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Viewing upcoming talks containing the keyword: 8
Speaker: Neil Champness (RSC Surfaces and Interfaces Award Winner) (Nottingham)
Molecular Organisation: Working with Molecules on the Nanoscale Neil R. Champness School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, UK Non -covalent directional intermolecular interactions provide a pre -determined recognition pathway which has been widely exploited in supramolecular chemistry to form functional nanostructures in both solution and in the solid -state. Our studies using hydro gen -bonding interactions to enable the directed assembly of extended nanostructures will be presented and in particular t he lecture will focus on our work investigating surface -based self -assembly processes. The talk will includ e studies that demonstrate u nprecedented control of supramolecular topology (Fig. i) 2 the first direct observation of a molecular -scale glass (Fig. ii) 3 and the generation of a new class of porphyrin molecular tiles that are functionalised with DNA bases. Most importantly our work es tablishes a direct connection between supramolecular chemistry and nanostructure fabrication. Figure: i STM image of a surface supramolecular framework hosting heptamers of C 60 molecules; 1 ii random rhombus tiling demonstrated using tetracarboxylic acid molecules ;2 iii NC -AFM image of a hydrogen -bonded array with sub -molecular detail. 4
1. J.A. Theobald, N.S. Oxtoby, M.A. Phillips, N.R. Champness, P.H. Beton, Nature , 2003, 424 , 1029 ; 2. M.O. Blunt, J. Russell, M.C. Giménez -López, J.P. Garrahan , X. Lin, M. Schröder, N.R. Champness, P.H. Beton, Science , 2008, 322 , 1077 ;3. A.G. Slater, Y. Hu, L. Yang, S.P. Argent, W. Lewis, M.O. Blunt, N.R. Champness, Chem. Sci ., 2015, 6, 1562 ; 4. A. M. Sweetman, S. Jarvis, H. Sang, I. Lekkas, P.Rahe , Y. Wang, J. Wang, N.R. Champness, L. Kantorovich, P.J. Moriarty, Nature Commun ., 2014, 5, 3931 . Download PDF
On: November 23, 2016 From: 15h30 To: 16h30View talk
Physics and Astronomy Colloquia
Speaker: Ilya Kuprov (University of Southhampton)
Pseudocontact shift (PCS) is an additional chemical shift caused by the presence of a rapidly relaxing paramagnetic centre near the nucleus. PCS is well understood theoretically and is widely employed as a source of structural restraints in metalloproteins, where commonly occurring Ca2+, Mg2+, Mn2+ and Zn2+ binding sites can often coordinate a lanthanide ion instead. A paramagnetic centre may also be introduced artificially by attaching a lanthanide ligand tag to the protein surface.
The subject has a long-standing problem â€“ lanthanide-containing protein tags have significant conformational mobility. Even DOTA-M8, which uses a sterically overcrowded â€“ and therefore rigid â€“ metal cage, still has a flexible linker. The conformational mobility of lanthanide tags is visible in the distance distributions measured by double electron resonance, and in molecular dynamics simulations. In this situation the commonly used point paramagnetic centre approximation for PCS is not expected to be valid, but quantum chemical calculations are prohibitively expensive.
In this talk I will describe a new method for extracting probability densities of lanthanide tags from PCS data. The method relies on Tikhonov-regularised 3D reconstruction and opens a new window into biomolecular structure and dynamics because it explores a very different range of conditions from those accessible to double electron resonance work on paramagnetic tags: a room-temperature solution rather than a glass at cryogenic temperatures. The method is illustrated using four different Tm3+ DOTA-M8 tagged mutants of human carbonic anhydrase II; the results are in excellent agreement with rotamer library and DEER data.
The wealth of high-quality pseudocontact shift data accumulated by the biological magnetic resonance community over the last 30 years, and so far only processed using point models, could now become a major source of useful information in conformational dynamics research.
On: November 25, 2016 From: 10h00 To: 11h00View talk
Cond Mat Seminars
Speaker: S. Thomson / S. Edkins (St Andrews)
Disordered Quantum Systems: From Ultracold Atoms to Dimerised Magnets and Back AgainNothing in life is perfect and whatâ€™s true in life is true for quantum materials. Disorder and impurities are present in every substance, no matter how much we try to avoid them, but sometimes these imperfections can lead to useful quantum mechanical effects.In this talk, Iâ€™ll summarise the main parts of my PhD research, telling the story of an unusual disordered phase of matter where insulating and superfluid regions coexist within a single sample. This phase is known as the Bose glass and is most conveniently realised in ultracold atomic gases. Iâ€™ll show how some of my work revealed this phase to be more exotic than previously thought, and how by chance some of my later research on insulating antiferromagnets turned out to rely crucially on a controversial claim made in my earlier work on ultracold atoms. Iâ€™ll then show how weâ€™ve recently proposed a new way for quantum gas microscopes to test these predictions, and outline where we go from here.
