

OO

O O

O

N

SiO

O

N

SiO

O

NN

NN

O

1111

H2O, H+

THF

OO

O O

N

Si

N

SiOH

NN

NN

1111

HO3

3

Silane-modified Motor

cyclohexane

Insoluble precipitate begins to form after

approximately 10 min.

Ellipsometric Thickness: 77±8 nm H2O Contact Angle: 79 ±3

Robust Faint Yellow Film

0.14

0.13

0.12

0.11

0.10

0.09

Ab

so

rba

nce

at

43

9 n

m

25x103

20151050

Time (s)

0.4

0.3

0.2

0.1

Ab

s

550500450400350

nm

60 min. 1 min. Pre-irradiation 28 h

Very slow thermal recovery

clearly demonstrates effect of

crowding on speed

26

250 300 350 400 450 500 550

0.0

0.2

0.4

0.6

0.8

1.0

Ab

so

rba

nc

e (

au

)

Wavelength (nm)

Stable, -20C, MeOH

PSS, 365nm

t1/2 (20oC)= 50 s (in MeOH)

The reverse reaction analogue

OHO

O

HOON3

O

N31. Mesyl-ClCHCl2, 2h, rt

2. NaN3 DMF

5h, 55oC.

63 %

SiO O Si O Si O

OO

NH NH NH

O

O

O

O

O

O

N3N3

SiO O Si O Si O

NH NH NH

O

O

O

O

O

O

NN

N

NN

N

OO

CuSO4*5H2O (2 %)Na-ascorbate (10%)

DMF, rt, 12h

8

6

4

2

0

x1

0-3

550500450400350

Ellipsometric Thickness: 0.8 ±0.1 nm H2O Contact Angle: 74 ± 10°

Ellipsometric Thickness: 1.9 ±0.1 nm H2O Contact Angle: 57 ±1°

Alkyne Surface

27

Two-legged Attachment

390392394396398400402404406408410

Motor monolayer

Azide monolayerXPS

In

ten

sit

y (

Arb

. U

nit

s)

Binding Energy (eV)

XPS

Azide

Triazole

S i O O S i O S i O

N H N H N H

O

O

O

O

O

O

N N

N

N N

N

O O

SiO O Si O Si O

NH NH NH

O

O

O

O

O

O

N3 NN

N

OO

410 405 400 395 390

Inte

ns

ity

(A

rb.

Un

its

)

Binding Energy (eV)

N1s

XPS after

reaction

1.4

1.2

1.0

0.8

0.6

0.4

0.2

x1

0-3

3000 2900 2800 2700 2600 2500 2400

1.4

1.2

1.0

0.8

0.6

0.4

0.2

x1

0-3

2300 2250 2200 2150 2100 2050 2000

ATR IR

No Azide

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

Visualization of Rotary Motion

Group Fluorescent

Group

29

Fast Motor on Surface

Choice of motor:

Me

Br

MeO2C CO2Me

Coupling to the arm

Coupling to the surface

› Fast Motor against Brownian storm

(t1/2 nanoseconds)

0.8

0.6

0.4

0.2

0.0

DA

800700600500400

Wavelength (nm)

Increment: 1 nsFrames: 98Accumulations: 50t0: 233203 nsT: 22.3 deg C

Prof. Fred Brouwer (Universiteit Van Amsterdam)

Rotation too fast to be measured using classical

techniques (CD, UV or NMR experiments)

O S i

O O S i

O O

N N

9 9

N N

N N

M e

O

O

O

O

Quartz

10

8

6

4

2

0

x10

-3

440420400380360340320300280

nm

Cu, Azide SAM Lower Coverage Cu, Unmodified Quartz Azide SAM, No Cu Cu, Azide SAM Higher Covarage

H2O Contact Angle: 65±2 Ellipsometric Thickness: 1.8 ±0.1 nm

30

Me

OPr

OPr

MeO2C CO2Me

N

O OEt2N

O

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

OPr

Target Molecule

Dr. Jerome Vachon

Considered to be relatively rigid structure

solubility

Converted to alkynes

31

Length of Arm

Dye for visualization with wide-field

fluorescence imaging

Two alkyne moieties for attachment of

the motor ‘stator’ to the surface

32

O

Si

OO

Si

OO

N3 N3

9 9

Quartz

Attachment to Surface

Cu2SO4 (1 mol%)Sodium Ascorbate (5 mol%)DMF

c ~ 10-8 M

O

O

O

O

O

O

N

OPr

OPr

OEt2N

8

NN

N NN

N

O

SiO

Si

OO O

10 10

33

O

O

O

O

O

O

N

OPr

OPr

OEt2N

8

NN

N NN

N

O

SiO

Si

OO O

10 10

Wide-field Microscopy

Filippo Lusitani University of Groningen

Fluorescence on Surface

34

A Cholesteric (Chiral) LC

Chiral Dopant:

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

ee.concHTP

1p

pitch (p)

35

Rotating Micro-scale Objects

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

Texture Rotation Rotation of Micro-rod

36

Motor-functionalized Polymers

O

N

N

O O

OO

C6H13H13C6

6H17C8C8H17H17C8

* *

x y z

X : Y : Z = 10 : 11 : 1

No changes upon irradiation

hn hn

37

Motor-terminated Polymer

Control over Helical

twist of single poly

(hexyl isocyanate)

macromolecule

D. Pijper et al, Angew. Chem. Int. Ed.,2007, 46, 3693.

Stiff helical conformations

Racemic P / M helicity (fast

dynamic equilibrium)

Subtle chiral influence can induce large preference for one helical sense:

38

Surface Adsorption

AFM SEM

Polymer on mica

Au

Mica

39

Acknowledgements

University of Groningen

Prof. Ben L. Feringa

Prof. Petra Rudolf

Dr. Michael Pollard Gabor London

Tatiana Fernandez-Landaluce

Dr. Jerome Vachon

Filippo Lusitani

Dr. Dirk Pijper Mahthild Jongejan

University of Amsterdam

Prof. Fred Brouwer

Nano Ned