Journal of Fluorescence最新文献

A dual-responsive fluorescent chemosensor based on a 1,3,4-oxadiazole-linked bis-indole scaffold (FM) was developed for the selective and sensitive detection of 2,4,6-trinitrophenol (TNP) and iron ions (Fe³⁺ and Fe²⁺) in aqueous media. The probe exhibits strong photophysical properties, including a prominent emission at 438 nm and a large Stokes shift of 79 nm. Upon interaction with TNP or iron ions, a significant fluorescence "turn-off" response and bathochromic shifts were observed, attributed to π-π stacking, hydrogen bonding, and coordination interactions. Job's plot analysis revealed a 2:3 binding stoichiometry for TNP and 1:1 for both iron species, indicating distinct recognition mechanisms. For TNP, a high Stern-Volmer quenching constant (K_sv = 113.98 × 10³ M⁻¹) and a low detection limit (LOD = 59 nM) were obtained, outperforming many previously reported sensors. The probe also demonstrated reliable detection of Fe³⁺ and Fe²⁺ ions with LOD values of 2.95 µM and 16.2 µM, respectively. The FM sensor exhibited excellent photostability, rapid response (< 30 s), and high selectivity in the presence of competing analytes. Furthermore, a paper-based detection platform was successfully fabricated, enabling rapid visual detection of TNP under UV and daylight. These results highlight FM as a promising fluorescent sensor for environmental and security-related applications involving nitroaromatic explosives and metal ions.

Zinc phthalocyanines can be used as exceptional chemical sensors due to their outstanding stability, strong NIR absorption, and intense fluorescence emission, which facilitate accurate analyte detection. 3-Hydroxypyridine substituted zinc phthalocyanine (ZnPcPy) has been employed as a dual probe for the fluorescent determination of biliverdin and colorimetric determination of bilirubin. The fluorescence of ZnPcPy is effectively quenched by biliverdin through a static quenching mechanism facilitated by the inner filter effect. Furthermore, when ZnPcPy interacts with bilirubin, it undergoes a distinctive color shift from colorless to pinkish-red, thereby enhancing its efficacy in colorimetric detection. This newly designed dual sensor demonstrates an impressive detection limit of 8.60 × 10^- 8 M and 2.42 × 10^- 7 M for biliverdin and bilirubin, respectively, revealing superior selectivity and sensitivity against other co-existing molecules. Additionally, the methodology has been effectively employed in artificial and real samples, delivering encouraging results.

Hydrogen peroxide (H₂O₂) plays a key role in diverse physiological and pathological processes, including immune responses, cancer progression and aging. Herein, we report a novel ratiometric fluorescent probe (CBN) for H₂O₂ detection, synthesized via a one-step condensation reaction between 3-cyano-7-hydroxycoumarin and 4-(bromomethyl)benzeneboronic acid pinacol ester. The probe exhibited excellent selectivity and sensitivity toward H₂O₂ (limit of detection [LOD] = 0.71 µM) with minimal interference from competing ions. Furthermore, CBN demonstrated application in exogenous H₂O₂ detection in living HepG2 cells, highlighting its potential for biomedical research.

Recently, the fluorescent probe (E)-3-(4-(di(p-toluylamino)phenyl)-1-(2-hydroxyphenyl)prop-2-en-1-one (TAPHP) was synthesized for hydrazine detection in living cells (Sensors and Actuators B 263 (2018) 229). However, the excited-state intramolecular proton transfer (ESIPT) mechanism of TAPHP has not been experimentally elucidated. In this work, we employ density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to investigate the ESIPT process, electronic spectra, and ring aromaticity of TAPHP in detail. Furthermore, four derivatives (TAPHP-1, TAPHP-2, TAPHP-3, TAPHP-4) were designed by substituting carbon atoms with nitrogen at various positions on the benzene ring to explore the effect of nitrogen substitution on TAPHP's properties. The calculated electronic spectra show good agreement with experimental data, validating the computational approach. Our results reveal that photoexcitation strengthens intramolecular hydrogen bonds, promoting the ESIPT process. Nitrogen substitution causes red-shifts in absorption and fluorescence wavelengths, modifies the ESIPT energy barrier, and reduces both intramolecular charge transfer (ICT) and aromaticity in TAPHP. These findings provide deeper insight into the structure-property relationships governing ESIPT processes and may guide the design of improved fluorescent probes.

A new Chemosensor, 5-ferrocenylsalicylaldehyde-2-pyridinehydrazone (SP-Fc), was designed and synthesized by condensing 5-ferrocenylsalicylaldehyde with 2-hydrazinopyridine. Its structure was characterized by ¹H NMR, ¹³C NMR and HRMS. SP-Fc could be used to identify Al³⁺ through dual optical and electrochemical responses. Upon addition of Al³⁺, The probe exhibited a significant fluorescence enhancement attributed to CHEF and the inhibition of both PET and ESIPT processes. The probe specifically regonized Al^3 + in a wide pH range and had a well linear range (0-200 µM). Job's plot analysis revealed that the interaction of SP-Fc with Al³⁺ was 1:1 binding stoichiometry. The detection limit of probe for Al³⁺ was observed as low as 1.30 × 10^- 7 M. The response mechanism of SP-Fc to Al^3 + was confirmed through NMR titration experiment. Additionally, the electrochemical signals of SP-Fc in the presence of the Al³⁺ was shifted significantly compared with those of the other metal cations tested. Moreover, Confocal fluorescence microscopy imaging demonstrated that SP-Fc can monitor Al³⁺ in living MCF-7 cells with low cytotoxicity. This showcases SP-Fc's promise for biological system and analytical chemistry, providing a robust tool for Al^3 + detection in diverse settings.