Detection of a Cooper-Pair Density Wave in Bi2Sr2CaCu2O8 using Scanned Josephson TunnellingThe quantum condensate of Cooper-pairs forming a superconductor was originally conceived to be translationally invariant. In theory, however, pairs can exist with finite momentum Q resulting in a new state with spatially modulating Cooper-pair density. This is the famous FFLO state [1,2] which has never been directly observed in any superconductor. Research has recently refocused on FFLO type physics because the cuprate pseudogap phase is hypothesised to contain a closely related â€˜pair density waveâ€™ state.
I will report on the use of scanned Josephson tunnelling microscopy (SJTM) to image Cooper-pair tunnelling from a d-wave superconducting STM tip at millikelvin temperatures to the Cooper-pair condensate of Bi2Sr2CaCu2O8. The resulting images of the Cooper-pair condensate show clear pair density modulations oriented along the Cu-O bond directionsÂ .
I will discuss the implications of this discovery for the microscopic theory of the cuprate pseudogap phase as well as the extension of SJTM to other emergent intertwined phases and quantum devices.
 P. Fulde and R.A. Ferrell, Phys. Rev. 135: A550 (1964). A.I. Larkin, Yu.N. Ovchinnikov, Sov. Phys. JETP 20, 762 (1965). M. HamidianÂ & S. D .EdkinsÂ et al. Nature 532, 343 (2016).
On: November 29, 2016 From: 15h00 To: 16h00View talk
Speaker: GonÃ§alo Bernardes (RSC Harrison-Meldola Memorial Prize Winner) (University of Cambridge)
Chemi cal Pharmacology of Protein Conjugates and Natural Products Gonçalo J. L. Bernardes University of Cambridge, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK, firstname.lastname@example.org Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, 1649 -028 Lisboa, Portugal , gbernardes@medicin a.ulisboa.pt Our work centers on reaction engineering for site -selective chemical protein modification and its use to provide insight into biology and for the development of protein therapeutics. 1 This lecture will cover recent examples of emerging areas in our group in: (i) site -selective chemical modification of proteins at cysteine and lysine , (ii) bioorthogonal labeling of specific protein targets in live cells , (iii) a new method for histidine -metallation of proteins with a [Ru(CO) 2]2+ fragment that yields artificial metalloproteins that are able to deliver CO in vivo in a controlled manner , (iv) CO -mediated immunomodulat ion for cancer therapy, and (v) the exploitation of natural product scaffol ds for targeting of calcium channels overexpressed in cancer cells.
(1) Krall, N.; da Cruz, F.P.; Boutureira, O.; Bernardes, G.J.L. Nat. Chem. 2016 , 8, 103 . Download PDF
On: January 11, 2017 From: 15h30 To: 16h30View talk
Speaker: Justin Hodgkiss (RSC Easterfield Prize Winner 2015) (Wellington)
Next generation photovoltaic materials, including polymers and organometal halide perovskites, offer tremendous potential for low cost clean energy. However, the design of more effective materials is hindered by lack of understanding of the mechanisms by which these complex and disordered materials convert light to electricity. We have developed a series of time-resolved optical spectroscopy experiments that resolve different properties of photoexcitations in these materials. In this talk, I will review some of our recent insights from ultrafast spectroscopy. In organic semiconductors, these highlights include evidence for ultrafast long-range charge separation,1 as well as the roles of delocalised excitons2 and disordered phases,3 ultrafast light harvesting,4 and singlet exciton fission.5 The organic materials will be contrasted with efficient organometal halide perovskites, where we find efficient free charge photogeneration.6,7
1.Â Â Â Â A. J. Barker, K. Chen, J. M. Hodgkiss J. Am. Chem. Soc. 2014, 136, 12018â€“12026.
2.Â Â Â Â K. Chen, A. J. Barker, M. E. Reish, K. C. Gordon, J. M. Hodgkiss J. Am. Chem. Soc. 2013, 135, 18502-18512.
3.Â Â Â Â J. K., Gallaher, S. K. K. Prasad, W. Lee, M. A. Uddin, J.-Y. Kim, H. Y. Woo, J. M. Hodgkiss, Energy Environ. Sci., 2015. 8, 2713-2724.
