WO2023131946A1

WO2023131946A1 - Polymer-coated metal-containing- or carbon-based- article and method for the preparation thereof

Info

Publication number: WO2023131946A1
Application number: PCT/IL2023/050010
Authority: WO
Inventors: Elad GROSS; Einav Amit; Iris BERG; Shahar DERY
Original assignee: Yissum Research Development Company Of The Hebrew University Of Jerusalem Ltd.
Priority date: 2022-01-05
Filing date: 2023-01-04
Publication date: 2023-07-13

Abstract

The present invention provides an article comprising a metal-containing material or a carbon-based material, having at least one surface coated with N-heterocyclic carbene-based polymeric layer, and a method for the preparation thereof. The N-heterocyclic carbene-based polymeric layer hinder oxidation of said material due to, e.g., exposure to external environment, while demonstrating high thermal- and chemical- stability under various oxidizing conditions.

Description

POLYMER-COATED METAL-CONTAINING- OR CARBON-BASED- ARTICLE

AND METHOD FOR THE PREPARATION THEREOF

[0001] The project leading to the present application has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 802769).

TECHNICAL FIELD

[0002] The present invention provides an article comprising a metal-containing material or a carbon-based material, having at least one surface coated with A-hctcrocyclic carbene- based polymeric layer, and a method for the preparation thereof.

BACKGROUND ART

[0003] A-hctcrocyclic carbenes (NHCs) are molecular ligands having strong affinity to metals. The strong NHC-metal interaction enabled forming stable and chemically - addressable self-assembled monolayers (SAMs) of NHCs on metals, metal-oxides and semimetals. The wide chemical-tunability of NHCs led to utilization of NHC-based SAMs as biosensors, molecular probes for surface reactivity and co-catalysts.

[0004] Thus far, NHC-based SAMs have been prepared on metallic surfaces, and specifically on Au surfaces, by two approaches, i.e., base-induced deprotonation of imidazolium salt precursors (Zhukhovitskiy et al., 2013; Crudden et al., 2014; ); and annealing of NHC(H)[HCO3] salts (Crudden et al., 2016; Jiang et al., 2017) or NHC-CO2 adducts (Zhukhovitskiy et al., 2013) under vacuum conditions.

[0005] The deposition process of imidazolium salt precursors with halide ions is conducted in THF under an anhydrous environment with a strong base, such as potassium tert-butoxide, for deprotonation and carbene formation (Zhukhovitskiy etal., 2013; Crudden et al., 2014; ). Although this deposition approach has been widely utilized for preparation of NHC-based SAMs, it has inherent drawbacks, including the requirements for high concentration of imidazolium salt (-1-10 mM), an extended deposition time (> 12 h), and an anhydrous environment (residual water may quench the active carbene); and the fact that base and solvent residues may remain on the surface following liquid-deposition and limit the formation of well-ordered monolayers (Dery et al., 2019a). [0006] The use of an inorganic base for deprotonation and active carbene formation can be circumvented by using NHC(H)[HCO3] salts or NHC-CO2 adducts as masked precursors to the free carbene (Zhukhovitskiy et al., 2013; Crudden et al., 2016; Jiang et al., 2017). Annealing of these precursors under vacuum conditions facilitates the formation and evaporation of an active carbene that can be anchored on metal surfaces. This approach excludes liquid or base residues from the surface, thereby allowing the formation of well- ordered monolayers (Crudden et al., 2016; Dery et al., 2019a). However, this approach also has several disadvantages: First, NHC-CO2 adducts and imidazolium carbonate salts precursors require specific preparation, which includes separation steps and ion exchange processes, respectively (Crudden et al., 2016). Additionally, various functional groups are incompatible with the imidazolium carbonate synthesis, which limits the preparation of chemically addressable NHC -based SAMs. Finally, the deposition technique involves annealing of the precursors and evaporation of the active carbene toward the metal surface. These steps restrict the use of high molecular-mass or temperature-sensitive precursors. Interestingly, NHC -based SAMs have been prepared from imidazolium carbonate salts that have been immersed in alcohols (Crudden et al., 2016). This approach overcomes the need for elevated temperatures but induces solvent residues on the surface and requires higher concentration of precursors (10 mM).

