title: Stabilizing Pentacene By Cyclopentannulation.
abstract: A new class of stabilized pentacene derivatives with externally fused five-membered rings are prepared by means of a key palladium-catalyzed cyclopentannulation step. The target compounds are synthesized by chemical manipulation of a partially saturated 6,13-dibromopentacene precursor that can be fully aromatized in a final step through a DDQ-mediated dehydrogenation reaction (DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The new 1,2,8,9-tetraaryldicyclopenta[fg,qr]pentacene derivatives have narrow energy gaps of circa 1.2 eV and behave as strong electron acceptors with lowest unoccupied molecular orbital energies between -3.81 and -3.90 eV. Photodegradation studies reveal the new compounds are more photostable than 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene).
authors.affiliation: Department of Chemistry and Biochemistry and the Materials Technology Center, Southern Illinois University, Carbondale, IL 62901 (USA).
authors.forename: Sambasiva R
authors.initials: SR
authors.lastname: Bheemireddy
authors.affiliation: Department of Chemistry and Biochemistry and the Materials Technology Center, Southern Illinois University, Carbondale, IL 62901 (USA).
authors.forename: Pamela C
authors.initials: PC
authors.lastname: Ubaldo
authors.affiliation: Department of Chemistry and Biochemistry and the Materials Technology Center, Southern Illinois University, Carbondale, IL 62901 (USA).
authors.forename: Peter W
authors.initials: PW
authors.lastname: Rose
authors.affiliation: Swiss Light Source, Paul Scherrer Institute, Villigen PSI (Switzerland).
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Finke
authors.affiliation: Department of Chemistry and Biochemistry and the Materials Technology Center, Southern Illinois University, Carbondale, IL 62901 (USA).
authors.forename: Junpeng
authors.initials: J
authors.lastname: Zhuang
authors.affiliation: Department of Chemistry and Biochemistry and the Materials Technology Center, Southern Illinois University, Carbondale, IL 62901 (USA).
authors.forename: Lichang
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Chemistry and Biochemistry and the Materials Technology Center, Southern Illinois University, Carbondale, IL 62901 (USA). kplunkett@chem.siu.edu.
authors.forename: Kyle N
authors.initials: KN
authors.lastname: Plunkett
keywords: acenes; conjugation; organic electronics; palladium; polycyclic aromatic hydrocarbons