Post on 25-Jul-2020
ICMR-JNCASR Winter School Bangalore - December 2006
Dr Martin Grossel
Supramolecular Approaches to Artificial Molecular Machines
School of ChemistryUniversity of SouthamptonUK
Functional Supramolecular Materials?
Applications of SupramolecularChemistry to Materials Science
Functional Supramolecular Materials?
Structure of Talk
• Introduction – What is a molecular-scale machine
• Simple Supramolecular devices – Catenanes and Rotaxanes
• π-Complex-based catenane and rotaxane assemblies
• Metal ion-templated catenane and rotaxane assemblies
• Hydrogen bond-templated catenane and rotaxane assemblies
<http://www.nanorex.com/>
Functional Supramolecular Materials?
Supramolecular Chemistry is the Chemistry of molecular assemblies.
In one of his key early reviews exploring the concepts of SupramolecularChemistry Jean-Marie Lehn noted that one of its main goals was the creation of fumctional molecular assemblies capable of:
• Recognition
• Transport
• Modification of substrates
J.-M.Lehn, “Supramolecular Chemistry. Concepts and Perspectives”, VCH (1995), ISBN 3-527-29312-4.
Functional Supramolecular Materials?
Supramolecular assemblies can be:
• Dynamic (internal motions etc)• Switchable (mechanically, optically, etc.)• Can change size and shape• Can be chiral
Each of these properties has potential applications in Materials Science
Functional Supramolecular Materials?
Supramolecular assemblies can be:
• Dynamic (internal motions etc)• Switchable (mechanically, optically, etc.)• Can change size and shape• Can be chiral
Each of these properties has potential applications in Materials Science
In this lecture I will focus mainly on the potential uses ofCatenanes and rotaxanes.
What constitutes a machine?
A Macroscopic Machine:
“An apparatus for applying mechanical power; having several partseach with a definite function.”
From: Oxford English Dictionary
What constitutes a machine?
A Macroscopic Machine:
“An apparatus for applying mechanical power; having several partseach with a definite function.”
From: Oxford English Dictionary
A machine is characterised by:
• the type(s) of energy required to make it work (heat, light, electrons)
What constitutes a machine?
A Macroscopic Machine:
“An apparatus for applying mechanical power; having several partseach with a definite function.”
From: Oxford English Dictionary
A machine is characterised by:
• the type(s) of energy required to make it work (heat, light, electrons)
• the type(s) of movements performed by its components (need large amplitude changes)
What constitutes a machine?
A Macroscopic Machine:
“An apparatus for applying mechanical power; having several partseach with a definite function.”
From: Oxford English Dictionary
A machine is characterised by:
• the type(s) of energy required to make it work (heat, light, electrons)
• the type(s) of movements performed by its components (need large amplitude changes)
• the manner by which its operation can be monitored and controlled (electrochemistry,
Uv-visible spectroscopy, etc.)
What constitutes a machine?
A Macroscopic Machine:
“An apparatus for applying mechanical power; having several partseach with a definite function.”
From: Oxford English Dictionary
A machine is characterised by:
• the type(s) of energy required to make it work (heat, light, electrons)
• the type(s) of movements performed by its components (need large amplitude changes)
• the manner by which its operation can be monitored and controlled (electrochemistry,
Uv-visible spectroscopy, etc.)
• the possibility to repeat the operation at will and to establish a cyclic process (lifetime,
stability)
What constitutes a machine?
A Macroscopic Machine:
“An apparatus for applying mechanical power; having several partseach with a definite function.”
From: Oxford English Dictionary
A machine is characterised by:
• the type(s) of energy required to make it work (heat, light, electrons)
• the type(s) of movements performed by its components (need large amplitude changes)
• the manner by which its operation can be monitored and controlled (electrochemistry,
Uv-visible spectroscopy, etc.)
