Synthesis and properties of triazole bridged BODIPY-conjugates

Abstract

A series of triazole bridged BODIPY-conjugates were synthesized under click reaction conditions. The 3-azido BODIPY was generated in situ by treating 3-bromo BODIPY with NaN₃ in CH₃CN at room temperature for 60 min and reacted with appropriate ethynyl containing chromophore/redox active unit, such as ferrocene, BODIPY, Zn(II) porphyrin, 21,23-dithiaporphyrin, BF₂-smaragdyrin in the presence of CuI/DIPEA in THF/CH₃CN solvent. The conjugates were purified by column chromatography and obtained pure compounds in 45–50 % yields. The conjugates were characterized by HR-MS, 1D, 2D, ¹⁹F and ¹¹B NMR and X-ray crystallography for BODIPY-ferrocene conjugate. Absorption and electrochemical studies showed features of both the moieties present in the conjugates and also support interaction between the two moieties in the conjugates. The fluorescence studies supported an efficient energy transfer from BODIPY unit to BF₂-smaragdyrin unit in BODIPY–BF₂-smaragdyrin conjugate but the energy transfer was not efficient in BODIPY–Zn(II) porphyrin and BODIPY–21,23-dithiaporphyrin conjugates.