Aggregation of nickel(II), copper(II), and zinc(II) derivatives of water-soluble porphyrins

The solution properties of the nickel(II), copper(II), and zinc(II) derivatives of tetracarboxyphenylporphine (TCPP) and tetra(N-methylpyridyljporphine (TMPyP) have been investigated. At μ = 0. 1 M and 25°, NiTMPyP, CuTMPyP, ZnTMPyP, and ZnTCPP show no tendency to aggregate. However, under these conditions NiTCPP and CuTCPP dimerize with concentration equilibrium constants of 1. 57×10 and 1. 69×10 M , respectively. The kinetics of the process 2MTCPP ⇆ (MTCPP), (k , k ) have been investigated via the temperature-jump technique. For NiTCPP, k = 6. 2×10 M sec and k = 4, 0×10 sec ; for CuTCPP, k22 = 4. 5×10 M sec and k = 2. 7×10 sec .