Simple azo‐based salicylaldimine as colorimetric and fluorescent probe for detecting anions in semi‐aqueous medium

Abstract

A series of novel, highly sensitive, and selective azo-based anion sensors 1-3 have been designed and synthesized from the condensation reaction between 4-amino azo benzene and three different aldehydes. The structure of the sensors 1-3 were confirmed by IR, HRMS, (1)H NMR, and (13)C NMR spectroscopic methods. Colorimetric naked-eye analysis revealed the anion detection by receptors 2 and 3 as color changes from yellow to pink and yellow to orange, respectively. Anion sensing ability of all receptors was further investigated by (1) H NMR titration, UV-vis experiment, and fluorescence titration. UV-vis measurements highly indicate the selective recognition of fluoride and acetate ions in 9:1 dimethyl sulfoxide-H2O (v/v) for receptors 2 and 3. Binding constant value showed among all receptors, receptor 3 has strong affinity toward F(-) and AcO(-) in semi-aqueous medium, which is due to the presence of chromogenic signaling unit in it. The F(-) ion detection property of receptor 2 in organic medium was also extended in the real sample like toothpaste.

Aluminium(iii) and zinc(ii) complexes of azobenzene-containing ligands for ring-opening polymerisation of ε-caprolactone and rac-lactide

“…1H has been reported previously by methods similar to those reported here. [31][32][33] The formation of the ligands was confirmed by NMR spectroscopy, with primarily (>97%) trans-azo species being present. The 1 H NMR spectra of 1-3H exhibit a sharp singlet resonance in the region δ = 8.50-8.70 ppm, corresponding to imine environments, with the concurrent 13 C{ 1 H} NMR signal at ca.…”

Novel chemosensor for multiple target anions: The detection of F− and CN− ion via different approach

“…To the best of our knowledge, a simple sensor that can sense differentially F À and CN À ion has rarely been reported [21][22][23]. Recently we reported azo Schiff base [24,25] to act as a colorimetric, fluorescent chemosensors for F À /AcO À ions in organic and semi-aqueous medium. In continuation of our research interest in the chemosensors, we herein report the application of receptor 1 toward sensing of CN À in pure aqueous medium.…”

An efficient ICT-based ratio/colorimetric tripodal azobenzene probe for the recognition/discrimination of F−, AcO− and H2PO4− anions

“…The visible colour changes are mainly because of the detection of anions by the receptor molecules through hydrogen bonding. 21 On the other hand, no significant signal changes can be observed in the presence of any other anions (Cl -, Br -, I -, NO3 -, HSO4 -, PF6 -) indicating the high selectivity of probe L. In order to investigate the detailed recognition processes, absorption titration experiments were carried out. Upon increasing the concentration of H2PO4 -, the absorption at 387 nm gradually decreased, whilst the absorption at 505nm dramatically increased with an isobestic point at 425 nm (Fig.…”