Highly Selective Bifunctional Luminescent Sensor toward Nitrobenzene and Cu²⁺ Ion Based on Microporous Metal–Organic Frameworks: Synthesis, Structures, and Properties

Two metal–organic frameworks (MOFs), namely, [Ni(DTP)(H 2 O)] n ( I ) and [Cd 2 (DTP) 2 (bibp) 1.5 ] n ( II) (H 2 DPT = 4′-(4-(3,5-dicarboxylphenoxy) phenyl)-4,2′:6′,4″-terpyridine; bibp = 1,3-di(1 H -imidazol-1-yl)propane), that present structural diversity were solvothermally prepared. Single-crystal X-ray diffraction analysis indicates that they consist of {NiN 2 O 4 } building units (for I ) and {CdO 4 N 2 } and {CdO 3 N 3 } building units (for II ), which are further linked by multicarboxylate H 2 DPT to construct microporous three-dimensional frameworks. The remarkable character of these frameworks is that coordination polymer II demonstrates highly selective and sensitive bifunctional luminescent sensor toward nitrobenzene and Cu 2+ ion. The fluorescence quenching mechanism of II caused by nitrobenzene is ascribed to electron transfer from electron-rich ( II ) to electron-deficient nitrobenzene. The result was also evidenced by the density functional theory. Furthermore, anti-ferromagnetic as well as electrochemical characters of Ni-MOF ( I ) were also investigated in this paper.