Regioselective Photocyclization To Prepare Multifunctional Blocks for Ladder-Conjugated Materials

Multifunctional building blocks 8 and 9 were efficiently synthesized by fusing a perylene-3,4,9,10-tetracarboxylic acid bisimide (PBI) core with o-phenylenediamine, and they were condensed with a pyrenedione and a pyrenetetraone, respectively, to construct new ladder-type conjugated oligomers 12 and 13. In the key photocyclization step, an unusual regioselectivity at the position ortho to the nitro group was discovered in the coupling of the o-nitroaniline functional units at the bay sites of PBI. Bulk-heterojunction solar cells based on 12 and 13 as the acceptors exhibited reasonable performance.