title: Redox control and high conductivity of nickel bis(dithiolene) complex π-nanosheet: a potential organic two-dimensional topological insulator.
abstract: A bulk material comprising stacked nanosheets of nickel bis(dithiolene) complexes is investigated. The average oxidation number is -3/4 for each complex unit in the as-prepared sample; oxidation or reduction respectively can change this to 0 or -1. Refined electrical conductivity measurement, involving a single microflake sample being subjected to the van der Pauw method under scanning electron microscopy control, reveals a conductivity of 1.6 × 10(2) S cm(-1), which is remarkably high for a coordination polymeric material. Conductivity is also noted to modulate with the change of oxidation state. Theoretical calculation and photoelectron emission spectroscopy reveal the stacked nanosheets to have a metallic nature. This work provides a foothold for the development of the first organic-based two-dimensional topological insulator, which will require the precise control of the oxidation state in the single-layer nickel bisdithiolene complex nanosheet (cf. Liu, F. et al. Nano Lett. 2013, 13, 2842).
authors.affiliation: Department of Chemistry, Graduate School of Science, The University of Tokyo , 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kambe
authors.forename: Ryota
authors.initials: R
authors.lastname: Sakamoto
authors.forename: Tetsuro
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authors.lastname: Kusamoto
authors.forename: Tigmansu
authors.initials: T
authors.lastname: Pal
authors.forename: Naoya
authors.initials: N
authors.lastname: Fukui
authors.forename: Ken
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authors.lastname: Hoshiko
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shimojima
authors.forename: Zhengfei
authors.initials: Z
authors.lastname: Wang
authors.forename: Toru
authors.initials: T
authors.lastname: Hirahara
authors.forename: Kyoko
authors.initials: K
authors.lastname: Ishizaka
authors.forename: Shuji
authors.initials: S
authors.lastname: Hasegawa
authors.forename: Feng
authors.initials: F
authors.lastname: Liu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nishihara