Complexation of Group IIIA metals with asymmetric tridentate ligands: Synthesis, characterization, formation constants and cytotoxicity

A series of new aluminum(III), gallium(III) and indium(III) complexes with some tridentate Schiff base, viz., N-{pyridine-2-ylmethyl}-2-hydroxy-5-methoxy-benzylideneamine [HL1], N-{pyridine-2-ylmethyl}-2-hydroxy-benzylideneamine [HL2], N-{pyridine-2-ylmethyl}-2-hydroxy-5-nitro-benzylideneamine [HL3], N-{pyridine-2-ylmethyl}-2-hydroxy-5-bromo-benzylideneamine [HL4], N-{pyridine-2-ylethyl}-2-hydroxy-5-methoxy-benzylideneamine [HL5], N-{pyridine-2-ylethyl}-2-hydroxy-benzylideneamine [HL6], N-{pyridine-2-ylethyl}-2-hydroxy-5-nitro-benzylideneamine [HL7], N-{pyridine-2-ylethyl}-2-hydroxy-5-bromo-benzylideneamine [HL8], with the general formula [ML2][Y] (M = Al3+, Ga3+, In3+; Y = NO3−, ClO4−) were synthesised and characterized by elemental analysis, 1H NMR, FT-IR, UV–Vis spectrophotometry and mass spectrometry. The thermodynamic formation constants of the complexes were determined spectrophotometrically at constant ionic strength (I = 0.10 M NaClO4) and at 25 °C in methanol. The trend of formation constants of the complexes are as follow: