The design, synthesis and fluorescent sensing applications of a thermo-sensitive Zn-MOF

A novel fluorescent Zn-MOF [Zn (cca)0.5 (TPB)0.5(H2O)2]·(NO3)·(H2O)2 (complex 1) and its multipurpose sensing applications have been revealed. By embedding 1, 2, 4, 5-tetra(4-pyridyl)benzene (TPB, the AIE ligand) into the framework of complex 1, a fluorescent Zn-MOF with good thermo-sensitive properties in a wide temperature range (30 ​°C–200 ​°C) was obtained. Remarkable fluorescent emission was observed for complex 1 both in solid and solvents. An emission red shift (30 ​nm) of complex 1 after dispersed in H2O compared with that in other solvents were recorded, which could be used in the distinguishing H2O from other solvents. PXRD tests revealed the good stability of complex 1 in both organic and inorganic solvents. Stable suspension was obtained after dispersed complex 1 in deionized water and used in the fluorescent detection acetone and metal ions in water. Real-time fluorescent quenching sensing of acetone in water was accomplished with an experimental detection limit as 0.03% (vol. %) based on the inner filter effect (IFE). Interestingly, significant fluorescent enhancement of complex 1-H2O suspensions was detected after mixed with Al3+, while, obvious fluorescent quenching was recorded after treatment with Cu2+. In addition, the experimental detection limits for Al3+ and Cu2+ were 1.33 ​μM and 0.67 ​μM, respectively.