LightInduced Sulfur to Oxygen Isomerization of Ruthenium Sulfoxide Complexes Jackson Majher Photoswitchable molecules molecules which change optically and electronically due to activation via electromagnetic radiation ID: 763560
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Light-Induced Sulfur to Oxygen Isomerization of Ruthenium Sulfoxide Complexes Jackson Majher
Photoswitchable molecules: molecules which change optically and electronically due to activation via electromagnetic radiation. Examples: Sodium nitroprusside Rhodopsin Oxazine
Background:
[Ru( bpy ) 2(OSO)]+ -Relatively large quantum yield (0.45) achieved. -Chelate effects changes mechanism-Ruthenium (w/ sulfoxide character) to * bpy transition assigned.-No evidence of O-bonded 3MLCT excited state.-Vibrationally relaxed 3MLCT 2 structure proposed.
Summary: -Series of ruthenium sulfoxide complexes that undergo S O isomerization were synthesized.-Characterization by electronic absorbance spectroscopy, IR, NMR and cyclic voltammetry. -Transient absorption spectroscopy utilized for kinetic information.-Results show picosecond timescale kinetics, suggestive of a mechanism including rapid nonradiative decay through conical intersection. Goals of Paper: -Study relationship between distortion energy andisomerization reactivity.-Effect of changing electronic and steric factorscontributing to exited state isomerization.
Absorption Spectra: -Absorption shift to lower wavelengths for BnF5 -Absorption applies to the d* transition.-fwhm highest for R=BnF5 complex which suggests larger nuclear displacement between ground and triplet excited state.-fwhm analysis showed metal-ligand contribution as being the major source of distortion.
E 0 = E op - * - ST -Zero-zero energy was calculated using known values and the absorption spectra to predict room temperature wavelength emission at 1070, 1530, and 1780 nm for R = Nap, BnF5, and Bn respectively. -Were unable measure emission at these wavelengths though they did not see any emission from 500-850 nm.-Emission max observed at 580, 576, and 572 nm for R = Nap, Bn, BnF5 respectively (77K).-Further testing required to see if NIR emission observed.-Relevant information: Strong affect of metal-ligand vibrations on absorptionspectra and PES has temperature dependence. Analysis Continued..
Picosecond Transient Absorption 5.0 , 10.2 , 20.3 , 50.7, 100.3, 495.3 ps1.0 , 2.0, 5.0, 10.3, 20.4, 50.4 101.1 , 203.0, 508.0, 1008 ps S-Bonded Isomer: O-Bonded Isomer
R = Me
Conclusions: -Distortion energy plays a large role in isomerization through conical intersections, primarily through metal-ligand interactions. -R = BnF5 complex shows good isomerization characteristics, electronic influence through sulfur bond achievable. -More testing needs to be done to narrow down specific electronic and steric factors needed to maximizeisomerization conditions. Criticisms:-Not a significant expansion of knowledge past their previous work.-Would be helpful to include more R group types to solidify trends observed. -No computational calculations that provide reasoning to their results.-Emission calculations not backed up by any experimental data.
Acknowledgements: And Eric R. Abrams Beth McClure J. J. Rack
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