Post-Synthetic Functionalization of Ni-MOF by Eu³⁺ Ions: Luminescent Probe for Aspartic Acid and Magnetic Property

Utilizing 5,5'-oxidiisophthalic acid (H₄odip) ligand, one 3D framework {[Ni₂(odip)(H₂O)₄(DMF)]·DMF·2H₂O}_<i>n</i> (<b>1</b>) with a rare 3-nodal (3,3,4)-connected topological net based on two types of Ni₁₂(odip)₁₂ and Ni₂₄(odip)₁₂ nanocages was prepared. To exploit the advantage of high porosity, <b>1</b> was employed as an MOF matrix, and then photoactive Eu³⁺ ions were introduced through a facile soaking method to get Eu³⁺ functionalized MOF composite Eu³⁺@<b>1</b>. Luminescent sensing experiment demonstrated that Eu³⁺@<b>1</b> has the potential to serve as a sensitive, recyclable, and fast luminescent probe for aspartic acid, with a quenching constant of 1.565 × 10³ L/mol. The result offers a new possibility for many MOF materials which are nonemissive and/or difficult to synthesize directly to realize luminescent sensing function similar to lanthanide MOFs. Moreover, <b>1</b> reveals a ferromagnetic character in the range of 6-35 K. The dynamic magnetization measurements displayed no frequency dependencies, suggesting the absence of slow magnetic relaxation.