Search for: All records

We report on a new water-soluble cobalt(II) complex capable of water splitting bifunctionality, i.e., water reduction and water oxidation. The species [CoII(LQpy)H2O]ClO4 (1), where LQpy is the deprotonated form of the new tripodal ligand N1,N1-bis(pyridin-2-ylmethyl)-N2-(quinolin-8-yl)benzene-1,2-diamine, HLQpy, was developed aiming to replace an oxidation prone methylene group by a sturdy and redox stable quinoline. The molecular and electronic structures of 1 were evaluated by multiple spectroscopic, spectrometric, electrochemical and computational methods, and detailed pre- and post-catalytic studies were conducted to ascertain the molecular nature of the conversions. Complex 1 performs water reduction at a low onset overpotential (eta) of 0.65 V at pH 7, reaching TON3h 2900 (TOF 970 h-1) and TON18h 12 100 (TOF 672 h-1) with up to 98% faradaic efficiency (FE). Species 1 also promotes water oxidation at eta = 0.34 V under pH 8, achieving TON3h 193 (TOF 64 h-1) at 84% FE. Experimental and DFT results enabled us to propose reaction intermediates and mechanisms. 

Aiming to develop a new class of metallosurfactants with unidirectional electron transfer properties, a (terpyridine) ruthenium complex containing a semiquinone derivative L 2 , namely [Ru III (L terpy )(L 2 )Cl]PF 6 (1), was synthesized and structurally characterized as a solid and in solution. The electronic and redox behaviour of 1 was studied experimentally as well as by means of DFT methods, and is indicative of significant orbital mixing and overlap between metal and ligands. The complex forms stable Pockels–Langmuir films at the air-water interface and allows for the formation of thin films onto gold electrodes to prepare nanoscale Au|LB 1|Au junctions for current–voltage ( I / V ) analysis. Complex 1 shows asymmetric electron transfer with a maximum rectification ratio of 32 based on tunnelling through MOs of the aminocatechol derivative.