SYMMETRICALLY SUBSTITUTED nido-CARBORANYLPHTHALOCYANINES: FACILE SYNTHESIS, CHARACTERIZATION, AND SOLUTION PROPERTIES. EVIDENCE FOR INTRA- AND INTERMOLECULAR H+/K+ EXCHANGE

Cyclotetramerization of a phthalic acid or phthalonitrile derivative bearing appropriate chemical functions has provided synthetic access to peripherally and non peripherally substituted phthalocyanines (Pcs). Although much success has been achieved over time in attenuating the harsh cyclization conditions, which are detrimental to chemically delicate substituents, or in using ex post synthetic methods, examples of complexly decorated Pcs are still scarce and structural diversity is severely restricted. Thus, the discovery of new synthetic routes to functionalized Pcs has been the focus of the research in recent years, particularly of water-soluble derivatives. In continuing our search for new molecules for application in boron neutron capture therapy (BNCT),1 we report herein the direct, non ex post synthesis of a novel phthalocyanine decorated with eight thiohexyl-nido-carborane functions, nido- [H2MCHESPc]K8 (Figure 1) where the anionic polyhedra are in the form of K+ salt. 2 The solution properties of this compound, including the unprecedented exchange between the pyrrolic protons and the peripheral alkali metal ions, are also analyzed, both experimentally and theoretically. Due to its chemical constitution and solution photo properties, the molecule has potential as multimodal anticancer agent. The unprecedented intra- and/or intermolecular H+ K+ exchange is accompanied by significant spectral changes, thus suggesting that the complex has a potential as proton sensing. ______________ References: 1. Pietrangeli, D.; Rosa, A.; Ristori, S.; Salvati, A.; Altieri, S.; Ricciardi, G. Coord. Chem. Rev., 2013, http://dx.doi.org/10.1016/j.ccr.2013.03.035 2. Pietrangeli, D.; Rosa, A.; Pepe, A.; Ricciardi, G. Inorg. Chem., 2011, 50, 4680-4682.