Covalent conjugates of ammine and diamine platinum(II) and octacarboxy substituted zinc phthalocyanine bearing one, two, three and four ammine platinum and ethylenediamine-N,N′-diacetic acid platinum moieties on the periphery of the Pc ligand have been synthesized and characterized. Complexes with two and three ammine platinum fragments and all diamine compounds have been synthesized for the first time. The solubility of conjugates with diamine platinum in aqueous solutions is higher than that for their ammine counterparts and for both series it significantly decreases as the number of platinum atoms increases. The effect of the stepwise introduction of the ammine and diamine platinums on the dynamics of the singlet and triplet excited states, on the ability to sensitize singlet oxygen formation and on the photostability of these compounds has been investigated in dimethylsulfoxide solution. Both ammine and diamine platinum moieties have only a limited effect on the photophysical and photochemical properties. Conjugates sensitize the formation of singlet oxygen with high quantum yields (Φ ∆ =0.47-0.60) and show higher activity in photoinactivation of cancer cells and cytotoxicity than parent octacarboxy-substituted PcZn.