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SUMMARY:MAGNETIC BLOCKING AND LARGE COERCIVITY IN LANTHANIDE-BASED  SINGLE
 -MOLECULE MAGNETS - Selvan Demir - University of Göttingen\, Institute of
  Inorganic Chemistry
DTSTART:20181108T140000Z
DTEND:20181108T150000Z
UID:TALK113542@talks.cam.ac.uk
CONTACT:Dr. Hugo Bronstein
DESCRIPTION:Molecules that possess an energy barrier to spin inversion hav
 e intriguing potential applications in areas such as magnetic refrigeratio
 n\, molecular spintronics and high-density information storage. For these 
 applications\, however\, key performance characteristics such as large spi
 n-relaxation barriers and high magnetic blocking temperatures are required
 . Lanthanides have been proven to be particularly well-suited for the desi
 gn of single-molecule magnets owing to their large magnetic moments and ma
 gnetic anisotropy that stem from strong spin-orbit coupling of the 4f orbi
 tals. By using lanthanide ions such as Tb3+\, Dy3+\, and Er3+ which posses
 s intrinsically large orbital angular momentum\, significantly higher barr
 iers and blocking temperatures can be achieved. A general methodology to e
 nhance single-molecule magnet properties in mononuclear lanthanide complex
 es comprises matching the ligand field symmetry with the anisotropic elect
 ron density distribution of the maximal MJ state. Employing this methodolo
 gy\, we will present the synthesis of mononuclear rare-earth metallocene c
 omplexes that function as new f-metal-based single-molecule magnets [1-3].
  Another particularly successful approach to improve blocking temperatures
  is to generate strong magnetic exchange between lanthanide centers throug
 h the employment of radical bridging ligands. If the magnetic exchange cou
 pling is large enough then quantum tunneling of the magnetization can be a
 ttenuated. Here\, we will further present the synthesis of multiple bimeta
 llic radical-bridged lanthanide-based single-molecule magnets and describe
  effective suppression of quantum tunneling pathways using various organic
  bridging radical ligands [4-7]. In addition\, we combine both methodologi
 es and demonstrate with the first series of N23- radical-bridged metalloce
 ne complexes that the combination of axial magnetic anisotropy provided by
  the cyclopentadienyl ligands with the strong magnetic exchange coupling e
 nabled by the inorganic N23- radical results in exceptionally large magnet
 ic hysteresis loops which remain open up to high temperatures\, Figure 1.[
 8]\n\n\nReferences \n[1-3] Demir et al.\, Chem. Eur. J.\, 2014\, 31\, 9524
 −9529\; Inorg. Chem.\, 2017\, 56\, 15049−15056\; J. Organomet. Chem.\,
  2018\,857\, 164−169.\n[4-7] Demir et al.\, J. Am. Chem. Soc.\, 2012\, 1
 34\, 18546−18549\; Chem. Sci.\, 2014\, 5\, 4701−4711\; Coord. Chem. Re
 v.\, 2015\, 289−290\, 149−176\; manuscripts in preparation. \n[8] Demi
 r et al.\, Nat. Commun.\, 2017\, 8\, 2144.\n\n
LOCATION:Wolfson Lecture Theatre\,  Department of Chemistry\, Lensfield Ro
 ad
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