Syntheses, characterization, and luminescent properties of Ca-based metal–organic frameworks based on 1, 4‑naphthalene dicarboxylate

Two Ca(II) metal-organic frameworks (MOFs) based on rigid 1,4‑naphthalene dicarboxylate ligand (1,4‑NDC) have been synthesized via solvothermal method. In these two compounds, [Ca(NDC)(DMF)] (1) and [CaZn(NDC)2(DMF)2] (2), the ligand of 1,4‑NDC exhibits two different coordination modes. Compound 1 features a 3D framework with 1D rods along the c-direction which is accomplished by connecting Ca-based building units to μ5-bridging NDC2− ligands. Compound 2 also exhibits a 3D framework. Moreover, the two compounds both exhibit strong solid-state fluorescence emissions at room temperature. Furthermore, the 1, 4‑NDC ligand is a good “antenna” ligand for Eu(III), when introduced the Eu(III) ions into 1 to get hybrid framework 1′, the hybrid material 1′ shows strong red luminescence and the temperature-dependent luminescent properties studies indicate that 1′ is a potential luminescent thermometer in the range from 270 to 400 K.