Transforming the fluorescent fluorine anion probe from on-off to ratiometric type by a tiny modification on the triarylborane group

Based on the electron-deficient property of the p pi orbital in boron atoms, varies of triarylborane-based materials have been designed as the fluorescent probes to detect fluorine anions. However, the strong Lewis acid/base interaction between the probes and F - anions usually quenches the fluorescence, leading to relatively low performance. In this work, two triarylborane-based fluorescent F - anion probes B1 and B2 were developed. Both were highly emissive with fluorescence quantum yields larger than 0.7 and showed impressive sensitivity and selectively to F - anions. The limit of detection (LOD) of B2 was as low as ca. 0.16 mu M, which was one of the lowest LOD for F - anions. More importantly, by simply replacing a sp 2 hybridized carbon atom in B1 with a sp 2 hybridized nitrogen atom to from B2 , the responses to F - anions were transformed from on-off to ratiometric fashion. Based on theoretical calculations, this admired transformation was assigned to the significant differences in the distribution of key molecular orbitals, the components of the S 1 state and the oscillator strengths between related species.(c) 2023 Elsevier B.V. All rights reserved.