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Viewing upcoming talks containing the keyword: 3
Speaker: Daniel Leznoff (Simon Fraser University, Canada)
The spectroscopic and redox properties of metallophthalocyanines (MPcs) are active areas of research. MPc complexes can be successively reduced using chemical, electrochemical, or photochemical methods to give rise to species containing reduced Pc3-, Pc4-, Pc5-, or Pc6-ligands. These species are usually generated and characterized in situ and have only very rarely been isolated for structural characterization, likely due to the extreme air and moisture sensitivity of these complexes. In particular, there are few examples of phthalocyanines with early-transition metals - despite their rich reactivity in organometallic chemistry - and thus we focused on this underdeveloped area of the periodic table with respect to new PcM complexes.
Using rigorously air- and moisture-free conditions, the isolation and structural characterization of highly reduced Pcn- (n=3,4,5) complexes – among the first ever reported - with early transition-metals, including Sc, Zr, Nb and Cr, will be described. The electronic structure of these materials will also be examined, using a combination of UV-vis-NIR and ESR spectroscopies, X-ray diffraction studies and DFT calculations.
Our efforts to prepare and characterize very rare mononuclear PcAu(II) complexes based on a prior report[2a] will also be discussed, in which we present the first synthesized and structurally characterized gold-containing phthalocyanines.[2b]
1. E.W.Y. Wong, C.J. Walsby, T. Storr, D.B. Leznoff, Inorg. Chem., 2010, 49, 3343-3350; E.W.Y. Wong, D.B. Leznoff, J. Porph. Phthalo., 2012, 16, 154-162; R. Platel, W. Zhou, T.T. Tasso, T. Furuyama, N. Kobayashi, D.B. Leznoff, Chem. Commun., 2015, 5986-89; W. Zhou, R. Platel, T.T. Tasso, T. Furuyama, N. Kobayashi, D.B. Leznoff, Dalton Trans., 2015, 44, 13955.
2. (a) A. MacCragh and W.S. Koski, J. Am. Chem. Soc., 1965, 87, 2496. (b) E.W.Y. Wong, A. Miura, M.D. Wright, Q. He, C.J. Walsby, S. Shimizu, N. Kobayashi and D.B. Leznoff Chem. Eur. J. 2012, 18, 12404.
On: April 6, 2016 From: 15h30 To: 16h30View talk
Cond Mat Seminars
Speaker: Alexander Balatsky (LANL/NORDITA)
SrTiO3 (STO) is one of the earliest examples of superconductivity in oxides. Superconducting state is STO exhibits the dome as a function of doping. STO is also a known quantum paraelectric. Historically quantum criticality and superconducting dome in STO were assumed to be unrelated. We propose that they are in fact intimately connected. We expand the well-known notion, that quantum criticality can induce superconductivity due to quantum ferroelectric fluctuations. We investigate the origin of superconductivity in doped STO using a combinationof density functional and strong coupling theories within the framework of quantum criticality. Our density functional calculations of the ferroelectric soft mode frequency as a function of doping reveal a crossover related to quantum paraelectricity at a doping level coincident with the experimentally observed top of the superconducting dome. Thus, we suggest a model in which the soft mode fluctuations provide the pairing interaction for superconductivity carriers. Within our model, the low doping limit of the superconducting dome is explained by the emergence of the Fermi surface, and the high doping limit by departure from the quantum critical regime. We further analyze the model using the isotope effect. This result in a prediction that the highest critical temperature will increase and shift to lower carrier doping with increasing 18O isotope substitution, a scenario that is experimentally verifiable. In addition we show a connection between the isotope exponent of superconductivity and the critical exponent pertaining to quantum phase transition.
On: April 6, 2016 From: 13h00 To: 14h00View talk
Physics and Astronomy Colloquia
Speaker: Prof Cait MacPhee (University of Edinburgh, Biomolecular Physics)
Janus particles are micro- or nano-scale particles whose surfaces have two or more distinct physical properties. Such asymmetry results in interesting self-assembly properties, but homogeneous Janus particles can be difficult to synthesize. The protein BslA (Bacterial Surface Layer A) is a small (~4 nm) protein produced by the bacterium acillus subtilis that has a hydrophilic ‘body’ to which is appended a surface-exposed hydrophobic ‘cap’. These properties allow the ellipsoidal protein to partition to oil- and air-water interfaces where it self-assembles to form a robust, elastic, and highly hydrophobic film. We have investigated the behaviour of BslA using a combination of biophysical experiments and multiscale simulations. I will describe how BslA provides an intriguing example of a colloidal particle with switchable, environmentally-responsive physical features that have potential applications in nanoscale self-assembly.
On: April 8, 2016 From: 10h00 To: 11h00View talk
Speaker: David Wales (Cambridge)
The potential energy landscape provides a conceptual and computational framework for investigating structure, dynamics and thermodynamics in atomic and molecular science. This talk will summarise new approaches for global optimisation, quantum dynamics, the thermodynamic properties of systems exhibiting broken ergodicity, and rare event dynamics. Applications will be presented that range from prediction and analysis of high-resolution spectra, to coarse-grained models of mesoscopic structures. Selected Publications: D.J. Wales, Curr. Op. Struct. Biol., 20, 3-10 (2010) D.J. Wales, J. Chem. Phys., 130, 204111 (2009) B. Strodel and D.J. Wales, Chem. Phys. Lett., 466, 105-115 (2008) D.J. Wales and T.V. Bogdan, J. Phys. Chem. B, 110, 20765-20776 (2006) D.J. Wales, Int. Rev. Phys. Chem., 25, 237-282 (2006) D.J. Wales, "Energy Landscapes", Cambridge University Press, Cambridge, 2003
On: April 13, 2016 From: 15h30 To: 16h30View talk
Physics and Astronomy Colloquia
Speaker: Prof Tim Harries (University of Exeter)
Massive stars (those greater than 20 solar masses) are hugely important in galactic ecology, enriching them chemically and providing strong feedback effects via radiation, stellar winds and supernovae. However, the process by which massive stars form is less well understood than that of lower-mass stars, both observationally, because massive protostars are rare and difficult to observe, and theoretically because radiation feedback has a much stronger influence on the dynamics than it does for solar-mass objects.
I present new radiation-hydrodynamical (RHD) simulations of massive star formation that treat the radiation feedback with unprecedented microphysical detail. The simulations following the collapse of a molecular cloud into a protostar with a circumstellar disc and a bipolar outflow. I show that by computing synthetic observables directly from the RHD models it is possible to
test the simulations against a variety of diagnostics, from molecular lines to interferometry.
On: April 15, 2016 From: 10h00 To: 11h00View talk
Physics and Astronomy Colloquia
Speaker: Dr Will Hossack (TBC)
The Kaleidoscope was one of the must have toys of the 1800s. Invented 200 years ago by the Scottish scientist Sir David Brewster, Principal of St Andrews from 1837-59, this fascinating gadget is still as popular today. Join us to hear about the life and work of Sir Brewster, one of the founding figures in physics in the mid nineteenth century, and find out how his discoveries are still relevant today.
On: April 15, 2016 From: 17h45 To: 19h00View talk