Cyclopenta-fused perylene: a new soluble, stable and functionalizable rylene building block

We report a facile synthesis of a [1,12-b,c,d]-cyclopenta-fused perylene 5 from the parent perylene via a formylation-oxidative esterification-nucleophilic addition-followed-by-Friedel-Crafts alkylation strategy. Compared with the perylene, dye 5 exhibits much higher solubility, smaller energy gap, and can undergo regio-selective bromination at the peri-positions. Compared with the N-annulated perylene 8, compound 5 shows lower HOMO energy level and is more stable in air. Therefore, 5 can be regarded a new versatile building block for the development of high-order soluble and stable rylenes and various perylene-based functional materials.