Novel Approach for Detecting Vapors of Acids and Bases with Proton-Transfer Luminescent Dyes Encapsulated within Metal–Organic Frameworks

Abstract

Luminescent metal–organic frameworks (LMOFs) are one of the most promising materials for being implemented as active layers in the fabrication of photonic devices such as luminescent sensors of harmful chemicals. It is highly desirable that these materials undergo quantifiable spectroscopic (absorption or emission) changes in the presence of vapors of those analytes, as in many industrial processes, these toxic compounds are in the gas phase. Although great progresses have been achieved in the field, in most of the examples reported hitherto, the detection of chemicals by LMOFs is attained in solution. Herein, we present a novel approach consisting of the encapsulation of proton transfer dyes (8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt, HPTS, and 3-hydroxyflavone, 3-HF) within the pores of two distinct MOFs. The trapped proton transfer dyes (PT-dyes) may exist as different structures (enol, anion, or zwitterion), each of these exhibiting unique optical properties. Indeed, our findings reveal that the dyes can be encapsulated as anionic or enol species. Remarkably, the PT-dye@MOF composites exhibit a high luminescence quantum yield (up to 30%), which is sensitive (showing shifting in the emission wavelengths with a concomitant quenching/enhancement of the intensity) in the presence of vapors of an acid (HCl) and a base (triethylamine). These results open a novel avenue for the development of smarter vapoluminescent MOF-based materials.

Unraveling the Optimal Cerium Content for Boosting the Photoresponse Activity of Mixed-Metal Zr/Ce-Based Metal–Organic Frameworks through a Photodynamic and Photocurrent Correlation: Implications on Water Splitting Efficiency

“…The SEM images also correlate with the above conclusions (Figure C). The morphology and size of the MOF crystals having low content of Ce­( x = 0–5) are very similar, showing an octahedral shape and a size around 0.3–0.5 μm, typical of UiO-type isostructural MOFs. ,− The NDC-Ce­( x = 9–12) crystals still preserve the octahedral morphology. However, the mean size of the crystals decreased to ∼100–200 nm.…”

Biomimetic Metal–Organic Framework-Based Photonic Crystal Sensor for Highly Sensitive Visual Detection and Effective Discrimination of Benzene Vapor

“…Heretofore, some studies have focused on adding new functional materials to PCs to detect VOCs, such as functional polymers, − biomass materials, graphene, inorganic materials, − and metal–organic frameworks (MOFs) . Among them, MOFs, which are formed by metals and organic ligands, have been paid much attention due to their adjustable and porous structures. − Currently, the sensing detection platform derived from MOFs has gradually entered the public’s vision. − However, the MOF-based PC sensors usually show the problems of insufficient color saturation and poor optical conversion performance to realize colorimetric gas sensing. Moreover, the interaction mechanism between the PC sensors and VOC gases, as well as the influence of composition materials on the detection results, has long been a shortcoming in the research process.…”

Development of highly permeable and antifouling poly(vinylidene fluoride) hybrid membranes tailored with ZIF‐8 metal–organic frameworks for water treatment

“…The metal clusters in MOFs act as joints, and the organic linkers act as struts to form an interconnected network via coordination bonds and intermolecular interactions. MOFs derived from polyhedral or small‐cluster coordination polymers were later extended into one‐dimensional (1D) chains, two‐dimensional (2D) layers, and finally 3D frameworks 13 . It is well established that MOFs are one of the most widely materials owing to their structural adaptability, controlled porosity, and high crystallinity.…”

“…MOFs derived from polyhedral or smallcluster coordination polymers were later extended into onedimensional (1D) chains, two-dimensional (2D) layers, and finally 3D frameworks. 13 It is well established that MOFs are one of the most widely materials owing to their structural adaptability, controlled porosity, and high crystallinity. MOFs and their composites have been applied in a wide spectrum of applications, including drug delivery, gas storage, catalysis, and luminescence sensing, water separation, etc.…”