Viewing archived talks containing the keyword: 18
Speaker: Prof Dan Nocera (Harvard)
The artificial leaf accomplishes a solar fuels process that captures the elements of photosynthesis – the splitting of water to hydrogen and oxygen using light, from neutral water, at atmospheric pressure and room temperature. These conditions are met owing to the development of water splitting catalysts of the elements of Mn, Co and Ni that are self-healing; the design principles for self-healing catalysis will be presented. The self-healing catalysts are coated on a silicon wafer in a buried junction configuration, which enables light harvesting and charge separation to be coupled to catalysis under simple conditions. We have advanced the design of the artificial leaf by utilizing the hydrogen from the artificial leaf and combining it with carbon dioxide to make liquid fuels. Using the tools of synthetic biology, a bio-engineered bacterium has been developed to convert carbon dioxide, along with the hydrogen produced from the artificial leaf, into biomass and fusel alcohols. This hybrid microbial | artificial leaf system scrubs 180 grams of CO2 from air, equivalent to 230,000 liters of air per 1 kWh of electricity. Coupling this hybrid device to existing photovoltaic systems leads to unprecedented solar-to-biomass (10.7%) and solar-to-liquid fuels (6.2%) yields, which greatly exceeding natural photosynthetic systems.
On: May 30, 2016 From: 16h00 To: 17h00View talk
Speaker: Michael Ward (Warwick)
Self -assembled coordination cages (hollow metal/ligand capsules) have the ability to encapsulate small molecule guests in the central cavity. In this talk is presented a coordination cage with a very well developed host guest chemistry, for which the factors responsible for guest binding have been dissected in detail to the extent that guest binding can be quantitatively predicted. The combination of b inding of hydrophobic guests in the cage cavity in water, and accumulation of anions around the positively -charged cage surface by ion -pairing, has led to his catalytic rate enhancements for reactions of cavity -bound guests with surface -bound anions. As g uest binding and ion -pairing are based on orthogonal interactions, this affords a system capable in principle of quite general bimolecular catalysis of reactions of electrophiles with anions.
On: November 14, 2018 From: 14h00 To: 15h00View talk
Speaker: Jennifer Love (UBC)
We report a mechanistic study of C(sp3) -H bond activation mediated by nickel. A cyclometalated Ni(II) ureate [(PEt3)Ni(κ3 -C,N,N -(CH2)N(Cy)(CO)N((N) -quinolin -8-yl))] was synthesized and isolated from a urea precursor, (Me)(Cy)N(CO)N(H)(quinolin -8-yl), via C(sp3) -H activation. We investigated the effects of solvents and base additives on the rate of C -H activation. Kinetic isotope effect experiments showed that C -H activation is rate determining. Through deuterium label ling and protonation studies, we also showed that C -H activation can be re versible. We extended this reac tion to a range of ureas with primary and secondary C(sp3) -H bonds, which activate readily to for m analogous nickelated products . Finally, we showed that carboxylate additives assist with both ligand dissociation and initial N-H bond activation, consistent with a concerted metalation deprotonation mechanism.
On: November 21, 2018 From: 14h00 To: 15h00View talk
Speaker: Jeremy Burroughes (Cambridge Display Technology Limited)
Flexible OLEDs for Display and Sensor Applications Dr Jeremy Burroughes FRS, FREng, FIET, FInstP One of the challenges for efficient and low voltage OLEDs is the need to use a low work function cathode material which leads to increased encapsulation requirements. For mainstream applications such as TVs and lighting, the additional cost is acceptable. For more price sensitive applications, such as displays for white goods and smart cards or sensor applications a method is required to mitigate this issue. This talk will explain how this can be achieved using an air -processable electron injection layer capped with just aluminium. This OLED technology can then be used to make a lower cost OLED display s suitable for a variety of applications, which will be discussed in this presentation. I will also finish off by giving some information on our other printed electronic activities.
On: November 27, 2018 From: 14h00 To: 15h00View talk
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: 15h00View talk
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.com
On: November 29, 2018 From: 14h00 To: 15h00View talk