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St Andrews
Multifunctional and Stimuli-responsive Coordination Cages
Speaker: Guido Clever (Dortmund)
Multifunctional and Stimuli-responsive Coordination Cages G. H. Clever * Department of Chemistry and Chemical Biology, TU Dortmund University, Germany guido.clever@tu -dortmund.de Banana -shaped bis-monodentate ligands react with Pd(II) cations to coordination compounds with a broad range of topologies from small Pd 2L4 cages, their interpenetrated dimers, rings of various size up to large Pd 24L48 spheres. 1 We introduce stimuli-responsive behaviour triggered by small molecules or light leading to the modulation of guest affinity 2 or complete structural reorganization (Figure a). 3 Interpenetrated double cages consisting of donor and acceptor moieties were shown to undergo light-induced charge separation but suffer from a lack of control over stoichiometry and stereochemistry (Figure b). 4 Therefore, we recently started to apply principles of geometric shape complementarity to control the structure and composition of heteroleptic cages (Figure c). 5 On the other hand, circularly polarized luminescence (CPL) was observed for chiral Pt(II) complexes (Figure d). 6 Advanced self -assembly strategies will enable the targeted synthesis of supra-molecular systems and materials with increasing structural and functional complexity. Figure 1 Light -responsive coordination cages and chiral organometallic luminophors 1. Reviews: a) M. Han, D. M. Engelhard, G. H. Clever, Chem. Soc. Rev. 2014, 43, 1848; b) M. Frank, M. D. Johnstone, G. H. Clever, Chem. Eur. J. 2016 , 22 , 14104. Recent examples: c) W. M. Bloch, J. J. Holstein, B. Dittrich, W. Hiller, G. H. Clever, Angew. Chem. Int. Ed. 2018, 57, 5534; d) R. Zhu, I. Regeni, J. J. Holstein, B. Dittrich, M. Simon, S. Prévost, M. Gradzielski, G. H. Clever, Angew. Chem. Int. Ed. 2018 , DOI: 10.1002/ani e.201806047. 2. a) S. Löffler, J. Lübben, L. Krause, D. Stalke, B. Dittrich, G. H. Clever, J. Am. Chem. Soc. 2015, 137, 1060; b) M. Han, R. Michel, B. He, Y. -S. Chen, D. Stalke, M. John, G. H. Clever, Angew. Chem. Int. Ed. 2013 , 52 , 1319. 3. a) R. Zhu, J. Lübben, B. Dittrich, G. H. Clever, Angew. Chem. Int. Ed. 2015, 54, 2796; b) M. Han, Y. Luo, B. Damaschke, L. Gómez, X. Ribas, A. Jose, P. Peretzki, M. Seibt, G. H. Clever, Angew. Chem. Int. Ed. 2016, 55 , 445 . 4. M. Frank, J. Ahrens, I. Bejenke, M. Krick, D. Schwarzer, G. H. Clever, J. Am. Chem. Soc. 2016 , 138 , 8279. 5. a) W. M. Bloch, Y. Abe, J. J. Holstein, C. M. Wandtke, B. Dittrich, G. H. Clever, J. Am. Chem. Soc. 2016, 138, 13750; b) W. M. Bloch, J. J. Holstein, W. Hiller, G. H. Clever, Angew. Chem. Int. Ed. 2017 , 56 , 8285. 6. T. R. Schulte, J. J. Holstein, L. Krause, R. Michel, D. Stalke, E. Sakuda, K. Umakoshi, G. Longhi, S. Abbate, G. H. Clever, J. Am. Chem. Soc. 2017 , 139 , 6863.On: November 28, 2018 From: 14h00 To: 15h00
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Heriot Watt
From the simple to the complex - supramolecular interactions in pharmaceutical materials
Speaker: Dr Katharina Edkins (Queen\'s University Belfast )
The information on this talk is not live. For up-to-date details please visit: https://projects.eps.hw.ac.uk/seminars/event/1306On: November 28, 2018 From: 14h15 To: 15h15
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St Andrews
Photoswitchable Organometallics
Speaker: Zoraida Freixa (University of the Basque Country, San Sebastian, Spain)
PHOTO SWITCHABLE ORGANOMETALLICS. Zoraida Freixa 1,2 1 Department of Applied Chemistry, Faculty of Chemistry, University of the Basque Country (UPV -EHU), Donostia -San Sebastián, 20018, Spain 2 IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain Zoraida_freixa@ehu.eus In the last few decades, the development of photoresponsive materials has become an intensive area of research. These substances are intended for the production of “smart chemical systems”, whose properties — and eventually functionality — are controlled by changes of the environment (light irradiation). These systems have been already implemented in a wide range of modern materials and devices for daily applications such as sunglass lenses, memory devices, photochromic inks, etc. In spite of the importance and versatility of organometallic complexes, smart photoresponsive examples remain rather unexplored in comparison with the plethora of well known light -triggered organic switches. In principle, photoresponsive metal complexes can be obtained by incorporation of organic photochromic units in the structure of their ligands. These photosensitive ligands, rather than acting as conventional spectators that tune the properties of their complexes, transform them into dynamic smart entities able to offer a functional response to an external stimulus. 1 In our group, we work on the development of such photoresponsive organometallics for diverse applications. We have explored several areas of application exploding some of the most prominent properties of organometallics. Namely, their luminescence, catalytic activity or their potential use as metallodrugs. As will be discussed, the compatibility of the metal coordination and the photoresponse of the molecular switch is an issue that needs to be carefully addressed. 1. Crabtree, R. H., Multifunctional ligands in transition metal catalysis. New J. Chem. 2011, 35, 18 -23. Website: www.freixagroup.comOn: November 29, 2018 From: 14h00 To: 15h00
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Strathclyde
TBC
Speaker: Dr David Mills (University of Manchester)
The information on this talk is not live. For up-to-date details please visit:https://www.strath.ac.uk/science/chemistry/events/On: December 5, 2018 From: 15h00 To: 15h00
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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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Strathclyde
A Biophysical Platform for Ensemble-Based Design of Cyclophilin Inhibitors
Speaker: Dr Julien Michel (University of Edinburgh)
The information on this talk is not live. For up-to-date details please visit:https://www.strath.ac.uk/science/chemistry/events/On: December 12, 2018 From: 15h00 To: 15h00
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