Fluorescent cadmium(II) metal–organic frameworks exhibit excellent stability and detection ability to Fe3+ and MnO4− ions.

Two new 3D Cd(II)-MOFs have been constructed from a tetrakis(4-carboxybiphenyl)ethylene ligand, namely [Cd_4.25(tcbpe)₃]·0.25(C₄H₁₁N)·7.5DEF (NLMOF-1) and [Cd₂K(H₂tcbpe)(Htcbpe)]_n·4DEF (NLMOF-2). Single-crystal X-ray analysis revealed that NLMOF-1 is of 3D framework constituted by 1D metal chains containing six-nuclear secondary building units (SBUs) and one-dimensional channel, while NLMOF-2 also exhibits a 3D structure in which the 1D channel is blocked by coordinated K ions, resulting in poor chemical stability. NLMOF-1 possesses excellent stability in both water and common organic solvents, conducive to investigating its utility as a chemical sensor. Fluorescence sensing studies show that NLMOF-1 is characteristic of highly sensitive and selective quenching effects toward Fe³⁺ ions in DMF, DMA, and acetonitrile, as well as MnO₄⁻ ions in H₂O, DMA, and acetonitrile. The above results suggest that NLMOF-1 can be considered a potential fluorescent sensor for detecting Fe³⁺ and MnO₄⁻ ions. [ABSTRACT FROM AUTHOR]