title: Dysprosium(III) complexes with a square-antiprism configuration featuring mononuclear single-molecule magnetic behaviours based on different β-diketonate ligands and auxiliary ligands.
abstract: Three mononuclear dysprosium(III) complexes derived from three β-diketonate ligands, 4,4,4-trifluoro-1-(4-methylphenyl)-1,3-butanedione (tfmb), 4,4,4-trifluoro-1-(4-fluorophenyl)-1,3-butanedione (tffb) and 4,4,4-trifluoro-1-(2-naphthyl)-1,3-butanedione (tfnb) as well as auxiliary ligands, 5-nitro-1,10-phenanthroline (5-NO2-Phen), DMF and 2,2'-bipyridine (bpy) have been synthesized and structurally characterized, namely [Dy(5-NO2-Phen)(tfmb)3] (1), [Dy(DMF)2(tffb)3] (2) and [Dy(bpy)2(tfnb)3]·0.5(1,4-dioxane) (3). The metal ions in 1-3 adopt an approximately square-antiprismatic (SAP) coordination environment with D4d axial symmetry. The magnetic properties of 1-3 have been investigated, displaying weak out-of-phase AC signals under a zero-DC field. With an applied DC field of 1200 Oe, the quantum tunnelling of the magnetization was suppressed in 1-3 with the pre-exponential factor τ0 = 5.3 × 10(-7) s and the effective barrier ΔE/kB = 83 K for 1 as well as the pre-exponential factor τ0 = 3.09 × 10(-7) s and the effective barrier ΔE/kB = 39 K for 3. Interestingly, for the frequency dependence of the out-of-phase (χ'') of the AC susceptibility of 2, two slow relaxation of the magnetization processes occurred under the applied magnetic field of 1200 Oe, corresponding to the fast relaxation (FR) phase and slow relaxation (SR) phase, respectively. Arrhenius analysis gave the effective energy barrier (ΔE/kB) of 55 K and the pre-exponential factor (τ0) of 8.23 × 10(-12) for the SR. It is thus very likely that the FR process in complex 2 results from QTM enhanced by dipolar interactions between the Dy ions or the presence of the applied field. The structure-property relationship of some Dy(III) based mononuclear SMMs with the SAP configuration was further discussed.
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, Shaanxi 710069, China. sanpingchen@126.com and College of Chemistry and Chemical Engineering, Baoji University of Arts and Sciences, Baoji 721013, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, Shaanxi 710069, China. sanpingchen@126.com.
authors.forename: Hongshan
authors.initials: H
authors.lastname: Ke
authors.affiliation: Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023, China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Shi
authors.affiliation: Department of Chemistry, Tsinghua University, Beijing 100084, China.
authors.forename: Jangwei
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, Shaanxi 710069, China. sanpingchen@126.com.
authors.forename: Qi
authors.initials: Q
authors.lastname: Yang
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, Shaanxi 710069, China. sanpingchen@126.com.
authors.forename: Qing
authors.initials: Q
authors.lastname: Wei
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, Shaanxi 710069, China. sanpingchen@126.com.
authors.forename: Gang
authors.initials: G
authors.lastname: Xie
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, Shaanxi 710069, China. sanpingchen@126.com.
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Wang
authors.affiliation: College of Chemistry and Chemical Engineering, Baoji University of Arts and Sciences, Baoji 721013, China.
authors.forename: Desuo
authors.initials: D
authors.lastname: Yang
authors.affiliation: Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, Shaanxi 710069, China. sanpingchen@126.com.
authors.forename: Sanping
authors.initials: S
authors.lastname: Chen