How Molecular Motors Work: Insights from the Molecular Machinst’s Toolbox
Dean Astumian, Dept. Physics, UMaine
Richard Feynman and Bill McClellan –A motor 1/64th of an inch on a side
http://www.pbs.org/newshour/rundown/three-share-nobel-prize-chemistry-building-worlds-tiniest-machines/
Nano-Car
Structure of the four wheeled molecule
Rotaxanes and Catenanes – Mechanically Interlocked Molecules (MIMs)
What is the “BIG” question?
how did complex matter arise and self-organize to form life?
Chemistry – Making, Measuring, and Modelling
Berthelot: La Chimie cree son objet (Chemistry creates it object)
Borromean Rings
PDB projections on the Dome
Catenane and GFP (Jellyfish Protein)
~ 2000 times / sec
@ RT in CD3COCD3
J. Am. Chem. Soc. 1991, 113, 5131
1991 A MOLECULAR SHUTTLE
1991
Motion
https://www.youtube.com/watch?v=-7AQVbrmzFw
https://www.youtube.com/watch?v=wJyUtbn0O5Y 1:15-1:30
https://www.youtube.com/watch?v=YAva4g3Pk6k
Daisy Chain Arrangement
Pallindromic Arrangement
KF =[ox]
[red] reduce
A B
oxidize
A B
K = [A−−B]
KB =[ox]
[red]
K′ = [A][B]
Keq
A--B A + B
+ e-
e- V2+ V●+
●
DNP
●
●
+ 2e-
2e- CBPQT4+ CBPQT2(●+)
K KBK′ KF
= Keq
A [B
A−−B ss
= KeqKFKB
i
j ss
= e−Δ𝐺ij eW𝒮n ij
Extension of equilibrium relations to non-equilibrium steady state
Coulombic
Barrier
Radical
Recognition
Site
Potentially
Steric
Barrier
Ring
Collecting
Chain
Initial Free Ring State Final Ring Resting State
Reduced State
Oxidized State
RED OX
Nature Nanotechnology 2015, 10, 547
MOLECULAR PUMP DESIGN BLUEPRINT
Bisradical Dication
Potentially
PUMPING ONE FOLLOWED BY TWO RINGS
Nature Nanotechnology 2015, 10, 547
0 1 2 3
ΔG≠2 = 23.1 kcal mol-1
Second Redox Cycle
Time / h
2nd 85%
77%
0 1 2 3
0.0
0.2
0.4
0.6
0.8
1.0
ΔG≠1 = 23.0 kcal mol-1
First Redox Cycle
1st 90%
RED
Zn
OX
NOPF6
AWAY
FROM
EQUILIBRIUM
PUMPING RINGS ON TO POLYMERS WITH DUAL PUMPS
K K K
K K
K K
Aox + Ared
Dox + [Dred ss
≈ 𝐾DI,red𝐾IA,ox = e−∆𝐺oute∆𝐺−∆𝐺∗
k k k k k k k k k k k k
k k
k k
k k
k k
Aox + Ared
Dox + [Dred ss
= e−∆𝐺out1 + sDe∆μ 1 + sI
1 + sD 1 + sIe∆μ
= e−∆𝐺outq + e∆μ + L
1 + qe∆μ + L
q =𝑘I2ox 𝑘𝐷1
ox
𝑘I1ox 𝑘𝐷2
ox
FLASHING ENERGY RATCHET
+
+
+
+
ΔE
J. Am. Chem. Soc. 2013, 135, 18609
Reduction
Directionally Controlled
Dethreading
Oxidation Relaxation
Directionally Controlled
Threading
J. Am. Chem. Soc. 2013, 135, 18609.
Bacteriorhodopsin
TAKING INSPIRATION FROM NATURE
Steric
Barrier
IPP
Recognition
Site
DNP
Coulombic
Barrier
PY+
Molecular Pump Prototype
Reduction
Oxidation
CHEMISTRY AWAY-FROM-EQUILIBRIUM
Artificial Molecular Pump
Nature Nanotechnology
2015, 10, 547
WHAT ARE SOME OF
THE BIG QUESTIONS?
What are the
consequences
of
dissipation
on
materials
properties?
How do we
design systems
that operate
repetitively
and
progressively
away-from-equilibrium?
Slide-Ring Gels
Kohzo Ito and Kazuaki Kato