Effect of Second-Sphere Interactions on the Magnetic Anisotropy of Lanthanide Single-Molecule Magnets: Electrostatic Interactions and Supramolecular Contacts

Abstract

To study how second-sphere interactions affect single-molecule magnet (SMM) properties of mononuclear lanthanide systems, two dysprosium­(III) complexes [Dy­(N-NCS)3(H2O)5]·0.45­(KSCN)­(18-crown-6) (1) and [Dy­(NO3)2(N-NCS)3(H2O)]·(H2O)­(NH4)22­(18-crown-6) (2) were synthesized and characterized by single-crystal X-ray diffraction, ac, dc magnetometry, and multireference ab initio calculations. For 1, DyIII complexes are encapsulated between two crown ether molecules, while crown ether molecules and DyIII complexes crystallize in separate rows for 2. Ab initio calculations indicate that encapsulation is detrimental for magnetic anisotropy in the case of 1. This effect is related to a mismatch of the anisotropy axis of the DyIII complex and the symmetry axis of the encapsulating crown ether molecules. Ab initio calculations show that the reorientation of the electrostatic potential exerted by the crown ethers to a more symmetric position produces an enhancement of magnetic anisotropy. We tested the general character of this effect by analyzing a reported DyIII complex encapsulated by crown ether molecules. We also investigated how specific hydrogen-bond interactions affect magnetic anisotropy and show that H-bonds can be beneficial or prejudicial for magnetic anisotropy, depending on their position with respect to the magnetic axis. Our conclusions give general orientations about tuning intermolecular interactions to promote single-molecule magnet properties by controlling electrostatic and supramolecular interactions.

Thermal Dependence of the Luminescent Properties of Mononuclear TbIII Macrocyclic Complexes

“…First the macrocycle was formed in presence of the triflate salt by a similar template reaction, and finally an in situ exchange reaction of the triflate anions by NCS À was carried out to obtain the desired complexes. The complexes were characterized by elemental analyses, IR spectroscopy (Figure S1), 1 H NMR spectroscopy (Figure S2), and single X-ray diffraction (Tables S1-S3; Figure S3 for yttrium complexes).…”

“…Elemental C, H, and N analyses were carried out with a Flash 2000 equipment. 1 H NMR spectra were recorded in DMSO-d 6 on a Bruker Advance NEO 400 NMR spectrometer. Photoluminescence (PL) emission spectra of the solid complexes were measured using a Horiba-Jobin Yvon spectrofluorimeter, Model Fluorolog-3 (FL3-221), under excitation with a 450 W Xe lamp, and a Horiba PPD-850 picosecond photon detector in the UV-Vis region.…”

“…Single crystals, suitable for X-ray diffraction, for all six complexes The FTIR spectra of both Tb III and Y III complexes were similar (Figure S1), and are given as supplementary material, together with the elemental analysis data. 1 H NMR data for the yttrium(III) and terbium(III) complexes are also provided as supplementary material (Figure S2).…”

“…Lanthanide compounds have attracted great attention of scientists for many years, due to their interesting properties, such as magnetic, [1][2][3] catalytic [4,5] and optical. [6,7] Based on lanthanide(III) emission that can be present in different regions of the electromagnetic spectrum, [8] these compounds have a broad variety of applications as emission devices, such as television, smartphones, LED, lasers, optical fibres, among others.…”

A Flexible Approach for Engineering Macrocyclic High Performance Pentagonal Bipyramidal Dy(III) Single-Ion Magnets

“…S15). We have employed the crown ether ligand in the equatorial plane of our model system because of its neutral nature, long metal-ligand distances, the popularity of crown ether ligands in 4f chemistry 24 and to compare it with the nitrogen based macrocyclic ligand, L N5 , used in 1. In the model system 1-O5 the strongly axial excited states are higher in energy than that of 1 (Table S6).…”