[0007] Copper is widely used in the electronic industry due to its high conductivity, ductility, and low price. However, the integration of copper in cutting-edge applications, such as printed electronics, is limited by its high susceptibility to corrosion, which degrades the electrical and mechanical properties of the metal. Unlike other metals such as aluminum, the oxide layer on copper is not self -protecting and can continuously grow and deteriorate the conductivity and ductility of the metal. In addition, the kinetic of copper oxidation is rapid and an oxide layer is formed on the metal even under ambient conditions.

[0008] Efforts for copper oxidation mitigation can be divided into two main approaches. Copper oxidation can be inhibited by alloying with other metals, e.g., Al, Be, and Mg. However, alloying is not necessarily limited to the copper surface, and can impact the bulk properties of copper films (Peng et al., 2020). A different approach is based on passivation of the copper surface with inorganic (Hymes et al., 1992) or organic (Peng et al., 2020) monolayers. The main advantage of this approach is that the protective monolayers do not modify the bulk properties of copper. However, it should be noted that monolayers on copper films were characterized with limited chemical and thermal stability. In addition, protection by monolayers was found less effective on corrugated surfaces or surfaces with a high density of defects, in which monolayers do not provide optimal coverage (Peng et al., 2020). [0009] Multilayer formation can thus offer improved protection against surface oxidation. Azole and benzotriazole compounds were used as precursors for multilayer formation on copper films for oxidation mitigation (Chadwick and Hashemi, 1978). The unsaturated nitrogen atoms in benzotriazole function as surface-anchoring points and benzotriazole complexation with Cu(I) enable the formation of polymeric chains (1-10 nm thick) that impede water and ion diffusion towards the copper surface. Despite their high efficiency in corrosion inhibition, benzotriazole films suffer from limited thermal stability, and degradation was observed upon exposure of benzotriazole-coated copper films to 100°C under atmospheric conditions.

[0010] The strong and stable anchoring of NHCs to coinage metals has led to their wide utilization for monolayer formation (Ranganath et al., 2010; Zhukhovitskiy et al., 2013; Crudden et al., 2014; Koy et al., 2021). It has been demonstrated that NHCs can bind to copper surfaces (Larrea et al., 2017; Jiang et al., 2017) and that NHCs’ deposition led to copper-oxide reduction (Veinot et al., 2020). However, the limited stability of NHC monolayers under harsh conditions and challenges in their uniform deposition has restricted their applicability for mitigating copper films oxidation. Self-assembly of chemically- addressable NHCs opened a new route for tuning surface properties, such as work function, wettability and chemical nature (Zhukhovitskiy et al., 2013; Crudden et al., 2014; Dery et al., 2019a; Dery et al., 2019b; Dery et al., 2020; Dery et al., 2021a; Dery et al., 2021b; Berg et al., 2021).

SUMMARY OF INVENTION

[0011] Disclosed herein is a new approach for the preparation of NHC-based SAMs, wherein deprotonation of the imidazolium salt is electrochemically induced. The electrochemical (EC) deposition utilizes the localized formation of hydroxide ions in proximity to the electrode surface, induced by water reduction under negative potential (-1 V) (Wu et al., 2017), for deprotonation of the imidazolium salt. The proximity between the active carbene thus formed and the metal electrode enables the formation of NHC-based SAMs under ambient conditions and in the presence of water.

[0012] As shown in the Experimental section (Study 1), 1,3-bis(2,4-dinitrophenyl)-NHC (NO2-NHC), utilized as a model system for addressable carbenes, was EC -deposited on various metal surfaces. Quantitative analysis revealed that EC-deposition induced monolayer formation of NO2-NHCS on Au films with higher surface density and improved chemical stability than those prepared by base-induced deprotonation. The higher surface density and improved chemical stability of EC-deposited SAMs were connected with the fact that during EC-deposition a small and constant concentration of active carbenes is formed near the electrode. This proximity provides a short time frame for the sequential deprotonation and surface-anchoring steps, thus limiting the competitive adsorption of carbene and Br on the Au surface. The wide metal scope of the EC-deposition approach was demonstrated and, in addition to Au, SAMs of NO2-NHCS were prepared on Pd, Pt and Ag films. The wide NHC scope of the EC-deposition approach was demonstrated as well and, in addition to NO2-NHCS, SAMs of 1,3-dimethyl-benzimidazole were prepared on Au films. [0013] In view of the above, trying to address the limitations of the two main strategies currently available for copper oxidation mitigation, a new approach for copper protection based on the self-assembly of NHCs has been developed. As demonstrated in Study 2, NHC- nanolayer formation on copper film was induced by exposure of alkyne-functionalized imidazolium cation to hydroxide ions that were formed near the copper electrode by electrochemical water reduction. Deprotonation of the imidazolium cation led to the formation and self-assembly of NHCs on copper surface. In addition, the alkyne side groups of the self-assembled NHCs were deprotonated by the hydroxide ions and functioned as an active group for on-surface polymerization between surface-anchored and solvated NHCs, yielding self-limited 2.0+0.5 nm thick NHC-nanolayer. The NHC-nanolayer effectively hindered copper oxidation while demonstrating high thermal- and chemical-stability under various oxidizing conditions (Scheme 1).

