Stability constants of metalloporphyrins. A study of the protonation, deprotonation, and formation of copper(II) and zinc(II) complexes of meso-tetra-(p-sulphonatophenyl)porphyrin

Abstract

Quantitative study of the protonation and deprotonation equilibria of meso-tetra-(p-sulphonatophenyl)porphyrin, H₂TPPS^4–, as well as the formation equilibria of the Cu²⁺ and Zn²⁺ complexes, in a Me₂SO-water (80 : 20) solution, has allowed us to determine for the first time the stability constants of two metalloporphyrins, CuTPPS^4–(log β 38.1) and ZnTPPS^4–(log β 34.6) at 25 °C and 0.1 mol dm^3–(KClO₄+ HClO₄).