- The control of Jahn-Teller distortions in copper-based coordination polymers is crucial for tuning their magnetic and structural properties. Here, we report the synthesis and characterization of two novel Cu(II)-based metal-organic frameworks (MOFs), Cu(mta)2 and Cu(cta)2, derived from modified triazole ligands. By introducing steric bulk through methyl and cyclopentyl substituents, we systematically investigate the effect of lattice enlargement on local coordination environments and magnetic behaviour.
Single-crystal and powder X-ray diffraction analyses reveal that Cu(mta)2 exhibits static Jahn-Teller distortions similar to those observed in Cu(ta)2, whereas Cu(cta)2 crystallizes in an undistorted, near-ideal cubic structure. Magnetic susceptibility and electron spin resonance measurements show strong antiferromagnetic interactions and temperature-dependent g-factor anisotropy for Cu(ta)2 and Cu(mta)2, while Cu(cta)2 displays nearly isotropic magnetic behavior and only dynamicallyThe control of Jahn-Teller distortions in copper-based coordination polymers is crucial for tuning their magnetic and structural properties. Here, we report the synthesis and characterization of two novel Cu(II)-based metal-organic frameworks (MOFs), Cu(mta)2 and Cu(cta)2, derived from modified triazole ligands. By introducing steric bulk through methyl and cyclopentyl substituents, we systematically investigate the effect of lattice enlargement on local coordination environments and magnetic behaviour.
Single-crystal and powder X-ray diffraction analyses reveal that Cu(mta)2 exhibits static Jahn-Teller distortions similar to those observed in Cu(ta)2, whereas Cu(cta)2 crystallizes in an undistorted, near-ideal cubic structure. Magnetic susceptibility and electron spin resonance measurements show strong antiferromagnetic interactions and temperature-dependent g-factor anisotropy for Cu(ta)2 and Cu(mta)2, while Cu(cta)2 displays nearly isotropic magnetic behavior and only dynamically JT distortions without a cooperative phase transition.
These results demonstrate that steric ligand design offers a powerful strategy to modulate the interplay between lattice structure and magnetic anisotropy. Our findings provide fundamental insights into the suppression of cooperative static Jahn-Teller distortions and open pathways for the targeted design of multifunctional MOFs with tailored structural and magnetic properties.…