Scheme 1

* TEATFB = tetraethylammonium tetrafluoroborate [0014] In one aspect, disclosed herein is an article comprising a metal-containing material or a carbon-based material, having at least one surface coated with a polymeric layer comprising a plurality of repeating units each independently of formula I or I’

wherein:

X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or more groups each independently selected from -NH-, =N-, -O-, -S-, and -CO-, which together with the - moiety form a divalent heterocyclic group, said heterocyclic

group being optionally substituted by one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, and -O-(C1-C6)alkyl, and/or fused with a carbocyclic, heterocyclic, aromatic, or heteroaromatic ring to form a bicyclic or polycyclic heterocyclic group; and

Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, cycloakenyl, heterocyclyl, aryl, or heteroaryl, optionally substituted by one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1- C6)alkyl, wherein said (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, cycloalkyl, and cycloakenyl each independently is optionally interrupted by one or more groups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-, and wherein at least one of Y and Y’ comprises the group , wherein the dot represents the point

of attachment; and the wavy lines each independently represents H, OH, a repeating unit of the formula I or I’ of said plurality of repeating units, linked via a group

thereof

(forming, e.g., a bridge between the two linked repeating units), or a repeating unit of the formula I of said plurality of repeating units linked via the carbene carbon atom thereof (such that said repeating unit of formula I is capable of binding with a further repeating unit(s) of the formula I or I’ via the at least one

group thereof), provided that at least one of the wavy lines represents a repeating unit (linked via the at least ^ one group thereof, or via the carbene carbon atom thereof when present),

wherein at least one of said repeating units is of the formula I and is either coordinated to a metal atom of said metal-containing material or linked to a carbon atom of said carbon- based material, via the carbene-carbon atom thereof.

[0015] In another aspect, disclosed herein is a method for coating a surface of a metal- containing- or carbon-based- material with a polymeric layer, said method comprising exposing said surface, in the presence of a base, to a plurality of compounds each independently of formula I’ :

I’ wherein:

X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or more groups each independently selected from -NH-, =N-, -O-, -S-, and -CO-, which together with + the -N— C— N- moiety form a divalent heterocyclic group, said heterocyclic group being optionally substituted by one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, and -O-(C1-C6)alkyl, and/or fused with a carbocyclic, heterocyclic, aromatic, or heteroaromatic ring to form a bicyclic or polycyclic heterocyclic group; and

Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, cycloakenyl, heterocyclyl, aryl, or heteroaryl, optionally substituted by one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1- C6)alkyl, wherein said (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, cycloalkyl, and cycloakenyl each is optionally interrupted by one or more groups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

thereby: (i) converting at least one of said compounds to carbene carbon atom- containing compounds thus enabling coordination or linkage of said at least one carbene carbon atom-containing compound, via the carbene-carbon atom thereof, to a metal atom in the surface of said metal-containing material, or a carbon atom in the surface of said carbon- based material, respectively; and (ii) polymerizing at least one of the coordinated/linked compounds obtained via the at least one acetylenyl group thereof with at least one of the non-coordinated/linked compounds via an acetylenyl group thereof or the carbene-carbon atom thereof, when present, to thereby form said polymeric layer on said surface of said metal-containing- or carbon-based- material.

BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 shows a suggested mechanism for EC-deposition of 1,3-bis(2,4- dinitrophenyl)-imidazolium and dimethyl-benzimidazolium on Au-coated Si electrode.