• the possibility to repeat the operation at will and to establish a cyclic process (lifetime,
stability)
• the timescale needed to complete a cycle of operation (nuclear motions to secs)
What constitutes a machine?
A Macroscopic Machine:
“An apparatus for applying mechanical power; having several partseach with a definite function.”
From: Oxford English Dictionary
A machine is characterised by:
• the type(s) of energy required to make it work (heat, light, electrons)
• the type(s) of movements performed by its components (need large amplitude changes)
• the manner by which its operation can be monitored and controlled (electrochemistry,
Uv-visible spectroscopy, etc.)
• the possibility to repeat the operation at will and to establish a cyclic process (lifetime,
stability)
• the timescale needed to complete a cycle of operation (nuclear motions to secs)
• the function(s) performed by the machine (problem of controlling direction of motion)
Why make molecular-scale machines?
Richard Feynman (1959)
“What would be the utility of such machines? Who knows? I cannot see exactly what would happen, but I can hardly doubt that when we have some control of the arrangements of things on a molecular scale we will get an enormously greater range of possible properties that substances can have, and of different things that we can do.”
From: “There is plenty of room at the bottom”, Eng. Sci., 1960, 23, 22-36; Saturday Rev., 1960, 43, 45-47.
What constitutes a molecular-scale machine?
Definition of a molecular scale machine
“A discrete assembly of molecular components designed to perform mechanical movements (output) as a consequence of appropriate external stimulae (input).”
See: V. Balzani, A. Credi, F. M.Raymo, and J. F. Stoddart, Angew Chem. Int. Ed., 2000, 39, 3348-3391.
What constitutes a molecular-scale machine?
Design Options:
Photons and electrons are the best energy inputs:
• good for both reading and writing
• no problems with chemical by-products
• use optical spectroscopy or electrochemistry
What constitutes a molecular-scale machine?
Design Options:
Photons and electrons are the best energy inputs:
• good for both reading and writing
• no problems with chemical by-products
• use optical spectroscopy or electrochemistry
What constitutes a molecular-scale machine?
Design Options:
Photons and electrons are the best energy inputs:
• good for both reading and writing
• no problems with chemical by-products
• use optical spectroscopy or electrochemistry
Photons – need a chromophore
Electrons – need a change of redox/charge state (use electrochemistry)
These avoid the problem of chemical by-products and need for continual
supply of reagents.
Supramolecular assemblies are more likely to undergo larger amplitude
changes in shape etc. than intramolecular changes (conformational etc.)
Functional Supramolecular Systems
Functional Supramolecular Systems
Molecular Logic Gates – an AND gate
See: A. P. de Silva, H.Q.N. Gunaratne, and C P. McCoy, J. Amer. Chem. Soc., 1997, 119, 7891-7891.
NR2
O
O O
O
O
Protonation site
R = Et, O
binding siteNa+
Functional Supramolecular Systems
Molecular Logic Gates – an AND gate
See: A. P. de Silva, H.Q.N. Gunaratne, and C P. McCoy, J. Amer. Chem. Soc., 1997, 119, 7891-7891.
Design features:
• Anthracene fluorophore attached to
two PET-active groups (one binds Na+;
other H+).
• If neither or only ONE complexed,
fluorescence is quenched
• If BOTH are complexed, no PET
occurs and fluorescence is observed
NR2
O
O O
O
O
Protonation site
R = Et, O
binding siteNa+
PET = photo-induced electron transfer
Catenanes and Rotaxanes
For an introduction see for example: M. C. T. Fyfe, and J. F. Stoddart, Acc. Chem. Res., 1997, 30, 393-41.