4.Â Â Â Â J. E. A. Webb, K. Chen, S. K. K. Prasad, J. P. Wojciechowski, A. Falber, P. Thordarson, J. M. Hodgkiss Phys. Chem. Chem. Phys. 2016, 18, 1712.
5.Â Â Â Â S. Lukman,Â A. J. Musser,Â K. Chen,Â S. Athanasopoulos,Â C. K. Yong,Â Z. Zeng,Â Q. Ye,Â C. Chi,Â J. M. Hodgkiss,Â J. Wu, R. H. FriendÂ N. C. Greenham, Adv. Funct. Mat., 2015, 25, 5452â€“5461.
6.Â Â Â Â K. Chen, A. J. Barker, F. L. C. Morgan, J. E. Halpert, J. M. Hodgkiss J. Phys. Chem. Lett. 2015, 6, 153-158.
7.Â Â Â Â M. Price, J. Butkus, T. C. Jellicoe, A. Sadhanala, A. Briane, J. E. Halpert, K. Broch, J. M. Hodgkiss, R. H. Friend, F. Deschler Nature Comm. 2015. 6, 8420.
On: January 13, 2017 From: 15h30 To: 16h30View talk
Speaker: Paul Attfield (Edinburgh)
Magnetic oxides revisited - new insights into manganites and magnetite J. Paul Attfield Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ, UK . email@example.com
Manganes e and iron based oxides a re important magne tic materials and continue to inspire new chemistry and electronic properties research . ‘Manganites’ are traditionally AMnO 3 perovskites such as La 0.7 Sr 0.3 MnO 3 with high Curie temperatures that show large magnetor esistances. High pressure has recently been used to synthesise new ‘A -site manganites’ with Mn 2+ cations at the A -sites. MnVO 3 perovskite has a helical spin order . Mn 2FeReO 6 has a high Curie temperature of 520 K and similar ferrimagnetic and spin -pola rised conducting properties to the much -studied magnetoresistive double perovskite Sr 2FeMoO 6, but also shows a novel switch from negative to large positive magnetoresistances at low temperatures driven by Mn 2+ spin ordering.  In contrast, Mn 2MnReO 6 (Mn 3ReO 6) shows successive antiferromagnetic ordering transitions for Re and Mn spins at 99 and 109 K respectively.  Investigation of possible rare earth (R) analogues has led to discovery of a new ‘double double perovskite’ type MnRMnSbO 6 (R = La, Pr, Nd, Sm) with simultaneous 1:1 cation order at both A and B sites [4 ].
Magnetite (Fe 3O4) is the original magnetic material and undergoes the complex Verwey structural distortion below 125 K. Determination of the full superstructure showed that charge order ing occurs , with a pronounced orbital ordering of Fe 2+ states, but an unexpected localization of electrons in linear, three -Fe ‘trimeron’ units was also discovered [5 ,6]. Trimerons are examples of orbital molecules, weakly bonded clusters of transition metal ions within an orbitally ordered solid . Recent studies of the orbital molecule orders in synthetic and natural magnetites [8,9], and related materials will be presented.
Our work on the magnetite structure has led to the development of a general new ellipsoidal method for analysing distorted polyhedra that will also be presented .
1. M. Markkula, A.M. Arevalo -Lopez, A. Kusmartseva, J.A. Rodgers, C. Ritter, H. Wu and J.P. Attfield. Phys. Rev. B 84, 094450 ( 2011). 2. Arévalo -López A.M., McNally G.M., Att field J.P. Angew. Chem. 54, 12074 (2015). 3. A. M. Arévalo -López, F. Stegemann, J. P Attfield. Chem . Comm . 2016, 52 , 5558. 4. E. Sola na -Madruga, Á. M. Arévalo -López, A. J. Dos Santos -García, E. Urones - Garrote, D. Ávila -Brande, R. Sáez -Puche, J. P. Attfield. Angew. Chem. 55, 9340 (2016). 5. Senn, M.S., Wright, J.P. & Attfield J.P. (2012), Nature 481, 173 -176. 6. Senn, M.S., Loa, I., Wright, J .P. & Attfield J.P. (2012). Phys. Rev. B 85, 125119. 7. J. P . Attfiel d (2015). Applied Physics Letters Materials 3, 041510. 8. Senn, M.S., Wright, J.P. , Cumby, J. & Attfield J.P. (2015 ). Phys. Rev. B 92 , 024104 . 9. G. Perversi , J Cumby , E. Pachoud , J. P. Wright, J. P. Attfield (2016). Chem. Comm. 52, 4864 -4867. 10. J. Cumby and J.P. Attfield. Nature Comm. (2017). Download PDF
On: February 1, 2017 From: 15h30 To: 16h30View talk