Electrochemical CO Reduction in Acidic Electrolytes: Spectroscopic Evidence for Local pH Gradients.

Inspired by recent advances in electrochemical CO reduction (COR) under acidic conditions, herein we leverage in situ spectroscopy to inform the optimization of COR at low pH. Using attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and fluorescent confocal laser scanning microscopy, we investigate the role that alkali cations (M) play on electrochemical COR. This study hence provides important information related to the local electrode surface pH under bulk acidic conditions for COR, both in the presence and absence of an organic film layer, at variable [M].

Reaction Discovery Using Spectroscopic Insights from an Enzymatic C-H Amination Intermediate.

Engineered hemoproteins can selectively incorporate nitrogen from nitrene precursors like hydroxylamine, -substituted hydroxylamines, and organic azides into organic molecules. Although iron-nitrenoids are often invoked as the reactive intermediates in these reactions, their innate reactivity and transient nature have made their characterization challenging. Here we characterize an iron-nitrosyl intermediate generated from NHOH within a protoglobin active site that can undergo nitrogen-group transfer catalysis, using UV-vis, electron paramagnetic resonance (EPR) spectroscopy, and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) techniques.

Nitrene Photochemistry of Manganese N-Haloamides*.

Manganese complexes supported by macrocyclic tetrapyrrole ligands represent an important platform for nitrene transfer catalysis and have been applied to both C-H amination and olefin aziridination catalysis. The reactivity of the transient high-valent Mn nitrenoids that mediate these processes renders characterization of these species challenging. Here we report the synthesis and nitrene transfer photochemistry of a family of Mn N-haloamide complexes.