Multicopper oxidase (MCO) enzymes can reduce oxygen to water via direct electron transfer between the enzyme and an electrode. These properties of MCOs make them attractive as catalysts for eco-friendly energy conversion in biofuel cells. Laccase enzymes are a part of the MCO family and have been investigated for their potential as biofuel cell cathode catalysts. In these applications, electrons transfer from the electrode directly to the T1 redox site within the enzyme. Over the years, resonance Raman (RR) spectroscopy has been utilized to probe relationships between structure and reactivity at the T1 site of laccases. Spectral interpretation has been guided by parallel studies of small molecule T1 site mimics formed from tridentate tris(pyrazolyl)hydroborate or bidentate β-diketiminate ligands. These small molecules have provided affordable models to support electronic structure calculations that explore T1 site properties. Building on recent advances in time-dependent density functional theory, this poster presents an analysis of the RR spectra for tris(pyrazolyl)hydroborate complexes with varying thiolate ligands and a thiolate containing β-diketiminate complex that serves as a T1 site model for fungal laccases. Calculated electronic absorption and RR spectra show excellent agreement with experiment. RR spectra are dominated by a strong Cu-S stretching transition near 400 cm<sup>-1</sup>, which is sensitive to molecular conformation within the thiolate ligand. The results provide a foundation to build from in advancing models of laccase catalytic active sites and perturbations due to enzyme-electrode interactions in support of sustainable technologies.

Calculation of resonance Raman spectra for copper-centered complexes relevant to in-situ spectral studies of bioelectrocatalysts

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