- EaStCHEM Colloquia
- Physics and Astronomy Colloquia
- Irvine Lectures
- Photonics Seminar
- Special Seminars
- Synthesis Seminars
- Cond Mat Seminars
- Organic Semiconductor Centre
- Theoretical Physics Discussion Group
- ScotCHEM Colloquia
- History of Mathematics
- RSC Award Lectures
- Toy List
- Special Mini-Symposium - Structural Chemistry at Central Facilities
- Strong coupling seminars
- Materials and Energy Special Seminars
- ScotCHEM Polymer and Soft Materials Conference
Viewing upcoming talks containing the keyword: 19
Photoprotection and photoactivation of biomolecules: lessons learned from femtosecond spectroscopy (Video Conference from Edinburgh)
Speaker: Vas Stavros (Warwick)
Photoprotection from harmful UV radiation occurs in many shapes and forms. For example eumelanins in skin provide a natural defence to UV radiation exposure in humans; sunscreens on the other hand provide artificial photoprotection. Combined, detrimental effects such as damage to DNA are largely prevented. However, even when photodamage does occur, photoactivated prodrugs can inhibit further photodamage. The flow of energy involved in photoprotection and photoactivation processes occurs on very short timescales. This talk will introduce some of the techniques that have been developed in our group to probe this energy flow in real time. Example systems recently studied will be presented, ranging from photodissociation of eumelanin building blocks in the gas- and solution-phase, electronic and vibrational dynamics in sunscreens and solvolysis of ruthenium prodrugs.
On: November 25, 2015 From: 15h30 To: 16h30View talk
Physics and Astronomy Colloquia
Speaker: Dr Ignacio Wilson-Rae (University of York)
Recent years have witnessed an explosion of activity in the emerging field of optomechanics which aims at controlling the motional state of mechanical resonators by optical means. Optomechanical systems seem ideal for testing notions of how our macroscopic "classical world", where quantum superpositions seem to be absent, can be reconciled with quantum mechanics. However, typical schemes, based on light forces in optical cavities, are seriously limited by the smallness of the resulting interaction between single phonons and photons. In this colloquium I will discuss an alternative approach, based on the optical excitation of quantum emitters embedded in nanomechanical structures and their strong electron-phonon interactions. I will present theoretical analyses of two realisations of this concept. The first one uses excitons in suspended carbon-nanotubes to explore strong-coupling phenomena in quantum decoherence. The second one uses colour centres in nano-cantilevers to monitor phonon quantum jumps providing direct evidence of nanomechanical energy quantization.
On: November 27, 2015 From: 10h00 To: 11h00View talk
Chiral indium and zinc catalysts for the living and immortal polymerization of cyclic esters (Video Conference from Edinburgh)
Speaker: Parisa Mehrkhodavandi (University of British Columbia)
Poly(lactic acid) (PLA) is a widely used, biodegradable polymer which is commercially synthesized The controlled ring opening polymerization of lactide and other cyclic esters to create a new generation of high functioning biodegradable material remains a challenge that is being addressed by many chemists. We have developed a family of indium compounds supported by chiral amino phenolate ligands and have explored their reactivity for the living and immortal ring opening polymerization of lactide. These complexes are highly active catalysts for living PLA formation and exhibit significant control of polymer macro- and microstructure. We have examined the origin of stereoselectivity during lactide polymerization and applied these catalysts to other cyclic esters. Cationic indium catalysts are capable of alternating copolymerization cyclic esters and ethers. The synthesis, reactivity, and potential applications of these indium compounds will be discussed.
On: December 2, 2015 From: 16h00 To: 17h00View talk
Speaker: Dave Smith (York)
Soft matter systems, self-assembled from molecular-scale building blocks, offer a powerful strategy by which we can program and control the nanoworld, from the molecular-level up. This lecture will explore the ways in which supramolecular chemistry can be used to direct the formation of nanostructures with potential uses as materials and medicines.
