Nanocage-Based N-Rich Metal–Organic Framework for Luminescence Sensing toward Fe³⁺ and Cu²⁺ Ions

Abstract

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 (LCU-103) has been constructed and characterized. It is a 2-fold interpenetrating structure built from N-rich {Zn6(dttz)4} nanocages extended by N-donor ligand Hdpa [H3dttz = 4,5-di­(1H-tetrazol-5-yl)-2H-1,2,3-triazole; Hdpa = 4,4′-dipyridylamine]. Notably, LCU-103 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 Fe3+ and Cu2+ ions with low limits of detection (LODs) of 1.45 and 1.66 μM, respectively, through a luminescent quenching mechanism. Meanwhile, LCU-103 as a LMOF sensor exhibits several advantages such as high sensitivity, appropriate selectivity (for Fe3+ in H2O), recycling stability, and fast response times in N,N-dimethylformamide. Moreover, LCU-103 also displays good luminescent quenching activity toward Fe3+ in H2O and a simulated 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid biological system with low LODs of 1.51 and 1.52 μM, respectively. LCU-103 test papers were further prepared to offer easy and real-time detection of Fe3+ and Cu2+ 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.

Preparation of Eu0.075Tb0.925-Metal Organic Framework as a Fluorescent Probe and Application in the Detection of Fe3+ and Cr2O72−

“…Ln-MOFs materials have outstanding luminescence characteristics; that is, they have the advantages of large Stokes shift, high quantum yield and luminescence intensity, narrow emission spectrum range, flexible coordination mode, and long luminescence life. MOFs fluorescent probes are commonly used as sensors [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Hna et al [26] synthesised Ce-MOF to detect Fe 3+ , and Gai et al [27] synthesised dual-sensor Eu-MOF to detect Fe 3+ and Cr 2 O 7 2− .…”

Quadruple Photoresponsive Functionality in a Crystalline Hybrid Material: Photochromism, Photomodulated Fluorescence, Magnetism and Nonlinear Optical Properties

“…Benefiting from the structural tunability and tailorability, metal-organic complexes have witnessed astonishing achievement in the last two decades. [58][59][60][61][62][63][64][65] The sound assembly of metal ions and predesigned ligands provides a wide platform to generate various functionalized hybrid materials under the guidance of crystal engineering. In this work, we utilise the ET and crystal engineering strategies to predesign CHPMs with potential multiple photoresponsive properties via the synergy of paramagnetic metal ion (Dy 3 + ), ED-ligand (benzene-1,2,3tricarboxylic acid, H 3 BTA) and EA-ligand (1,10-phenanthroline, phen) (Figure 1).…”

Applications of Density Functional Theory on Heavy Metal Sensor and Hydrogen Evolution Reaction (HER)

“…DFT studies revealed the HOMO-LUMO energy difference of unbound probe as 1.07 eV and [probe-Zn 2+ ] has a decrement to 0.15 eV, confirming the strong complexation. The luminescent metal organic frameworks (LMOFs) as nanocages to recognize Fe 3+ and Cu 2+ ions in trace quantity was designed and synthesized by Li et al [53] The fluorescent quenching activity of the nanocages was due to their weak interaction with the metal ions at N-rich sites. DFT calculations confirmed the uncoordinated N atoms in the nanocage interact weakly with the metal ions and hence the fluorescence was quenched.…”