Versatile Micropatterns of N‐Heterocyclic Carbenes on Gold Surfaces: Increased Thermal and Pattern Stability with Enhanced Conductivity

Nguyen, Dzung T.; Freitag, Matthias; Körsgen, Martin; Lamping, Sebastian; Rühling, Andreas; Schäfer, Andreas; Siekman, Martin Herman; Arlinghaus, Heinrich F.; Wiel, Wilfred G. van der; Glorius, Frank; Ravoo, Bart Jan

doi:10.1002/anie.201807197

Cited by 80 publications

(112 citation statements)

References 56 publications

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“…While N‐heterocyclic carbenes (NHCs) are known to form strong bonds with noble metals, the extreme robustness of NHC self‐assembled monolayers (NHC SAMs) was only recently recognized . Following these initial studies, progress has been rapid with NHCs supplanting thiols in applications from catalysis and biosensing to drug delivery because of their enhanced stability and accessibility for chemical modifications . NHC‐coated materials are particularly appealing when non‐ideal conditions are required, such as large variations in pH or temperature …”

Section: Introductionmentioning

confidence: 99%

A Benchtop Method for Appending Protic Functional Groups to N‐Heterocyclic Carbene Protected Gold Nanoparticles

et al. 2020

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The remarkable resilience of N-heterocyclic carbene (NHC) gold bonds has quickly made NHCs the ligand of choice when functionalizing gold surfaces.D espite rapid progress using deposition from free or CO 2 -protected NHCs, synthetic challenges hinder the functionalization of NHC surfaces with protic functional groups,s uch as alcohols and amines,p articularly on larger nanoparticles.H ere,w es ynthe-sizeN HC-functionalized gold surfaces from gold(I) NHC complexes and aqueous nanoparticles without the need for additional reagents,e nabling otherwise difficult functional groups to be appended to the carbene.T he resilience of the NHC À Au bond allows for multi-step post-synthetic modification. Beginning with the nitro-NHC,w ef orm an amine-NHC terminated surface,w hichf urther undergoes amide coupling with carboxylic acids.T he simplicity of this approach, its compatibility with aqueous nanoparticle solutions,a nd its ability to yield protic functionality,g reatly expands the potential of NHC-functionalized noble metal surfaces.

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Section: Introductionmentioning

confidence: 99%

A Benchtop Method for Appending Protic Functional Groups to N‐Heterocyclic Carbene Protected Gold Nanoparticles

et al. 2020

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“…-Heterocyclic carbenes (NHCs) are molecular ligands characterized with strong affinity to metals 1,2 . The strong NHC-metal interaction enabled the formation of stable self-assembled monolayers (SAMs) of NHCs on metals [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] , metal-oxides 22,23 and semimetals 24 . The wide chemical-tunability of NHCs led to utilization of NHC-based SAMs as biosensors 10,25,26 , molecular probes for surface reactivity [27][28][29] , and co-catalysts 3,[30][31][32][33] .…”

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confidence: 99%

Electrochemical deposition of N-heterocyclic carbene monolayers on metal surfaces

Amit

Dery

et al. 2020

Nat Commun

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N-heterocyclic carbenes (NHCs) have been widely utilized for the formation of self-assembled monolayers (SAMs) on various surfaces. The main methodologies for preparation of NHCs-based SAMs either requires inert atmosphere and strong base for deprotonation of imidazolium precursors or the use of specifically-synthesized precursors such as NHC(H)[HCO3] salts or NHC–CO2 adducts. Herein, we demonstrate an electrochemical approach for surface-anchoring of NHCs which overcomes the need for dry environment, addition of exogenous strong base or restricting synthetic steps. In the electrochemical deposition, water reduction reaction is used to generate high concentration of hydroxide ions in proximity to a metal electrode. Imidazolium cations were deprotonated by hydroxide ions, leading to carbenes formation that self-assembled on the electrode’s surface. SAMs of NO2-functionalized NHCs and dimethyl-benzimidazole were electrochemically deposited on Au films. SAMs of NHCs were also electrochemically deposited on Pt, Pd and Ag films, demonstrating the wide metal scope of this deposition technique.

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“…NHCs based on this structure have been reported in both flat-lying and upright surface geometries. 15,19,23,24 SAMs of this NHC and closely related structures are known on Au(111), 11 Cu(111), 15 Ag(111) 24 and Pt(111) 22 surfaces, on Au nanoparticles, 18,[29][30][31][32] in molecular electronics, [33][34][35] in microcontact printing, 36 and in biosensing applications, 12,37 illustrating the generality and impact of this family of NHCs. Our study illustrates the importance of NHC structure, deposition temperature, annealing temperature, and ligand density, providing much needed information on NHC orientation, mobility, self-assembly, and adatom generation, setting out a roadmap for the preparation of high quality, densely packed self-assembled NHC monolayers with predictable and tunable properties.…”

mentioning

confidence: 80%

Self-Assembly of N-Heterocyclic Carbenes on Au(111)

Inayeh¹,

Groome²,

Singh³

et al. 2020

Preprint

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The production of ordered arrays of organic molecules on metallic surfaces by means of self-assembly is one of the most powerful methods for controlled patterning on the nanometer scale. Although the self-assembly of sulfurbased ligands has been studied for decades, the thermal and oxidative instability of these systems introduces challenges in many potential applications. In recent years, it has been shown that a new ligand class, N-heterocyclic carbenes (NHCs), bind to metal surfaces via a metal–carbon covalent bond, resulting in monolayers with much greater stability. However, fundamental questions surrounding self-assembly in this new ligand class remain unanswered, including the simple questions of what controls NHC orientation on the surface and under what conditions they self-assemble. Herein we describe how NHC structure, surface density, deposition temperature, and annealing temperature control mobility, thermal stability, NHC surface geometry, self-assembly, and the exact chemical nature of the surface structures. These data provide the first general set of guidelines to enable the rational design of highly ordered NHC-based monolayers. Considering that NHCs may supplant thiols as the functionalization agent of choice in a wide range of applications, a detailed understanding of their surface chemistry is crucial for the success of these next-generation monolayers.

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Versatile Micropatterns of N‐Heterocyclic Carbenes on Gold Surfaces: Increased Thermal and Pattern Stability with Enhanced Conductivity

Cited by 80 publications

References 56 publications

A Benchtop Method for Appending Protic Functional Groups to N‐Heterocyclic Carbene Protected Gold Nanoparticles

A Benchtop Method for Appending Protic Functional Groups to N‐Heterocyclic Carbene Protected Gold Nanoparticles

Electrochemical deposition of N-heterocyclic carbene monolayers on metal surfaces

Self-Assembly of N-Heterocyclic Carbenes on Au(111)

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