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Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
Published on: July 4, 2016
The Relevance of Non-Axiality and Low-Lying Excited States for Slow Magnetic Relaxation in Pentagonal-Bipyramidal
Jan Arneth1, Lena Spillecke1, Changyun Koo1,2
1Kirchhoff Institute for Physics, Heidelberg University, INF 227, D-69120, Heidelberg, Germany.
Abstract:
High-frequency/high-field electron paramagnetic resonance studies on a series of seven-coordinate pentagonal-bipyramidal (PBP) erbium(III) complexes Er(DAPMBH/H2DAPS)X (H2DAPMBH = 2,6-diacetylpyridine bis-4-methoxy benzoylhydrazone, H4DAPS = 2,6-diacetylpyridine bis-(salicylhydrazone)) demonstrate the effects of different apical ligands (X = (H2O)Cl (1), (CH3OH)N3 (2), Cl2 (3)) on the local magnetic anisotropy of the central ErIII ions. In particular, we report direct experimental determination of the effective g-values and zero field splittings of the energetically low-lying Kramers doublets. Our quantitative determination of the magnetic anisotropy highlights the relevance of an axial g-tensor for SMM behavior and suggests that fast magnetic relaxation is mainly driven by a thermally assisted quantum tunnelling process via low-lying excited states.
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