Coherent Control of the Primary Event in Human Vision Samuel Flores and Victor S. Batista Yale...

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Coherent Control of the Primary Event in Human Vision

Samuel Flores and Victor S. Batista

Yale University, Department of Chemistry

Victor.Batista@yale.edu

(Submitted to J. Phys. Chem. B)

Primary Event in Vision

Ultrafast Photo-Isomerization Mechanism

Technological applications: associative memory devices R.R. Birge et.al. J. Phys. Chem. B 1999,103, 10746

Femto-second Spectroscopic Measurements

Isomerization coordinate, )cc( 1211

Quantum interference of molecular wavepackets associated with indistinguishable pathways to the same

target state

Quantum interference of indistinguishable pathways to the same target state

O. Nairz, M. Arndt and A. Zeilinger Am. J. Phys. 71, 319, 2003

| xi >

| xf >

Bichromatic coherent-control(Weak-field limit)

Ground vibrational state

First Excited Vibrational State

Bichromatic coherent-control

Pulse Relative Intensities

Chirped Pump Pulses (Wigner transformation forms)

Bichirped Coherent Control

Positively Chirped Pulse (PC)

Negatively Chirped Pulse (NC)

Excited State S1

Ground State S0

cis trans

Exact Quantum Dynamics Simulations (t=218 fs, CR=212 fs2)

)fs35FWHM(nm500

Excited State S1

Ground State S0

cis trans

Exact Quantum Dynamics Simulations (t=218 fs, CR=-146 fs2)

)fs35FWHM(nm500

Energy

Reaction coordinate

Impulsive Stimulated Raman Scattering

Conclusions

We have shown that the photoisomerization of rhodopsin can be controlled by changing the coherence properties of the initial state in accord with a coherent control scenario that entails two femtosecond chirped pulses.

We have shown that the underlying physics involves controlling the dynamics of a subcomponent of the system (the photoinduced rotation along the C11-C12 bond) in the presence of intrinsic decoherence induced by the vibronic activity.

Extensive control has been demonstrated, despite the ultrafast intrinsic decoherence phenomena, providing results of broad theoretical and experimental interest.

QM/MM Investigation of the Primary Event in Vision

Jose A. Gascon and Victor S. Batista

Yale University, Department of Chemistry

Victor.Batista@yale.edu

(Submitted to JACS)

1F88, Palczewski et. al., Science 289, 739, 2000

Boundary C-Cof Lys296

ONIOM QM/MM B3LYP/631G*:Amber

QM Layer (red): 54-atoms MM Layer (red): 5118-atoms

EONIOM =EMM,full+EQM,red -EEMM,red

Reaction Path: negative-rotation

Energy Storage

Reaction Energy Profile: QM/MM ONIOM-EE (B3LYP/6-31G*:Amber)

*Exp Value :

Dihedral angle

11-cis rhodopsin

all-trans bathorhodopsin

Intermediate conformation

11-cis rhodopsin

all-trans bathorhodopsin

Intermediate conformation

Isomerization Process

C12 C11

Glu113

Superposition of Rhodopsin and Bathorhodopsin in the Binding-Pocket:

Storage of Strain-Energy

Charge-Separation Mechanism

Reorientation of Polarized Bonds

Energy Storage[QM/MM ONIOM-EE (B3LYP/6-31G*:Amber)]

Energy Storage[QM/MM ONIOM-ME(B3LYP/6-31G*:Amber)]-

Electrostatic Contribution of Individual Residues

Electrostatic Contribution to the Total Energy Storage 62%

TD-DFT Electronic ExcitationsONIOM-EE (TD-B3LYP/6-31G*:Amber)

E rhod. E

TD-B3LYP//B3LYP/6-31G*:Amber

CASPT2//CASSCF/6-31G*:Amber

E batho.

Experimental

Values in kcal/mol

60.3 3.2

54.0 3.4

Conclusions

We have shown that the ONIOM-EE (B3LYP/6-31G*:Amber) level of theory, in conjunction with high-resolution structural data, predicts the energy storage through isomerization, in agreement with experiments.

We have shown that structural distortions account for 40% of the energy stored, while the remaining 60 % is electrostatic energy due to stretching of the salt-bridge between the protonated Schiff-base and the Glu113 counterion.

We have shown that the salt-bridge stretching mechanism involves reorientation of polarized bonds due to torsion of the polyene chain at the linkage to Lys296, without displacing the linkage relative to Glu113 or redistributing charges within the chromophore

Conclusions (cont.)

We have demonstrated that a hydrogen-bonded water molecule, consistently found by X-ray crystallographic studies, can assist the salt-bridge stretching process by stabilizing the reorientation of polarized bonds.

We have shown that the absence of Wat2b, however, does not alter the overall structural rearrangements and increases the total energy storage in 1 kcal/mol.

We have demonstrated that the predominant electrostatic contributions to the total energy storage result from the interaction of the protonated Schiff-based retinyl chromophore with four surrounding polar residues and a hydrogen bonded water molecule.

We have shown that the ONIOM-EE (TD-B3LYP/6-31G*:Amber//B3LYP/6-31G:Amber) level of theory, predicts vertical excitation energy shifts in quantitative agreement with experiments, while the individual excitations of rhodopsin and bathorhodopsin are overestimated by 10%.

Funding Agencies

• Yale University Start-up Package• Yale University F. Warren Hellman Family

Fellowship• Yale University Rudolph J. Anderson Fellowship• American Chemical Society (PRF – Type G)• Research Corporation (Innovations Programs)• NSF Career Program

Coherent Control of the Primary Event in Human Vision Samuel Flores and Victor S. Batista Yale...

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