Catenanes and Rotaxanes
Catenanes
A [2]-Catenane
Catenanes and Rotaxanes
Rotaxanes
Ring
Stopper
ThreadMovieA two-station [2]-Rotaxane
Catenanes and Rotaxanes
Pseudorotaxanes
A Pseudorotaxanane
Catenanes and Rotaxanes
Synthetic strategies
(i) Catenanes (ii) Rotaxanes
Stoddart’s Machines
J. F. Stoddart(UCLA)
Catenanes and Rotaxanes
Stoddart’s Machines
Catenanes and Rotaxanes
Stoddart’s Machines – the molecular abacus
Catenanes and Rotaxanes
Stoddart’s Machines – Muscle mimics
Catenanes and Rotaxanes
For many years catenanes (and rotaxanes) were a synthetic curiosity.
Stoddart developed efficient routes to such structures using non-covalent interactions, e.g.:
• π−π association• C-H•••π contacts• C-H•••O interactions
Stoddart’s Machines – synthetic routes
Molecular ComplexationBy Crown Ethers
See: J. F. Stoddart, Pure Appl. Chem., 1988, 60, 467-472.
Paraquat2+ complexes with Dibenzo-34-crown-10
Paraquat complex
See: J. F. Stoddart, Pure Appl. Chem., 1988, 60, 467-472.
Intermolecular Contacts in Paraquat2+ - Crown Complexes
ΔG(complexation) = 16.3 kJ mol-1
Stoddart’s Catenane Synthesis
First attempted Box Synthesis
12%
2PF6̄
NH PF4 6
H O2
Δ
then
OMe
OMe
MeCN+
++
+
4PF6̄
4PF6̄
OMe
+
++
+
OMe
Br Br
N
N
N
N+ +
Reversing the roles of the electron-rich and electron-deficient units
First attempted Box Synthesis
12%
2PF6̄
NH PF4 6
H O2
Δ
then
OMe
OMe
MeCN+
++
+
4PF6̄
4PF6̄
OMe
+
++
+
OMe
Br Br
N
N
N
N+ +
Reversing the roles of the electron-rich and electron-deficient units
First attempted Catenane Synthesis
O
O
O
OO
O
O O
O
O
70%
O
O
O
OO
O
O O
O
O
2PF6̄
Ambient TemperatureMeCN 3PF6̄
threading≡
NH PF4 6
H O2
O
O
O
OO
O
O O
O
O
+
++3PF6̄
..
Br
4PF6̄
O
O
O
OO
O
O O
O
O
+
+
+
+
Br Br
+ +
N
N
N
N
+
+
..
+
Br
First attempted Catenane Synthesis
O
O
O
OO
O
O O
O
O
70%
O
O
O
OO
O
O O
O
O
2PF6̄
Ambient TemperatureMeCN 3PF6̄
threading≡
NH PF4 6
H O2
O
O
O
OO
O
O O
O
O
+
++3PF6̄
..
Br
4PF6̄
O
O
O
OO
O
O O
O
O
+
+
+
+
Br Br
+ +
N
N
N
N
+
+
..
+
Br
Dynamic Processes in 2-Catenanes
4PF6̄
+
+
+
+
O
O
O
OO
O
O O
O
O
4PF6̄
+
+
+
+
O
O
O
OO
O
O O
O
O
4PF6̄
+
+
+
+
O
O
O
OO
O
O O
O
O
4PF6̄
+
+
+
+
O
O
O
OO
O
O O
O
O
Routes to [3]-Catenanes
BrBr
N N
N N: :
++
O O O O O
OOOOO
O O O O O
OOOOO
O O O O O
N N
N N
++
++
OOOOO OOOOO
O O O O O
Expanding the Paraquat4+ Box leads to [3]-Catenanes
Crowns rotate through box at ca 8000 Hz at 298K (increased rate perhaps a reflection of hydroquinone ring repulsion)
oreither
The Molecular Train Set
O
O
O
O
O
O
OOO
O
O OO
O
O
O
O
O
O O
4+
O
O
O
O
O
O
OOO
O
O OO
O
O
O
O
O
O O
4+
O
O
O
O
O
O
OOO
O
O O
O
O
O
O
O
O
O O
4+
O
O
O
O
O
O
OOO
O
O O
O
O
O
O
O
O
O O
4+Box rolls through crown at ca 28000 times/sec at 298K and hops around from station at 300 times/sec
4PF6̄
O
O
O
OO
+
+
+
+
O
O O
O
O
O
O
O
O
OO
O
O
O
O
The Molecular Train Set
Paraquat4+ boxes chase each other around the ring, hopping at ca. 500 times/sec and always keeping one station apart.
