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A dual-emission ratiometric fluorescent sensor consisting of a Tb-based metal organic framework (MOF, Tb-DOBDC) has been developed based on an excited-state proton transfer (ESPT) response linker. Due to the ESPT process, Tb-DOBDC exhibits dual emission, which affords a crucial condition for the detection of ammonia as a ratiometric fluorescent sensor. [ABSTRACT FROM AUTHOR]

The design and application of functional metal–organic frameworks are very important and meaningful. Herein, based on a V-shape carboxylic acid ligand, a rigid nitrogen heterocyclic ligand with a triazole group, and Zn(NO3)2·6H2O, a 3D luminescent Zn-MOF [Zn2(OBA)2(L1)·3DMF·4H2O]n (compound 1; H2OBA = 4,4′-oxybis(benzoic acid), L1 = 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole) with a pillared-layer structure, has been synthesized under solvothermal conditions. Two independent skeletons penetrate each other, forming a 2-fold interpenetrated structure. As an excellent chemical sensor, compound 1 can detect Fe3+ and Cr2O72− by luminescence quenching with high selectivity and sensitivity. The limits of detection of compound 1 are 0.58 μM for Fe3+ and 1.37 μM for Cr2O72−, respectively. Meanwhile, compound 1 can serve as a host to encapsulate Eu3+/Tb3+ ions, realizing the tunable luminescence emission of Eu3+/Tb3+-doped samples. Furthermore, the Eu3+/Tb3+-co-doped compound 1 obtained by soaking the as-synthesized MOF into Ln3+ ion solution (total 25 mM; Eu3+ : Tb3+ = 2 : 3, molar ratio) exhibits white-light emission with ideal Commission International de I'Eclairage coordinates of (0.32, 0.33), a moderate correlated color temperature value of 6180 K, and an absolute quantum yield of 25.3%. These results indicate that compound 1 has promising applications in ion sensing and white-light emission. [ABSTRACT FROM AUTHOR]