A novel chemosensor based on rhodamine and azobenzene moieties for selective detection of Al3+ ions

The high absorption coefficient, fluorescence quantum yield, photo stability and relatively long wavelengths of rhodamine dye have expanded its applicability as a promising fluorescent probe. In the present investigation, two dyes, namely rhodamine and azobenzene, have been conjugated for the detect...

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Bibliographic Details
Published in:New journal of chemistry 2018-06, Vol.42 (12), p.10191-10201
Main Authors: Mabhai, Subhabrata, Dolai, Malay, Dey, Satyajit, Dhara, Anamika, Das, Bhriguram, Atanu Jana
Format: Article
Language:English
Subjects:
Absorptivity
Aluminum
Binding
Chelation
Chemical sensors
Chemoreceptors
Coordination compounds
Dyes
Electron transfer
Ethanol
Fluorescent indicators
NMR
Nuclear magnetic resonance
Photoluminescence
Rhodamine
Ring opening
Titration
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Summary:The high absorption coefficient, fluorescence quantum yield, photo stability and relatively long wavelengths of rhodamine dye have expanded its applicability as a promising fluorescent probe. In the present investigation, two dyes, namely rhodamine and azobenzene, have been conjugated for the detection of Al3+ in aqueous ethanol. The turn on fluorescence response of chemosensor L towards Al3+ is attributed to the inhibited PET (photo-induced electron transfer) and CHEF (chelation enhanced fluorescence) process along with the spirolactam (non-fluorescent) to ring-opened amide (fluorescent) process. The presence of the PET and CHEF process was corroborated by time-resolved photoluminescence study and the spirolactam ring opening was confirmed by 13C NMR and infrared spectroscopy. In the presence of Al3+, the opened spirolactam ring forms a 1 : 1 binding complex with the metal, which is supported by its high binding constant (Ka = 7.033 × 103 M−1). The limit of detection (LOD) and limit of quantification (LOQ) values are found to be 1.1 × 10−7 M and 3.6 × 10−7 M, respectively. The reversible recognition of Al3+ was also proved in the presence of Na2EDTA by both UV-Vis and fluorometric titration. The sensing behaviour of the chemosensor towards Al3+ was supported by DFT/TDDFT calculations.
ISSN:1144-0546
1369-9261
DOI:10.1039/c8nj00436f