Carboxylate pentapyridines: Pathway to surface modification and tuneable catalytic proton reduction

Marissa K. Melvin, Paul K. Eggers, Colin L. Raston

Research output: Contribution to journalArticlepeer-review


The ability to synthetically tune catalytic performance is a key advantage in the use of molecular catalysts. A series of cobalt pentapyridine carboxylate esters [Co(Py5Me2COOMe)(CH3CN)]2+ (Co-Me), [Co(Py5Me2COOn-Pr)(CH3CN)]2+ (Co-Pr) and [Co(Py5Me2COOPh)(CH3CN)]2+ (Co-Ph) were successfully synthesised and characterised through HD-MS, FT-IR and cyclic voltammetry. Electrochemical studies reveal the complexes are active for electrocatalytic proton reduction in acetonitrile with acetic acid as the proton source. At an acid concentration of 2 mM, the required overpotential for proton reduction was calculated to be 465 mV for Co-Me, 485 mV for Co-Pr and 360 mV for Co-Ph. The rate constant is calculated to be 9.41 s−1, 4.09 s−1 and 7.25 s−1 for complexes Co-Me, Co-Pr and Co-Ph respectively. The cobalt carboxylate complex [Co(Py5Me2COO)(OH)]1+ (Co-COOH) was used to prepare chemically modified electrodes from fluorine doped tin oxide (FTO) coated glass and glassy carbon with a calculated surface coverage of 6.38 × 10−11 mol/cm2 and of 6.18 × 10−11 mol/cm2 respectively. The successful reduction of catalytic overpotential through esterification offers an alternative pathway for the design of molecular catalysts.

Original languageEnglish
Article number116177
Publication statusPublished - 1 Dec 2022


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