FeCl3-promoted regioselective synthesis of BODIPY dimers through oxidative aromatic homocoupling reactions.

The direct 3,3'-dimerization of BODIPYs lacking substituent groups in the 1,2,6, and 7 positions was developed by oxidative coupling with FeCl3. This regioselective dimerization was achieved for BODIPYs substituted only in the 5-position with Cl or aryl groups. Further functionalization of the 5,5'-dichloride dimer gave the corresponding pyrrole or 4-(2-aminoethyl)morpholine disubstituted dimers 2f and 2g, respectively. While dimer 2f exhibited intense NIR absorption/emission maxima at 773/827 nm in toluene, dimer 2g showed favorable lysosome-targeting NIR fluorescence in living cells.