title: Spiral intramolecular charge transfer and large first hyperpolarizability in Möbius cyclacenes: new insight into the localized π electrons.
abstract: Much effort has been devoted to investigating the unusual properties of the π electrons in Möbius cyclacenes, which are localized in a special region. However, the localized π electrons are a disadvantage for applications in optoelectronics, because intramolecular charge transfer is limited. This raises the question of how the intramolecular charge transfer of a Möbius cyclacene with clearly localized π electrons can be enhanced. To this end, [8]Möbius cyclacene ([8]MC) is used as a conjugated bridge in a donor-π-conjugated bridge-acceptor (D-π-A) system, and NH(2)-6-[8]MC-10-NO(2) exhibits a fascinating spiral charge-transfer transition character that results in a significant difference in dipole moments Δμ between the ground state and the crucial excited state. The Δμ value of 6.832 D for NH(2)-6-[8]MC-10-NO(2) is clearly larger than that of 0.209 D for [8]MC. Correspondingly, the first hyperpolarizability of NH(2)-6-[8]MC-10-NO(2) of 12,467 a.u. is dramatically larger than that of 261 a.u. for [8]MC. Thus, constructing a D-π-A framework is an effective strategy to induce greater spiral intramolecular charge transfer in MC although the π electrons are localized in a special region. This new insight into the properties of π electrons in Möbius cyclacenes may provide valuable information for their applications in optoelectronics.
authors.affiliation: Institute of Functional Material Chemistry, Faculty of Chemistry, Northeast Normal University, Changchun, 130024 Jilin, China.
authors.forename: Rong-Lin
authors.initials: RL
authors.lastname: Zhong
authors.forename: Hong-Liang
authors.initials: HL
authors.lastname: Xu
authors.forename: Zhong-Min
authors.initials: ZM
authors.lastname: Su
authors.forename: Zhi-Ru
authors.initials: ZR
authors.lastname: Li
authors.forename: Shi-Ling
authors.initials: SL
authors.lastname: Sun
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Qiu