Coherent Control of the Primary Event in Human Vision Samuel Flores and Victor S. Batista Yale University, Department of Chemistry (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

| k > | j > Isomerization coordinate, Quantum interference of molecular wavepackets associated with indistinguishable pathways to the same target state

Quantum interference of indistinguishable pathways to the same target state x O. Nairz, M. Arndt and A. Zeilinger Am. J. Phys. 71, 319, 2003 | j > | k > | x i > | x f >

Bichromatic coherent-control (Weak-field limit)

Ground vibrational state

First Excited Vibrational State

Bichromatic coherent-control Pulse Relative Phases Pulse Relative Intensities

Bichromatic coherent-control Pulse Relative Phases Pulse Relative Intensities

Bichromatic coherent-control Pulse Relative Phases

Chirped Pump Pulses (Wigner transformation forms) CR = Bichirped Coherent Control

Positively Chirped Pulse (PC)

Negatively Chirped Pulse (NC)

Excited State S1 Ground State S0 cistrans Exact Quantum Dynamics Simulations (t=218 fs, CR=212 fs 2 )

Excited State S1 Ground State S0 cistrans Exact Quantum Dynamics Simulations (t=218 fs, CR=-146 fs 2 )

Energy Reaction coordinate S1S1 NC : PC : Impulsive Stimulated Raman Scattering

Pulse Relative Phases Pulse Relative Intensities Bichirped Coherent Control

Pulse Relative Phases Pulse Relative Intensities

Bichirped Coherent Control Pulse Relative Intensities Pulse Relative Phases

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 (Submitted to JACS) 1F88, Palczewski et. al., Science 289, 739, 2000

Boundary C  -C  of Lys296 ONIOM QM/MM B3LYP/631G*:Amber QM Layer (red): 54-atomsMM Layer (red): 5118-atoms E E ONIOM =E MM,full +E QM,red -E MM,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 N H2O Glu113 C13

Superposition of Rhodopsin and Bathorhodopsin in the Binding-Pocket: Storage of Strain-Energy

Charge-Separation Mechanism Reorientation of Polarized Bonds H H

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 Excitations ONIOM-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

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