Multicenter Metal–Organic Framework‐Based Ratiometric Fluorescent Sensors

Abstract

Metal–organic frameworks (MOFs) with multiple emission centers are newly emerging as ratiometric sensors owing to their high sensitivity and high selectivity toward a wide range of targeted functional species. Energy transfer between the light‐absorbing group and emission centers and between different emission centers is the key to rationally design and synthesize MOF‐based ratiometric sensors. A good match between the energy levels of the light‐absorbing groups and emission centers is the prerequisite for MOF‐based sensors to exhibit multiple emissions, and a good match of the MOF‐based sensors and those of the targeted species can increase the sensitivity and selectivity, but this match is highly challenging to obtain via synthesis. MOFs with multiple emission centers can be produced by functionalizing MOFs with multiple lanthanide centers, organic luminophores, dyes, carbon dots, and other such emissive groups. In this progress report, recent advances in the strategies for synthesizing MOFs with multiple emission centers and their applications for ratiometric sensing of solution conditions, including the pH value, and ion, organic molecule, and biomolecule concentrations, are summarized, as are the related sensing mechanisms.

A stable pillared metal–organic framework constructed by H4TCPP ligand as luminescent sensor for selective detection of TNP and Fe3+ ions

“…As newly developed materials constructed by the self‐assembly of organic ligands and metal nodes into robust crystalline open structures, metal–organic frameworks (MOFs) have given rise to the new field of reticular chemistry, where metal ions and organic ligands are stitched together by strong bonds to make robust porous frameworks. This type of material has shown significant applications in modern material science, such as gas storage and separation, sensing, optical/electronic devices, catalysis, and drug delivery . In particular, MOF‐based fluorescent sensors show enchanting advantages of fast response, specific selectivity, and simplicity in detecting parts per million (ppm) levels of toxic species in ecological systems, such as metal ions, anion, gases vapor, and nitroaromatic explosives .…”

Fluorescent “Turn‐on” Sensing Based on Metal–Organic Frameworks (MOFs)

“…is relevant directly to health and normalg rowth of human beings. [47] Since biomolecules play important role in variouscomplex biological processes, qualitative or even quantitative detectiono fs uch speciesw ould lead to important steps towards development of biosensors. Such MOF based biosensors could ultimately pavew ay towards usage in MR imaging and could helpi nm edical diagnostics.…”

Functional Construction of Dual‐Emitting 4‐Aminonaphthalimide Encapsulated Lanthanide MOFs Composite for Ratiometric Temperature Sensing

“…Because lanthanide MOF (LnMOF) exhibits extremely sharp emissions, long luminescence lifetimes and large Stokes shifts, and its structure shows diversity, it has become the first choice to construct dual‐emission MOF luminescent sensors . Furthermore, a dual‐emission MOF sensor can also achieve ratiometric detection, thus eliminating background interference and improving sensitivity …”

“…Qian, Chen, and co‐workers have designed and developed a series of ratiometric luminescent temperature sensors and elaborated the concept of thermometry . The dual‐emission LnMOF temperature sensors can be divided into two modes: 1) Mixed‐lanthanide dual‐emission MOF, most reported temperature sensors belong to this type, but its shortcoming is that the emission peak is relatively fixed, so it cannot be adjusted and expanded and 2) upon encapsulating fluorescent dye guest into a luminescent LnMOF host (dye⊂LnMOF), by choosing different kinds of fluorescent guests, not only the luminescent range can be extended, but also the luminescent properties can be adjusted by the interaction between different fluorescent guests and LnMOF hosts . However, this method is not blind encapsulation, but should fully consider the size effect and functionalized pore interaction between dyes and MOFs .…”