title: Multifaceted Regioregular Oligo(thieno[3,4-b]thiophene)s Enabled by Tunable Quinoidization and Reduced Energy Band Gap.
abstract: Thiophene-based materials have occupied a crucial position in the development of organic electronics. However, the energy band gaps of oligo- and polythiophenes are difficult to modulate without resorting to push-pull electronic effects. We describe herein a new series of monodisperse oligo(thieno[3,4-b]thiophene) derivatives with well-defined regioregular structures synthesized efficiently by direct C-H arylation. These compounds show a unique palette of colors and amphoteric redox properties with widely tunable energy band gaps. The capacity to stabilize both cations and anions results in both anodic and cathodic electrochromism. Under excitation, these compounds can produce photoionized states able to interconvert into neutral triplet or form these through singlet exciton fission or intersystem crossing. These features arise from a progressive increase in quinoidization on a fully planar platform making the largest effective conjugation length among hetero-oligomers. Oligo(thieno[3,4-b]thiophene)s might represent the more distinctive family of oligothiophenes of this decade.
authors.affiliation: †Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.affiliation: ‡Department of Physical Chemistry, University of Málaga, Campus de Teatinos s/n, Málaga, 29071, Spain.
authors.forename: Guzmán L
authors.initials: GL
authors.lastname: Espejo
authors.affiliation: †Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
authors.forename: Shuhai
authors.initials: S
authors.lastname: Qiu
authors.affiliation: ‡Department of Physical Chemistry, University of Málaga, Campus de Teatinos s/n, Málaga, 29071, Spain.|§Coimbra Chemistry Centre, Department of Chemistry, University of Coimbra, Rua Larga Coimbra, 3004-535, Portugal.
authors.forename: María Moreno
authors.initials: MM
authors.lastname: Oliva
authors.affiliation: §Coimbra Chemistry Centre, Department of Chemistry, University of Coimbra, Rua Larga Coimbra, 3004-535, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Pina
authors.affiliation: §Coimbra Chemistry Centre, Department of Chemistry, University of Coimbra, Rua Larga Coimbra, 3004-535, Portugal.
authors.forename: J Sérgio
authors.initials: JS
authors.lastname: Seixas de Melo
authors.affiliation: ‡Department of Physical Chemistry, University of Málaga, Campus de Teatinos s/n, Málaga, 29071, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Casado
authors.affiliation: †Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China.
authors.forename: Xiaozhang
authors.initials: X
authors.lastname: Zhu