O
O
O
O
O
O
OOO
O
O O
O
O
O
O
O
O
O O
4+4+
O
O
O
O
O
O
OOO
O
O O
O
O
O
O
O
O
O O
4+
4+
O
O
O
O
O
O
O
OO
O
O O
O
O
O
O
O
O
O O
4+
4+
O
O
O
O
O
O
OOO
O
O O
O
O
O
O
O
O
O O
4+ 4+
4PF6̄
O
O
O
OO
+
+
+
+
O
O
O
O
OO
O
O
O
O
O
O
O
OO
+
+
+
4PF6̄
Catenane-based Machines
Colour-Switching Catenanes
See: J. F. Stoddart et al, Angew. Chem. Int. Edn., 1998,37,333; C. P. Collier et al, Science, 2000, 289, 1172.
A Redox-switchable Catenane
Colour-Switching Catenanes
See: C. P. Collier et al, Science, 2000, 289, 1172=1175.
A Redox-switchable Catenane
TTF/PQT4+ complex is green1,5-Dialkoxynaphthalene/PQT4+ complex is red
Colour-Switching Catenanes
Tuning PQT4+ complex colours
λmax (nm)
4+
333 473 677601494 854
red greenblue
S
S
S
S
R
R
OMe
OMe
OMe
OMe
NHMe
MeNH
NHMe
MeNH
F
F
NHMe
MeNH
F F
FF
weakest complex strongest complex
See: W.-Q. Deng, A. H. Flood, J. F. Stoddart, and W. A. Goddard III, J. Amer. Chem. Soc., 2005, 127, 15994-15995.
Colour-Switching Catenanes
See: W.-Q. Deng, A. H. Flood, J. F. Stoddart, and W. A. Goddard III, J. Amer. Chem. Soc., 2005, 127, 15994-15995.
Approaches to display devices – an RGB dye
Rotaxanes
Rotaxanes and PseudorotaxanesFirst Rotaxane Synthesis
14%
O
O
O
O
+
+
+
+4PF6̄
O
O
O
O
+
BrBr
+N
N N
N
++
O
O
(iPr) SiO3
O
O
OOSi(iPr)3
O
Rotaxanes and PseudorotaxanesPseudorotaxane Synthesis - a simple PQT4+ box preparation
+
O
O
HO
O
OOH
BrBr
+
4PF¯
N+
N+
N+
N+
6
O
O
OH
+
+
+
+4PF6̄
HO
O
O
NH PF¯/H O4 6 2+ 2,6-lutidine
i-PrSiOTfMeCN
Distribute betweenDCM and water
DCM
Water
O
O
O
+
+
+
+O
O
O
4PF6̄
N
N N
N
++
Self-Assembling (Pseudo)rotaxanes
N
N
+
+
N
N
+
+
4PF6̄
O
O OO
O
+
+
+
+OO O
O
O OO
O
OO
O
O
O
O O O
O
O
O
Muscle Mimics
Rotaxane-based Machines - Muscles
See: Yi Liu et al: J. Amer. Chem. Soc, 2005, 127, 9745-9759.
