Kalendář akcí VŠCHT Praha

Unexpected Cooperativity in Multifunctional Fe(III) Spin Labile Systems

 

Datum: 15.1.2019  14:30 - 16:00      
Místo konání: posluchárna A02, budova A -Technická 5, VŠCHT Praha
Kategorie: Věda
Typ akce: Přednáška
Přednášející: prof. Paulo N. Martinho, Universidade de Lisboa
Jazyk akce: CZ
Popis:

Téma materiálů schopných spinového přechodu by mohlo zajímat všechny, kdo se zabývají novými materiály, ať už z hlediska základních poznatků nebo z hlediska aplikací.

Podrobná anotace

Spin crossover (SCO) complexes have long been considered as promising candidates for the next generation of data storage devices.[1,2] SCO candidate compounds can be found among a limited group of 3d4–3d7 transition metal ions, the most common being Fe(II), Fe(III) and Co(II). Fe(III), with its advantageous redox stability, is a good candidate for fabrication of SCO materials, an area towards which research has been moving.[3] Much effort has been expended in recent years to develop the materials assembly of SCO complexes and impressive results have been achieved in stabilising and isolating monodisperse nanoparticles, nanocrystals, nanowires, thin films, micro- and nanopatterned media, Langmuir- Blodgett surface mono- and multilayers and hysteretic soft media assemblies.

We recently synthesised mononuclear Fe(III) compounds, all displaying spin crossover, that show to be highly sensitive to the halogen substituent on the ligand. Spin crossover profiles range from stepped to abrupt, two of which display hysteresis centred at room temperature. We also found that while the bromo-substituted compound undergoes a phase transition coupled with the thermosalient effect (TSE) resulting in crystal fragmentation with no loss of both SCO and hysteresis,[4] the iodo-subsituted undergoes a irreversible TSE-SCO.[5]  We have also found that amphiphilic Fe(III) SCO compounds undergo self-aggregation in solution and form cooperative systems in dichloromethane.[6] Here I discuss the unexpected cooperative nature of these spin labile compounds and our attempts to fabricate materials with these compounds.

References

  1. O. Kahn and J. P. Launay, Chemtronics 3, 140-144, (1988).
  2. O. Kahn, J. Krober and C. Jay, Adv. Mater. 4, 718-728, (1992).
  3. M. A. Halcrow, Spin-Crossover Materials: Properties and Applications (John Wiley & Sons Ltd, 2013).
  4. A. I. Vicente, A. Joseph, L. P. Ferreira, M. D. Carvalho, V. H. N. Rodrigues, M. Duttine, H. P. Diogo, M. E. M. da Piedade, M. J. Calhorda, P. N. Martinho, Chem. Sci. 7, 4251-4258 (2016).
  5. F. F. Martins, A. Joseph, H. P. Diogo, M. E. Minas da Piedade, L. P. Ferreira, M. D. Carvalho, S. Barroso, M. J. Romão, M. J. Calhorda, P. N. Martinho, Eur. J. Inorg. Chem., 2018, 2976-2983 (2018).
  6. A. I. Vicente, X. Wu, Y. Ortin, L. P. Ferreira, S. Realista, A. O’Connor, G. G. Morgan, N. Galamba, P. J. Costa, M. J. Calhorda, P. N. Martinho, under revision.
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