Viewing archived talks in: St Andrews
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St Andrews
Single-site Catalysts by Metal-ligand Complexation at Surfaces: From Model Systems in Vacuum to High-pressure Catalysis on Oxide Supports
Speaker: Steve Tait (Indiana University Bloomington)
A grand challenge in heterogeneous catalysis is to achieve high levels of selectivity by _x000D_controlling the chemical uniformity of metal catalyst sites at surfaces . Our group is working to _x000D_apply principles of on -surface metal -organic redox assembly to develop a new approach to this _x000D_problem. Metal -organic coor dination networks at surfaces hold promise for selective chemical _x000D_function , but there is a limited understanding of the chemical reactivity of these systems. We _x000D_tested chemical activity of vanadium single -site complexes that are stabilized by tetrazine -bas ed _x000D_ligands. We demonstrate activity toward dioxygen activation and a high degree of selectivity _x000D_compared to vanadium nanoparticles. Reaction with O 2 causes an increase in V oxidation state _x000D_from V II to V IV, resulting in a single strongly bonded V -oxo produc t and spillover of O to the Au _x000D_surface [1] . The metal centers are stabilized in extended, ordered metal -organic complexes that _x000D_self -assemble through an on -surface redox process on the Au( 100) surface and are characterized _x000D_by X -ray photoelectron spectroscopy, scanning tunneling microscopy, high -resolution electron _x000D_energy loss spectroscopy, and density functional theory. New results extend these chemical _x000D_studies to more complex system s that include bimetallic sites and redox isomer systems [2] , _x000D_which will also be highlighted in this presentation. _x000D_We have also developed synthesis schemes to assemble quasi -square planar metal -organic _x000D_complexes on high surface area powdered oxides through a mod ified wet -impregnation -style _x000D_method. X-ray photoelectron spectroscopy measurements demonstrate loading of metal and _x000D_ligand on the surface and synchrotron -based X -ray absorption spectroscopy measurements of the _x000D_coordination shell of the metal centers demons trates single site formation rather than _x000D_nanoparticle assembly [3] . These systems are shown to be active for the catalysis of _x000D_hydrosilylation reactions at a level that is competitive with current homogeneous catalysts.On: December 10, 2018 From: 14h00 To: 15h00
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St Andrews
EaStCHEM Colloquia: Femtosecond charge and spin dynamics in molecular magnets
Speaker: Olof Johansson (Edinburgh)
The information on this talk is not live. For up-to-date details please visit: https://talks.st-andrews.ac.uk/On: December 13, 2018 From: 15h30 To: 16h30
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St Andrews
Mathew Horocks
Speaker: Mathew Horocks (Edinburgh)
testOn: January 30, 2019 From: 14h00 To: 15h00
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St Andrews
Using ab initio approaches to model, predict and understand the optical properties of organic and inorganic dyes - Joint Chemistry/Physics Colloquium
Speaker: Denis Jacquemin (Nantes)
Using ab initio approaches to model, predict and understand the optical properties of organic and inorganic dyes Denis Jacquemin Laboratoire CEISAM, UMR CNRS n°6230, Université de Nantes, 2, rue de la Houssinière, 44322 Nantes, Cedex 3, France. Denis.Jacquemin@univ -nantes.fr During this lecture, I will illustrate some of the successes and failures of Time-Dependent Density Functional Theory (TD -DFT) in simulating the properties of electronically excited -states, with a specific interest on structures of interest for dye chemistry. 1-2 Notably, I will discuss the importance of calculating vibronic effects to obtain accurate comparisons with experimental data, including 0 -0 energies and band shapes, and illustrate this aspect with several examples. 3 I will also present examples of applications of TD -DFT to real-life structures used in LEDs focussing on two examples: ESIPT -based organic dyes for white OLEDs 4 and inorganic complexes used in blue/green/red phosphors. 5 1 D. Jacquemin, C. Adamo, Chem. Soc. Rev., 2013, 42, 845 . 2 D. Jacquemin, C. Adamo, Top. Curr. Chem.. , 2016 , 368 , 345 . 3 F. Santoro, D. Jacquemin, Wires. Comput. Mol. Sci. 2016, 6, 460. 4 A. Steffen, K. Costuas, A. Bouccekkine, M. H. Thibault, A. Beeby, A. S. Batsanov, D. Jacquemin, A. Charaf -Eddin, J. F. Halet, T. D. Marder Inorg. Chem. , 2014 , 53 , 7055 . 5 E. Heyer, K. Benelhadj, S. Budzak, D. Jacquemin, J. Massue, G. Ulrich Chem. Eur. J ., 2017, 23, 7324 . 6 D W . Zhang, D. Jacquemin, Q. Peng, Z. Suhai, D. Escudero, J. Phys. Chem. C, 2018 , 122 , 6340 .On: February 6, 2019 From: 14h00 To: 15h00
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St Andrews
Probing Ultrafast Chemical Dynamics Inspired by the Rhythms of Fireflies
Speaker: Greg Scholes (Princeton)
Probing Ultrafast Chemical Dynamics Inspired by the Rhythms of Fireflies Coherence phenomena arise from interference, or the addition, of wave -like amplitudes in phase [1] . While coherence has been shown to yield transformative new ways for improving function, advances have been limited to pristine matter, as quantum coherence is considered fragile. Here I will discuss how vibrational an d vibronic wavepackets entrain ensembles of molecules, like the synchronized flashing of fireflies . I will discuss how this can be used to probe mechanisms of ultrafast dynamics and how in -step vibrational motion might be employed to control function on ul trafast timescales. I will give examples that include light -harvesting in photosynthesis, energy flow in organometallic molecules that is ‘wired’ by Fermi resonance, and ultrafast electron transfer in molecular systems. [1] Scholes, et al. “Optimal Coherence in Chemical and Biophysical Dynamics” Nature 543, 647 – 656 (2017) .On: February 11, 2019 From: 13h00 To: 14h00
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St Andrews
Small molecule activation and catalysis using earth abundant metal complexes
Speaker: Deborah Kays (Nottingham)
Small molecule activation and catalysis using earth abundant metal complexOn: February 13, 2019 From: 14h00 To: 15h00
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