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DFT Studies of Photochromic Mercury Complexes

DFT Studies of Photochromic Mercury Complexes. Karel G von Eschwege & Jeanet Conradie. CONTENT. INTRODUCTION STRUCTURES & ISOMERS TDDFT STUDIES MECHANISM ACKNOWLEDGEMENTS. INTRODUCTION. PHOTOCHROMIC REACTION. ABSORBANCE. h n. D. WAVELENGTH / nm.

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DFT Studies of Photochromic Mercury Complexes

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  1. DFT Studies of Photochromic Mercury Complexes Karel G von Eschwege & JeanetConradie

  2. CONTENT • INTRODUCTION • STRUCTURES & ISOMERS • TDDFT STUDIES • MECHANISM • ACKNOWLEDGEMENTS

  3. INTRODUCTION

  4. PHOTOCHROMIC REACTION ABSORBANCE hn D WAVELENGTH / nm The spontaneous radiationless thermal back-reaction of (o-MeO)dithizonatophenylmercury(II) in dichloromethane. Von Eschwege, K. G., J. Photochemistry & Photobiology, 252, 159-166, 2013

  5. STRUCTURES & ISOMERS

  6. Possible Geometries of the Photo-activated Blue Isomer

  7. ORANGE RESTING STATE

  8. PHOTO-GENERATED BLUE STATE

  9. Von Eschwege, Bosman, Conradie & Schwoerer, J. Phys. Chem. A, 2013, submitted for publication

  10. b c a d PhHgHDz geometries and orbitals during the photo-isomerization reaction:(a) orange resting state (0 kJ mol-1), (b) vertically excited state (259 kJ mol-1), (c) blue excited state (228 kJ mol-1), and (d) blue ground state (17 kJ mol-1). The C=N double bond becoming single, allows free rotation.

  11. TDDFT STUDIES

  12. Unsubstituted DPM (orange) Von Eschwege, Bosman, Conradie & Schwoerer, J. Phys. Chem. A, 2013, submitted for publication

  13. MECHANISM

  14. ADF calculated potential energy of DPM along the -C=N- twist coordinate, displaying minima in the planar configurations and ground state E barrier at orthogonal geometry.

  15. Conical Intersection N N N C C C Hirai & Sugino, PhysChemChemPhys, 2009, 11:22, 4570-4578

  16. PROPOSED PATH for unsubstituted DPM Proposed reaction pathway for DPM after S0 S1 photo-excitation. After excitation the molecule immediately starts twisting to minimize its energy. This corresponds to a slope down the S1 potential energy surface and runs into a region of a conical intersection with S0. After fast vibrational relaxation it proceeds onto S0 where it bifurcates to orange & blue. 1 ps 30 fs (1.5 ps) (2/3 : 1/3) (100 ps in CH3OH) Schwoerer, Von Eschwege, Bosman, et al, ChemPhysChem, 2011, 12, 2653-2658

  17. FEMTOSECOND LASER SPECTROSCOPYLaser Research Institute, Stellenbosch Von Eschwege, Bosman, Conradie & Schwoerer, J. Phys. Chem. A, 2013, submitted for publication

  18. - CHPC- J Conradie- LRI at SUTHANK YOU

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