Anion Effects on Lanthanide(III) Tetrazole-1-acetate Dinuclear Complexes Showing Slow Magnetic Relaxation and Photofluorescent Emission

Abstract

Three types of lanthanide complexes based on the tetrazole-1-acetic acid ligand and the 2,2'-bipyridine coligand were prepared and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analyses; the formulas of these complexes are [Ln2(1-tza)4(NO3)2(2,2'-bipy)2] (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5)), [Dy2(1-tza)4Cl2(2,2'-bipy)2] (6), and [Yb2(1-tza)4(NO3)2(2,2'-bipy)2] (7) (1-tza = tetrazole-1-acetate and 2,2'-bipy = 2,2'-bipyridine). They are dinuclear complexes possessing similar structures but different lanthanide(III) ion coordination geometries because of the distinction of peripheral anions (such as NO3(-) and Cl(-)) and the effect of lanthanide contraction. The variable-temperature magnetic susceptibilities of 1-6 were measured. Both Dy(III) complexes (5 and 6) display field-induced single-molecule magnet behaviors. Ab initio calculations revealed that the Dy(III) complex 6 possesses a more anisotropic Dy(III) ion in comparison to that in 5. The room-temperature photoluminescence spectra of Sm(III) (1), Eu(III) (2), Tb(III) (4), and Dy(III) (5 and 6) complexes exhibit strong characteristic emissions in the visible region, whereas the Yb(III) (7) complex shows near-infrared (NIR) luminescence.

Three Phenoxo‐Bridged Dinuclear Lanthanide Complexes: Syntheses, Crystal Structures, and Magnetic Properties

“…The least‐squares fit of the relaxation time to Arrhenius law gave the effective energy barrier Δ E/k B = 10.84 K and pre‐exponential factor τ o = 4.50 × 10 –7 s for low temperature region as well as Δ E/k B = 23.81 K and τ o = 2.64 × 10 –7 s for high temperature domain. Herein, the two τ o values of 1 are comparable with the typical values (10 –6 –10 –11 s) for SMMs, indicating field‐induced SMM behavior of 1 . Notably, the two effective relaxation barriers of 1 are comparable with the related phenoxido‐bridged dinuclear {Dy 2 } complexes with different Schiff base derivative ligands.…”

Structural diversity and photo-physical and magnetic properties of dimeric to 1D polymeric coordination polymers of lighter lanthanide(iii) dinitrobenzoates

“…The most popular lanthanides to design SMMs are the heavier ions such as Dy(III), Tb(III) and Er(III), [41][42][43][44][45][46][47][48][49][50][51][52][53][54] notwithstanding the fact that that lighter ions such as Ce(III), Pr(III) and Nd(III) have been recently used as elaborated SMMs. [55][56][57][58][59][60][61][62] The latter, however suffer from weak spin-orbit coupling and thus the isolation of molecular magnets among them is a relatively less visited arena.…”

Homochiral Ferromagnetic Coupling Dy2 Single-Molecule Magnets with Strong Magneto-Optical Faraday Effects at Room Temperature

“…The simplest one is the lanthanide (III) dinuclear SMM. The ferromagnetic coupling strategy may make the magnetic orientation of the two lanthanide (III) ions uniform, but it is still a very difficult task. − The main reason is that the 4f electrons from different lanthanide (III) ions are not easily magnetically exchanged with each other; even if this magnetic exchange occurs, it is usually a weak antiferromagnetic interaction.…”