Naphthyridine series: Probing steric effects with the "Bocarsly" pyridinium-based catalyst system for reduction of CO₂ directly to methanol

In 2008 Bocarsly reported a stunning result: pyridinium cation acts as an extremely efficient catalyst for the electrochemical reduction of CO₂ directly to methanol. It is assumed that the electrocatalytic mechanism requires the presence of both low lying π* energy levels in an aromatic amine, and a nitrogen pK_a that allows for a Lewis acid-base interaction between the amine and CO₂. Subsequent results strongly suggest that steric interference with the interaction between CO₂ and the pyridyl-nitrogen may be an important factor that can modulate the catalytic reaction. In this poster, we will describe the synthesis of three sets of naphthyridine derivatives which present varying degrees of potential steric interference about the pyridyl nitrogen, thus offering the opportunity to probe the importance of steric effects on this potentially very important electrocatalytic mechanism. The relative catalytic activity of these naphthyridine derivatives for reduction of CO₂ will be measured collaboratively with the Bocarsly lab.