Pursuit of Record Breaking Energy Barriers: A Study of Magnetic Axiality in Diamide Ligated Dy^III Single-Molecule Magnets

Abstract

Dy III single-ion magnets (SIMs) with strong axial donors and weak equatorial ligands have recently been sought after as model systems with which to harness the maximum magnetic anisotropy of Dy III ions. Utilizing a rigid ferrocene diamide ligand (NN TBS ), a Dy III SIM, (NN TBS )DyI(THF)2, 1-Dy (NN TBS = fc(NHSitBuMe2)2, fc = 1,1' ferrocenediyl), composed of a near linear arrangement of donor atoms, exhibits a large energy barrier to spin reversal (770.8 K) and magnetic blocking (14 K). The effects of the transverse ligands on the magnetic and electronic structure of 1-Dy were investigated through ab initio methods, eliciting significant magnetic axiality, even in the 4 th Kramers doublet, thus, demonstrating the potential of rigid diamide ligands in the design of new SIMs with defined magnetic axiality.

A Study of Magnetic Relaxation in Dysprosium(III) Single‐Molecule Magnets

“…Low‐temperature magnetisation studies also show a distinction between 1 and the other compounds (insets in Figures S1–S11 in the Supporting Information). Compound 1 shows a simple increase in M ( H ) at 2, 5 and 10 K, whereas 2 – 11 show S‐shaped curves at 2 K, suggesting significant memory effects . These S‐shaped curves cannot be reproduced by our CASSCF calculations because they arise from the confluence of the field dependence of the relaxation rates (not studied here, see ref.…”

Magnetic Slow Relaxation in a Metal–Organic Framework Made of Chains of Ferromagnetically Coupled Single‐Molecule Magnets

“…where q i , p i , and Q i are the charge, dipole moment, and quadrupole moment, respectively, of the i th atom of the ligand, whereas r i is the position vector of the i th atom. All the charges and moments are extracted from ab initio calculations (see above) followed by a LOPROP analysis of the electronic density. It is important to stress that this method is an analysis of the results of calculations done with high level of theory and therefore it does not have any prediction power by itself.…”

“…In fact, high‐performance lanthanide SMMs possess highly symmetric electrostatic environments that induce strong stabilization of the magnetic ground state . A striking illustration of the latter concept is given by the Ln–phthalocyanine (LnPc) systems, where the organic ligands impose a strict D 4 d site symmetry to the lanthanide ion and dramatically improve its magnetic properties when compared with a distorted coordination environment .…”

“…Compounds based on cyclooctatetraene (COT) are also remarkable examples of such an approach with D 8 d symmetry able to induce strong SMM behavior in a wide range of lanthanide ions such as Ce III , Nd III , Dy III , and Er III . The library of such systems is continuously growing with the recently added pentagonal bipyramidal environment ( D 5 h ) that provides excellent SMM behavior with Dy III adducts . Last, an astonishing example of electrostatic engineering around a Dy III center has been reported with observation of magnetic slow relaxation at record temperatures …”

Probing Optical Anisotropy and Polymorph‐Dependent Photoluminescence in [Ln2] Complexes by Hyperspectral Imaging on Single Crystals

“…[1][2][3][4][5][6][7][8][9][10] Most of these studies focusingo nc orrelations between crystal packing, polymorphism,a nd optical properties are foundw ithin the field of p-conjugated materials foro ptoelectronicd evices, that is, organic light-emitting diodes (OLEDs), organic thin-filmt ransistors, waveguides,r esonators or solar devices.A lternatively, photoluminescent lanthanide (Ln)-based molecules and materials are highly attractive candidates for opto-magnetic applications spanning the broad range from optical sensors, biomedical probesa nd contrast agents to waveguides, and single-molecule magnets, to name af ew. [11][12][13][14][15][16][17][18][19][20][21][22][23] While significant effect of crystal packing on the optical properties of Ln 3 + -based materials has been shown for coordi-nationp olymers and metal-organicframeworks (MOFs), surprisinglyt his has not yet been exploited in molecular species that exhibit polymorphism. [24][25][26][27][28][29] It has been demonstrated that the ligand sphereo ft he Ln 3 + centers plays an important role with respect to molecular geometry and arrangement ultimately influencing the photoluminescence (PL) behavior.…”