Tafesse, Fikru (PhD)Bizuneh, Damene2018-06-162023-11-092018-06-162023-11-091994-06http://etd.aau.edu.et/handle/12345678/1047The complexation of 1,2,5,8-tetrahydroxyanthraquinone (quinalizarin) with some trivalent lanthanide ions: Sm(III), Tb(III), Ce(III), and La(III) has been studied spectrophotometrically and potentiometrically. The methods of continuous variation and mole ratio indicate the metal to ligand ratio is 1:1. The stability of the complexes were found to be in the order Sm > Tb > Ce > La. Solid lanthanide-quinalizarin complexes were also isolated. The solid complexes are fine dark powders,insoluble in water and common organic solvents. From elemental analysis, thermal analysis and infrared spectra the complexes are characterized as chelate polymers, with a formula of [Ln(Cu H,O.)XH201 n (X = 5 when Ln = Sm, Ce and X = 6 when Ln = La, Tb). The relative thermal stability of three of the complexes were determined from differential thermal analysis, and are in the order: Sm > Ce~La.enLa(III); Ce(III); Sm(III) and Tb(III)Thesis