Researchers propose a 'domino effect' sensing mechanism to detect amines approaching picomolar levels

Accurate and sensitive detection of amines is important in industrial safety, environmental monitoring, and clinical diagnosis. Current research and development of sensitizers offers promise for improving the sensitivity and selectivity of amine detection. Optical/fluorescent amine-detecting materials are particularly promising due to their easy handling, readability with the naked eye, and portability.

However, reported fluorescent probes suffer from modest sensitivity due to inherent limitations in their “one-to-one” stoichiometric sensing mechanism. In general, an amine molecule interacts with only one (or, at most, several) fluorescent molecules, which has a small effect on the overall emission of the system. A significant number of amine molecules are required to achieve a detectable signal change, yielding low sensitivity.

In A study Published in Journal of the American Chemical SocietyA research team led by Professor Huang Weiguo from the Fujian Institute of Research on Structure of Matter, Chinese Academy of Sciences, created a domino chain consisting of a fluorescent molecule (eg, PTF1) and up to 40 non-emissive polymer chains. pPFPA) contains more than 1,000 repeat units (PFPA).

The fluorophore PTF1 acts as a domino inducer, interacting with the surrounding polymer repeating units (PFPA, following domino units) through polar-π interactions, leading to an amplified yellow fluorescence signal at 570 nm. Upon exposure to amines, the PTF1-pPFPA-based domino chain is rapidly cleaved, restoring the blue emission at 455 nm assigned to intrinsic PTF1, thus creating an ultrasensitive method for amine detection.

The pentafluorophenyl motif is known for its electron-withdrawing properties. Conversely, amines are strong electron-donating compounds and strong bases. Upon mixing, the lone pair of electrons on the „N” atom of triethylamine (TEA) can readily interact with the electron-deficient pendant groups in pPFPA, leading to an inductive effect that changes the electron cloud distribution in the PFPA units. -space conjugation (DSC) with PPFPA chain.

Density functional theory (DFT) calculation revealed that the binding energy (ΔG) of pPFPA with TEA was -15.5 kcal mol.^-1, indicating a strong association and interaction between TEA and pPFPA. If amines are embedded in PFPA repeating units or block charge transfer between PTF1 and pPFPA and are in direct proximity to PTF1 fluorophores, they can cleave the TSC with domino. In either case, the established PTF1-pPFPA supramolecular domino chain is cleaved and the original amplified yellow fluorescence signals are significantly suppressed.

This study presents a „domino effect” sensing mechanism that provides a general approach for chemical detection.