Studies on Monolayer Formation and Electron Transport in Au|LB|Au Junctions Containing 3d4 MnIII Metallosurfactants
Year: 2023
Journal: The Journal of Physical Chemistry C, Volume 127, 24/08/2023
Authors: Cousino, Abigail; Wickramasinghe, Lanka D.; Kaushalya, Widana; Perera, S. Sameera; Baydoun, Habib; Walker, Alice R.; Verani, Cláudio N.
Three new metallosurfactants containing 3d4 manganese(III) ions, namely, [MnIII(LNO2-N2O2)Cl(MeOH)] (1), [MnIII(LN2O2)(H2O)(MeOH)]Cl (2), and [MnIII(LN2O3)] (3), bound to three distinct phenylenediamine-bridged phenolate-rich ligands were designed, deposited as Langmuir–Blodgett monolayer films on gold electrodes, and probed for directional electron transfer in Au|LB|Au junctions. All three MnIII metallosurfactants promote current rectification, and we compare the behavior of these metallosurfactants with that of our previously studied 3d1 V═OIV, 3d3 CrIII, and 3d5 FeIII species in similar environments through a rigorous effort. Based on the analysis of electrochemical, spectroscopic, microscopic, and DFT results, we propose distinct mechanisms by which electronic configurations and ligand frameworks influence and modulate the energy gap between the electrode Fermi levels and the molecular orbitals responsible for electron transport. Our previous work characterized distinct mechanisms, i.e., electron transport through below-Fermi for VIVO-based SOMOs and above-Fermi for FeIII-based SOMOs and ligand-based HOMOs for the CrIII species. These MnIII species show electron transport similar to FeIII; however, low current capacities suggest that film quality is an important factor to be considered.
