Investigation on the fluorescence detection mechanism of NIR fluorescent probes based on intramolecular spiro cyclization

The consistency between the calculated optical parameters and experimental data validates the proposed detection mechanism centered on spiro cyclization/ring-opening processes and associated changes in π-electron conjugation. This mechanism clarifies how the structural flexibility of the probes (driven by analyte binding) regulates their fluorescence properties, providing a theoretical basis for the rational design of high-performance NIR-II fluorescent probes with tunable optical responses. Future work may leverage this mechanism to develop probes for a broader range of analytes, further advancing their utility in biological imaging and environmental monitoring.