title: para-Quinodimethane-bridged perylene dimers and pericondensed quaterrylenes: the effect of the fusion mode on the ground states and physical properties.
abstract: Polycyclic hydrocarbon compounds with a singlet biradical ground state show unique physical properties and promising material applications; therefore, it is important to understand the fundamental structure/biradical character/physical properties relationships. In this study, para-quinodimethane (p-QDM)-bridged quinoidal perylene dimers 4 and 5 with different fusion modes and their corresponding aromatic counterparts, the pericondensed quaterrylenes 6 and 7, were synthesized. Their ground-state electronic structures and physical properties were studied by using various experiments assisted with DFT calculations. The proaromatic p-QDM-bridged perylene monoimide dimer 4 has a singlet biradical ground state with a small singlet/triplet energy gap (-2.97 kcal mol(-1)), whereas the antiaromatic s-indacene-bridged N-annulated perylene dimer 5 exists as a closed-shell quinoid with an obvious intramolecular charge-transfer character. Both of these dimers showed shorter singlet excited-state lifetimes, larger two-photon-absorption cross sections, and smaller energy gaps than the corresponding aromatic quaterrylene derivatives 6 and 7, respectively. Our studies revealed how the fusion mode and aromaticity affect the ground state and, consequently, the photophysical properties and electronic properties of a series of extended polycyclic hydrocarbon compounds.
authors: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543 Singapore, Fax: (+65) 6779-1691.
authors: Soumyajit
authors: S
authors: Das
authors: Sangsu
authors: S
authors: Lee
authors: Minjung
authors: M
authors: Son
authors: Xiaojian
authors: X
authors: Zhu
authors: Wenhua
authors: W
authors: Zhang
authors: Bin
authors: B
authors: Zheng
authors: Pan
authors: P
authors: Hu
authors: Zebing
authors: Z
authors: Zeng
authors: Zhe
authors: Z
authors: Sun
authors: Wangdong
authors: W
authors: Zeng
authors: Run-Wei
authors: RW
authors: Li
authors: Kuo-Wei
authors: KW
authors: Huang
authors: Jun
authors: J
authors: Ding
authors: Dongho
authors: D
authors: Kim
authors: Jishan
authors: J
authors: Wu
keywords: aromaticity; polycycles; radicals; rylene; zethrene