Copper(II)-2, 2'-Bipyridine-Chromazurol S Mixed Ligand Complex and Its Application to the Spectrophotometric Determination of Copper(II)

Abstract

Copper (II) ion reacted with 2, 2'-bipyridine (Bipy) and Chromazurol S (ChS) to form a mixed ligand complex, and it had an absorption maximum at 510 nm in a weakly basic pH medium. The molar ratio of three components in the complex was estimated to be Cu( II ) Bipy: ChS =1: 1: 2 by means of the continuous variation method and by the mole ratio method, and then the logarithmic value of the apparent formation constant of the complex was calculated to be about 19.12. The mixed ligand complex gave a maximum absorbance at 510 nm in the pH range from 10.0 to 10.6. The color development was almost instantaneous, and the absorbance remained constant for many hours. Under the optimum conditions of pH, Bipy and ChS concentrations, a linear relationship was found between the absorbance and copper (II) concentration up to 6. Ox 10-5 mol/l (Beer's law). The molar absorptivity at 510 nm was about 20600 /cm-imol-', corresponding to Sandell's sensitivity index' of 0.003g/cm².