Synthesis of ether- and carbon-linked polycarboranyl porphyrin dimers for cancer therapies

Porphyrin dimers bearing multiple carborane cages for potential use as sensitizers in boron neutron capture therapy (BNCT) and photodynamic therapy (PDT) were synthesized from protoporphyrin dimethyl ester and characterized. Diastereomeric ether-linked dimers bearing four closo carborane cages (40 boron atoms) were found to be unstable to the acidic conditions necessary for conversion into water-soluble salts. In contrast, the carboncarbon-linked dimers bearing six icosahedral carboranes (60 boron atoms) were stable to acid and could be isolated as water-soluble sodium salts. In vitro and in vivo studies of these novel molecules are currently under investigation.