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Light, Molecules, Action! Using light to power molecular devices
USING ULTRAFAST UV-VISIBLE AND X-RAY SPECTROSCOPY TO PROBE EXCITED STATE DYNAMICS IN PHOTOACTIVE MOLECULES. R Cobalamin (Vitamin B12) Photochemistry
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Acknowledgements Students: Ted Wiley Nick Miller Laura Kiefer
William Miller Jon Elrod Anushka Gupta Collaborators: Pawel Kozlowski (Univ. Louisville) Bernhard Kräutler (Univ. of Innsbruck) Ken Spears Kevin Kubarych Jim Penner-Hahn Aniruddha Deb Synthesis of novel designed compounds Bernhard Kräutler Theoretical simulation and prediction Spectroscopic and Physical measurements Development of light sources Pawel Kozlowski Roberto Alonso-Mori James M. Glownia Jake Koralek Marcin Sikorski Diling Zhu Our group, Jim Penner-Hahn Kevin Kubarych LCLS Beamline scientists Funding:
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Light, Molecules, Action! Using light to power molecular machines
Light is a versatile energy source Light (esp. laser light) can be shaped, timed, tuned, focused, aimed and delivered at a target as required. Spatial and temporal control of molecular activation. Optically controlled molecular devices motors, switches, activators, junctions, memory, logic circuits, actuators, sensors, and delivery platforms. Function is controlled by photochemistry Photon energy produces action via movement of charge, change in shape or cleavage of a bond – light activates a change in the chemical nature of a molecular system.
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B12 Analogs Anti-Vitamins and Optical Control
The photochemistry of cobalamins is of interest: Newly discovered B12 based photoreceptor proteins use light to control gene activation and carotenoid synthesis. The upper group “R” can be replaced by a drug (eg. a cancer drug) to allow photoactivated drug delivery. Reactive radicals can be produced with spatiotemporal control. Photoresponsive “anti-vitamins” allow control of biological availability. Molecular switches and sensors can be developed by designing appropriate ligands, “R”.
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B12 Photolysis HOCbl exc = 253 nm
Photochemistry is controlled by the lowest singlet state (S1) surface or by branching of states at higher energy, bypassing S1 state barriers.
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B12 Spectra R Typical UV-Visible Spectra
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HOCbl (B12b) Photolysis pH 10.3, 99+% HOCbl exc: 269 nm 404 nm 535 nm
Wiley, T. E.; Miller, W. R.; Miller, N. A.; Sension, R. J.; Lodowski, P.; Jaworska, M.; Kozlowski, P. M. J. Phys. Chem. Lett. 2016, 7,
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HOCbl (B12b) Photolysis
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HOCbl (B12b) Photolysis pH 10.3, 99+% HOCbl 269 nm only:
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HOCbl (B12b) Photolysis The surfaces for three different electronic configurations define the lowest excited state surface for cobalamins. (Calculations: Kozlowski et al.) Photochemistry is controlled by the lowest surface or by branching of states at higher energy. <~300 nm R ~2%
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HOCbl (B12b) Photolysis The surfaces for three different electronic configurations define the lowest excited state surface for cobalamins. (Calculations: Kozlowski et al.) Photochemistry is controlled by the lowest surface or by branching of states at higher energy. <~300 nm ~2%
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Antivitamin B12 EtPhCbl Photo conditional “anti-vitamin” B12.
Metabolically inert. Optical control of biological availability. Miller, N. A.; Wiley, T. E.; Spears, K. G.; Ruetz, M.; Kieninger, C.; Kräutler, B.; Sension, R. J. J. Am. Chem. Soc. 2016, 138,
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Antivitamin B12 EtPhCbl
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Antivitamin B12 EtPhCbl
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Coenzyme B12: AdoCbl In Ethylene Glycol
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Coenzyme B12: AdoCbl In Water (~pH 7)
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Vitamin B12: CNCbl 5
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Vitamin B12: CNCbl
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Vitamin B12: CNCbl Lodowski, P.; Jaworska, M.; Andruniów, T.; Garabato, B. D.; Kozlowski, P. M.: Phys. Chem. Chem. Phys. 2014, 16,
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Femtosecond XANES of Vitamin B12
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Femtosecond XANES of Vitamin B12
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Polarized XANES of Electronically Excited Vitamin B12
X-ray absorption near edge structure Sensitive to electronic and structural changes. y Optical excitation is along “x”. Perpendicular in- plane direction is “y”. The “z” direction is out-of-plane. Miller, N. A. et al. J. Am. Chem. Soc. 2017, 139,
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Polarized XANES Probe at the cobalt K-edge excited Co 1s electrons.
Measuring the difference signal across the near edge region. 1s3d pre-edge 1snp K-edge Perpendicular difference signal.
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Excited State XANES
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Excited State XANES Comparison with Simulation
Co-CN 1.857 2.216 Co-Nimd 2.054 2.275 S0 Lodowski, P.; Jaworska, M.; Kornobis, K.; Andruniow, T.; Kozlowski, P. M.: J. Phys. Chem. B 2011, 115, Lodowski, P.; Jaworska, M.; Andruniów, T.; Garabato, B. D.; Kozlowski, P. M.: Phys. Chem. Chem. Phys. 2014, 16,
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Polarized XANES Comparison with Simulation
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XANES Time Dependence
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XANES Time Dependence
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XANES Time Dependence Potential energy curves of the lowest vertical excited singlet (red dot) and the optimized first excited state (red solid line) of the CNCbl model along the structural parameter q computed at BP86/6-31G(d) with solvent using the COSMO/H2O model. Lodowski, P.; Jaworska, M.; Kornobis, K.; Andruniow, T.; Kozlowski, P. M.: J. Phys. Chem. B 2011, 115,
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XANES Time Dependence (5)
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XANES Time Dependence Potential energy curves of the lowest vertical excited singlet (red dot) and the optimized first excited state (red solid line) of the CNCbl model along the structural parameter q computed at BP86/6-31G(d) with solvent using the COSMO/H2O model. Lodowski, P.; Jaworska, M.; Kornobis, K.; Andruniow, T.; Kozlowski, P. M.: J. Phys. Chem. B 2011, 115,
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XANES Time Dependence z y
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Conclusions Structural changes around the Co atom.
With pulse: modest ring changes (1*1) 1 = 0.11 ps: Axial bond elongation ((/d)1(*/dxy+n*/*dz2)1) 2 = 0.26 ps: Corrin ring/axial relaxation (1(*dz2)1) 3 = 6.2 ps: Excited state population decay (2) Ultrafast XAS and UV-Vis combine to give picture of the structural and electronic dynamics on the excited state surface.
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Acknowledgements Students: Ted Wiley Nick Miller Laura Kiefer
William Miller Jon Elrod Anushka Gupta Collaborators: Pawel Kozlowski (Univ. Louisville) Bernhard Kräutler (Univ. of Innsbruck) Ken Spears Kevin Kubarych Jim Penner-Hahn Aniruddha Deb Synthesis of novel designed compounds Bernhard Kräutler Theoretical simulation and prediction Spectroscopic and Physical measurements Development of light sources Pawel Kozlowski Roberto Alonso-Mori James M. Glownia Jake Koralek Marcin Sikorski Diling Zhu Our group, Jim Penner-Hahn Kevin Kubarych LCLS Beamline scientists Funding:
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