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Microwave-assisted one-pot multicomponent synthesis of indole derived fluorometric probe for detection of Co2+ ions

Authors:

Rizana Azees,

University of Sri Jayewardenepura, LK
About Rizana
Department of Chemistry, Faculty of Applied Sciences
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Asitha T. Cooray,

University of Sri Jayewardenepura, LK
About Asitha T.
Department of Chemistry, Faculty of Applied Sciences
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K. G. U. R. Kumarasinghe

University of Sri Jayewardenepura, LK
About K. G. U. R.
Department of Chemistry, Faculty of Applied Sciences
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Abstract

Cobalt (Co2+) is an essential constituent in the human body while excessive exposure leads to severe systemic toxic reactions which highlight the importance of developing effective methods to detect Co2+ ions. A simple and highly efficient fluorescence enhanced turn OFF-ON chemosensor was synthesized to detect the paramagnetic Co2+. The ligand, N-((1H-indol-3-yl) (phenyl)methyl)aniline (L), was synthesized in 92% yield by means of hydrated ferric chloride catalyzed one -pot multicomponent microwave irradiation in the presence of Indole, benzaldehyde, and aniline as reactants. The major green principles of waste prevention, high atom economy (94.3%), green solvent, higher energy efficiency, and catalysis were the highlights of the ligand synthesis. The ligand exhibited remarkable fluorescence enhancement with Co2+ and a turn ON ratio of over 160-fold in MeOH/H2O (at pH 3.5) solution at an excitation wavelength of 369 nm in the Ultra-Violet range. The detection limit of L- Co2+ was 2.2 μM. The excitation and the emission spectra indicated stoke’s shift of 93 nm which supports the fluorescence enhancement observed in L- Co2+ with respect to the free ligand. The Job’s plot indicated fluorometric sensing of Co2+ ascribed to the complex formation with a stoichiometric ratio of 2:1 (L-Co2+). Furthermore, the high linearity (r2 =0.992) observed in the Benesi Hildebrand plot in a wide concentration range of 0.5−80 μM confirmed the above stoichiometric ratio. The association constant (Ka) for the L-Co2+ was determined to be 8.382 ×1 04 M−1 ± 5.8 ×103M−1.The prepared Co2+ fluorometric probe indicated long-term stability in −18℃ up to 45 days. Furthermore, the presence of Fe2+ and Fe3+ in the medium with Co2+ exhibited an interference effect in the fluorescence intensities. Upon further concentration studies, it was evident that the interference of Fe2+ and Fe3+ starts around 10.00 μM and rises exponentially.
How to Cite: Azees, R., Cooray, A.T. and Kumarasinghe, K.G.U.R., 2021. Microwave-assisted one-pot multicomponent synthesis of indole derived fluorometric probe for detection of Co2+ ions. Vidyodaya Journal of Science, 24(2), pp.27–42.
Published on 31 Dec 2021.
Peer Reviewed

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