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Updated: Oct 25, 2026
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
A Tetrameric Cobalt(II) Assembly Integrating Aggregation-Induced Emission and Weak Antiferromagnetic Coupling
Sharsti Goyal1, Sakshi Mehta2, Shashank Kumar Mishra1
1Department of Chemistry, Malaviya National Institute of Technology (MNIT), Jaipur302017, India.
Abstract:
A supramolecularly rigidified tetrameric cobalt(II) assembly, [Co4T8(H2O)2] (T-Co), where T = Tropolonate ion, has been constructed using tropolonate ligands to investigate the interplay between aggregation-controlled photophysics and magnetic exchange interactions in multinuclear 3d systems. Single-crystal analysis reveals a distorted octahedral Co4 framework interconnected through oxygen-bridged pathways and reinforced by cooperative O-H···O hydrogen bonding, π-π stacking, and C-H···π interactions, producing an extended caterpillar-like supramolecular arrangement. The restricted structural dynamics imposed by this densely packed architecture give rise to pronounced aggregation-induced emission (AIE) behavior, in which progressive aggregation in water-rich media enhances fluorescence by suppressing nonradiative relaxation channels. Dynamic light scattering measurements correlate the emissive enhancement with aggregate growth, confirming aggregation-governed excited-state modulation. Magnetic studies reveal weak antiferromagnetic exchange between high-spin Co(II) centers, accompanied by pronounced single-ion magnetic anisotropy arising from spin-orbit coupling and rapid magnetization dynamics, although slow magnetic relaxation characteristic of robust single-molecule magnets is not observed. The present study demonstrates how supramolecular organization within a polynuclear cobalt framework simultaneously dictates excited-state confinement and magnetic communication, providing a viable strategy for engineering multifunctional luminescent magnetic materials through cooperative structural rigidification.
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