Tripodal synthetic receptors based on cyclotriphosphazene scaffold for highly selective and sensitive spectrofluorimetric determination of iron(III) in water samples

Abstract

Two novel tripodal synthetic receptors based on cyclotriphosphazene scaffolds were prepared for spectrofluorimetric quantification of iron ions in environmental water samples. The receptors were designed by using the planar structure of cyclotriphosphazene which were modified by metal ion detecting naphtalene or anthracene-triazole groups above the plane and water solubility interacting triethylene glycol monomethyl ether (TEGME) groups below. All compounds were characterized by standard spectroscopic techniques such as 1H, 13C, 31P NMR and mass spectrometry (MALDI-TOF). The new developed methods based selective and sensitive complexation of CBTSRs with iron prior to spectrofluorimetric determination without any preconcentration processes. The experimental conditions such as pH, buffer and buffer concentration, initial CBTSRs concentration and time before measurement were optimized for selective complexation, which provided submicromolar spectrofluorimetric determination of iron under optimized conditions. The obtained results demonstrated that CBTSRs led to develop sensitive (LODs, 0.54 and 0.44 μM), selective and time-saving spectrofluorimetric methods for quantification of iron ions in environmental water samples under the optimized conditions (pH, 7.0; initial CBTSRs concentration, 10 μM and 5 μM; solvent, aqueous ethanol, (3:1 v/v and 9:1 v/v); buffer and buffer concentration, 0.1 M Britton-Robinson buffer; time before measurement, 20 and 25 s).