Long-range substituent effect on the TICT process of a fluorescent probe for reactive oxidative species

The sensing mechanism of a hemicyanine-based fluorescence probe for reactive oxidative species was investigated using TDDFT method. Geometries of probe and oxidation product were optimized at the M06/TZVP/SMD level. Vertical excitation energies of probe molecule corresponded well with experimental UV-Vis bands. The planar ground-state geometry and vertical excited-state geometry of probe suggested a TICT process that led to the fluorescence quenching. By contrast, the oxidation product would not go through the TICT process due to long-range substituent effect, thus, displaying strong fluorescence. The analysis results of their frontier orbitals and potential energy scan also confirmed the above conclusions.

Automated summary

In this study, the sensing mechanism of a hemicyanine-based fluorescence probe for reactive oxidative species was investigated using the TDDFT method. The results showed that the probe molecule went through a TICT process leading to fluorescence quenching, while the oxidation product displayed strong fluorescence due to the long-range substituent effect.