Complex formation between aluminum(III) and hydroxysalicylic acid derivatives in aqueous solution

Abstract

Equilibria between aluminum(III) and hydroxysancylic acids, (H3L), (2,X-DHBA, X = 4-6) were investigated in 0.1 M (NaCl) medium at 25.0 +/- 0.1 degrees C. pH-potentiometric solution speciation measurements were performed within the limits 2:5 pH:5 10 and Al(III) to ligand ratios were within the ranges 1 : 1 to 1 : 10. The stoichiometries of the formed complexes between AI(III) and these hydroxysalicylic acids were defined by means of spectroscopy. The results of potentiometric titrations were analyzed with two different computer programmes: BEST and RANA. All data can be explained with the occurrences of binary Al(HL)(+) and Al(HL)(OH) mixed hydroxo complexes and their formation constants were found. as: log 0 = 8.67 +/- 0.02, 9.24 +/- 0.02, 10.87 +/- 0.01 and log 0 = 5.16 +/- 0.04, 4.69 +/- 0.04, 4.73 +/- 0.04, respectively. The formation constants and the stoichiometries of AI(III)-2,X-DHBA complexes were compared to the values resulted in earlier studies of aluminium(III)-2, XDHBA systems.