Novel aza-BODIPY-carborane conjugates: synthesis and characterization

Abstract

With the objective of preparing efficient photo/radiosensitizers for PDT and BNCT, a synthetic approach was developed for the introduction of carborane clusters into the aza-BODIPY core based on the S_NAr substitution reaction of para-fluorine atoms in 1,7-dipentafluorophenyl-3,5-diphenyl-4,4-difluoro-4-bora-3a,4a,8-triaza-s-indacene with mercapto-carborane. The possibility for the synthesis of boron-enriched (33%) aza-BODIPYs was also demonstrated starting from the reaction of corresponding aza-dipyrromethenes with carborane S-nucleophile, followed by complexation with BF₃·OEt₂. The new compounds were characterized via¹H-NMR, ¹¹B-NMR, ¹⁹F-NMR, UV-vis, FTIR and mass spectrometry. The crystal structures of the key aza-BODIPY-carborane conjugates were determined via single-crystal X-ray diffraction.