Synthesis and Properties of Covalently Linked Trichromophore Systems

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 degrees 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.