SÍNTESE E CARACTERIZAÇÃO DO COMPLEXO DE ALUMÍNIO COM O AURINTRICARBOXILATO DE AMÔNIO (ATA) COMO LIGANTE.

Abstract

The [Al(H2ATA)]SO4.H2O complex was synthesized and characterized in order to understand the coordination aurintricarboxilato the ligand to the metal aluminum, since this metal is considered for the scientific community as neurotoxic. The compound is of the type [Al(H2ATA)]SO4.H2O and was characterized by elemental analysis, infrared absorption and UV-visible, palarografia voltammetry and differential pulse, conductance and potentiometry techniques.The vibrational frequencies υ (AlO) for the complex were 923cm-1 and 707cm-1. This complex exhibits three bands 233 nm (máx = 2,34 104 L. cm-1. mol-1), 318 nm (máx = 1,84 x 104 L. cm-1. mol-1) and 520 nm (máx = 2,0 x 103 L. cm-1. mol-1) assigned to charge transfer π→π*. We obtained the value of E1/2 = -260 mV reference electrode), glassy carbon (working electrode) and platinum (auxiliary electrode) for the complex from the cyclic voltammetry and differential pulse polarogram. The stoichiometry of 1:1 (M:L) for the complex was determined by Job's method and confirmed by measures of conductance. Were determined pKa's for the free ligand ATA: pK1 = 4.80, pK2 = 5.73 and pK3 = 10.50, concerning the first, second and third deprotonation of the ligand H3ATA. The potentiometric measurement of the complex under study shows value of pK1 = 4.41 and pK2 = 4.55 for the first and second equivalence point, respectively, showing the presence of two ionizable hydrogens present in the complex.