Germanium-dihydroxy-phthalocyanine GePc(OH2) was synthesized and used as starting material for several new, axially disubstituted derivatives of the general formula GePc[OSi(R2)R']2. The preparation of the monosubstituted silanol side chains HOSi(R)2R' was performed either by Mitsunobu reaction starting from diphenylsilandiol Si(Ph)2(OH)2 followed by direct coupling of the side-chain with GePc(OH)2, or by synthesis from a dichlorosilyl derivative. The new compounds were fully characterized and the chemical and main photophysical properties determined. The absorption maxima of these compounds lie in the range of 675 nm. They were found to possess a high quantum efficiency of singlet-oxygen production and fluorescence. The compounds were incorporated into small, unilamellar liposomes following a technology developed by Ciba-Geigy. The dye-to-lipid ratio was 1:100. The liposomal suspensions were freeze-dried for storage. The new compounds were evaluated for their pharmacokinetic and phototherapeutic properties.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.