We will discuss the self-assembly of soft gel-phase nanomaterials, and in particular, will explore how molecular structure can be translated into nanoscale architectures through non-covalent interactions.1 Directed self-assembly can occur within complex mixtures in order to yield multi-component materials with multiple functions.2 This approach generates soft materials with potential applications ranging from pharmaceutical formulation and pollution control to nanoscale electronics and tissue engineering.3We will also consider how self-assembled systems can interface with biological targets via the formation of multivalent arrays of interactions.4 Such systems can exhibit high affinity binding, with surprising levels of control and selectivity.5 We will demonstrate how this approach can target goals as diverse as gene delivery and coagulation control during major surgery.6
References. 1 (a) W. Edwards, D.K. Smith, J. Am. Chem. Soc. 2013, 135, 5911. (b) W. Edwards, D.K. Smith, J. Am. Chem. Soc. 2014, 136, 1116-1124. 2 (a) D.J. Cornwell, B.O. Okesola, D.K. Smith, Angew. Chem. Int. Ed. 2014, 53, 12461. (b) D.J. Cornwell, D.K. Smith, Mater. Horiz. 2015, 2, 279. 3. (a) A.R. Hirst, B. Escuder, J.F. Miravet, D.K. Smith, Angew. Chem. Int. Ed. 2008, 47, 8002. (b) E.J. Howe, B.O. Okesola, D.K. Smith, Chem. Commun. 2013, 51, 7451. (c) B.O. Okesola, S.K. Suravaram, A. Parkin, D.K. Smith, Angew. Chem. Int. Ed. 2015, in press. 4. A. Barnard, D. K. Smith, Angew. Chem. Int. Ed. 2012, 51, 6572. 5. S.M. Bromfield, D.K. Smith, J. Am. Chem. Soc. 2015, 137, 10056. 6. (a) A. Barnard, P. Posocco, S. Pricl, M. Calderon, R. Haag, M.E. Hwang, V.W.T. Shum, D.W. Pack, D.K. Smith, J. Am. Chem. Soc. 2011, 133, 20288. (b) S.M. Bromfield, P. Posocco, C.W. Chan, M. Calderon, S. E. Guimond, J.E. Turnbull, S. Pricl, D.K. Smith, Chem. Sci. 2014, 5, 1484.
On: December 9, 2015 From: 15h30 To: 16h30View talk
Speaker: Prof Richmond Sarpong (University of California Berkeley)
Abstract: Natural products continue to provide intricate problems that expose limitations in the strategies and methods employed in the synthesis of complex molecules. Several strategies and methods that have been developed in our laboratory and applied to the syntheses of architecturally complex diterpenoid alkaloids, indole alkaloids, and several Lycopodium alkaloids, will be presented and discussed.
Key Words: Total Synthesis, Alkaloids, Natural Products, Strategy for Synthesis
On: January 15, 2016 From: 15h30 To: 16h30View talk
Mechanistic Insights into the Structure-Property Relationship through detailed Crystallographic Studies
Speaker: Mark Senn (University of Oxford )
Engineering a ground state structure to produce a desired physical property is becoming more widespread, particularly in the field of ferroelectrics where the symmetry of the paraelectric parent phase may be intentionally broken by chemical design to lead to a polar distortion, e.g., Ref. 1. Here it is our ability to characterise the structure via crystallographic methods and qualify its average symmetry which allows us to inform the structure-property relationship which underpins this work. I will give two examples from my own research where symmetry analysis of the ground state crystallographic structure has led to mechanistic insight into metal-insulator phase transitions2 and improper ferroelectric mechanisms3.
However, despite the success of this approach, several limitations exist. Firstly, many physical properties such as thermal expansion and superconductivity do not arise solely from the ground state crystal structure but due to excitations and lattice dynamics. Secondly, not all functional materials are fully ordered and their physical properties often arise from so called order-disorder phase transitions. Here, long-range crystallographic symmetry does not reflect the local underlying microscopic mechanism, and it is unclear what insight conventional crystallography can bring. In the second half of my talk I will extend the application of symmetry analysis further to tackle these problems. I will show how we can gain insight into negative thermal expansion though the study of closely competing ground state structures3 and how in the archetypal ferroelectric Barium Titanate we can reconcile the observed order-disorder phase transitions with its long range crystallographic symmetry and its observed macroscopic properties4.
1) A. T. Mulder, N. A. Benedek, J. M. Rondinelli, C. J. Fennie, Adv. Funct. Mater. 23, 4810–4820 (2013).
2) M.S. Senn, J.P. Wright, and J.P. Attfield, Nature 481, 173 (2012).
3) M.S. Senn, A. Bombardi, C.A. Murray, C. Vecchini, A. Scherillo, X. Luo, and S.W. Cheong, Phys. Rev. Lett. 114, 23 (2015).
4) M.S. Senn, D.A. Keen, T.C.A. Lucas, J.A. Hriljac, and A.L. Goodwin, http://arxiv.org/abs/1512.03643 (2015).
On: January 22, 2016 From: 14h00 To: 15h30View talk