Metal-free and metallo-porphyrazines (M = Mg or Co) carrying eight dimethylaminoethylthia-groups on peripheral positions have been synthesized from the disodium salt of dithiomaleonitrile and the hydrochloride of dimethylaminoethylchloride. The magnesium derivative (MgPza) was converted into quaternized product (MgPzq) by reaction with methyl iodide. The metal-free derivative was obtained by treatment with trifluoroacetic acid and its reaction with cobalt (II) acetate led to the cobalt derivative (CoPza). Aggregation of MgPzq molecules has been observed in aqueous solution by the blue-shift of the Q-band absorption with an accompanying decrease in intensity. The new compounds have been characterized by elemental analysis, IR, NMR and their electronic spectra. (C) 2000 Elsevier Science Ltd. All rights reserved.