Excitation-Wavelength-Dependent Functionalities of Temporally Controlled Sensing and Generation of Singlet Oxygen by a Photoexcited State Engineered Rhodamine 6G-Anthracene Conjugate.

The present study provides design guidance for unique multipotent molecules that sense and generate singlet oxygen ( O ). A rhodamine 6G-aminomethylanthracene-linked donor-acceptor molecule (RA) is designed and synthesized for demonstrating wavelength-dependent functionalities as follows; (i) RA acts as a conventional fluorogenic O sensor molecule like the commercially available reagent, singlet oxygen sensor green (SOSG), when it absorbs ultraviolet (UV)-visible light and reacts with O . (ii) RA acts as a temporally controlled O sensing reagent under the longer wavelength (∼700 nm) photosensitization. RA enters an intermediate state after capturing O and does not become strongly fluorescent until it is exposed to UV, blue, or green light. (iii) RA acts as an efficient photosensitizer to generate O under green light illumination. The spin-orbit charge transfer mediated intersystem crossing (SOCT-ISC) process achieves this function, and RA shows a potential cancer-killing effect on pancreatic cancer cells. The wavelength-switchable functionalities in RA offer to promise molecular tools to apply O in a spatiotemporal manner.