Constraining the coordination geometries of lanthanide centers and magnetic building blocks in frameworks: a new strategy for molecular nanomagnets

Abstract

Single-molecule magnets (SMMs) and single-chain magnets (SCMs), also known as molecular nanomagnets, are molecular species of nanoscale proportions with the potential for high information storage density and spintronics applications. Metal-organic frameworks (MOFs) are three-dimensional ordered assemblies of inorganic nodes and organic linkers, featuring structural diversity and multiple chemical and physical properties. The concept of using these frameworks as scaffolds in the study of molecular nanomagnets provides an opportunity to constrain the local coordination geometries of lanthanide centers and organize the individual magnetic building blocks (MBBs, including both transition-metal and lanthanide MBBs) into topologically well-defined arrays that represent two key factors governing the magnetic properties of molecular nanomagnets. In this tutorial review, we summarize recent progress in this newly emerging field.

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

“…The organization of molecular magnetic building blocks (MBBs) into extended frameworks to form metal–organic frameworks (MOFs) is a dynamic field of research . MOFs have been proposed as a potential way to constrain coordination geometries of metallic ions to form arrays of single‐molecule magnets (SMMs) or single‐chain magnets (SCMs) .…”

Coupling Influences SMM Properties for Pure 4 f Systems

“…Given the aforementioned factors influencing the SMM properties, the coordination chemistry of lanthanide elements can provide an alternative approach that involves the use of these compounds with infinite structures for SMM assemblies. The advantages of this approach are: 1) the in situ regular arrangement of SMMs can be formed at the molecular level, which is one of the key prerequisites for the use of SMMs in molecular devices; 2) the specific coordination symmetry can be constrained in the nodes of the infinite structures, especially some magnetic units that cannot easily form in discrete systems, such as the unusual six‐coordinate lanthanide SMM in a two‐dimensional network that we previously reported; and 3) information exchange among the magnetic units can be well controlled chemically through modification of the linkers or diamagnetic‐ion dilution to fine‐tune both the magnetization dynamics and the hysteresis loops.…”

Using the Singly Deprotonated Triethanolamine to Prepare Dinuclear Lanthanide(III) Complexes: Synthesis, Structural Characterization and Magnetic Studies

“…This situation is different from the magnetic relaxation of transition-metal-based SMMs, in which both the spin and exchange interactions contribute simultaneously to the magnetization dynamics [3]. As an alternative candidate, Ln III centers that are usually weakly coupled in dinuclear and polynuclear complexes have shown advantages with respect to SMM studies because large magnetization reversal energy barriers can be achieved via single-ion anisotropy originating from strong spin-orbit coupling and crystal field effects [6,8,9].…”

“…In 2003, Ishikawa's group reported SMM behavior in the double-decker phthalocyanine complexes (Bu n 4 N)[Ln(pc) 2 ] (Ln = Tb, Dy) [5], which gave birth of the Ln III SMM era [6,7]. The magnetization dynamics of dinuclear and polynuclear Ln III SMMs mainly originate from single-ion behavior because it is difficult to create effective pathways for magnetic interactions between metal centers due to the nature of inner 4f electrons; in general, both the exchange and dipolar interactions between Ln III ions are weak [8]. This situation is different from the magnetic relaxation of transition-metal-based SMMs, in which both the spin and exchange interactions contribute simultaneously to the magnetization dynamics [3].…”