Spectral study of the supramolecular assemblies porphyrins–phthalocyanines

The mixture between the solutions of one anionic porphyrin-5,10,15,20-tetra(p-sulfonato-phenyl-porphyrin (TSPP) and a charged-positive phthalocyanine-4,4″-bis(4-trimethyl amino-ethyl sulphanyl) 4′,4‴-di-amino-phthalocyanine dimethyl sulphate (Pc56) in polar solvent (DMSO), yielding to a well-defined supramolecular heterodimer (Pc/P) and a supra-molecular heterotrimer (Pc/P2), are reported in this paper. The absorption spectra of such heterocomplexes are drastically changed with respect to the corresponding monomers, indicating the existence of a strong electrostatic interaction between these chromophores. The stoichiometry and formation constant of the heterocomplex are evaluated by means of Job method. The lifetimes for the first excited singlet states of the studied compounds were calculated and correlated with the singlet oxygen generation efficiency for the heterodimer and heterotrimer.