Resin-supported iridium complex for low-temperature vanillin hydrogenation using formic acid in water.

Biorefinery seeks to utilize biomass waste streams as a source of chemical precursors with which to feed the chemical industry. This goal seeks to replace petroleum as the main feedstock, however this task requires the development of efficient catalysts capable of transforming substances derived from biomass into useful chemical products. In this study, we demonstrate that a highly-active iridium complex can be solid-supported and used as a low-temperature catalyst for both the decomposition of formic acid (FA) to produce hydrogen, and as a hydrogenation catalyst to produce vanillyl alcohol (VA) and 2-methoxy-4-methylphenol (MMP) from vanillin (V); a lignin-derived feedstock.

Ultrasensitive and Label-Free Detection of the Measles Virus Using an N-Heterocyclic Carbene-Based Electrochemical Biosensor.

With the current intense need for rapid and accurate detection of viruses due to COVID-19, we report on a platform technology that is well suited for this purpose, using intact measles virus for a demonstration. Cases of infection due to the measles virus are rapidly increasing, yet current diagnostic tools used to monitor for the virus rely on slow (>1 h) technologies. Here, we demonstrate the first biosensor capable of detecting the measles virus in minutes with no preprocessing steps.

N-Heterocyclic carbene and thiol micropatterns enable the selective deposition and transfer of copper films.

Microcontact printed patterns of N-heterocyclic carbenes (NHCs) and thiols were prepared on gold substrates and utilized as templates for the creation of metallic Cu structures using electroplating. The presence of the NHC in the pattern is essential to enable the transfer of the resulting copper microstructures to a second substrate.

Optimization of Synthetically Versatile Pyridylidene Amide Ligands for Efficient Iridium-Catalyzed Water Oxidation.

The synthetic versatility of pyridylidene amide (PYA) ligands has been exploited to prepare and evaluate a diverging series of iridium complexes containing C,N-bidentate chelating aryl-PYA ligands for water oxidation catalysis. The phenyl-PYA lead structure 1 was modified (i) electronically through introduction of one, two, or three electron-donating methoxy substituents on the aryl ring, (ii) by incorporating long aliphatic chains to the pyridyl fragment of the PYA unit, and (iii) by altering the PYA positions from para-PYA to its ortho- and meta-isomers. Electrochemistry indicated no substantial electronic effect of the aliphatic chains, and only minor changes of the electron density at iridium when modifying the aryl ligand site, yet substantial alteration if the PYA ligand is the ortho- (E =+0.

Enhanced Catalytic Activity of Iridium(III) Complexes by Facile Modification of C,N-Bidentate Chelating Pyridylideneamide Ligands.

A set of aryl-substituted pyridylideneamide (PYA) ligands with variable donor properties owing to a pronounced zwitterionic and a neutral diene-type resonance structure were used as electronically flexible ligands at a pentamethylcyclopentadienyl (Cp*) iridium center. The straightforward synthesis of this type of ligand allows for an easy incorporation of donor substituents such as methoxy groups in different positions of the phenyl ring of the C,N-bidentate chelating PYA. These modifications considerably enhance the catalytic activity of the coordinated iridium center toward the catalytic aerobic transfer hydrogenation of carbonyls and imines as well as the hydrosilylation of phenylacetylene.

Simple direct formation of self-assembled N-heterocyclic carbene monolayers on gold and their application in biosensing.

The formation of organic films on gold employing N-heterocyclic carbenes (NHCs) has been previously shown to be a useful strategy for generating stable organic films. However, NHCs or NHC precursors typically require inert atmosphere and harsh conditions for their generation and use. Herein we describe the use of benzimidazolium hydrogen carbonates as bench stable solid precursors for the preparation of NHC films in solution or by vapour-phase deposition from the solid state.