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Schegolev Memorial Symposium Chernogolovka, Russia, 12-15 October 2009

Schegolev Memorial Symposium Chernogolovka, Russia, 12-15 October 2009 Organic-Inorganic Layer Salts as Molecular Functional Materials: Multilayers and Chirality. Peter Day UCL and Royal Institution, London, UK. Layered structures – foundation of micro-electronics (MOS etc).

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Schegolev Memorial Symposium Chernogolovka, Russia, 12-15 October 2009

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  1. Schegolev Memorial Symposium Chernogolovka, Russia, 12-15 October 2009 Organic-Inorganic Layer Salts as Molecular Functional Materials: Multilayers and Chirality Peter Day UCL and Royal Institution, London, UK

  2. Layered structures – foundation of micro-electronics (MOS etc) • Fabricated by ‘top down’ methods Molecular beam epitaxy Laser ablation Spin coating etc etc • But is it possible to make multilayers by self-assembly? YES

  3. A self-assembled multilayer Insulating layer Metallic layer Insulating layer

  4. An old story of layers – soluble ferromagnets (CnH2n+1NH3)2CrX4 Bellitto and Day 1978

  5. Halide Layer Conductors –from metals to insulators Mitzi et al. 1995

  6. Conducting multilayers –BEDT-TTF charge transfer salts The BEDT-TTF molecule Electrochemical crystal growth

  7. Organic-Inorganic Charge Transfer SaltsFirst paramagnetic molecular superconductorb”-(ET)4[(H3O)Fe(C2O4)3].C6H5CN Day, Kurmoo, Graham 1995

  8. What we want to do next…. First objective - Superlattices of layers D+X- salts form layers: DXDXDX…. Make e.g.DXD’XDXD’X…. D, D’– same molecule, different packing D, D’– different molecules

  9. Multi-layers means multi-functions….An early example of DXD’X… stackingab”(ET)4[(H3O)Ga(C2O4)3].PhCH2CN X D’ D D X Akutsu, Day et al. 2003

  10. Different layers have different functionsmetallic proton conductorH3O+-crown ether layer:– proton conductingET layer:– electron conducting Akutsu, Day et al. 2005

  11. Superstructure with purely inorganic layer Na+ and H2O Martin, Day et al 2007

  12. Second objective - Chiral organic-inorganicmultilayers Why? Maybe novel properties – magneto-chiral anisotropy (Rikken) chiral Fermi surface? chiral superconductor?? How? chiral anions chiral donor molecules chiral guest molecules chiral solvents

  13. Chiral anions – [M(C2O4)3]3-b”-(ET)4[M(C2O4)3]C6H5CNEach anion layer contains one enantiomer Day, Kurmoo, Graham 1995

  14. Chiral anions – [M(C2O4)3]3-Two polymorphs of (ET)4[(H3O)M(C2O4)3]C6H5CNC2/c is superconducting; Pbcn is semiconducting! Anion layers Cation layers Turner, Day, Howard et al 2001

  15. chiral tetra(methyl)-BEDT-TTF Incorporating a chiral donor molecule b”-(TM-ET)2.7[MnCr(C2O4)3]CH2Cl2 Ferromagnetic Metallic Ferromagnetic Gomez-Garcia, Giminez-Sal, Wallis & Coronado 2007

  16. Chiral guest molecules - DXD’X superstructure (R)- and (S)-sec-phenyl alcohol Martin, Day, Akutsu et al 2007

  17. Anion layers contain NH4+, [Fe(C2O4)3]3- and guest molecules Martin, Day, Akutsu et al 2007

  18. Crystals with chiral (R)- or racemic (R,S)- guest molecules Single crystal resistivities (R) (R,S) Disorder of guest molecules in (R,S)- crystal Martin, Day, Akutsu et al 2007

  19. Chiral solvent Crystallising (NH4)3[Fe(C2O4)3] with 18C6 gives chiral [(NH4)(18C6)]3[Fe(C2O4)3].9H2O containing only one enantiomer of the anion. Helical array of [(NH4)(18C6)]+ [Fe(C2O4)3]3- and H2O

  20. In an achiral solvent the same reactants crystallize in a racemic polymorph with a different structure[(NH4)(18C6)]3[Fe(C2O4)3].6H2O Martin 2008

  21. ET salts from chiral solvent:ET3[(Na)D-Cr(C2O4)3].CH2Cl2 Martin, Day et al, 2009

  22. ET3[(Na)D-Cr(C2O4)3].CH3NO2Polymorph I – P212121 ET layer Anion layer Martin Martin, Day et al 2009

  23. ET3[(Na)D-Cr(C2O4)3].CH3NO2Polymorph 2 – P21 Anion layer ET layer Martin, Day et al 2009

  24. What have we learned? • Multi-layers of alternating organic and inorganic components can be crystallized with defined superstructures. • Each layer can have its own properties (metallic, superconducting, magnetic etc). • Chirality can be built into the structures by crystal engineering.

  25. Collaborators • Lee Martin, NottinghamTrent University, UK - synthesis, structures and properties • Hiroki Akutsu; Akane Akutsu-Sato, Hyogo University, Japan – structures and properties • John Wallis, Nottingham Trent University, UK – new donor molecules • Mike Hursthouse; Peter Horton; Sussex University, UK – crystal structures • Carlos Gomez, Valencia University, Spain – physical properties • Amalia Coldea, Bristol University, UK – magnetoresistance

  26. Our funding • Engineering and Physical Sciences Research Council (UK) • European Commission: MAGMANet; COST D35 • Royal Society (UK)-JSPS (Japan)

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