Zirconium (IV)-3-hydroxy-2-tolyl-4H-chromen-4-one complex—the analytical and DFT studies

Abstract

Trace determination of Zr(IV) was carried out by its complexation with a newly synthesized chromone derivative, 3-hydroxy-2-tolyl-4H-chromen-4-one (HToC) for the formation of a 1:4 (M:L) yellow-colored complex from the bicarbonate medium maintained at pH 7.90–8.13. The complex was extractable into the non-aqueous organic solvents showing maximum and stable color intensity in dichloromethane in the wavelength range 414–430 nm. The complex obeyed Beer’s law showing linearity of calibration curve in the range 0.0–1.1 µg Zr(IV) ml⁻¹ with an optimum range of determination as 0.44–1.0 ppm Zr(IV) detected from the Ringbom plot. Molar absorptivity, specific absorptivity, and Sandell’s sensitivity of thus prepared complex were ascertained, respectively as 4.1971 × 10⁴ l mol⁻¹ cm⁻¹, 0.4601 ml g⁻¹ cm⁻¹, and 0.0022 µg Zr(IV) cm⁻² at 420 nm. The linear regression equation being $Y=0.4485X+0.0114$ (Y = absorbance, X = µg Zr(IV) ml⁻¹) with the correlation coefficient of 0.9977 and detection limit of the procedure as 0.0729 µg ml⁻¹. Theoretical calculations were used to determine and compare structural and bonding properties of the Zr(IV)-HToC complex along with justification of the donor sites provided by ligand for complexation with respect to the metal. The consequences obtained were highly cogent with standard deviation of ± 0.0021 absorbance unit. The procedure was applied to various synthetic (some analogous to cooperate and nickel zirconium) and technical (reverberatory flue dust and water) samples with satisfactory results.

Graphical abstract