Synthesis, Characterization, Fluoride Ion Sensing and DFT Studies of Carbamate-Based Bistriazole

Abstract

A carbamate-linked-bistriazole (5) was prepared by click reaction of diethynyl 1,3-phenylenedicarbamate (2) and phenyl azide derivative (4) in DMF/H₂O using copper sulfate and sodium ascorbate as a catalyst at room temperature for fluoride ion sensing. The structural analysis of synthesized compound was done by using ¹HNMR, ¹³C NMR, FTIR and HRMS. The sensing behavior of carbamate-linked-bistriazole (5) was examined by ¹HNMR, UV–vis and fluorescence study. NMR titration study suggested the participation of triazole, amide and aromatic protons in binding of fluoride ion. UV–visible study established the 1:1 complexation ratio between sensor 5 and F^– ion with stability constant K of 2.64 × 10⁴ M⁻¹ and detection limit in µM range (9.372 µM). Further, fluorescence titration for 5 (9.2 × 10⁻⁶ M) with fluoride ions exhibited an emission quenching at 424 nm along with small bathochromic shift. Density functional theory (DFT) calculations also confirmed interaction mechanism in 5a-F^– complex established by, UV–visible, ¹H NMR and fluorescence studies.

Keywords:

• Click reaction
• carbamate
• bis-triazole
• sensor
• anion sensing
• fluoride ion

Acknowledgement

We are gratefully acknowledging the Dr. APJ Abdul Kalam CIL, Guru Jambheshwar University of Science and Technology, Hisar for recording HRMS, FTIR, NMR and UV–Visible spectra. PR thanks UGC New Delhi for funding as Senior Research Fellowship. This work was assisted by the Department of Chemistry, Manipal University Jaipur, India, for providing fluorescence titration facility and Department of Chemistry, NIT, Kurukshetra, India for providing the DFT study facility.