A Redox-switchable Rotaxane
Rotaxane-based Machines - Muscles
A Redox-switchable “Palindromic” Rotaxane
TPR8+
Rotaxane-based Machines - Muscles
Change in dimensions between TPR8+
and its oxidised form TPR12+
Rotaxane-based Machines - Muscles
Random coating on Au-coated felixible microcantileverbeams 500 x 500 x 1 μm with a monolayer of ca 6 billion rotaxane units
Rotaxane-based Machines - Muscles
Cycling of TPR8+ using sequential chemical oxidation (FeIII) and reduction (ascorbic acid)
Random coating on Au-coated felixible microcantileverbeams 500 x 500 x 1 μm with a monolayer of ca 6 billion rotaxane units
Rotaxane-based Machines - Muscles
Cycling of reference compound (no PQT4+ ring and tethered through stoppers)
Cycling of TPR8+ using sequential chemical oxidation (FeIII) and reduction (ascorbic acid)
Can be cycled more than 25 times
Random coating on Au-coated felixible microcantileverbeams 500 x 500 x 1 μm with a monolayer of ca 6 billion rotaxane units
Using Metal-ion Templates
J.-P. Sauvage(Strasbourg)
Catenanes and RotaxanesSauvage’s strategy
N
N
≡
-
See: D. J. Cardenas, A. Livoreil, and J. – P. Sauvage, J. Amer. Chem. Soc.., 1996, 118, 11980-11981.
Catenanes and RotaxanesSauvage’s catenane synthesis
N
N
OH
OH
Cs2CO3
DMF
N
N
O
O
O
O
O
O
N
N
N
N
O
O
O
O
O
O
HO
HO
Cu+Cu+
A
A
X = Br, I
O
O
O
O
X
X
N
N
O
O
-
-
CuI binds tetrahedrallywith two BiPyunits.
Catenanes and RotaxanesSauvage’s catenane synthesis
O
O
O
O
O
O
N
N
O
O
O
O
N
N
O
O
KCN
(demetallation)
O
O
O
O
N
N
N
N
O
O
O
O
O
O
O
O
Cu+
O
O
O
O
X
X
Cs2CO3
DMF
N
N
N
N
O
O
O
O
O
O
HO
HO
Cu++
Catenanes and RotaxanesSauvage’s catenane synthesis
O
O
O
O
O
O
N
N
O
O
O
O
N
N
O
O
O
O
O
O
N
N
N
N
O
O
O
O
O
O
O
O
Cu+
Rotary Motors
A Catenane-based Motor
See: A. Livoreil, C. O. Dietrich-Buchecker, and J. –P. Sauvage, J. Amer. Chem. Soc., 1994, 116, 9399; see also D. J. Cardenas, A. Livoreil, and J. – P. Sauvage, J. Amer. Chem. Soc.., 1996, 118, 11980-11981 for a three-state system.
Metal complex-based Rotaxanes
For a review see: M.-J. Blanco, M. C. Jiminez, J.-C. Chambron, V. Heitz, M. Linke, and J. – P. Sauvage, Chem. Soc., Rev., 1999, 28, 293-305.
Metal-complex-based Rotaxanes
Redox-controlled Molecular Shuttles
See: J. –P. Collin, P. Gavana, and J. –P. Sauvage, New J. Chem., 1997, 21, 525.
Multiply-entwined Catenanes- Knotanes (Knots)
J.-P. Sauvage
Sauvage’s catenane synthesis
Multiply-interlocked catenanes are chiral
Multiply-entwined Catenanes
See: J. J. Nierengarten, C. O. Dietrich-Buchecker, and J. – P. Sauvage, J. Amer. Chem. Soc.., 1994, 116, 375-376.
