Synthesis of hexasubstituted boron-dipyrromethenes having a different combination of substituents

A series of sterically crowded, mixed hexasubstituted BODIPYs containing two different types of substituents on the pyrrole carbons have been synthesized in high yields by a stepwise approach. The mixed BODIPYs were synthesized by bromination of BODIPYs followed by coupling with appropriate boronic acids under Suzuki coupling conditions. This approach has allowed the introduction of two different types of methyl/aryl substituents at the designated positions of the BODIPY core. All the hexasubstituted BODIPYs are readily soluble in common organic solvents and have been characterized by various spectral and electrochemical techniques. The spectral studies indicated that the presence of mixed methyl/aryl substituents on the BODIPY core significantly alters the electronic properties, and the electrochemical studies revealed that the BODIPYs are stable under redox conditions