A study of the composition and properties of the ion-association complex of Rhodamine B with silicomolybdic acid, with a view to its analytical application

Abstract

The composition of the ion-association complex of Rhodamine B with silicomolybdate has been examined by Job's method and spectrophotometric titration. The ratio of Rhodamine B to silicon in the complex is 4 : 1. The same ratio is obtained by analysis of the crystalline complex. The composition of the complex is identical in aqueous medium, an organic solvent (ethanol) and in the crystalline state (C 28H 30N 2O 3) 4SiMo 12O 40). The complex is stable in the organic solvent and has its absorption maximum at 555 nm and a molar absorptivity of 5 × 10 5 1.mole −1cm −1. The complex can be advantageously used for the determination of silicon.