[0017] Figs. 2A-2D show spectroscopic measurements of NO2-NHCS prepared on Au film by EC-deposition and base-induced deprotonation. N1s XPS and LSV measurements of NO2-NHCS which were deposited on Au films by EC-deposition (2A and 2B, respectively) and base-induced deprotonation (2C and 2D, respectively). Measurements were performed prior to and after one cycle of LSV. LSV conditions: 0.1 M HC1 and scan rate of 0.1 V/sec.

[0018] Figs. 3A-3D show AFM-IR measurements of EC-deposited NO2-NHCS on Au film. AFM topography (3A) and AFM-IR point spectra measurements (3B) following EC- deposition of NO2-NHCS on a patchy Au film that was deposited on Si electrode. Circles in 3A mark the local IR measurement positions, and the measured IR spectra are shown in 3B respectively. AFM topography image at higher magnification and the corresponding AFM- IR image at 1533 cm^-1 are shown in 3C and 3D, respectively.

[0019] Figs. 4A-4D show AFM-IR measurements of NO2-NHCS that were deposited on Au film by base-induced deprotonation. AFM topography (4A) and AFM-IR point spectra measurements (4B) following base-induced deprotonation deposition of NO2-NHCS on a patchy Au-coated Si substrate. Circles in 4A mark the local IR measurement positions, and the measured IR spectra are shown in 4B respectively. Higher magnification AFM topography image and the corresponding AFM-IR image at 1533 cm^-1 are shown in 4C and 4D, respectively.

[0020] Figs. 5A-5D show AFM-IR measurements of EC-deposited NO2-NHCS on Au film following exposure to one LSV cycle. AFM topography (5A) and AFM-IR point spectra (5B) of EC-deposited NO2-NHCs after one LSV cycle. The vibrational signals were acquired at different locations as indicated by dots in the AFM topography image. Higher magnification AFM topography image and the corresponding AFM-IR image at 1460 cm^-1 are shown in 5C and 5D, respectively.

[0021] Fig. 6 shows N1s XPS measurements of EC-deposited NO2-NHCS on various metal films. N1s XPS signals of EC-deposited NO2-NHCS on Pt, Pd and Ag films (lower-, mid- and upper- spectra, respectively).

[0022] Fig. 7 shows N1s XPS signals of EC-deposited dimethyl-benzimidazole on Au film. EC-deposition was conducted with either 5 or 25 mM dimethyl-benzimidazolium iodide (lower- and upper- spectra, respectively).

[0023] Figs. 8A-8B showN1s XPS spectrum of NHC-nanolayer and DMBI monolayer that were electrochemically-deposited on copper film (8A, spectra i and ii, respectively); and STEM-EDS analysis of a lamella extracted from the NHC-nanolayer coated copper film. Protective iridium film was deposited on the nanolayer before extraction (8B).

[0024] Figs. 9A-9B show Raman spectra of alkyne-functionalized imidazolium salt (i) and NHC nanolayer (ii) on copper film, in the double bond frequency range (9A) and triple bond frequency range (9B).

[0025] Fig. 10 shows a hypothesized scheme for on-surface nanolayer formation. For simplicity, polymerization is shown for only one of the two alkyne groups. R = alkyne- functionalized NHC.

[0026] Figs. 11A-11B show Cu2p XPS spectra (11A) and Cu LMM Auger spectra (1 IB) of a nanolayer-coated copper film before (i) and after (ii) exposure to 100°C for 4 h under air; and bare copper surface following exposure to 100°C for 4 h under air (iii).

[0027] Figs. 12A-12B show Cu2p XPS (12A) and Cu LMM Auger spectra (12B) of (i) nanolayer-coated copper film and (ii) bare copper film following their immersion in 0.1 M NaOH for 2 h.

