Lanthanide(III) Hexanuclear Circular Helicates: Slow Magnetic Relaxation, Toroidal Arrangement of Magnetic Moments, and Magnetocaloric Effects

Jingjing Lu; Vincent Montigaud; Olivier Cador; Jianfeng Wu; Lang Zhao; Xiao-Lei Li; Mei Guo; Boris Le Guennic; Jinkui Tang

doi:10.1021/acs.inorgchem.9b01068

Lanthanide(III) Hexanuclear Circular Helicates: Slow Magnetic Relaxation, Toroidal Arrangement of Magnetic Moments, and Magnetocaloric Effects

Inorg Chem. 2019 Sep 16;58(18):11903-11911. doi: 10.1021/acs.inorgchem.9b01068. Epub 2019 Jun 13.

Authors

Jingjing Lu^{1

2}, Vincent Montigaud³, Olivier Cador³, Jianfeng Wu¹, Lang Zhao¹, Xiao-Lei Li¹, Mei Guo¹, Boris Le Guennic³, Jinkui Tang^{1

2}

Affiliations

¹ State Key Laboratory of Rare Earth Resource Utilization , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Changchun 130022 , P. R. China.
² School of Applied Chemistry and Engineering , University of Science and Technology of China , Hefei 230026 , P. R. China.
³ Univ Rennes, CNRS, ISCR (Institut des Sciences Chimiques de Rennes) - UMR 6226 , F-35000 Rennes , France.

PMID: 31192594
DOI: 10.1021/acs.inorgchem.9b01068

Abstract

Four hexanuclear circular helicates, {[Dy₆L₆(DMF)₁₂]·6CF₃SO₃·12DMF}₂ (1Dy), {[Gd₆L₆(DMF)₁₂]·6CF₃SO₃·12DMF}₂ (1Gd), [Dy₆L₆(DMF)₁₀(H₂O)₂]·6ClO₄·4H₂O·10DMF (2Dy), and [Gd₆L₆(DMF)₁₂]·6ClO₄·2H₂O·10DMF (2Gd), where DMF = N,N-dimethylformamide, were synthesized by employing a glutaratedihydrazide-bridged bis(3-methoxysalicylaldehyde) ligand (H₂L) and characterized structurally and magnetically. Direct-current magnetic susceptibility studies indicated predominant weak antiferromagnetic exchange interactions among gadolinium analogues, which were quantified using the PHI software, giving J = -0.003 cm^-1 with g = 2.00 for 1Gd and J = -0.001 cm^-1 with g = 2.02 for 2Gd. Alternating-current magnetic susceptibility measurements indicated that complexes 1Dy and 2Dy show slow relaxation of magnetization behavior, further supported by theoretical calculations that also highlighted the toroidal arrangement of the magnetic moments.