Abstract
Metal–organic frameworks (MOFs), as a class of crystalline hybrid architectures, consist of metal ions and organic ligands and have displayed great potential in luminescent sensing applications due to their tunable structures and unique photophysical properties. Until now, many studies have been reported on the development of MOF-based luminescent sensors, which can be classified into two major categories: MOF chemosensors based on reversible host–guest interactions and MOF chemodosimeters based on the irreversible reactions between targets with a probe. In this review, we summarize the recently developed luminescent MOF-based chemodosimeters for various analytes, including H2S, HClO, biothiols, fluoride ions, redox-active biomolecules, Hg2+, and CN−. In addition, some remaining challenges and future perspectives in this area are also discussed.
Highlights
Metal–organic frameworks (MOFs), constructed by metal ions with organic ligands, are a subclass of coordination polymers with highly crystalline structures [1,2]
In the past two decades, enormous progress has been made in the synthesis and application of MOFs [3,4,5]
Due to the versatile building blocks of MOFs, as well as their structural diversity, the photoluminescence of MOFs can arise from a variety of possibilities [20]: (i) luminescence from organic linkers, which are normally extended π-conjugation systems with rigid structures, such as pyrene, anthracene, and their derivatives; (ii) metal-based emissions, e.g., MOFs with metal centers of lanthanoid; (iii) a metal–to–ligand charge transfer (MLCT), e.g., d10 Cu(I)- and Ag(I)-based MOFs; (iv) a ligand–to–metal charge transfer (LMCT), e.g., Zn(II)/Cd(II) and carboxylate ligand based MOFs; (v) antennae effects; and (vi) sensitization, e.g., MOFs with absorbing ligands and emitting lanthanoid ions (Figure 1)
Summary
Metal–organic frameworks (MOFs), constructed by metal ions (or clusters) with organic ligands, are a subclass of coordination polymers with highly crystalline structures [1,2]. The competent luminescence features of MOFs have been extensively studied and exploited in fluorescence imaging and sensing applications [24]. These developed MOF-based luminescent probes can be classified into two types according to the recognition mechanism between the probe with the target analyte: (1) an MOF-based chemosensor, Nanomaterials 2019, 9, 974 imaging and sensing applications [24]. The promising prospects and remaining challenges for future research in the field will be discussed
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