Viewing archived talks containing the keyword: 20
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A complete artificial photosynthesis at high efficiency
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: 17h00
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Non-covalent synthesis of functional supramolecular systems
Speaker: E W Meijer (Eindhoven University of Technology)
The intriguing prospects of molecular electronics, nanotechnology, biomaterials, and the aim to close the gap between synthetic and biological molecular systems are important ingredients to study the cooperative action of molecules in the self-assembly towards functional supramolecular systems. The design and synthesis of well-defined supramolecular architectures requires a balanced choice between covalent synthesis and the self-assembly of the fragments prepared. The current self-assembly processes are primarily controlled by solvent, temperature or concentration. For synthetic chemists, the non-covalent synthesis of these supramolecular architectures is regarded as one of the most challenging objectives in science: How far can we push chemical self-assembly and can we get control over the kinetic instabilities of the non-covalent architectures made? How can we go from self-assembly to self-organization? Where the number of different components is increasing the complexity of the system is increasing as well. Mastering this complexity is a prerequisite to achieve the challenges in creating functional systems. In the lecture we illustrate our approach using a number of examples out of our own laboratories, with the aim to come to new strategies for multi-step non-covalent synthesis of functional supramolecular systems.
On: June 17, 2016 From: 15h30 To: 16h30
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Gas Separations in Metal-Organic Frameworks
Speaker: Jeff Long (University of California, Berkeley)
Owing to their high surface areas, tunable pore dimensions, and adjustable surface functionality, metal-organic frameworks (MOFs) can offer advantages for a variety of gas storage and gas separation applications. In an effort to help curb greenhouse gas emissions from power plants, we are developing new MOFs for use as solid adsorbents in post- and pre-combustion CO2 capture, and for the separation of O2 from air, as required for oxy-fuel combustion.1 In particular, MOFs with open metal cation sites or diamine-functionalized surfaces are demonstrated to provide high selectivities and working capacities for the adsorption of CO2 over N2 under dry flue gas conditions.2 Multicomponent adsorption measurements further show compounds of the latter type to be effective in the presence of water,3 while calorimetry and temperature swing cycling data reveal a low regeneration energy compared to aqueous amine solutions.4 MOFs with open metal sites, such as Mg2(dobdc) (dobdc4– = 2,5-dioxido-1,4- benzenedicarboxylate), are highly effective in the removal of CO2 under conditions relevant to H2 production, including in the presence of CH4 impurities.5 Redox-active Fe2+ sites in the isostructural compound Fe2(dobdc) allow the selective adsorption of O2 over N2 via an electron transfer mechanism.6 The same material is demonstrated to be effective at 45 °C for the fractionation of mixtures of C1 and C2 hydrocarbons, and for the high-purity separation of ethylene/ethane and propylene/propane mixtures.7 Finally, it will be shown that certain structural features possible within MOFs, but not in zeolites, can enable the fractionation of hexane isomers according to the degree of branching or octane number.8
 References
1.     Sumida, K.; Rogow, D. L.; Mason, J. A.; McDonald, T. M.; Bloch, E. D.; Herm, Z. R.; Bae, T.-H.; Long, J. R. Chem. Rev. 2012, 112, 724.
2.     McDonald, T. M.; Lee, W. R.; Mason, J. A.; Wiers, B. M.; Hong, C. S.; Long, J. R. J. Am. Chem. Soc. 2012, 134, 7056.
3.     Mason, J. A.; McDonald, T. M.; Bae, T.-H.; Bachman, J. E.; Sumida, K.; Dutton, J. J.; Kaye, S. S.; Long, J. R. J. Am. Chem. Soc. 2015, 137, 4787.
4.     McDonald, T. M.; Mason, J. A.; Kong, X.; Bloch, E. D.; Gygi, D.; Dani, A.; Crocellà , V.; Giordano, F.; Odoh, S.; Drisdell, W.; Vlaisavljevich, B.; Dzubak, A. L.; Poloni, R.; Schnell, S. K.; Planas, N.; Kyuho, L.; Pascal, T.; Prendergast, D.; Neaton, J. B.; Smit, B.; Kortright, J. B.; Gagliardi, L.; Bordiga, S.; Reimer, J. A.; Long, J. R. Nature 2015, 519, 303.
