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Miljanić Group Meeting / Literature University of Houston ▪ Houston, TX ▪ January 9 th 2009

A Nanoball Switch. Jaebum Lim. Miljanić Group Meeting / Literature University of Houston ▪ Houston, TX ▪ January 9 th 2009. Specialists in Monash University. Assoc. Prof. S. R . Batten. Prof. Keith S Murray PhD, Manc. 1966; FRACI Personal Chair in Chemistry, 1997 .

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Miljanić Group Meeting / Literature University of Houston ▪ Houston, TX ▪ January 9 th 2009

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  1. A Nanoball Switch • Jaebum Lim • Miljanić Group Meeting / Literature • University of Houston ▪ Houston, TX ▪ January 9th2009

  2. Specialists in Monash University Assoc. Prof. S. R. Batten Prof. Keith S Murray PhD, Manc. 1966; FRACI Personal Chair in Chemistry, 1997 Magnetic Materials Group Dr. Suzanne Neville Martin Duriska (PhD student) Dr. Boujemaa Moubaraki

  3. Melbourne Has Good Environment • • Melbourne is the second most populous city in Australia (3.8 million in 2007) • • Oceanic climate: 14–26 oCin summer; 6–13 oCin winter; 54 mm of precipitation • • The largest university in Australia is MonashUniversity • about 55,000 students, UH about 36,000 students • • The cultural and sport capital of Australia • Street Art in Melbourne, 1956 Summer Olympics games

  4. The Concept of Molecular Switch Is Simple • Molecular-switching can occur by spin-crossover (SCO) phenomenon • A crossover between a low-spin and a high-spinstate is observed from some molecular species containing an octahedrally coordinated transition metal ion with the 3dn (4 ≤ n ≤ 7) electronic configuration Kahn, O. C.; Martinez, J. Science, 1998, 279, 44–48. • When the compounds shows repetitive cycling of a metastable HS state (switching “on”) and a stable LS state (switching “off”) through external stimuli, they are able to behave like molecular switch Murray, K. S. et al.Angew. Chem. Int. Ed., 2008, 47, xxxx–xxxx.

  5. A New Nanoscale Molecular Switch Was Reported • This compound was made by using a “bottom-up” approach. • It shows a magnetic response to a range of external stimuli such as temperature, light, and solvent molecules. • An “on” or “off” magnetic state is able to be selected by wavelength variation. • Its possible application is a light-sensitive magnetic device. • The control of the electronic state is possible through solid-state guest exchange and removal. [{CuI(Tp4-py)(CH3CN)}8{FeII(NCS)2}10/3{FeII(NCS)(CH3CN)}8/3]∙(ClO4)8/3∙(CH3CN)n Murray, K. S. et al.Angew. Chem. Int. Ed., 2008, 47, xxxx–xxxx.

  6. Bottom-Up Approach to the Metal-Organic Nanoball a) ligand (Tp4-py)- b) metalloligand: [CuI(Tp4-py)(CH3CN) + CuI Batten, S. R. et. al.Dalton Trans.2005, 1910. + FeII(NCS)2 d) solid-state packing c) Supramolecular nanoball crystallization Murray, K. S. et al.Angew. Chem. Int. Ed., 2008, 47, xxxx–xxxx.

  7. Nanoball Structure as Determined by Single Crystal XRD (a) (d) (e) ORTEP representation (30%) of the asymmetric unit of the Fe-nanoball. [Fe(NCS)2(py)4] (left) and [Fe(NCS)(MeCN)(py)4] (right) Structural representation of one entire Fe-nano A rhombic dodecahedron The intersection of a cube and an octahedron Murray, K. S. et al.Angew. Chem. Int. Ed., 2008, 47, xxxx–xxxx.

  8. Important Detection Methods of SCO of Nanoball 1. Magnetic susceptibility study Plot of χMT versus temperature over the range 10 – 275 K for the thermal and LIESST effect. (○: thermal spin transition, ◊: irradiation at 532 nm followed by relaxation) a) Plot of χMT versus T per FeII ion for the CH3CN-sorbed (○) and desorbed species(●). b) Plot of χMT versus temperature per FeII ion for sorbed solvents: CH3CN (○), acetone (□), ethanol (△), and methanol (◊). Murray, K. S. et al.Angew. Chem. Int. Ed., 2008, 47, xxxx–xxxx.

  9. Important Detection Methods of SCO of Nanoball 2. Synchrotron Radiation Study Powder X-ray diffraction peak position evolution (240–80–240 K) showing the shift from HS to LS states. Associated with this change the sample goes from a yellow color in the HS state to purple in the LS state. Plot of the unit cell a-axis and volume versus temperature for each PXRD pattern fit (240-80 K) Murray, K. S. et al.Angew. Chem. Int. Ed., 2008, 47, xxxx–xxxx.

  10. Important Detection Methods of SCO of Nanoball 3. Spin Transition Curve 4. Mössbauer Spectroscopy Reversible switching between HS and LS states through stimulation with laser light – The LIESST effect. Green lines represent excitation and red lines represent extinction of the HS state. Mössbauer spectra of Fe-nano at (a) at liquid nitrogen (77 K) and (b) liquid helium (4.2 K) temperatures for the solvated sample and (c) at liquid helium (4.2 K) temperature for the desolvated sample. HS: red and LS: blue. Murray, K. S. et al.Angew. Chem. Int. Ed., 2008, 47, xxxx–xxxx.

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