Mesoionic carbene-based self-assembled monolayers on gold

Lee, Dianne S.; Singh, Ishwar; Veinot, Alex J.; Aloisio, Mark D.; Lomax, Justin T.; Ragogna, Paul J.; Crudden, Cathleen M.

doi:10.1039/d3sc04720b

Cited by 3 publications

(1 citation statement)

References 48 publications

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“…The NHC-functionalized AuNP is a milestone discovery from the main group chemistry perspective . Apart from imidazolium- and benzimidazolium-based NHCs, acyclic and mesoionic − NHCs have also found their use as surface capping ligands very recently. The stabilization of AuNPs by NHCs can be best rationalized using the hard–soft Lewis acid–base concept .…”

Section: Introductionmentioning

confidence: 99%

Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO₂ Reduction

Ghosh,

Saha,

Roy

et al. 2024

ACS Catal.

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N-heterocyclic carbenes (NHCs) have recently gained significant attention as capping ligands for gold nanoparticles due to their strong σ-donation properties. It has already been established that the strong σ-donation of NHCs enriches the surface of the gold nanoparticles, which controls the catalytic activity of the metal nanoparticles. Cyclic (alkyl)(amino)carbene (CAAC) is a special class of carbene that offers stronger σ-donation than NHCs. This extremely electron-rich nature of CAAC projects it as a better surface capping ligand upon extrapolation on the Au(0) surface. In this work, we have isolated stable CAAC-stabilized AuNPs via a ligand exchange method and studied their catalytic behavior toward electrochemical CO 2 reduction. These newly synthesized CAACstabilized AuNPs furnish a remarkable faradaic efficiency (FE) of 94% [at pH 6.3 for 2 h of controlled potential electrolysis at −0.7 V vs NHE (normal hydrogen electrode)] toward selective CO formation. Our work sets the platform for CAAC as a robust main group ligand on the surface of different metal nanoparticles, bridging the gap between main group ligands and surface chemistry.

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Section: Introductionmentioning

confidence: 99%

Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO₂ Reduction

Ghosh,

Saha,

Roy

et al. 2024

ACS Catal.

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Tailored functional monolayers made from mesoionic carbenes

Sadek,

Rabah,

Sowid

et al. 2024

Electrochimica Acta

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Strong Substrate–Adsorbate Interactions Direct the Impact of Fluorinated N-Heterocyclic Carbene Monolayers on Au Surface Properties

Berg,

Mondal,

Sims

et al. 2024

ACS Appl. Mater. Interfaces

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Fluorinated self-assembled monolayers (SAMs) have been utilized in a variety of applications such as transistors and optoelectronic devices. However, in most SAMs the fluorinated groups could not be positioned in high proximity to the surface due to steric effects. This limitation hinders the direct analysis of the impact of the fluorination level on surface properties. Herein, fluorinated aromatic N-heterocyclic carbenes (NHCs), with 1−5 fluorine atoms, were self-assembled on a gold substrate. These NHCs enabled the positioning of fluorinated groups in high proximity to the metal surface to identify the influence of the fluorination level on surface properties. Experimental measurements and theoretical calculations identified that all fluorinated NHCs formed SAMs and adopted a flat-lying adsorption configuration while anchored to the metal surface via Au adatom. A higher fluorination level induced a stronger interaction of the fluorinated side groups with the Au surface. The stronger interaction and surface proximity of the fluorinated side groups deteriorated the overall binding energy of the NHC due to the lessoptimized adsorption geometry of the carbene carbon. Ultraviolet photoelectron spectroscopy measurements revealed that fluorinated NHC monolayers lowered the surface work function by up to 1 eV and induced an increase of 15−20°in the water contact angle. The impact on surface properties did not vary according to the fluorination level of NHCs, and similar values were measured for NHC with 1−5 fluorine atoms. It is therefore identified that dominant adsorbate−substrate interactions between the fluorinated side groups and the Au surface quenched the distinct impact of the fluorination level on surface functionality.

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Mesoionic carbene-based self-assembled monolayers on gold

Abstract: N-heterocyclic carbenes (NHC) have been widely studied as ligands for surface chemistry, and have shown advantages compared to existing ligands (e.g. thiols). Herein, we introduce mesoionic carbenes (MICs) as a...

Cited by 3 publications

References 48 publications

Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO₂ Reduction

Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO₂ Reduction

Tailored functional monolayers made from mesoionic carbenes

Strong Substrate–Adsorbate Interactions Direct the Impact of Fluorinated N-Heterocyclic Carbene Monolayers on Au Surface Properties

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Mesoionic carbene-based self-assembled monolayers on gold

Abstract: N-heterocyclic carbenes (NHC) have been widely studied as ligands for surface chemistry, and have shown advantages compared to existing ligands (e.g. thiols). Herein, we introduce mesoionic carbenes (MICs) as a...

Cited by 3 publications

References 48 publications

Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO2 Reduction

Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO2 Reduction

Tailored functional monolayers made from mesoionic carbenes

Strong Substrate–Adsorbate Interactions Direct the Impact of Fluorinated N-Heterocyclic Carbene Monolayers on Au Surface Properties

Contact Info

Product

Resources

About

Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO₂ Reduction

Cyclic(alkyl)(amino)carbene-Stabilized Gold Nanoparticles for Selective CO₂ Reduction