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

Abstract

Metal-organic frameworks (MOFs)h ave evolveda s an exciting class of materials in the domain of porousm aterials. The unique features of these materials arise from the combined properties of metal ions/clusters and organic struts which form the building blockso ft hese fascinating architectures. Amongo ther multifarious applications,M OFs have shown tremendous applications as sensory materials for aw ide variety of species. Thes ignal transduction induced mechanism in these confined nanospaces generate opticalo utput in response to ap articular analyte which can be detected by wide variety of detection techniques. Fluorometric methods of sensing is one of widely studied method over past few decades. MOF-based fluorometric detection is ak ey research theme developed over the past few years. In this review,w egive ab rief overview of the recent developments of MOFs as "turn-on" sensors for aw ider ange of analytes (viz. cations,a nions, volatile organic compounds (VOCs),e tc.).

A Highly Efficient Coordination Polymer for Selective Trapping and Sensing of Perrhenate/Pertechnetate

“…We may conclude that, the incorporated nitrite acts as electron donating moiety to generate hydrogen-bonding interaction with the ligand, promoting the electron transfer between metal and ligand. 30,50 Moreover, by adding the simulated Hanford LAW Melter…”

Recent Advances in Developing Lanthanide Metal–Organic Frameworks for Ratiometric Fluorescent Sensing

“…Moreover, the boric acid exhibits a strong affinity to fluoride ions, while its interaction with other anions is relatively weak, making it perfect for fluoride selective sensing. Reports on enhancing antenna effect resulted in "turn-on" sensing are rather few comparing to the "turn-off" mechanism discussed above (Karmakar et al, 2019;Fueyo-González et al, 2020;Min et al, 2020;Wang et al, 2020;Yue et al, 2020). However, it is obvious that "turn-on" sensors have advantages over the "turn-off" sensors, especially in the quantitative determination of an analyte in low concentration (Luo et al, 2020).…”

Multichromic Metal-Organic Framework for Multimode Photonic Sensing

“…For example, the vast majority of Guest@MOF sensing mechanisms are based on the luminescence quenching effect, where the analytes 'switch off' the emission of the guest. [15] However, this mechanism might be susceptible to moisture exposure or temperature fluctuation in the environment giving inaccurate readouts. [11,15,16] There are other Guest@MOF materials exhibiting luminescent sensing through a 'turn-on' or luminescence colour switching mechanism, but they often require very specific chemical interactions to function [11] thus limiting multimodal applications.…”

“…[15] However, this mechanism might be susceptible to moisture exposure or temperature fluctuation in the environment giving inaccurate readouts. [11,15,16] There are other Guest@MOF materials exhibiting luminescent sensing through a 'turn-on' or luminescence colour switching mechanism, but they often require very specific chemical interactions to function [11] thus limiting multimodal applications. To address some of the foregoing challenges, we propose that multichromic sensing can be achieved by using MOF pores to induce different caging effects on luminescent monomers and their aggregates, thereby producing distinctive luminescent behaviours when subject to different physical and chemical stimuli.…”