5.     Herm, Z. R.; Swisher, J. A.; Smit, B.; Krishna, R.; Long, J. R. J. Am. Chem. Soc. 2011, 133, 5664.
6.     Bloch, E. D.; Murray, L. J.; Queen, W. L.; Maximoff, S. N.; Chavan, S.; Bigi, J. P.; Krishna, R.; Peterson, V. K.; Grandjean, F.; Long, G. J.; Smit, B.; Bordiga, S.; Brown, C. M.; Long, J. R. J. Am. Chem. Soc. 2011, 133, 14814.
7.     Bloch, E. D.; Queen, W. L.; Krishna, R.; Zadrozny, J. M.; Brown, C. M.; Long, J. R. Science 2012, 335, 1606.
8.     Herm, Z. R.; Wiers, B. M.; Mason, J. A.; van Baten, J. M.; Hudson, M. R.; Zajdel, P.; Brown, C. M.; Masciocchi, N.; Krishna, R.; Long, J. R. Science 2013, 340, 960.
On: November 15, 2016 From: 13h30 To: 14h30
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St Andrews
ScotCHEM Colloquia: Prof David MacMillan FRS
Speaker: Prof David MacMillan FRS (Princeton)
New Photoredox ReactionsDavid W. C. MacMillan
Merck Center for Catalysis, Princeton University,
Princeton, NJ 08544
Abstract. This lecture will discuss the advent and development of new concepts in chemical synthesis, specifically the application of visible light photoredox catalysis to the discovery or invention of new chemical transformations. This lecture will explore a strategy the discovery of chemical reactions using photoredox catalysis. Moreover, we will further describe how mechanistic understanding of these discovered processes has led to the design of new yet fundamental chemical transformations that we hope will be broadly adopted. In particular, a new catalysis activation mode that allows for the development of C–H abstraction and decarboxylative coupling reactions that interface with organometallic catalysis
On: May 29, 2018 From: 15h30 To: 16h30
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Edinburgh
ScotCHEM Colloquia: Prof David MacMillan FRS
Speaker: Prof David MacMillan FRS (Princeton)
New Photoredox ReactionsDavid W. C. MacMillan
Merck Center for Catalysis, Princeton University,
Princeton, NJ 08544
Abstract. This lecture will discuss the advent and development of new concepts in chemical synthesis, specifically the application of visible light photoredox catalysis to the discovery or invention of new chemical transformations. This lecture will explore a strategy the discovery of chemical reactions using photoredox catalysis. Moreover, we will further describe how mechanistic understanding of these discovered processes has led to the design of new yet fundamental chemical transformations that we hope will be broadly adopted. In particular, a new catalysis activation mode that allows for the development of C–H abstraction and decarboxylative coupling reactions that interface with organometallic catalysis.
On: May 30, 2018 From: 9h00 To: 17h00
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Glasgow
ScotCHEM Colloquia: Prof David MacMillan FRS
Speaker: Prof David MacMillan FRS (Princeton)
New Photoredox ReactionsDavid W. C. MacMillan
Merck Center for Catalysis, Princeton University,
Princeton, NJ 08544
Abstract. This lecture will discuss the advent and development of new concepts in chemical synthesis, specifically the application of visible light photoredox catalysis to the discovery or invention of new chemical transformations. This lecture will explore a strategy the discovery of chemical reactions using photoredox catalysis. Moreover, we will further describe how mechanistic understanding of these discovered processes has led to the design of new yet fundamental chemical transformations that we hope will be broadly adopted. In particular, a new catalysis activation mode that allows for the development of C–H abstraction and decarboxylative coupling reactions that interface with organometallic catalysis.
On: May 31, 2018 From: 16h00 To: 17h00
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