A novel fluorescent chemosensor bearing a rhodamine and a dansyl moiety was developed for highly selective detection of Fe 3+ based on fluorescence resonance energy transfer (FRET) mechanism. Binding of Fe 3+ to the chemosensor induced spirolactam ring opening in the rhodamine moiety and subsequent off–on FRET from the dansyl energy donor to the rhodamine energy acceptor due to the spectral overlap between the emission of the dansyl moiety and the absorption of the ring opened rhodamine moiety. Job’s plot analysis indicated a 1:1 binding stoichiometry between the chemosensor and Fe 3+ . The association constant was estimated to be 2.72 × 10 3 M −1 according to the Benesi–Hildebrand method. With the feature of easy synthesis, simple structural skeleton and excellent sensing ability, the newly synthesized chemosensor provided the potential for applying as a highly selective fluorescent probe in complex samples containing various competitive metal ions and developing other metal ion chemosensors to fulfill various needs of biological and environmental field.
Dansyl chloride fluorophore exhibits typical aggregation induced fluorescence emission behavior in acetone/water solution. To realize the integration of detective and adsorptive functions, dansyl chloride is covalently immobilized on cellulose substrate to fabricate an efficient adsorbent for mercury ions in water. The as-prepared material exhibits excellent fluorescence sensing performance exclusively for Hg (II) with the presence of other metal ions . A sensitive and selective fluorescence quenching across the concentration range of 0.1–8.0 mg/L is observed with a detection limit of 8.33 × 10 −9 M as a result of the inhibition of aggregation induced emission caused by the coordination between adsorbent and Hg (II). Besides, the adsorption properties for Hg (II) including the influence of initial concentration and contact time are investigated. Langmuir model and pseudo-second-order kinetics are demonstrated to fit well with the adsorption experiment for the uptake of Hg (II) by the functionalized adsorbent, also, intraparticle diffusion kinetic model is proved to aptly describe the Hg (II) removal in aqueous solution. In addition, the recognition mechanism is considered to originate from the Hg (II) triggered structural reversals of naphthalene ring units which are verified by the X-ray photoelectron spectroscopy and density functional theory calculation. Moreover, the synthesis method used in this work also provides a strategy for the sensing application of organic sensor molecules with AIE properties in which the aggregated behavior could be appropriately realized.
Great efforts have been made to detect hydrogen sulfide (H 2 S) due to its involvements in various physiological processes and disease diagnosis. In the present work, a novel dansyl-based derivative ( DBr ) was synthesized and used as a FRET donor, and pyronine Y ( PyY ) was used as a FRET acceptor for constructing a ratiometric fluorescent sensor with assisstance of surfactant. The non-covalent ternary sensor platform could interact with H 2 S, causing an orange to blue-green fluorescence change as the acceptor emission decreased and the donor emission increased. The remarkable ratiometric response empowers the present system a high sensitivity to H 2 S with a detection limit of 110 nM. Moreover, the detection of H 2 S in serum could also be realized, providing the possibility for practical applications.
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