Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Novel coumarin-triphenyliminophosphorane (TPIPP) fluorophores, synthesized via a nonhydrolytic Staudinger reaction, exhibit remarkable redox-responsive optical properties. Upon chemical and electrochemical oxidation, these compounds display a hypsochromic shift in absorption from 430 to 350 nm, accompanied by up to 11-fold fluorescence enhancement under 405 nm excitation. The fluorescence switching occurs at an electrochemical oxidation potential of approximately +2.0 V. This enhanced one-photon excited fluorescence is attributed to an emissive radical effect, stemming from in situ generated radical cations at the polarizable iminophosphorane (P=N) bond. The radical formation was confirmed by trapping experiments using tetracyanoquinodimethane, which produced characteristic absorption of radical anions around 850 nm, and by electron spin resonance studies using 5,5-dimethyl-1-pyrroline N -oxide as a spin trap. Conversely, two-photon excited fluorescence under 800 nm pulsed laser excitation decreases upon oxidation, likely due to reduced two-photon absorption resulting from altered π-conjugation. This work demonstrates that external redox modulation can induce significant changes in absorption profiles and enable switching between enhanced one-photon and diminished two-photon excited fluorescence, highlighting the potential of leveraging the controllable radical character of the P=N bond in designing redox-responsive fluorophores.
Source: ACS Physical Chemistry Au
Authors: Wei-Chu Huang, Yi-Yin Lu, Shiao-Chen Huang, Tai-Chung Lo, Shun-Yuan Luo, Wei-Hong Huang, Chih-Wei Luo, Vincent K.-S. Hsiao, Chih-Chien Chu
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,500
Award: G4816939320
OpenAlex ID: W4404029439