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).

High temperature ferromagnetism in π-conjugated two-dimensional metal–organic frameworks

“…This is consistent with the fact that 2D MOFs with some of the highest measured electrical conductivity were realized by π-conjugation through square-planar Ni–N linkage. 9,11 We also find that replacing the nitrogen linker atoms in the square-planar Ni–N moieties by sulfur or oxygen does not significantly increase or decrease the magnetic exchange energy, suggesting that catechol and thiocatechol moieties may also mediate effective π electron conjugation (see also Fig. S2†).…”

First-principles design of a half-filled flat band of the kagome lattice in two-dimensional metal-organic frameworks

“…Owing to their typically trivial and localized electronic states, MOFs have not attracted much attention from condensed-matter physicists. However, recent experimental success in fabricating atomically layered two-dimensional (2D) MOFs with kagome lattice structures, initiated by the Nishihara group [2][3][4][5], is bridging the gap between condensedmatter physics and chemistry. The Dincȃ group also succeeded in creating 2D MOFs [6,7].…”

Bis(dipyrrinato)metal(ii) coordination polymers: crystallization, exfoliation into single wires, and electric conversion ability

“…4,5,31,32 For example, a liquid/liquid interfacial synthesis using 1,2,4,5-benzenetetrathiol and nickel( ii ) ions produced a nickel bis(dithiolene) 1D-CP that aligns to form two-dimensional ordered structures. 31 In the present work, the coordination reaction between bridging dipyrrin ligand L1 in dichloromethane and divalent metal ions M 2+ ( M = Zn, Ni, and Cu) in water was carried out at the liquid/liquid interface, and it produced crystals of M1 that floated on the interface or sank to the bottom of the reaction container (Fig.…”