Studies on the synthesis and potentiometric properties of three novel tripodal ligands and their complexes

Three novel tripodal ligands, N,N',N''-tri-(3'-phenylpropionic acid-2'-yl-)-1,3,5-triaminomethylbenzene (Ll), N,N',N''-tri-(4'-methylvaleric acid-2'-y1-)-1,3,5-triaminomethylbenzene (L2) and N,N',N''-tri-(3'methylvaleric acid-2'-yl-)-1,3,5-triaminomethylbenzene (L3), have been synthesized and fully characterized. The stabilizing ability of complexes of the three ligands with transition metal ions Cu(II), Ni(II), Zn(II) and Co(II) and rare earth metal ions La(III), Nd(III), Sm(III), Eu(III) and Gd(III) has been investigated by the pontentiometric method in water and in aqueous KNO3 (0.1 mol dm(-3)) at 25.0 +/- 0.1 degrees C, respectively. The results show that there is a great deal of difference between two series of complexes' stabilities. An explanation of the difference has been given.