Robust covalent pyrazine anchors forming highly conductive and polarity-tunable molecular junctions with carbon electrodes

Abstract

In molecular electronics, electrode-molecule anchoring strategies play a crucial role in the design of stable and high-performance functional single-molecule devices. Herein, we employ aromatic pyrazine as anchors to connect a...

Oxazine: an anchoring group serving as functional kernels to construct single-molecule switches

“…Another possibility to enhance the low-bias conductance of graphene-M1 dH -graphene is to replace the pristine graphene electrodes with nitrogen-doped (N-doped) ones, in which the Dirac point is shifted below E F and the DOS around E F increases markedly due to the additional π-electrons brought by the nitrogen dopants. 70,83,84 Importantly, a remarkable conductance switching effect is also observed in this type of junction. In fact, after substituting one carbon atom with nitrogen in a rectangular unit cell of graphene containing 40 atoms, as shown in Fig.…”

High-performance molecular spin filters based on a square-planar four-coordinate Fe complex and covalent pyrazine anchoring groups

“…S17 of the ESI† for further elaboration of the increasing electronic coupling). 32,83 The transmission peaks are therefore significantly broadened as shown in Fig. 5(b) and (d), compared to those in Fig.…”

“…11,21,[26][27][28][29] It is well-known that for electronic devices based on single molecules, the interaction of frontier molecular orbitals (FMOs) with the continuum states of the electrodes dictates the energy level alignment and the electronic coupling, which are two fundamental factors determining the device performance. [30][31][32] Generally speaking, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the central molecule are energetically closer to the electrodes' E F than other orbitals and therefore they play a dominant role in the transport properties of a single-molecule junction. 33,34 As a result, electron transport in the second type of molecular spintronic devices is intricately linked to the spindependent electronic structure of the central magnetic molecule, especially the difference in the HOMOs and LUMOs between the two spin types.…”

“…In both cases, it is expected that the interaction between the p-type continuum of states of the carbon electrodes and the p-type FMOs of the central molecule can result in efficient electron transport. Since both fused benzene and pyrazine groups promote planarity and enhance conjugation, thus shrinking the energy gap between the delocalized HOMO and LUMO, 32,54 we employ both benzene and pyrazine as end groups to functionalize FeN 4 . We find that both the resulting molecules have the desired feature, namely the delocalized HOMO and LUMO for the spin-up electrons together with the completely localized HOMO and LUMO for the spin-down ones.…”

“…In these, the localized spin-down HOMO and LUMO do not contribute to the junction transmission. Notably, since pyrazine anchors can induce partial electron transfer from the electrodes to the central molecule due to their electronegative N atoms, 32 the spin-up LUMO-dominated transmission peak lies exactly at E F , making spin-filtering efficient and effective. Further calculations show that this remarkable spin-filtering performance is robust against different SWCNT edges, SWCNT's curvature, and even with N-doped graphene electrodes.…”