Understanding the stability of a plastic-degrading Rieske iron oxidoreductase system.

Rieske oxygenases (ROs) are a diverse metalloenzyme class with growing potential in bioconversion and synthetic applications. We postulated that ROs are nonetheless underutilized because they are unstable. Terephthalate dioxygenase (TPA PDB ID 7Q05) is a structurally characterized heterohexameric αβ RO that, with its cognate reductase (TPA), catalyzes the first intracellular step of bacterial polyethylene terephthalate plastic bioconversion.

Understanding Copper(I)-Ethylene Bonding Using Cu K-Edge X-ray Absorption Spectroscopy.

Copper plays many important roles in ethylene chemistry, thus generating significant interest in understanding the structures, bonding, and properties of copper(I)-ethylene complexes. In this work, the ethylene binding characteristics of a series of isolable Cu(I)-ethylene compounds supported by a systematic set of fluorinated and nonfluorinated bis- and tris(pyrazolyl)borate and the related bis(pyrazolyl)methane ligands have been investigated. Through a combination of X-ray absorption spectroscopy and quantum chemical calculations, we characterize their geometric and electronic structures and the role that fluorinated ligands play in lowering the electron density at Cu sites.

E-selective Semi-hydrogenation of Alkynes under Mild Conditions by a Diruthenium Hydride Complex.

The synthesis, characterization and catalytic activity of a new class of diruthenium hydrido carbonyl complexes bound to the PNNP expanded pincer ligand is described. Reacting PNNP with two equiv of RuHCl(PPh ) (CO) at 140 °C produces an insoluble air-stable complex, which was structurally characterized as [Ru ( PNNP)H(μ-H)Cl(μ-Cl)(CO) ] (1) using solid-state NMR, IR and X-ray absorption spectroscopies and follow-up reactivity. A reaction with KOtBu results in deprotonation of a methylene linker to produce [Ru ( PNNP )H(μ-H)(μ-OtBu)(CO) ] (3) featuring a partially dearomatized naphthyridine core.

Steering CO hydrogenation toward C-C coupling to hydrocarbons using porous organic polymer/metal interfaces.

The conversion of CO into fuels and chemicals is an attractive option for mitigating CO emissions. Controlling the selectivity of this process is beneficial to produce desirable liquid fuels, but C-C coupling is a limiting step in the reaction that requires high pressures. Here, we propose a strategy to favor C-C coupling on a supported Ru/TiO catalyst by encapsulating it within the polymer layers of an imine-based porous organic polymer that controls its selectivity.

Bridging Thermal Catalysis and Electrocatalysis: Catalyzing CO Conversion with Carbon-Based Materials.

Understanding the differences between reactions driven by elevated temperature or electric potential remains challenging, largely due to materials incompatibilities between thermal catalytic and electrocatalytic environments. We show that Ni, N-doped carbon (NiPACN), an electrocatalyst for the reduction of CO to CO (CO R), can also selectively catalyze thermal CO to CO via the reverse water gas shift (RWGS) representing a direct analogy between catalytic phenomena across the two reaction environments. Advanced characterization techniques reveal that NiPACN likely facilitates RWGS on dispersed Ni sites in agreement with CO R active site studies.

Understanding Structure-Property Relationships of MoO-Promoted Rh Catalysts for Syngas Conversion to Alcohols.

Rh-based catalysts have shown promise for the direct conversion of syngas to higher oxygenates. Although improvements in higher oxygenate yield have been achieved by combining Rh with metal oxide promoters, details of the structure of the promoted catalyst and the role of the promoter in enhancing catalytic performance are not well understood. In this work, we show that MoO-promoted Rh nanoparticles form a novel catalyst structure in which Mo substitutes into the Rh surface, leading to both a 66-fold increase in turnover frequency and an enhancement in oxygenate yield.