Heterometallic Hexanuclear [Cu2 Ln4 ] Complexes Showing Zero-field SMM Behaviour and Magnetocaloric Effect
Arindam Gupta1, Sandhya Kapurwan1, Siba Prasad Bera1
1Department of Chemistry, Indian Institute of Science Education and Research Bhopal Bhopal By-pass road, Bhauri, Madhya Pradesh, 462066, India.
Chemistry, an Asian Journal
|June 21, 2022
Summary
New 3d-4f metal complexes show intriguing magnetic properties. Complex 1 exhibits a magnetocaloric effect, while Complex 2 displays single-molecule magnet behavior, offering potential for advanced magnetic materials.
Area of Science:
- Coordination Chemistry
- Magnetochemistry
- Materials Science
Background:
- Heterometallic complexes combining 3d and 4f metals are crucial for developing advanced magnetic materials.
- Understanding magnetic exchange coupling in these systems is key to controlling their properties.
Purpose of the Study:
- To synthesize and characterize novel hexanuclear 3d-4f complexes.
- To investigate the magnetic properties, including magnetic exchange coupling and magnetocaloric effects.
- To explore single-molecule magnet (SMM) behavior and relaxation dynamics.
Main Methods:
- Synthesis and characterization of three heterometallic hexanuclear complexes: [Cu2(L)2Ln4(L)4(o-van)2] (Ln = Gd, Dy, Tb).
- DC magnetic susceptibility measurements to determine magnetic interactions.
- Analysis of magnetocaloric effect and SMM behavior.
- Computational studies including Bonded-Spin Density Functional Theory (BS-DFT) and ab initio calculations.
Main Results:
- Complexes 1 (Gd) and 3 (Tb) exhibit overall antiferromagnetic interactions.
- Complex 2 (Dy) shows co-existing ferromagnetic and antiferromagnetic interactions.
- Complex 1 demonstrates a magnetocaloric effect with an entropy change of 22.3 J kg⁻¹ K⁻¹ at 3 K and 7 T.
- Complex 2 exhibits zero-field single-molecule magnet (SMM) behavior, influenced by Raman relaxation and quantum tunneling of magnetization (QTM).
- Cu-O-Ln angles correlate with observed magnetic exchange coupling.
- Computational methods provide good agreement with experimental magnetic relaxation dynamics for complex 2.
Conclusions:
- The synthesized heterometallic complexes display diverse magnetic behaviors.
- Complex 1 is a promising candidate for magnetocaloric applications.
- Complex 2 showcases SMM properties, with relaxation dynamics explained by theoretical calculations.
- The study highlights the importance of metal-metal interactions and structural features in dictating magnetic properties.
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