Manipulating the Relaxation of Quasi-D_4d Dysprosium Compounds through Alternation of the O-Donor Ligands

Abstract

Three mononuclear Dy complexes with the same auxiliary ligand Lz (2,4-diamino-6-pyridyl-1,3,5-triazine), [Dy(TTA)Lz] (1Dy) (TTA = 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate), [Dy(acac)Lz]·CHOH·0.5HO (2Dy) (acac = acetylacetonate), and [Dy(MQ)Lz]Br·CHOH (3Dy) (HMQ = 2-methyl-8-quinolinol), have been synthesized through alteration of the ligands containing O donors. In all three complexes, the Dy ions are eight-coordinate and submitted to pseudo- D symmetry in the first coordination sphere. It is noteworthy that the TTA ligands in 1Dy are easily substituted by other bidentate capping ligands with O donors, leading to distinct magnetic properties, which were studied experimentally and via ab initio calculations. All three complexes were found to exhibit single-molecule magnet behavior with U of 22 cm (1Dy), 112 cm (2Dy), and 56 cm (3Dy) under zero applied dc field. Complex 1Dy demonstrates inferior SIM properties compared with 2Dy and 3Dy, which can be attributed to the strong electron-withdrawing effects of TTA ligands, as confirmed by theoretical calculations. However, butterfly-shaped magnetic hysteresis in 1Dy and 3Dy was observed at 1.9 K, while not in 2Dy.

Regulation of Substituent Effects on Configurations and Magnetic Performances of Mononuclear DyIIISingle-Molecule Magnets

“…As shown in our previous results, ,,, the electronic structure, suitable for promising SIM properties of the Dy III ion, could be approached via an electrostatic route because of the oblate electron density of the ground multiplet. , This means that the electrostatic repulsion along the direction of the easy axis, i.e., axial direction, should be stronger than along the other direction, i.e., equatorial direction, as much as possible. According to the ab initio magnetic easy axis (Figure ), the atoms of the first coordination spheres of the compounds studied here could be separated into axial ones and equatorial ones (Table ).…”

Synchronous Temperature and Magnetic Field Dual‐Sensing by Luminescence in a Dysprosium Single‐Molecule Magnet

“…Note that ab initio calculations on [Dy(acac) 3 (H 2 O) 2 ] complexes and related derivatives showed an energy difference between the ground and first doublets of about 150 cm −1 . [ 57–59 ] The discrepancy might be ascribed to a different geometry of the Dy 3+ ion. Since the spectrum of the complex is dominated by the 4 F 9/2 → 6 H 13/2 transition, a special emphasis was given to this region in the measurements performed changing T and H .…”

In Situ Ligand Formation in the Synthetic Processes from Mononuclear Dy(III) Compounds to Binuclear Dy(III) Compounds: Synthesis, Structure, Magnetic Behavior, and Theoretical Analysis

“…Because of the oblate electron density of the ground-state multiplet of the Dy­(III) ion, − a suitable electronic structure for a promising Dy SIM could be analyzed via an electrostatic route. ,− This means that the electrostatic repulsion (ESP) along the easy axis should be as strong as possible. The ab initio magnetic easy axes are shown in Figure .…”

“…With the atomic charges and lengths to the central Dy­(III) ion (Table ), we could estimate the ESP along the axial direction at a semiquantitative level. ,− As shown in Table , 1 has the largest value of ESP­(ax), suggesting that the ESP from the axial atoms of 1 is the strongest among all of the systems here. Thus, our semiquantitative analysis does support that 1 has the best SMM properties because of its best fulfillment of the electrostatic route.…”