Thermal behavior of tetrapyrrole derivatives and their mixed complexes

The thermal properties of CoPc and ZnPc (Pc = phthalocyanine) and ZnTPP (TPP = tetraphenylporphyrin), pyrazine adducts and heterotriads [CoPc(pyz)ZnTPP(pyz)CoPc] and [ZnTPP(pyz)CoPc(pyz)ZnTPP] were investigated using TGA and DSC. The thermal stability of axial coordination was investigated for adduct complexes and it increased in the order ZnPc(pyz)2 < ZnTPP(pyz)2 ≈ CoPc(pyz)2. The phthalocyanine–porphyrin mixed complexes decompose in several steps; the initial step corresponds to the degradation of the spacer ligand. It was shown that the breakdown mechanism of phthalocyanine macrocycle was affected by the triad formation.