Water-soluble carboranyl-phthalocyanines for BNCT. Synthesis, characterization, and in vitro tests of the Zn(ii)-nido-carboranyl-hexylthiophthalocyanine

Daniela Pietrangeli, Angela Rosa, Antonietta Pepe, Saverio Altieri, Silva Bortolussi, Ian Postuma, Nicoletta Protti, Cinzia Ferrari, Laura Cansolino, Anna Maria Clerici, Elisa Viola, Maria Pia Donzello, Giampaolo Ricciardi

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


The zinc(ii) complex of the octa-anionic 2,3,9,10,16,17,23,24-octakis-(7-methyl-7,8-dicarba-nido-undeca-boran-8-yl)hexyl-thio-6,13,20,27-phthalocyanine (nido-[ZnMCHESPc]Cs8, 7) has been obtained in the form of caesium salt through mild deboronation of the neutral precursor, the closo-[ZnMCHESPc] complex, 6, with CsF. 6 has been synthesized, in turn, by heating a finely ground mixture of the appropriate phthalonitrile and zinc(ii) acetate at 180.0 °C. The complexes have been characterized by elemental analyses, FT-IR, UV-visible absorption and fluorescence emission spectroscopy, and their structures were assessed by 1H, 13C, 11B, and two-dimensional homo- and hetero-correlated NMR spectroscopy experiments. 7 showed appreciable solubility in water solution, together with a marked tendency to aggregate. Aggregation of 7 in the hydrotropic medium resulted in significant fluorescence quenching. Instead, fluorescence quantum yields (ΦF) of 0.14 and 0.08, and singlet oxygen quantum yields (ΦΔ) of 0.63 and 0.24 were obtained for 6 and 7, respectively, in a DMF solution. In vitro boron neutron capture therapy (BNCT) experiments, employing boron imaging techniques as implemented in qualitative and quantitative neutron autoradiography methods, showed that 7 is capable of increasing the boron concentration of two selected cancerous cell lines, the DHD/K12/TRb of rat colon adenocarcinoma and UMR-106 of rat osteosarcoma, with the large-size Cs+ counter-ions used to neutralize the negatively charged carborane polyhedra not presenting a significant obstacle to the process. Taken together, BNCT and photophysical measurement results indicated that 7 is potentially suitable for bimodal or multimodal anticancer therapy.

Original languageEnglish
Pages (from-to)11021-11028
Number of pages8
JournalDalton Transactions
Issue number24
Publication statusPublished - Jun 28 2015
Externally publishedYes

ASJC Scopus subject areas

  • Inorganic Chemistry


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