211 / 2024-07-15 09:50:30

Crystalline Porous Organic Frameworks for Fluorescence Sensing

Metal-organic frameworks (MOFs), Hydrogen-bonded organic frameworks (HOFs), Luminescent sensing, X-ray scintillation, Mixed-matrix membranes (MMMs)

The synthesis and application of advanced materials for sensing and imaging applications have been a vibrant field of research, with a particular focus on the development of metal-organic frameworks (MOFs) and hydrogen-bonded organic frameworks (HOFs). These materials have demonstrated unique properties such as high surface area, tunable pore sizes, and versatile functionalization capabilities, which have been harnessed for a variety of applications including gas sensing, catalysis, and biomarker detection.

In the realm of biomarker detection, we discuss the utilization of MOFs and HOFs as fluorescent sensors. The case of 3-methoxytyramine (3-MT), a biomarker for neuroendocrine tumors, is presented, illustrating how a microporous HOF material, HOF-BTB, was employed for ratiometric fluorescent detection of this biomarker with exceptional sensitivity and selectivity. The detection limit achieved was 46 nM, which is comparable to high-performance liquid chromatography or liquid chromatography-tandem mass spectrometry, yet with the added benefits of simplicity and rapid response.

The development of CJLU-1, a Zr-based MOF nanoflower, is also highlighted, showcasing its application in the highly sensitive detection of nitroaromatics. The material's 2D layered structure and optimal synthesis method resulted in an ordered nanoflower morphology with ultrathin nanosheets, providing a large number of accessible active sites for analyte interaction. This material demonstrated a detection limit of 0.362 mM for 2,4,6-trinitrophenol (TNP), with strong anti-interference capabilities and a rapid response time. Furthermore, the integration of these nanomaterials into mixed-matrix membranes (MMMs) for vapor sensing is discussed. The fabrication of CJLU-1 MMMs combines the porosity and functionality of MOFs with the flexibility and processability of polymeric membranes. These MMMs have shown efficient and reversible detection of nitroaromatic molecules, highlighting their potential for practical sensing applications.

This work also reports the application of 2D MOF nanosheets, such as NTU-9-NS, for the luminescent sensing of Fe3+ ions. These nanosheets, fabricated via top-down delamination, exhibit a fast response time and a detection limit of 0.45 mM, underscoring the potential of 2D MOF nanosheets in luminescent sensing applications.

In the context of X-ray scintillation, we explore the development of zirconium-based MOFs that can convert X-ray energy into visible light efficiently. The material CJLU-1, with its high-Z hexagonal Zr clusters, has shown tunable radioluminescence (RL) upon the accommodation of different guest molecules, such as xylene and Rhodamine B (RhB), providing a new class of scintillating materials with luminescence intensity tunability.

The research underscores the transformative potential of MOFs and HOFs in the field of sensing and imaging. Their unique structural features, coupled with their functional versatility, position these materials at the forefront of modern analytical chemistry and materials science. The development of these materials not only advances the sensitivity and selectivity of detection methods but also paves the way for the creation of more efficient, cost-effective, and user-friendly sensing technologies.