DETAILED DESCRIPTION

[0028] In one aspect, disclosed herein is an article comprising a metal-containing- or a carbon-based- material, having at least one surface coated with a polymeric layer comprising a plurality of repeating units each independently of formula I or I’

wherein:

X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or more groups each independently selected from -NH-, =N-, -O-, -S-, and -CO-, which together with the - - moiety form a divalent heterocyclic group, said heterocyclic

Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, cycloakenyl, heterocyclyl, aryl, or heteroaryl, optionally substituted by one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1- C6)alkyl, wherein said (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, cycloalkyl, and cycloakenyl each independently is optionally interrupted by one or more groups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-, and wherein at least one of Y and Y’ comprises the group

, wherein the dot represents the point of attachment; and the wavy lines each independently represents H, OH, a repeating unit of the formula I or I’, linked via a group thereof, or a repeating unit of the formula

I linked via the carbene carbon atom thereof, provided that at least one of the wavy lines represents a repeating unit, wherein at least one of said repeating units is of the formula I and is either coordinated to a metal atom of said metal-containing material or linked to a carbon atom of said carbon- based material, via the carbene-carbon atom thereof.

[0029] The term "alkyl" typically means a linear or branched hydrocarbyl, i.e., a univalent group derived from a saturated linear or branched aliphatic chain by removal of hydrogen atom from any of the carbon atoms. Particular alkyl groups are (C1-C6)alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec -butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, 2,2-dimethylpropyl, n-hexyl, isohexyl, and the like. The alkyl may be substituted with one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1-C6)alkyl; and may further be interrupted by one or more groups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-.

[0030] The terms "alkenyl" and "alkynyl" typically mean linear or branched hydrocarbyls containing at least one double or triple bond, respectively, i.e., univalent groups derived from unsaturated linear or branched aliphatic chains by removal of hydrogen atom from any of the carbon atoms. Particular alkenyl and alkynyl groups are (C2-C6)alkenyl and (C2- C6)alkynyl groups, such as ethenyl, propenyl, 3-buten-l-yl, 2-ethenylbutyl, and the like; and propynyl, 2-butyn-l-yl, 3-pentyn-l-yl, 3-hexynyl, and the like. Each one of the alkenyl and alkynyl, independently, may be substituted with one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1-C6)alkyl; and may further be interrupted by one or more groups each independently selected from -O-, -CO-, - NH-, -CO-NH-, -NH-CO-, and -S-.

[0031] The term "alkylene" refers to a linear or branched divalent hydrocarbon group derived by removal of hydrogen atom from an alkyl. Particular alkylene groups are (C2- C4)alkylene such as methylene, ethylene, propylene, butylene, 2-methylpropylene, and the like. The term "alkenylene” denotes a divalent hydrocarbon group derived by removal of hydrogen atom from an alkenyl. Particular alkenylene groups are (C2-C4)alkenylene such as ethenylene, propenylene, butenylyne, and the like.

[0032] The term “aliphatic ring” or “carbocyclic ring” used herein interchangeably refers to a mono-, bi-, or poly-cyclic non-aromatic hydrocarbon having, e.g., 3-12 carbon atoms. The carbocyclic ring may be saturated, such as cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, adamantane, and the like; or unsaturated, i.e., having at least one double bond, such as cyclopropene, cyclobutene, cyclopentene, cyclohexene, and the like.

[0033] The term “cycloalkyl” means a univalent mono- or bicyclic saturated hydrocarbyl derived from a saturated carbocyclic ring by removal of hydrogen atom from any of the carbon atoms. Examples of such groups include, without limiting, (C3-Ci2)cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantyl, and the like. The cycloalkyl may be substituted with one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1- C6)alkyl; and may further be interrupted by one or more groups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-.

[0034] The term “cycloalkenyl” refers to a univalent mono- or bicyclic hydrocarbyl derived from an unsaturated carbocyclic ring by removal of hydrogen atom from any of the carbon atoms. Examples of such groups include, without limiting, (C3-Cs)cycloalkenyl such as cyclopropenyl (e.g., 2-cyclopropen-l-yl), cyclobutenyl (e.g., 2-cyclobuten-l-yl), cyclopentenyl (e.g., 2-cyclopenten-l-yl, or 3-cyclopenten-l-yl), cyclohexenyl (e.g., 2- cyclohexen-l-yl, or 3-cyclohexen-l-yl), and the like. The cycloalkenyl may be substituted with one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1-C6)alkyl; and may further be interrupted by one or more groups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-.

