Dual-responsive solvatochromic sensor for simultaneous detection and mechanism of Cr(III) and Co(II) cations by a new N2O4-donor tetrabenzodiaza-crown ether Macrocyclic ligand anchored to dipyridine moieties

Abstract

The present study describes the chemosensing capability of an N2O4-donor tetrabenzodiaza-crown ether macrocyclic ligand derivatized by two pyridine side arms to afford the flexible macrocyclic ligand, 5,20-bis(pyridin-4-ylmethyl)-5,6,12,13,19,20,26,27octahydrotetrabenzo [e,i,o,s][1,4,11,14]tetraoxa[7,18]diazacycloicosine (PMHBOA). A selective colorimetric behavior of PMHBOA for the prompt detection of Cr(ΙΙΙ) and Co(ΙΙ) can be observed with naked eyes. The 1H, 13C{H} NMR, and infrared spectroscopy disclosed the ligand binding capability for selective metal ions, ascribed to a 1:1 complex formation with Cr(III) and Co(II) cations in isopropanol. The limit of detection (LOD) values were calculated as 580 and 850 nM for Cr(ΙΙΙ) and Co(ΙΙ), respectively, accompanied with suitable LOQs as 1.95 µM for Cr(III) and 2.85 µM for Co(II), respectively. The reusability was confirmed in the presence of ethylenediaminetetraacetic acid (EDTA). Moreover, a TLC-based fabricated paper strip successfully applied PMHBOA as a chemosensor for synchronous visible detection of Cr(III) and Co(II) in their alcoholic solution. Meanwhile, the observed color change along with the turn-off fluorescent of PMHBOA guaranteed a felicitous choice of candidate for Cr(III) in the presence of other library metal ions in isopropanol:H2O (9/1 v/v) solution. A fast separation test on the filter paper, impregnated with PMHBOA, was also employed to separate Cr(III) and Co(II) cations from aqueous solutions by recording UV–vis spectra. The 1H NMR spectroscopy supported the macrocycle ring and side arms as the parallel coordination site of PMHBOA with Cr(III) and Co(II).