R = (CH2)6N N
N N
N NR R
O
O O O O
O
OO
RR
N N
N N
HO
RR N N
OH
N N
N N
N N
O
O O O O
O
OO
= Cu+
R = (CH2)6
OHHO
N N
N N
N NR R
Multiply-entwined CatenanesSauvage’s Knots (Knotanes)
R RR R
N N
N N
N N
N N
O
N N
N N
OO O O
O O
O
O
O O O O
O
OO
OO O O
OX XO
RR
N N
N N
HO
RR N N
OH
N N
N N
N N
O
O O O O
O
OO
+
KCN=demetallation
Cs CO / DMF2 3
Yields: 2% doubly wound catenane (= knotane)1% singly wound catenane+ lots of Macrocycle
Multiply-entwined CatenanesSauvage’s Knots (Knotanes)
R RR R
N N
N N
N N
N N
O
N N
N N
OO O O
O O
O
O
O O O O
O
OO
OO O O
OX XO
RR
N N
N N
HO
RR N N
OH
N N
N N
N N
O
O O O O
O
OO
+
KCN=demetallation
Cs CO / DMF2 3
Multiply-entwined CatenanesSauvage’s Knots (Knotanes)
(Cu Complex)
Borromean Rings
J. F. Stoddart
Borromean Knots
What are Borromean Rings?
Multiply-entwined CatenanesStoddart’s Borromean Rings
See: K. S. Chichak et al., Science , 2004, 304, 1308 -1312.
The analysis:
Multiply-entwined CatenanesStoddart’s Borromean Rings
See: A. J. Peters et al., Chem. Commun. , 2005,3394-3396.
The strategy:
O ON
N
N
N
N
N
O O
XX
N N
N N
exo-receptor
endo-receptor
Multiply-entwined CatenanesStoddart’s Borromean Rings
See: A. J. Peters et al., Chem. Commun. , 2005,3394-3396.
Zn2+
N N
NH2H2N
O O
N
The chemistry:
Conditions: Zn(OAc)2 / iPrOH / 70°C / 24 hCondensation gives the Borromean ring in > 95% yield
Multiply-entwined CatenanesStoddart’s Borromean Rings
See: A. J. Peters et al., Chem. Commun. , 2005,3394-3396.For chiral Borromeates see: C. D. Pentecost et al, Angew. Chem. Int. Edn., 2006, 45, 4099-4104.
Multiply-entwined CatenanesStoddart’s Borromean Rings
See: K. S. Chichak et al., Science , 2004, 304, 1308 -1312.
**
Hydrogen-bonded Catenane Assembly
For an introductory overview see: R. Jäger and F Vögtle, Angew. Chem. Int. Edn., 1997, 36, 930-944.
H-Bonded Catenane Synthesis
C. J. Hunter(Sheffield)
Hunter’s Benzoquinone Receptor
O
ON
H
N
H
O
ON
H
N
H
O O
HH
H H
C-H--- ContactπSee: C. J. Hunter, Chem. Soc. Rev., 1994, 101.
Hunter’s First Catenane SynthesisH N 2NH2
O
O
NH
NHNH
NH
2
2
CH Cl2 2
Et N3
A B
AX
X
X
B
A
A
B
A
A+ +
+
O O
Cl Cl
X
O O
Cl Cl
A
B
B, X = CHC, X = N
DimerTetramer Catenane
See: C. J. Hunter, Chem. Soc. Rev., 1994, 101.
Rel. yields: (high dilution)10% : 51% : 34%
Hunter’s First Catenane Synthesis
From Catenanes to Knotanes
F. Vögtle(Bonn)
Vögtle’s Knotane Synthesis
H N 2NH2
O
O
NH
NHN
H
NH
2
2
OCl
OCl
O
N
O
NH
NHNH
N
H2
2
OCl
O
Cl
NO
Cl
O
Cl
O
Cl
O
Cl
N
Cyclic monomerCyclic dimerCyclic oligomers
Knotane
(ca 50%)(ca 20%)(ca 2%)
Knotane(ca 20%)
See: O. Lukin and F. Vögtle et al, Angew. Chem. Int. Edn., 2005, 44, 1456-1477.
(trimerises)
Knotanes
Vögtle’s Knots - 1
See: F. Vögtle <http://www.chemie,uni-bonn.de/oc/ak_vo/ >
Knotanes
Vögtle’s Knots - 2
Vögtle’s Knotanes
See: O. Lukin and F. Vögtle et al, Angew. Chem. Int. Edn., 2005, 44, 1456-1477.