[0035] The term "heterocyclic ring" as used herein refers to a mono-, bi-, or poly-cyclic non-aromatic ring having, e.g., 3-12 atoms, and consisting of at least one carbon atom and at least one heteroatom selected from oxygen, sulfur (optionally oxidized) and nitrogen, which may be saturated or unsaturated, i.e., containing at least one unsaturated bond. Non- limiting examples of heterocyclic rings include azetidine, pyrrolidine, piperidine, morpholine, thiomorpholine, piperazine, oxazolidine, thiazolidine, imidazolidine, oxazoline, thiazoline, imidazoline, dioxole, dioxolane, dihydrooxadiazole, pyran, dihydropyran, tetrahydropyran, thiopyran, dihydrothiopyran, tetrahydrothiopyran, 1- oxidotetrahydrothiopyran, 1,1-dioxidotetrahydrothiopyran, tetrahydrofuran, pyrazolidine, pyrazoline, tetrahydropyrimidine, dihydro triazole, tetrahydrotriazole, azepane, dihydropyridine, tetrahydropyridine, and the like. The term "heterocyclyl" as used herein refers to a univalent group derived from a heterocyclic ring by removal of hydrogen atom from any of the ring atoms; and the term “divalent heterocyclic group” refers to a divalent group derived from a heterocyclic ring by removal of two hydrogen atoms from any of the ring atoms. The heterocyclyl may be substituted, at any position thereof, with one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1-C₆)alkyl.

[0036] The term “aromatic ring” as used herein refers to an aromatic carbocyclic ring having, e.g., 6-14 carbon atoms, and consisting of a single ring or multiple rings either condensed or linked by a covalent bond. Non-limiting examples of aromatic rings include benzene, naphthalene, anthracene, naphthacene, phenanthrene, pyrene, chrysene, tetracene, and triphenylene. The term "aryl" denotes a univalent aromatic carbocyclic group derived from an aromatic ring by removal of hydrogen atom from any of the ring atoms. The aryl may be substituted with one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1-C6)alkyl.

[0037] The term “heteroaromatic ring” as used herein refers to a mono-, bi-, or poly-cyclic aromatic ring having, e.g., 4-12 atoms, and consisting of at least one carbon atom and at least one heteroatom selected from oxygen, sulfur (optionally oxidized) and nitrogen. Non- limiting examples of heteroaromatic rings include thiophene, imidazole, pyridine, furan, pymole, oxazole, thiazole, purine, indole, pyrrole, pyrazine, isoquinoline, pyrazole, isoxazole, thiazole, isothiazole, pyrazine, pyrimidine, pyridazine, carbazole. The term “heteroaryl” refers to a univalent group derived from a heteroaromatic ring by removal of hydrogen atom from any of the ring atoms. The heteroaryl may be substituted, at any position thereof, with one or more groups each independently selected from (C1-C6)alkyl, (C2- C6)alkenyl, (C2-C6)alkynyl, and -O-(C1-C6)alkyl.

[0038] The article of the present invention comprises a metal-containing material or a carbon-based material, having at least one surface coated with a polymeric layer comprising a plurality of, i.e., identical or different, repeating units each independently of the formula I or I’. Said repeating units each consists of a divalent heterocyclic group formed by a group

X as defined herein and the moiety

respectively, linked via the two nitrogen atoms to the groups Y and Y’ each as defined herein. Said heterocyclic group may optionally be substituted as defined herein, and/or fused with a carbocyclic, heterocyclic, aromatic, or heteroaromatic ring to form a bicyclic or polycyclic heterocyclic group.

[0039] In certain embodiments, X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or two groups each independently selected from -NH- and =N-, and together with the

moiety form a 5-9-membered divalent heterocyclic group. In particular such embodiments, X is (C2-C4)alkenylene optionally interrupted by the group -NH- or =N-, and together with the - moiety

form a 5-8-membered divalent heterocyclic group. More particular such embodiments are + those wherein X is ethenylene, and together with the

moiety form the divalent heterocyclic group

(l//-imidazol-3-ium-1,3-di-yl), respectively. [0040] In certain embodiments, Y and Y’ each independently is (C1-C6)alkyl, (C2- C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more groups each independently selected from (C1-C3)alkyl, (C2-C3)alkenyl, (C2-C3)alkynyl, and -O-(C1- C3)alkyl, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ comprises the grou , wherein the dot represents the point of attachment; and the

wavy lines each independently represents H, OH, a repeating unit of the formula I or I’, - linked via a group thereof (forming, e.g., a bridge between

the two linked repeating units), or a repeating unit of the formula I linked via the carbene carbon atom thereof (such that said repeating unit of formula I is capable of binding with a > further repeating unit(s) of the formula I or I’ via the at least one

group thereof), provided that at least one of the wavy lines represents a repeating unit. In particular such embodiments, Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, - CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ comprises the group

