Synthesis and properties of covalently linked trichromophore systems

Abstract

Four covalently linked trichromophore systems containing a central boron dipyrromethene (BODIPY) unit connected to a porphyrin unit through the 3-position and a core-modified porphyrin or a porphyrin expanded through the 5-position were synthesized by treating 3-bromo-5-porphyrinyl BODIPY or 3-bromo-5-rubyrinyl BODIPY with the corresponding hydroxy porphyrin or hydroxy-expanded porphyrin in CHCl₃ at 60°C. The compounds are freely soluble in common organic solvents and confirmed by mass spectrometry and 1D and 2D NMR spectroscopy techniques. The absorption and electrochemical studies support weak ground-state interactions among the three chromophore units within the trichromophore systems. The fluorescence studies indicate that BODIPY emission is quenched to a significant degree in all trichromophore systems due to a transfer of energy to one or both macrocyclic units attached to the BODIPY chromophore.