Ammonium salt-based Rotaxanes
J. F. Stoddart
Ammonium Complexes with Crown Ethers
+ +
+ +H
H HN
NH
+
+
HN
H
+
+
+
O
O
O
O
O
O
O
ODB24C8
Dibenzo-24-crown-8
Pseudorotaxane formation
Ammonium Complexes with Crown Ethers
Pseudorotaxane formation
Ammonium Complexes with Crown Ethers
Pseudorotaxane formation
+NH2
O
O O O
O
O O
OOO
+NH2
Front Side
Ammonium Complexes with Crown Ethers
Pseudorotaxane formation
O
O
O
OO
O
O O
O
O
+
≡ ≡
NH2+
H2N+
NH2+
Ammonium Complexes with Crown Ethers
An Interwoven Supramolecular Cage
Rotaxane-based Machines
Plugs and Sockets
Plugs and Sockets
Turning on a light (Balzani)
See: E. Ishow et al, Chem. Eu. J., 1999, 5, 984-989.
O O
O O
O O
O
RN
H
Acid (R = Me)
Base
R N
H
H
+
O O
O O
O O
O
hν
h 'ν
+
energytransfer
Ammonium Complexes with Crown Ethers
Plugs and Sockets
N.B. Chloride ions can impede rotaxaneformation here of competitive hydrogen-bonding in the dialkylammonium hydrochloride. (see: M. Montalti and L. Prodi, Chem Comm., 1998, 1461)
Valves – 1
Rotaxane-based Machines - Valves
See: T. D. Nguyen et al, Proc. Natl. Acad. Sci., 2005, 102, 10029-10034; Org. Lett., 2006, 8, 3383-3366
Rotaxane-based Machines - Valves
See: T. D. Nguyen et al, Proc. Natl. Acad. Sci., 2005, 102, 10029-10034; Org. Lett., 2006, 8, 3383-3366
(EtO)3Si N C O
HO O
N
OBut F
N
H
O
O FO OBut
N
SiO
O
O
SiO
O
ON C O
+
+
TFA (deprotect amine)
N
H
O
O F
NH H
+
SiO
O
O
Rotaxane attached to surface of MCM-41
Rotaxane-based Machines - Valves
O ON
Me
Me
Me
Base
N
H
O
O F
N
HSi
OO
O +
O ON
Me
Me
Me
N
H
O
O
NH H
+
SiO
O
OF
N
H
O
O F
NH H
+
SiO
O
O
O ON
Me
Me
Me
(1) (2)O
O
Rotaxane-based Machines - Valves
O
O
O
O
O
ODB24C8=
See: T. D. Nguyen et al, Proc. Natl. Acad. Sci., 2005, 102, 10029-10034; Org. Lett., 2006, 8, 3383-3366
HMPT
DIPEA
TEA
Most basic/least crowded
Least basic/most crowdedMost efficient release of dye occurs with the most basic and least stericallyhindered base
Rotaxane-based Machines - Valves
Valves - 2
Rotaxane-based Machines – The Valve
See: T. D. Nguyen et al, Proc. Natl. Acad. Sci., 2005, 102, 10029-10034.
The Elevator
Rotaxane-based Machines – The Elevator
O
O
O
O
+
+
H
NN
N
O
O
O
O
+ Acid + Base
O
O
O
OH H
N
N
N+
+
+
O
O
O
O
See: J. D. Badjic et al: Science, 2004, 303, 1845.
Rotaxane-based Machines – The Elevator
Rotaxane-based Machines – The Elevator
Vertical distance moved by platform is ca 0.7nm (generating a force of ca 200 pN – ca. 1 order of magnitude larger than that generated in natural linear motors like myosin or kinesin)
Catenanes and Rotaxanes made easy!
