Enhancing magnetic relaxation through subcomponent self-assembly from a Dy₂ to Dy₄ grid

Area of Science:

• Coordination Chemistry
• Materials Science
• Magnetism

Background:

• Subcomponent self-assembly is a powerful strategy for constructing complex molecular architectures.
• Dysprosium(III) (Dy^III) complexes are of interest for their potential single-molecule magnet (SMM) properties.
• Controlling magnetic properties in lanthanide-based SMMs requires precise structural design.

Purpose of the Study:

• To synthesize novel Dy^III-containing coordination compounds using a subcomponent self-assembly approach.
• To investigate the influence of axial coordinating anions on the structural diversity and magnetic properties of these Dy^III complexes.
• To explore the potential for enhancing slow magnetic relaxation and SMM behavior in 4f-based systems.

Main Methods:

• Subcomponent self-assembly reactions involving 4,6-dihydrazinopyrimidine, o-vanillin/salicylaldehyde, and various Dy^III salts.
• X-ray crystallography for structural characterization of the resulting Dy₂ and Dy₄ compounds.
• Magnetic susceptibility and relaxation measurements to study magnetic interactions and SMM behavior.

Main Results:

• Formation of two distinct Dy^III compounds: Dy₂ (complexes 1-3) and grid-like Dy₄ (complex 4).
• Diverse coordination geometries observed due to variations in solvent molecules and anions.
• Progressive enhancement of effective energy barriers (52–207 K) with increasing anion electronegativity.
• Clear single-molecule magnet (SMM) behavior observed for complexes 1-3 with anisotropy barriers of 52–58.4 K.
• Complex 4 exhibited two distinct relaxation processes with energy barriers of 94.9 and 207.2 K upon benzoate incorporation.

Conclusions:

• The choice of axial coordinating anions significantly impacts the structural diversity and magnetic properties of Dy^III complexes.
• Incorporating diverse coordination anions into subcomponent self-assembly systems provides a viable route to enhance slow magnetic relaxation in 4f-based SMMs.
• This study offers valuable insights into tailoring SMM performance through rational design of coordination environments.