study of artificial molecular engines action through comsol multiphysics program

7/28/2019 Study of Artificial Molecular Engines Action Through COMSOL Multiphysics Program

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Study of Artificial Molecular Engines ActionThrough COMSOL Multiphysics Program

Lorenzo Moro

Francesca LugFrancesco Zerbetto

Dipartimento di Chimica G.Ciamician,Universit di Bologna

ALMA MATER STUDIORUM UNIVERSITA DI BOLOGNA

Presented at the COMSOL Conference 2009 Milan


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artificial molecular motoscapable to do useful work

was first advanced byRichard P. Feynman



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In the last ears the have been succes ulldeveloped; they can be of a various type



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A two stations switchable rotaxane


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Station A Station AStation B Station B

CF3COOH

iPr2NEt



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e wan o quan y some mec an ca parame ers;The distribution probability evolution in time is

needed



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rown an o on an angev n qua ons2

d x dx t

2mdt dt

fluctuations, it is called whitenoise



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The Fokker-Planck Equation

equation of motion for the distribution probability.This leads to the 1-D Fokker-Planck e uation:

2( , )W x tU x D W x t

t x x

( , )W x t 1


,FP

tB


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- .Methods of solution

a onary so u ons eas y o a na eNonstationary solutions obtainable only in a few cases

( , )( , )

FP

W x tL W x t

t

n n nL

2

2( )L D V x

2 2

2

1 ( ) 1 ( )( ) /

dU x d U xV x D



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potential


Ref. Phis.A 277 (2000) 335-348


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The first target is to find the match between the

ana y ca so u on an e compu a ona one or egeneral Fokker-Planck equation



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2, 1W x t 2

,B

x x

t m x x



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Modeling the potential

Station A Station B

U=-14 kcal/mol1.38954002810-19J

Distance between the wells = 10



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The Diffusion Coefficient

1( )B

D k T m Molecular Weight of the ring:533 g/mol

This rotaxane has best performances in MeOH and DMFwhich have different viscositydifferent different D

DMeOH=3.6410-10m2/s @ 298KDDMF=2.42510-10m2/s @ 298K



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The Diffusion Coefficient

Before solving the system, a last consideration about D

eff=



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se o w rea mo ecu es

MeOH



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MeOh vs DMF @ 0.3ns



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Making the ring where I want

Station BStation A



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Making the ring where I want



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Calculation of Realistic Diffusion coefficients from Molecular

Dynamics simulations.

Determination of the Useful system properties (Force and

Entropy) from the solutions of the Fokker-Planck Equation



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study of artificial molecular engines action through comsol multiphysics program

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