D. A. Leigh(Edinburgh)
Leigh’s Molecular-scale Machinery
Hydrogen-bonded Catenanes and Rotaxanes
Leigh’s First Catenane Synthesis
OCl
OCl H N
NH2
2
CHCl , NEt , CO3 3 2
ON
HN
H
O
ON
H
ON
H
OCO
N
H
N
H
O
OO
OO
NH HNO
HN
O
NHO
NH
NH
A.G.Johnston, D.A.Leigh, R.J.Prichard, and M.D.Deegan, Angew. Chem. Int Ed., 1995, 34, 1209-1212A.G.Johnston, D.A.Leigh, L.Nezhat, J.P.Smart, and M.D.Deegan, Angew. Chem. Int. Ed., 1995, 34, 1212-1216
Leigh’s Linear Motor
The Components
D. A. Leigh et al, Nature Materials, 2005, 4, 704
N+
N+
O O
OO
NH
NH
NH
NH
H
H
(CH2)8
F F
FF
O
N
H
N
H O
N
H
O
O
N
H
(CH2)8
F F
FF
O
N
H
N
H O OO N
H
N
H
The shuttle
The fumaramide thread
The maleamide thread
Leigh’s Linear Motor
The Rotaxane
D. A. Leigh et al, Nature Materials, 2005, 4, 704
O
Cl Cl
N
ONH2
NH2
(CH2)8
F F
FF
O
N
H
N
H O
N
H
O
O
N
H
Ph
Ph
O
O
R
N
H
N
O
HN
O
H
N
H
O
NH
O
NH
+
+
65%
Et N3
CHCl3
Leigh’s Linear Motor
Switching the Rotaxane
D. A. Leigh et al, Nature Materials, 2005, 4, 704
O
N
H
HN O
Ph
Ph
(CH2)8
Ph
Ph
F F
FF
O
N
H
N
H O
Ph
Ph
N
H
O
O
N
H
(CH2)8
Ph
Ph
F F
FF
O
N
H
N
H O
254 nm
5 min50%
CH Cl2 2
115°CCHCl CHCl2 224 h90%
Δhν
50:50 mixture at photoequilibrium
Leigh’s Linear Motor
Switching a Rotaxane-based coating
D. A. Leigh et al, Nature Materials, 2005, 4, 704
Au
OOH
SS
OOH
Leigh’s Linear Motor
Switching a Rotaxane-based coating
D. A. Leigh et al, Nature Materials, 2005, 4, 704
Au
OOH
SS
OOH
Leigh’s Linear Motor
Switching a Rotaxane-based coating
D. A. Leigh et al, Nature Materials, 2005, 4, 704
Au
OOH
SS
OOH
Leigh’s Linear Motor
Switching a Rotaxane-based coating
D. A. Leigh et al, Nature Materials, 2005, 4, 704
Leigh’s Linear Motor
Switching a Rotaxane-based coating
D. A. Leigh et al, Nature Materials, 2005, 4, 704
On a 12° slope a drop of diiodomethanecan move up about 1.38mm.
Nanovehicles
J. M. Tour(Rice)
Nanovehicles
Nanocars
see: J. M. Tour et al, Chem..Soc. Rev., 2006, 35, 1043-1055
Nanovehicles
Nanocars
see: J. M. Tour et al, Chem..Soc. Rev., 2006, 35, 1043-1055
Nanovehicles
Nanocars
see: J. M. Tour et al, Chem..Soc. Rev., 2006, 35, 1043-1055
Nanovehicles
Nanocars
see: J. M. Tour et al, Chem..Soc. Rev., 2006, 35, 1043-1055
Rotary Motors
A Biaryl-based rotary motor
Feringa et al.
Nanovehicles
Nanocars
see: J. M. Tour et al, Chem..Soc. Rev., 2006, 35, 1043-1055
Conclusions
• Organic chemists have now produced a wide variety of promising machine-like structures
• Lateral thinking and wide-ranging collaborations are now required to develop this area.
The End