TY - JOUR
T1 - Cyanide Single-Molecule Magnets Exhibiting Solvent Dependent Reversible "on" and "off" Exchange Bias Behavior
AU - Pinkowicz, Dawid
AU - Southerland, Heather I.
AU - Avendaño, Carolina
AU - Prosvirin, Andrey
AU - Sanders, Codi
AU - Wernsdorfer, Wolfgang
AU - Pedersen, Kasper S.
AU - Dreiser, Jan
AU - Clérac, Rodolphe
AU - Nehrkorn, Joscha
AU - Simeoni, Giovanna G.
AU - Schnegg, Alexander
AU - Holldack, Karsten
AU - Dunbar, Kim R.
PY - 2015/11/6
Y1 - 2015/11/6
N2 - The syntheses, structures, and magnetic properties of four new complex salts, (PPN){[MnIII(salphen)(MeOH)]2[MIII(CN)6]}·7MeOH (Mn2M·7MeOH) (M = Fe, Ru, Os and Co; PPN+ = bis(triphenylphosphoranylidene)ammonium cation; H2salphen = N,N′-bis(salicylidene)-1,2-diaminobenzene), and a mixed metal Co/Os analogue (PPN){[MnIII(salphen)(MeOH)]2[CoIII0.92OsIII0.08(CN)6]}·7MeOH were undertaken. It was found that all compounds exhibit switchable single-molecule magnet (SMM) and exchange-bias behavior depending on the interstitial methanol content. The pristine (PPN){[Mn(salphen)(MeOH)]2[Os(CN)6]}·7MeOH (Mn2Os·7MeOH) behaves as an SMM with an effective barrier for the magnetization reversal, (Ueff/kB), of 17.1 K. Upon desolvation, Mn2Os exhibits an increase of Ueff/kB to 42.0 K and an opening of the hysteresis loop observable at 1.8 K. Mn2Os·7MeOH shows also exchange-bias behavior with magnetic hysteresis loops exhibiting a shift in the quantum tunneling to 0.25 T from zero-field. The FeIII and RuIII analogues were prepared as reference compounds for assessing the effect of the 5d versus 4d and 3d metal ions on the SMM properties. These compounds are also SMMs and exhibit similar effects but with lower energy barriers. These findings underscore the importance of introducing heavy transition elements into SMMs to improve their slow relaxation of the magnetization properties. The (PPN){[MnIII(salphen)(MeOH)]2[CoIII(CN)6]}·7MeOH (Mn2Co·7MeOH) analogue with a diamagnetic CoIII central atom and the mixed Co/Os (PPN){[MnIII(salphen)(MeOH)]2[CoIII0.92OsIII0.08(CN)6]}·7MeOH (Mn2Co/Os·7MeOH) "magnetically diluted" system with a 9:1 Co/Os metal ratio were prepared in order to further probe the nature of the energy barrier increase upon desolvation of Mn2Os. In addition, inelastic neutron scattering and frequency-domain Fourier-transform THz electron paramagnetic resonance spectra obtained on Mn2Os·7MeOH and Mn2Os in combination with the magnetic data revealed the presence of anisotropic exchange interactions between MnIII and OsIII ions.
AB - The syntheses, structures, and magnetic properties of four new complex salts, (PPN){[MnIII(salphen)(MeOH)]2[MIII(CN)6]}·7MeOH (Mn2M·7MeOH) (M = Fe, Ru, Os and Co; PPN+ = bis(triphenylphosphoranylidene)ammonium cation; H2salphen = N,N′-bis(salicylidene)-1,2-diaminobenzene), and a mixed metal Co/Os analogue (PPN){[MnIII(salphen)(MeOH)]2[CoIII0.92OsIII0.08(CN)6]}·7MeOH were undertaken. It was found that all compounds exhibit switchable single-molecule magnet (SMM) and exchange-bias behavior depending on the interstitial methanol content. The pristine (PPN){[Mn(salphen)(MeOH)]2[Os(CN)6]}·7MeOH (Mn2Os·7MeOH) behaves as an SMM with an effective barrier for the magnetization reversal, (Ueff/kB), of 17.1 K. Upon desolvation, Mn2Os exhibits an increase of Ueff/kB to 42.0 K and an opening of the hysteresis loop observable at 1.8 K. Mn2Os·7MeOH shows also exchange-bias behavior with magnetic hysteresis loops exhibiting a shift in the quantum tunneling to 0.25 T from zero-field. The FeIII and RuIII analogues were prepared as reference compounds for assessing the effect of the 5d versus 4d and 3d metal ions on the SMM properties. These compounds are also SMMs and exhibit similar effects but with lower energy barriers. These findings underscore the importance of introducing heavy transition elements into SMMs to improve their slow relaxation of the magnetization properties. The (PPN){[MnIII(salphen)(MeOH)]2[CoIII(CN)6]}·7MeOH (Mn2Co·7MeOH) analogue with a diamagnetic CoIII central atom and the mixed Co/Os (PPN){[MnIII(salphen)(MeOH)]2[CoIII0.92OsIII0.08(CN)6]}·7MeOH (Mn2Co/Os·7MeOH) "magnetically diluted" system with a 9:1 Co/Os metal ratio were prepared in order to further probe the nature of the energy barrier increase upon desolvation of Mn2Os. In addition, inelastic neutron scattering and frequency-domain Fourier-transform THz electron paramagnetic resonance spectra obtained on Mn2Os·7MeOH and Mn2Os in combination with the magnetic data revealed the presence of anisotropic exchange interactions between MnIII and OsIII ions.
UR - http://www.scopus.com/inward/record.url?scp=84947773666&partnerID=8YFLogxK
U2 - 10.1021/jacs.5b09378
DO - 10.1021/jacs.5b09378
M3 - Article
AN - SCOPUS:84947773666
SN - 0002-7863
VL - 137
SP - 14406
EP - 14422
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 45
ER -