Lanthanide-Based Single-Molecule Magnets Derived from Schiff Base Ligands of Salicylaldehyde Derivatives

Abstract

The breakthrough in Ln(III)-based SMMs with Schiff base ligands have been occurred for the last decade on account of their magnetic behavior, anisotropy and relaxation pathways. Herein, we review the synthetic strategy, from a structural point of view and magnetic properties of mono, di, tri and polynuclear Ln(III)-based single-molecule magnets mainly with Schiff bases of Salicylaldehyde origin. Special attention has been given to some important breakthroughs that are changing the perspective of this field with a special emphasis on slow magnetic relaxation. An overview of 50 Ln(III)-Schiff base complexes with SMM behavior, covering the period 2008–2020, which have been critical in understanding the magnetic interactions between the Ln(III)-centers, are presented and discussed in detail.

A dinuclear dysprosium Schiff base complex showing slow magnetic relaxation in the absence of an external magnetic field

“…In this context, Schiff bases are ideal candidates because of their fine tunability for the ligand field by varying the substituents of both aldehydic and amine precursors. 31,42,43 This fact is supported by the large number of reports on constructing lanthanide-based SMMs [25][26][27][28][29][30][31][32][33][34][35][36][37] especially those based on dysprosium 19,31,34,44 and Schiff bases, which can be effectively employed in constructing SMMs with desired properties.…”

“…1,2,[19][20][21][22][23] Ever since the discovery of the exotic Dy 3 by Powell et al 24 and because of its large magnetic moment and high anisotropy, Dy(III) based SMMs have drawn the attention of many investigators. [25][26][27][28][29][30][31][32][33][34][35][36][37] The significance of Dy-SMM chemistry is very remarkable as evident from the discovery of dinuclear 38 and pentanuclear 39 aggregates with a high energy barrier for the reversal of magnetization.…”

Triangulo-{ErIII3} complex showing field supported slow magnetic relaxation

“…The reports on lanthanide based SIMs and SMMs increased recently, aer the report of Ishikawa's phthalocyanine mononuclear double decker SIMs 16 and Powell's exotic Dy 3 triangles showing SMM behavior in a thermally populated excited state with an almost nonmagnetic ground state. 17 In continuation of these reports, pure Dy(III) based SMMs have drawn the attention of many investigators as evident by the huge number of contributions to this particular eld of molecular magnetism, [18][19][20][21][22][23][24][25][26][27][28][29][30][31] generating a variety of SMM's with Dy(III). 4,[32][33][34][35][36][37] But their characteristics with respect to the blocking temperature and energy barrier need further improvement and advancement.…”

One-Dimensional Gadolinium (III) Complexes Based on Alpha- and Beta-Amino Acids Exhibiting Field-Induced Slow Relaxation of Magnetization

“…Since the discovery of the mononuclear phthalocyanine-based lanthanide (III) complexes, which exhibit the single-molecule magnet (SMM) phenomenon, in 2003 [1,2], many efforts have focused on the synthesis and development of lanthanide(III)-based complexes in order to study this singular magnetic behavior, which allows SMMs to become promising candidates for potential applications in high-density data storage, quantum computing, molecular refrigeration and spintronics investigations [3][4][5][6][7][8].…”