Kinetics of zinc ion incorporation in base into a centrally aprotic beta-octabrominated cationic water-soluble porphyrin and its monolithium complex

The kinetics of zinc incorporation from pH 12 to 13 into the centrally aprotic BrP(4)(2+) form of beta- octabromo-meso-tetrakis (N-methy1-4-pyridyl)porphyrin and its monolithium complex were studied at 25.0degreesC, ionic strength (l) = 0.10. The reactions were first order in porphyrin and total zinc concentrations. For BrP(4)(2+) the specific rate constant was 5.1 X 10(5) M-1 s(-1) for Zn(OH)(2)aq, 9.9 X 10(4) M-1 S-1 for Zn(OH)(3)(-), and Zn(OH)(4)(2-) was unreactive. The Li-BrP(4)(3+) complex had a formation constant with BrP(4)(2+) from both kinetic and equilibrium measurements. In solutions containing both BrP(4)(2+) and Li-BrP(4)(3+), zinc incorporation proceeded 21 only through BrP(4)(2+). Copyright (C) 2001 John Wiley Sons, Ltd.