As discussed above, singlet oxygen 1O2 and base medium were both important for such radical interaction. To further prove this
conclusion, the 1O2 photosensitizing of BODIPY-DT in THF/Et3N or 1,4-dimethyl benzene/Et3N solvent mixture triggered by UV light
was also studied. As seen from Fig. S12 (Supporting information), after irradiation for 90 min, there was no significant changes in UV-
vis spectra of DPBF solution, indicating that singlet oxygen 1O2 is not generated. Meanwhile, no drastic color or emission color changes
were observed in the solvent mixtures. Similar phenomena were also found in the solvent mixtures of Et3N with other organic solvents
including THF, acetone, 1,4-dimethyl benzene, CH2Cl2, methyl benzene, CHCl3, 2-methoxy ethanol, acetonitrile, and ethyl acetate.
On the other hand, when BODIPY-DT in the mixed solvent of DMSO/Et3N was triggered by light (365 nm) for 2 h, the color faded
quickly and the emission color changed from red to darkseagreen. The generation of 1O2 was further certified by singlet oxygen
photosensitizing measurement as seen from Fig. S13 (Supporting information). Therefore, the radical reaction could just happen both in
DMSO/DMF and DMSO/Et3N mixture, which made DMSO as another special solvent in the second-step sensing visually and
selectively. However, to date, the role of DMSO in radical generation process is not clear and the relevant reports are very rare.
In conclusion, a novel BODIPY based fluorescent sensor for selective, dynamic and visual sensing of DMF is developed for the first
time. This work described above presents a novel solvatochromic sensor strategy based on chemical interactions for the first time. By
taking advantage of energy transfer of resulting fluorophores produced in the reaction process, we are able to prepare solvatochromic
sensors that can achieve the demanding task of visualized discrimination of solvents. Finally, the sensing process displays time-
controllable, dynamic signal outputs in the emission colors. Especially, white emission color is also achieved, which is also meaningful
for preparing full-color emission systems with dynamic characteristics. We believe that the novel strategy developed in this study would
have wide application in the fields of solvatochromic sensors and light harvesting systems.
Declaration of Interest Statement
We have no known competing financial interests or personal relationships that could have appeared to influence
the work reported in this paper.
Acknowledgments
The authors thank for the support of the National Natural Science Foundation of China (Nos. 21401040, 21301047, 21771051),
Young Talent Plan of Hebei Province and High-level Talent Project of Hebei Province (No. 2016002014), Natural Science Foundation
of Hebei Province (Nos. B2016208115, B2019208282), Excellent Youth Funding of Hebei Province (No. B2018208112), Outstanding
Youth Fund of Hebei Province (No. B2019208415), and One Hundred Excellent Innovative Talents Project in Hebei Province.
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