A Simple Water-Soluble ESIPT Fluorescent Probe for Fluoride Ion with Large Stokes Shift in Living Cells

Abstract

Developing an effective method for monitoring fluoride ion in biological samples is meaningful because fluoride ion plays a vital role in biological processes. In this contribution, a simple water-soluble ESIPT fluorescent probe 2-((4-(( tert -butyldiphenylsilyl)oxy)-1,3-dioxoisoindolin-2-yl)methyl)-1-ethylpyridin-1-ium iodide ( SPI ) was constructed for monitoring fluoride ion. The probe SPI containing pyridinium salt group exhibited preeminent water solubility. The probe SPI introducing a trimethyldiphenylsilyl ether recognition group displayed excellent selectivity for fluoride ion over other biologically relevant species. Additionally, the probe SPI exhibited a fast response for a fluoride ion, suggesting that it could provide real-time fluoride ion detection. Importantly, the probe could detect fluoride ion with a linear range of 0–70.0 × 10 –6 M and a low detection limit of 1.16 × 10 –6 M. Furthermore, probe SPI could detect fluoride ion with a large Stokes shift (98 nm), which was attributed to ESIPT fluorescence sensing process. At last, probe SPI was successfully employed to monitor fluoride ion in living cells.

Correlation between Excited-State Intramolecular Proton Transfer and Electron Population on Proton Donor/Acceptor in 2-(2′-Hydroxyphenyl)oxazole Derivatives

“…to proton acceptor (carbonyl oxygen, pyridyl nitrogen, etc. ), − plays an important role in chemistry, biology, and material sciences. − As illustrated in Scheme , the ground-state molecules with enol-normal form (N) are populated to the excited state (N*) via photoexcitation. They subsequently transform into keto-tautomer (T*) through the ESIPT reaction, then deactivate to the ground-state tautomer (T) via radiative or nonradiative relaxation, and finally T state molecules transform back to the N state through ground-state intramolecular proton transfer (GSIPT) reaction. , Due to the presence of two excited-state electronic configurations, the ESIPT molecules generally exhibit largely Stokes-shifted T* fluorescence or even dual fluorescence from both N* and T* states. , …”

Interplay of conformational relaxation and hydrogen bond dynamics in the excited states of fluorescent Schiff base anions

“…For neutral Schiff bases, a similar observation is ascribed to the excited state intramolecular proton transfer (ESIPT) and the rapid non radiative depopulation of the cis-keto excited state associated with segmental motions of C-N bonds. 17,20,21,[48][49][50][51][52][53][54] ESIPT is precluded for anions, as they lack the proton that is essential for its occurrence. In polar aprotic solvents like N,N-dimethyl formamide (DMF) and acetonitrile (ACN), the emission spectra are slightly blue shifted (5-10 nm) compared to those in polar protic solvents (the Stokes shift for salampy À is 67 nm in DMF, but 84 nm in ACN, Table 1).…”

ESIPT-Active 8-Hydroxyquinoline-Based Fluorescence Sensor for Zn(II) Detection and Aggregation-Induced Emission of the Zn(II) Complex

“…Fluorescence sensors based on ESIPT usually exhibit abnormally large Stokes shifts to avoid selfabsorption. 1,3,7,8 A strong intramolecular H-bond interaction was observed in 8-hydroxyquinoline with five-membered ring structure enhancing the probability of ESIPT. In the meanwhile, 8-hydroxyquinoline, as a strong metal chelator, exhibits good ability to coordinate with transition-metal ions due to the formation of a stable five-membered chelate ring.…”

“…The chelation of metal cations could remove the proton of −OH or −NH 2 , then the ESIPT process would be prohibited with significant spectral changes. − Therefore, one of the most important applications of ESIPT is the fluorescence sensors for metal ions. Fluorescence sensors based on ESIPT usually exhibit abnormally large Stokes shifts to avoid self-absorption. ,,, A strong intramolecular H-bond interaction was observed in 8-hydroxyquinoline with five-membered ring structure enhancing the probability of ESIPT. In the meanwhile, 8-hydroxyquinoline, as a strong metal chelator, exhibits good ability to coordinate with transition-metal ions due to the formation of a stable five-membered chelate ring.…”