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Coherent Control of the Primary Event in Human Vision Yale University, Department of Chemistry Samuel Flores and Victor S. Batista (Submitted to J. Phys. Chem. B) [email protected] 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 Quantum interference of molecular wavepackets associated with indistinguishable pathways to the same target state |j> |k> Isomerization coordinate,(c11 c12) Quantum interference of indistinguishable pathways to the same target state x | xi > |j> |k> O. Nairz, M. Arndt and A. Zeilinger Am. J. Phys. 71, 319, 2003 | xf > Bichromatic coherent-control (Weak-field limit) Ground vibrational state First Excited Vibrational State Pulse Relative Phases Bichromatic coherent-control Pulse Relative Intensities Pulse Relative Phases Bichromatic coherent-control Pulse Relative Intensities Pulse Relative Phases Bichromatic coherent-control Bichirped Coherent Control Chirped Pump Pulses (Wigner transformation forms) CR = CR= Positively Chirped Pulse (PC) Negatively Chirped Pulse (NC) Exact Quantum Dynamics Simulations (t=218 fs, CR=212 fs2) Excited State S1 500nm(FWHM 35fs) Ground State S0 cis trans Exact Quantum Dynamics Simulations (t=218 fs, CR=-146 fs2) Excited State S1 500nm(FWHM 35fs) Ground State S0 cis trans Impulsive Stimulated Raman Scattering Energy S1 Reaction coordinate NC: PC: Pulse Relative Phases Bichirped Coherent Control θ Pulse Relative Intensities Pulse Relative Phases Bichirped Coherent Control Pulse Relative Intensities Pulse Relative Phases Bichirped Coherent Control Pulse Relative Intensities 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 Yale University, Department of Chemistry Jose A. Gascon and Victor S. Batista (Submitted to JACS) [email protected] 1F88, Palczewski et. al., Science 289, 739, 2000 ONIOM QM/MM B3LYP/631G*:Amber QM Layer (red): 54-atoms MM Layer (red): 5118-atoms EONIOM =EMM,full+EQM,red -EMM,red Boundary Ca-Cd of Lys296 Reaction Path: negative-rotation Reaction Energy Profile: QM/MM ONIOM-EE (B3LYP/6-31G*:Amber) all-trans bathorhodopsin Intermediate conformation Exp Value : * 11-cis rhodopsin Energy Storage Dihedral angle Intermediate conformation all-trans bathorhodopsin 11-cis rhodopsin Isomerization Process C13 H2O C12 C11 N Glu113 Superposition of Rhodopsin and Bathorhodopsin in the Binding-Pocket: Storage of Strain-Energy Charge-Separation Mechanism Reorientation of Polarized Bonds H H Electrostatic Contribution to the Total Energy Storage 62% - 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 TD-DFT Electronic Excitations ONIOM-EE (TD-B3LYP/6-31G*:Amber) Values in kcal/mol DE rhod. TD-B3LYP//B3LYP/6-31G*:Amber 63.5 CASPT2//CASSCF/6-31G*:Amber 64.1 Experimental 57.4 DE batho. DDE 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/631G*: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