Selective detection of fluoride via amplified donor-acceptor interaction of 6H-indolo[2,3-b]quinoline

Rupa Pegu; Gopal Pandit; Ankur Kanti Guha; Sajal Kumar Das; Sanjay Pratihar

doi:10.1016/j.saa.2018.11.064

Selective detection of fluoride via amplified donor-acceptor interaction of 6H-indolo[2,3-b]quinoline

Spectrochim Acta A Mol Biomol Spectrosc. 2019 Mar 15:211:246-253. doi: 10.1016/j.saa.2018.11.064. Epub 2018 Dec 4.

Authors

Rupa Pegu¹, Gopal Pandit¹, Ankur Kanti Guha², Sajal Kumar Das³, Sanjay Pratihar⁴

Affiliations

¹ Department of Chemical Sciences, Tezpur University, Assam 784028, India.
² Department of Chemistry, Cotton College State University, Panbazar, Guwahati, Assam 781001, India.
³ Department of Chemical Sciences, Tezpur University, Assam 784028, India. Electronic address: sajalkd@tezu.ernet.in.
⁴ Department of Chemical Sciences, Tezpur University, Assam 784028, India. Electronic address: spratihar@tezu.ernet.in.

PMID: 30553994
DOI: 10.1016/j.saa.2018.11.064

Abstract

In this report, 6H-indolo[2,3-b]quinoline (hereafter 2a) was synthesized and employed as an optical chemosensor for fluoride. The sensitivity of 2a towards fluoride was established from the change in both the absorption and emission signals. The various in-situ¹H NMR, UV-Vis, and density functional studies indicate that the 1:2 binding interaction between 2a and fluoride followed by deprotonation to its corresponding di-anion (2a^2-), which in turn boosted the donor-acceptor interaction between indole and quinoline moiety in 2a^2-via expansion of torsion angle by 10.2° as compared to 2a. Consequently the significant changes in both the absorption and emission signal of 2a allow us to detect and estimate the concentration of fluoride up to 0.2 μM from the mixture of different anions.

Keywords: 6H-indolo[2,3-b]quinoline; Acceptor; Donor; Fluoride; Sensor.