Triacetone triperoxide (TATP) is synthesized from acetone and hydrogen peroxide under acid catalysis. TATP detection primarily relies on a two-step indirect method which first uses a strong acid to decompose TATP into hydrogen peroxide and acetone, and then detects these products. However, this method has disadvantages including operational complexity, lengthy processing times, and a high false positive rate due to interference from environmental hydrogen peroxide and acetone.

In a study published in Aggregate, a team led by Prof. DOU Xincun from the Xinjiang Technical Institute of Physics and Chemistry (XTIPC) of the Chinese Academy of Sciences proposed a one-step fluorescence turn-on sensing strategy for TATP detection based on an H₂O-driven cascade reaction. The strategy emphasizes tuning the number of hydroxyl groups in ligands to decrease background fluorescence and improve both the detection efficiency and the signal-to-noise ratio.

Based on the intersystem crossing mechanism, researchers designed and synthesized three nonfluorescent Eu-MOFs. They found that when the ligand was 2,5-dihydroxyterephthalic acid, the introduction of a small amount of H₂O could trigger the cascade reaction of Eu-MOF-3 toward TATP.

In detail, H₂O molecules first converted the strong intramolecular hydrogen bond of the ligand in Eu-MOF-3 into a weaker intermolecular hydrogen bond. The strong oxidizing property of TATP further broke this hydrogen bond and oxidizes the ligand from the enol structure to the ketone structure.

The nonfluorescent Eu-MOFs design strategy based on cascade reaction proposed achieved one-step, rapid (<1 s), ultra-sensitive (LOD = 36.1 nM), and highly specific detection of TATP. This method simplifies complex operational procedures and reduces susceptibility to interference from environmental hydrogen peroxide and acetone in two-step detection methods.

The development of a glass fiber-based sensing film and a portable detection system verified the outstanding performance of this strategy for detecting trace TATP particles in practical, on-site applications. This study provides a methodology for the functional customization of metal-organic frameworks (MOFs) materials and the development of novel sensing systems.

Schematic illustration of the Eu-MOF design strategy and the mechanism for TATP detection. (Image by XTIPC)