Regulation of Substituent Effects on Configurations and Magnetic Performances of Mononuclear DyIII Single-Molecule
Sheng Zhang1, Wenjiao Mo1, Jiangwei Zhang2
1College of Chemistry and Chemical Engineering , Baoji University of Arts and Sciences , Baoji 721013 , China.
Abstract:
A series of mononuclear DyIII compounds, [Dy(tmpd)3(4,4'-dmpy)] (1), [Dy(tffb)3(4,4'-dmpy)] (2), [Dy(tffb)3(5,5'-dmpy)] (3), and [Dy(tmpd)3(5,5'-dmpy)] (4) [tmpd = 4,4,4-trifluoro-1-(4-methoxyphenyl)-1,3-butanedione, tffb = 4,4,4-trifluoro-1-(4-fluorophenyl)-1,3-butanedione, 4,4'-dmpy = 4,4'-dimethyl-2,2'-bipyridyl, and 5,5'-dmpy = 5,5'-dimethyl-2,2'-bipyridyl], have been synthesized by modifying β-diketonate ligands and capping N-donor co-ligands. DyIII ions in 1-4 possess N2O6 octacoordinated environments. Compounds 1 and 2 exhibit distorted trigonal dodecahedron configurations, while 3 and 4 display distorted square antiprismatic configurations. Systematic investigations of the alternating current measurements indicate the different magnetic relaxation dynamics with energy barriers (Ueff) of 66 K (1, 45 cm-1), 189 K, (2, 131 cm-1), 115 K (3, 79 cm-1), and 205 K (4, 142 cm-1). To deeply understand their different magnetic behaviors, the magnetic anisotropies of 1-4 were studied by ab initio calculations. From ab initio calculations, the energies of the first excited state (KD1) are consistent with the experimental Ueff under zero direct current field. Compound 4 presents the largest Ueff because of the smallest g and μQTM as well as the most strong axial crystal field parameters (CFPs) among compounds 1-4. The M versus H data exhibit butterfly-shaped hysteresis loops at 2 K for 1-4. The different coordination geometries, the magnetic dynamics, the electrostatic repulsion, and CFPs result from the different substituent effects of ligands, including the electronic effect, the steric effect, and the positions of substituted groups.
More Related Videos
06:49Radio Frequency Magnetron Sputtering of GdBa2Cu3O7âˆ'ÃŽ ´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates
Published on: April 12, 2019
09:06Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope
Published on: March 24, 2019
Related Concept Videos
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
02:42Valence Bond Theory
01:27π Electron Effects on Chemical Shift: Overview
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...