Potentiometric Study of a Benzene-based Tripodal Triamine as Chelator for Zn(II) Ion

The complexation of a C3-symmetrical tripodal triamine ligand, N1,N3,N5-tris(2-aminoethyl)benzene-1,3,5-tricarboxamide (TAT, L) with Zn(II) ion was investigated at an ionic strength of 0.1 M NaClO4 and 25 ± 1 °C in aqueous medium. Formation of complex species [ZnL(H2O)]2+ and [ZnL(OH)]+ were depicted in solution, where the ligand is tri-coordinated through three amine N-atoms and their stability constants were calculated with the HYPERQUAD 2000 computer program. The pKa of the zinc-bound water molecule is 7.84, making the Zn(TAT) complex a viable model of carbonic anhydrase.