Observation of current rectification by a new asymmetric iron(iii) surfactant in a eutectic GaIn|LB monolayer|Au sandwich

Abstract

In this paper we expand on the search for molecular rectifiers of electrical current and report on a hexacoordinate metallosurfactant [FeIII(LN3O)(OMe)2], where (LN3O)- is the deprotonated form of the new asymmetric ligand 2-((E)-((4,5-bis(2-methoxyethoxy)-2-(((E)-pyridin-2-ylmethylene)amino)phenyl)imino)methyl)-4,6-di-tert-butyl-phenol. This species rectifies current when deposited as a Langmuir-Blodget film in a "EGaIn/Ga2O3|LB|Au" sandwich with rectification ratios ranging from 25 to 300 at 1 Volt.

Influence of Electronic Configurations on the Modulation of Fermi/Orbital Junction Energies for Directional Electron Transport through 3d1, 3d3, and 3d5 Metallosurfactants

“…9,10 When the energy of the SOMOs was mismatched with that of the Fermi levels of the electrode, e.g., in Cu II 3d 9 configuration leaves the highest 3d x2-y2 as the only singly occupied MO, an insulating behavior was observed. These results were validated statistically 11,12 and permitted us to postulate that for some systems containing transition metals, the SOMOs rather than the LUMOs are the operative orbitals for tunneling. The semioccupied nature of these orbitals may limit the amplitude of the current response due to spin restrictions imposed by Pauli's exclusion; however, this property may be advantageous for spin transport research in electronic materials.…”

“…g ., in Cu II surfactants in which a 3d 9 configuration leaves the highest 3d x2‑y2 as the only singly occupied MO, an insulating behavior was observed. These results were validated statistically , and permitted us to postulate that for some systems containing transition metals, the SOMOs rather than the LUMOs are the operative orbitals for tunneling. The semioccupied nature of these orbitals may limit the amplitude of the current response due to spin restrictions imposed by Pauli’s exclusion; however, this property may be advantageous for spin transport research in electronic materials. , Accordingly, the formation of a radical in an initially closed-shell organic species leads to SOMO transport, while HOMO rectification is observed in organometallic species such as ferrocene .…”

Electron transport through a (terpyridine)ruthenium metallo-surfactant containing a redox-active aminocatechol derivative

“…9 The semi-occupied nature of these orbitals limits the amplitude of the current response due to Pauli's exclusion, but precludes the limiting LS (t 2g 6 e g 0 ) configuration when the metal center is momentarily reduced to 3d 6 Fe II during electron transport. The rectification process has been verified independently, 10 and other SOMO based rectifiers have been identified. 11…”

Studies on Monolayer Formation and Electron Transport in Au|LB|Au Junctions Containing 3d4 MnIII Metallosurfactants

“…We are interested in the role of 3d n electronic configurations on directional electron transport and how the energies of empty LUMO, singly occupied SOMO, and filled HOMO orbitals in these configurations can be controlled by the number of electrons and by ligand fields to match with the Fermi levels of the electrodes, thus enabling directional transport. We have studied the electrochemical, spectroscopic, and I / V response of Au|LB|Au junctions containing Langmuir–Blodgett films of 3d 1 , 3d 3 , HS 3d 5 , and 3d 9 metallosurfactants containing [N 2 O 2 ] or [N 2 O 3 ] donors. − We notice that the 3d 1 species [V = O IV (L N2O2 )], the 3d 3 species [Cr III (L N2O2 )­(H 2 O)­(MeOH)]­Cl, and high-spin 3d 5 species [Fe III (L N2O2 )­Cl] and [Fe III (L N2O3 )] are able to engage in directional electron transfer through different mechanisms. Both the VO IV and HS Fe III species mediate electron transport through the metal SOMO; however, while the 3d 1 species relies on the 3d xy -based molecular orbital (MO) about 0.5 eV below the Fermi level of Au, the 3d 5 species relies on a (3d xz + 3d yz ) linear combination within 1 eV above the Fermi levels.…”