Synthesis and Investigation of Magnetic Properties of Rod Shaped Micron Sized Ni₄ and Co₂Ni₂ Cluster based MOFs

Abstract

Two new metal cluster (Ni 4 and Co 2 Ni 2 ) based rod shaped micron sized metal-organic frameworks (MOFs) of formulas(compound-2), {OBA = 4,4'-Oxybis(benzoate)} are synthesized via solvothermal technique. Structural, morphological and magnetic properties of both the compounds are characterized using x-ray diffraction, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and DC magnetization measurements. The homogeneous presence of Co and Ni with a molar ratio of ~1 : 1 in compound-2 is confirmed by EDX elemental mapping analysis. Magnetic measurements reveal that both the compounds are magnetically frustrated due to competing antiferromagnetic (AFM) and ferromagnetic (FM) interactions.Compound-1 has dominant FM while compound-2 has dominant AFM interactions. At low temperatures, magnetic longrange-order sets in, which is identified to be canted FM and canted AFM type for compound-1 and 2, respectively. Below the ordering temperature, multiple magnetic transitions including spin-glass transitions are detected, which can be ascribed to the effect of strong frustration in both the compounds.