Dinuclear Tb and Dy complexes supported by hybrid Schiff-base/calixarene ligands: synthesis, structures and magnetic properties. Issue 31 (28th July 2020)

• Record Type: Journal Article
• Authors: Hahn, Peter; Ullmann, Steve; Klose, Jennifer; Peng, Yan; Powell, Annie K.; Kersting, Berthold
• Is Part Of: Dalton transactions. Volume 49:Issue 31(2020)
• Page Start: 10901
• Page End: 10908
• Publication Date: 2020-07-28
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0dt02209h
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The anisotropy barrier for relaxation of magnetization of Dy 3+ Schiff-base/calix[4]arene complexes increases significantly upon going from NO6 to N2 O5 donor sets. Abstract : The synthesis of the new lanthanide complexes [HNEt3 ][Dy2 (HL 1 )(L 1 )] (5 ), and [Ln2 (L 2 )2 ] (Ln = Tb III (7 ), Dy III (8 )) supported by the hybrid Schiff-base/calix[4]arene ligands H4 L 1 (25-[2-((2-methylphenol)imino)ethoxy]-26, 27, 28-trihydroxy-calix[4]arene) and H3 L 2 (25-[2-((2-methylpyridine)imino)ethoxy]-26, 27, 28-trihydroxy-calix[4]arene) are reported. Spectroscopic data (for 5 ) and X-ray crystallographic analysis (for 7 ·4MeCN, 8 ·4MeCN) reveal the presence of dimeric structures, featuring doubly-bridged NO4 Ln(μ-O)2 LnO4 N (5 ) or N2 O3 Ln(μ-O)2 LnO3 N2 cores (7, 8 ) with seven-coordinated Ln 3+ ions. The magnetic properties of polycrystalline samples of 5, 7 and 8 were studied by variable temperature dc and ac magnetic susceptibility measurements. The χ ′′( T ) vs. T plots show no maxima in zero field, but the maxima can be detected under a 3 kOe dc field. The relaxation times τ obey the Arrhenius law above 5 K. Anisotropy barriers of ∼18 cm −1 (26 K) for 5 and ∼23 cm −1 (33 K) for 8 were determined.