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Description
Ligands with chelating properties, such as Schiff bases, imines, and Salan-type ligands, are promising materials for photochemical sensors of metal ions, which require good sensitivity and selectivity. The ability of such ligands to host metal ions in their molecular structure and specific optical properties, such as high intensity photoluminescence, create new opportunities to define metal ion concentration in aqueous media by optical methods with fairly high accuracy. In addition, the structure of the ligand could be chemically tuned according to the requirements of the sensor. ¹
In this work, the sensitivity and selectivity of Salan ligands TFA salts were investigated by photoluminescence (PL) and transmittance (TM) methods.
Salan ligands were synthesized in salt form to make them soluble in water and alcohols. For sensor testing, the ligands and metal salts were dissolved in ethanol at a concentration of 100 mkM/L.
Sensor testing was performed in a home-built system with a quartz cuvette equipped with a magnetic stirrer, Fiber optic spectrometer, system of lenses and filters, Fiber optic cables, and a portable 325 nm UV light source with detector.
During the measurement steady-state PL and TM spectra were saved after each metal ion probe. The kinetics of local PL and TM peaks were recorded. The sensitivity to Cu²⁺ and Fe³⁺ ions in sub micromolar range was observed. Complex formation of ligand with Cu and Fe was proofed by FTIR. Mechanisms of interaction were proposed, main sensors parameters were calculated.
Keywords: photochemical sensors, metal ions detection, chelators
References:
1. S. Memon et al. Schiff Bases as Chelating Reagents for Metal Ions Analysis. Curr Anal Chem 10, 393–417 (2014).
