Understanding Single-Molecule Magnet properties of lanthanide complexes from 4f orbital splitting.

We present an approach for connecting the magnetic anisotropy of lanthanide mononuclear complexes with their f-orbital splitting for both idealized and real coordination environments. Our proposal is straightforward to apply and provides sensible estimations of the energy spacing of the ground multiplet for axial magnetic systems. This energy splitting controls Single-Molecule Magnet properties of lanthanide complexes, determining key parameters such as the demagnetization energy barrier ().

Influence of symmetry on the magneto-optical properties of a bifunctional macrocyclic Dy complex.

In this work, a novel complex, [Dy(L)(NO)]·(HO)·(NO) (1), containing a highly distorted macrocyclic ligand (L) and weak axial anions (NO), was synthesized and characterized. Even though this coordination environment is not ideal for maximizing the magnetic anisotropy of a Dy ion, a magneto-structural analysis reveals that the high distortion of the macrocycle promotes a disposition of the hard plane and easy axis opposite to the expected one. This results in a quite symmetrical environment which allows obtaining a field induced SMM behaviour.

Tuning the Emission of Homometallic Dy, Tb, and Eu 1-D Coordination Polymers with 2,6-Di(1-1,2,4-triazole-1-yl-methyl)-4-R-phenoxo Ligands: Sensitization through the Singlet State.

This work reports the structural characterization and photophysical properties of Dy, Tb, and Eu coordination polymers with two phenoxo-triazole-based ligands [2,6-di(1-1,2,4-triazole-1-yl-methyl)-4-R-phenoxo, LTr (R = CH; Cl)]. These ligands permitted us to obtain isostructural polymers, described as a 1D double chain, with Ln being nona-coordinated. The energies of the ligand triplet (T) states were estimated using low-temperature time-resolved emission spectra of Y analogues.

Dual visible and near-infrared luminescence in mononuclear macrocyclic erbium(III) complexes ligand and metal centred excitation.

Considering the structural design of some of the scarce molecular-based Er-centred emitters in the literature, we explored the optical properties of three Er hexaazamacrocyclic complexes, namely Er-EDA (1), Er-OPDA(2) and Er-DAP(3). The macrocyclic ligands in these complexes differ in the lateral spacers, and are derived from 2,6-pyridine-dicarbaldehyde and ethylenediamine (EDA), -phenylenediamine (OPDA) or 1,3-diaminopropane (DAP). Upon ligand-centred excitation, the bluish-green and green emissions of the Er ion were detected only for the complexes containing macrocycles with aliphatic spacers (1 and 3), which evidenced that these ligands can sensitize the Er luminescence.

Luminescence of Macrocyclic Mononuclear Dy Complexes and Their Immobilization on Functionalized Silicon-Based Surfaces.

Two mononuclear Dy complexes, [Dy(L)(NCS)] () and [Dy(L)(NCS)] (), where L ( = 1-2) corresponds to a macrocyclic ligand derived from 2,6-pyridinedicarboxaldehyde and ethylenediamine (L) and 1,3-diaminepropane (L) were immobilized on functionalized silicon-based surfaces. This was achieved by the microcontact printing (μCP) technique, generating patterns on a functionalized surface via covalent bond formation through the auxiliary -NCS ligands present in the macrocyclic complex species. With this strategy, it was possible to control the position of the immobilized molecules on the surface.

Lanthanide SMMs Based on Belt Macrocycles: Recent Advances and General Trends.

Enhancement of axial magnetic anisotropy is the central objective to push forward the performance of Single-Molecule Magnet (SMM) complexes. In the case of mononuclear lanthanide complexes, the chemical environment around the paramagnetic ion must be tuned to place strongly interacting ligands along either the axial positions or the equatorial plane, depending on the oblate or prolate preference of the selected lanthanide. One classical strategy to achieve a precise chemical environment for a metal centre is using highly structured, chelating ligands.

Control of magnetic anisotropy by macrocyclic ligand distortion in a family of Dy and Er single molecule magnets.

A family of hexaazamacrocyclic lanthanide complexes, [Ln(Ln)(NCS)3] (LnIII = Dy, Er; n = 1-3) has been synthesized and characterized by single-crystal X-ray diffraction, magnetic measurements and ab initio calculations. Macrocyclic ligands (Ln) differ in the lateral spacers, which are aliphatic chains with two and three carbons (for Ln, n = 1 and 2, respectively), and an aromatic ring for Ln = 3. Modification of the macrocycle spacer tunes planarity and rigidity of the equatorial coordination for both oblate (Dy) and prolate (Er) lanthanide ions.