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Novel 4,4′-Fluoresceinoxy Bisphthalonitrile Showing Aggregation-Induced Enhanced Emission and Fluorescence Turn off Behavior to Fe3+ Ions
摘要： A novel 4,4′-fluoresceinoxy bisphthalonitrile FPN is synthesized from fluorescein and 4-nitrophthalonitrile by aromatic nucleophilic ipso nitro substitution reaction. The structure of FPN constitutes phthalonitrile-fluorescein-phthalonitrile, acceptor-donor-acceptor, A-D-A form and the solvatochromic study of newly synthesized compound FPN was done in hexane, cyclohexane, CHCl3, DCM, DMF, acetonitrile, ethanol and in methanol. The aggregation behavior of FPN was investigated in good-poor solvent mixture DMF-water in various proportions and the molecule was found to be exhibiting Aggregation Induced Emission Enhancement AIEE for volume percentage of water beyond 50% with a significant hypsochromic shift of 70 nm in the emission maxima from 458 to 388 nm. This phenomenon is termed as Aggregation Induced Blue Shifted Emission Enhancement AIBSEE and was reported in substituted phthalonitrile for the first time. The chemo sensing activity of FPN with various transition metal ions also has been checked by fluorescence spectroscopy where the new molecule FPN exhibited fluorescence turn OFF behaviour towards Fe3+ ion in acetonitrile-methanol ACN-MeOH solution. The binding stoichiometry of FPN with Fe3+ was verified by Job’s plot analysis and Density Functional Theory DFT-B3LYP computational methodology by using Gaussian 09 software.
关键词： Fe3+ ion,Substituted phthalonitrile,4,4′-fluoresceinoxy bisphthalonitrile FPN,Chemo sensing,Aggregation induced blue shifted emission enhancement AIBSEE
更新于2025-09-23 15:22:29
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Probing the Aggregation and Signaling Behavior of Some Twisted 9,9′-Bianthryl Derivatives: Observation of Aggregation-Induced Blue-Shifted Emission
摘要： With an aim to understand the photophysical behavior of twisted organic fluorescent molecules in their aggregated state, two twisted biaryl molecules, namely, 9,9′-bianthryl and 10,10′-dicyano-9,9′-bianthryl, have been synthesized and characterized by conventional spectroscopic methods. To understand the role of C?C bond twisting on the photophysical response of biaryl aggregates, monoaryl counterparts (anthracene and 9-anthracenecarbonitrile) of the biaryl systems are also investigated. Photophysical behaviors of these systems along with their monoaryl counterpart are investigated in both solution and aggregated state. Investigations reveal that fluorescence spectra of the biaryl compounds show blue-shifted emission upon aggregation. Interestingly, no blue shift of the emission has been observed for monoaryl aggregates. Photophysical data of biaryl systems compared to monoaryl unit reveal that change in geometry, during self-assembly process, disfavors the formation of charge-transfer state, which eventually causes blue shift in the emission upon aggregation. In addition to this, potential of these systems toward signaling of nitroaromatic explosive has also been explored. Among all of the nitroaromatics, the highest fluorescence quenching is observed for nitrophenols (say picric acid (PA)). The investigation also reveals that compared to monoaryl systems, biaryl systems are more responsive to fluorescence quenching by nitroaromatics. Perrin’s model of quenching sphere action has been attributed to nitrophenol (PA) selective signaling behavior of biaryl systems.
关键词： aggregation-induced blue-shifted emission,twisted biaryl molecules,fluorescence quenching,photophysical behavior,nitroaromatic explosives
更新于2025-09-09 09:28:46