Nanocage-Based N-Rich Metal-Organic Framework for Luminescence Sensing toward Fe and Cu Ions.

Luminescent metal-organic frameworks (LMOFs) as sensors showing highly efficient detection toward toxic heavy-metal ions are in high demand for human health and environmental protection. A novel nanocage-based N-rich LMOF () has been constructed and characterized. It is a 2-fold interpenetrating structure built from N-rich {Zn(dttz)} nanocages extended by N-donor ligand Hdpa [Hdttz = 4,5-di(1-tetrazol-5-yl)-2-1,2,3-triazole; Hdpa = 4,4'-dipyridylamine]. Notably, contains abundant N functional sites anchoring on both the windows of nanocages and the inner channels of the framework that can interact with metal ions and then recognize them. As a result, it can serve as a luminescent sensing material for detecting trace amounts of Fe and Cu ions with low limits of detection (LODs) of 1.45 and 1.66 μM, respectively, through a luminescent quenching mechanism. Meanwhile, as a LMOF sensor exhibits several advantages such as high sensitivity, appropriate selectivity (for Fe in HO), recycling stability, and fast response times in ,-dimethylformamide. Moreover, also displays good luminescent quenching activity toward Fe in HO and a simulated 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid biological system with low LODs of 1.51 and 1.52 μM, respectively. test papers were further prepared to offer easy and real-time detection of Fe and Cu ions. Importantly, when density functional theory calculations and multiple experimental evidence, including X-ray photoelectron spectroscopy, UV-vis absorption, luminescence decay lifetimes, and quantum efficiencies, are combined, a preferred N-donor site and possible weak interaction sensing mechanism is also proposed to elucidate the quenching effect.