Dual-Emission Zr-MOF-Based Composite Material as a Fluorescence Turn-On Sensor for the Ultrasensitive Detection of Al³⁺

Abstract

In this work, a novel zirconium-based metal–organic framework (MOF) composite material, UiO-(OH)2@RhB, has been solvothermally prepared with zirconyl chloride octahydrate, 2,5-dihydroxyterephthalic acid, and rhodamine B (RhB) for ratiometric fluorescence sensing of Al3+ ions in an aqueous medium. The luminescence measurement results showed that, at the single excitation wavelength of 420 nm, the fluorescence intensity of the ligand at 500 nm increased significantly in the case of Al3+, while that of RhB at 583 nm changed slightly, together with an apparent color change. Under optimal conditions, UiO-(OH)2@RhB exhibited an extraordinary sensitivity (10 nM), good selectivity, and a fast response (2 min) for Al3+. As far as we know, the limit of detection is superior to that of the current reported MOF-based Al3+ fluorescence sensors. The response mechanism suggested that −OH could capture Al3+ in water through coordination and high electrostatic affinity and achieved turn-on ratiometric fluorescence through the excited-state intramolecular proton transfer process and stable fluorescence of RhB. In addition, this sensor was also applied to actual food samples (grain beans), with the recoveries ranging from 89.08% to 113.61%. Such a turn-on ratiometric fluorescence sensor will provide a constructive strategy for the ultrasensitive detection of Al3+ in practical applications.

PB@UiO-67-CDC-(CH3)2 as an Ultrasensitive Ratiometric Fluorescence Sensor: Visible “Turn-On” Effect for Detecting Preservatives and Amino Acids

“…Generally, detection based on a single band fluorescence emission, whether MOF or Dye, depends on the changes of fluorescence signals in a band, which is usually interfered with by other substances and uncontrollable factors . However, PB-embedded MOF UiO-67-CDC-(CH 3 ) 2, which possesses double emission peaks, allows for building a cross-referenced self-calibration system with sensitive and colorimetric changes . Given the vivid color appear under UV light and stable dual-emission properties, we explored the potential sensing capability of the as-prepared PB@UiO-67-CDC-(CH 3 ) 2 for preservatives and amino acids.…”

“…61 However, PB-embedded MOF UiO-67-CDC-(CH 3 ) 2, which possesses double emission peaks, allows for building a cross-referenced self-calibration system with sensitive and colorimetric changes. 62 Given the vivid color appear under UV light and stable dual-emission properties, we explored the potential sensing capability of the as-prepared PB@UiO-67-CDC-(CH 3 ) 2 for preservatives and amino acids. Five common preservatives were selected: benzoic acid (BEN), paraben, hydrogen peroxide (H 2 O 2 ), sodium acetate (NaOAc), and sodium nitrate (NaNO 3 ) (Figure 4b, inset).…”

Nanoscale Metal-Organic Frameworks as Fluorescence Sensors for Food Safety

“…However, aluminum is also one of the hazardous metals [101] and excessive intake of it may result in various illnesses such as Alzheimer's disease [102]. UiO-(OH) 2 @RhB was prepared for ratiometric determination of Al 3+ by encapsulating redemitting RhB into Zirconium-based NMOFs (UiO-(OH) 2 ) with 2,5-dihydroxyterephthalic acid (H 2 DHT) as the organic ligand [103]. UiO-(OH) 2 @RhB emitted fluorescence both at 500 nm and 583 nm, which were originated from H 2 DHT and RhB, respectively.…”

Anthracene‐Modified Cadmium Metal‐Organic Framework as an Excellent Sensor for the Detection of 2,4,6‐Trinitrophenol and Nitrofurantoin

“…As a new class of functional materials, metal-organic frameworks (MOFs) have demonstrated their advantages in many areas such as catalysis, sensing, adsorption and separation by virtue of their adjustable pore structure, large surface area, and abundant active sites. [18][19][20][21][22][23][24] When constructing MOFs, organic ligands such as anthracene or lanthanide metals can be selected directly as chromophores, resulting the fascinating luminescence properties of Luminescent metal-organic frameworks (LMOFs). [25] Therefore, LMOFs for chemical sensing have outstanding advantages and wide applications to detection environmental pollutants.…”