Fluorescence "Turn-Off" and Colorimetric Sensor for Fe2+, Fe3+, and Cu2+ Ions Based on a 2,5,7-Triarylimidazopyridine Scaffold

Sonakshi Sasan; Tavishi Chopra; Annah Gupta; Dolma Tsering; Kamal K Kapoor; Raman Parkesh

doi:10.1021/acsomega.1c07193

Fluorescence "Turn-Off" and Colorimetric Sensor for Fe²⁺, Fe³⁺, and Cu²⁺ Ions Based on a 2,5,7-Triarylimidazopyridine Scaffold

ACS Omega. 2022 Mar 22;7(13):11114-11125. doi: 10.1021/acsomega.1c07193. eCollection 2022 Apr 5.

Authors

Sonakshi Sasan¹, Tavishi Chopra², Annah Gupta¹, Dolma Tsering¹, Kamal K Kapoor¹, Raman Parkesh²

Affiliations

¹ Department of Chemistry, University of Jammu, Jammu 180006, India.
² CSIR-Institute of Microbial Technology, Chandigarh 160036, India.

Abstract

Two cyanoimidazopyridine-based sensors (SS1 and SS2) were explored for the colorimetric and fluorometric detection of Fe²⁺, Fe³⁺, and Cu²⁺ ions in the semi-aqueous medium. The "turn-off" fluorescence response of both sensors to these ions was due to the restriction in internal charge transfer. Job's plot and semi-empirical calculations revealed that SS1 and SS2 complexed with Cu²⁺ ions in a 1:1 ratio and Fe^2+/3+ ions in a 2:1 ratio, respectively. The sensors were found to have high binding constant (K _a) values and low detection limit values. FMO analysis using the semi-empirical quantum mechanics method revealed the decrease in energy gap after complexation with metal ions. Sensor-coated filter paper strips were prepared and analyzed, where the color changes in the strips could be utilized for the real-time detection of Fe²⁺, Fe³⁺, and Cu²⁺ ions.