. In more particular such embodiments, Y and Y’ each independently is (C1-

C6)alkyl or (C2-C6)alkenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and wherein at least one of Y and Y’ comprises the group In yet more particular

such embodiments, Y and Y’ each independently is (C1-C4)alkenyl comprising the group . According to the present invention, preferred embodiments are those wherein Y

and Y’ are identical. [0041] In specific such embodiments, each one of Y and Y’ is of the formula

, wherein the dot represents the point of attachment to the nitrogen atom of the divalent heterocyclic group, e.g., wherein the wavy lines each independently represents H, OH, or a repeating unit of the formula I or I’, linked via a group

thereof. Particular such embodiments are those wherein the polymeric layer coating said at least one surface of the metal-containing- or carbon-based- material is represented by the formula

, wherein W represents said divalent heterocyclic ring; n is the number of repeating units comprised within said polymeric layer; and said polymeric layer is either coordinated to a metal atom of said metal-containing material or linked to a carbon atom of said carbon-based material, via a carbene-carbon atom thereof.

[0042] In certain embodiments, (i) X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or two groups each independently selected from -NH- and =N-, and together with the -N— C— N- or -N— C— N- moiety form a 5-9-membered divalent heterocyclic group; and (ii) Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more groups each independently selected from (C1-C3)alkyl, (C2-C3)alkenyl, (C2-C3)alkynyl, and -O-(C1-C3)alkyl, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, - CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ comprises the group

, wherein the dot represents the point of attachment; and the wavy lines each independently represents H, OH, a repeating unit of the formula I or I’, linked via a group

thereof (forming, e.g., a bridge between the two linked

repeating units), or a repeating unit of the formula I linked via the carbene carbon atom thereof (such that said repeating unit of formula I is capable of binding with a further repeating unit(s) of the formula I or I’ via the at least one

group thereof), provided that at least one of the wavy lines represents a repeating unit.

[0043] In particular such embodiments, (i) X is (C2-C4) alkenylene optionally interrupted by the group -NH- or =N-, and together with the - moiety form a 5-

8-membered divalent heterocyclic group; and (ii) Y and Y’ each independently is (C1- C6)alkyl, (C2-C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ comprises the group

[0044] In more particular such embodiments, (i) X is ethenylene, and together with the

- moiety form the divalent heterocyclic group

respectively; and (ii) Y and Y’ each independently is (C1-C6)alkyl or (C2-C6)alkenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and wherein at least one of Y and Y’ comprises the group

. In yet more particular such embodiments, Y and Y’ each independently is (C1-C4)alkenyl comprising the group

[0045] In preferred embodiments, the polymeric layer coating said at least one surface of the metal-containing- or carbon-based- material comprises a plurality of repeating units each independently of the formula I or I’, as defined in any one of the embodiments above, wherein Y and Y’ are identical.

[0046] In specific embodiments, X is ethenylene, and together with the

+ X

-N— c— N- moiety form the divalent heterocyclic group . respectively;

and each one of Y and Y’ is of the formula

, wherein W represents the divalent heterocyclic ring

; n is the number of repeating units comprised within said polymeric layer; and said polymeric layer is either coordinated to a metal atom of said metal-containing material or linked to a carbon atom of said carbon-based material, via a carbene-carbon atom thereof.

[0047] The term “article” as used herein refers to any article having at least one metal - containing (i.e., metal-based)- or carbon-based material region that needs to be protected from oxidation, e.g., due to exposure to the external environment. Non-limiting examples of such articles include pipelines, railways, car shielding, ships, etc.

[0048] In certain embodiments, the article of the present invention, according to any one of the embodiments above, comprises a metal-containing material comprising a metal atom, having at least one surface coated with said polymeric layer, and is thus further referred to herein as “a polymer-coated metal-containing article Said metal atom may be, e g., an alkali metal atom such as lithium (Li), sodium (Na), and potassium (K); an alkali-earth metal atom such as magnesium (Mg); and a transition metal atom such as titanium (Ti), vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), or platinum (Pt). In particular embodiments, the article disclosed is a polymer-coated metal-containing article, wherein said metal atom is copper or iron.

