Study of the stability of 5,10,15,20-tetraphenylporphine (TPP) and metalloporphyrins NiTPP,CoTPP, CuTPP,and ZnTPP by differential scanning calorimetry and thermogravimetry

In this work, the stability of 5,10,15,20-tetraphenylporphine (TPP) and its metallic derivatives, NiTPP, CoTPP, CuTPP, and ZnTPP has been studied through differential scanning calorimetry and thermogravimetry. The decomposition temperatures are (712, 710, 708, 702, and 671) K for NiTPP, CoTPP, CuTPP, ZnTPP, and TPP, respectively. These values are in correspondence with the N–M bond length d_M–N, of the metalloporphyrins. The corresponding molar enthalpies of melting Δ_fusH_m, were determined as (58, 57, 55, 52, and 44) kJ · mol^?1 for the same series. These values are discussed in terms of the crystallographic features in the solid state.