[0049] In certain embodiments, the article of the present invention is a polymer-coated metal-containing article, wherein the metal-containing material is either a film having a thickness in the range of about 1 nm to about 200 nm, e.g., from about 1 nm to about 10, 15, 20, 25, 50, 75, 100, 125, 150, or 175 nm.

[0050] In other embodiments, the article of the present invention is a polymer-coated metal-containing article, wherein the metal-containing material is a conductive- or semi conductive material comprising metal atoms dispersed thereon. Examples of conductive- and semi-conductive materials include, without being limited to, silicon (Si), tin (Sn), and graphite.

[0051] In certain embodiments, the article of the present invention, according to any one of the embodiments above, comprises a carbon-based material having at least one surface coated with said polymeric layer, and is thus further referred to herein as “a polymer-coated carbon-based article Examples of carbon-based materials include, without being limited to, graphene, graphite, and carbon nanotubes.

[0052] In certain embodiments, the polymeric layer coating said at least one surface of the metal-containing- or a carbon-based- material, according to any one of the embodiments above, is a nanolayer having a thickness in the range of from about 0.5 nm to about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 nm, e.g., about 1, 2, 3, 4, or 5 nm.

[0053] The Experimental section herein shows the preparation of an article according to the present invention in a process wherein a surface of a copper film, representing a metal- containing material, is exposed, in the presence of an aqueous base, more specifically hydroxide ions obtained by electrochemical reduction of water, to an alkyne-functionalized imidazolium salt, more specifically 1,3-di(prop-2-yn-l-yl)-lH-imidazolium iodide, thereby converting the carbon atom of the

- moiety of at least one of the alkyne- functionalized imidazolium compounds to a carbene carbon atom, which then coordinates with a copper atom of said copper film; and polymerizing at least one of the coordinated compounds, via the acetylenyl group(s) thereof, with at least one of the non-coordinated compounds via either an acetylenyl group thereof or the carbene-carbon atom thereof when present.

[0054] In other words, disclosed herein is an article as defined above, i.e., an article comprising a metal-containing material or carbon-based material, having at least one surface coated with a polymeric layer according to any one of the embodiments above, wherein said article is obtained by exposing said metal-containing- or carbon-based- material, in the presence of a base, to a plurality of compounds each independently of formula I’ :

I’ wherein:

X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or more groups each independently selected from -NH-, =N-, -O-, -S-, and -CO-, which together with the

moiety form a divalent heterocyclic group, said heterocyclic group being optionally substituted by one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, and -O-(C1-C6)alkyl, and/or fused with a carbocyclic, heterocyclic, aromatic, or heteroaromatic ring to form a bicyclic or polycyclic heterocyclic group; and

Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, cycloakenyl, heterocyclyl, aryl, or heteroaryl, optionally substituted by one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1- C6)alkyl, wherein said (C1- C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, cycloalkyl, and cycloakenyl each is optionally interrupted by one or more groups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group (’^“^H ), thereby converting at least one of said compounds to carbene carbon atom- containing compounds, at least one of which is either coordinated to a metal atom of said metal-containing material, or linked to a carbon atom of said carbon-based material, via the carbene-carbon atom thereof, and polymerizing at least one of the coordinated/linked compounds, via the at least one acetylenyl group thereof, with at least one of the non- coordinated/linked compounds via an acetylenyl group thereof or the carbene-carbon atom thereof when present.

[0055] In certain embodiments, the article of the present invention, according to any one of the embodiments above, is obtained by exposing said metal-containing- or carbon-based- material to said plurality of compounds, in the presence of an aqueous base. In particular embodiments, said aqueous base is hydroxide ions obtained by electrochemical reduction of an aqueous medium such as water, i.e., by applying voltage to said aqueous medium.

[0056] In specific embodiments, the electrochemical reduction of the aqueous medium, e.g., water, is performed in the presence of a suitable electrolyte such as, without being limited to, tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate (TEATFB), tetrabuthylammonium tetrafluoroborate, and tetrabutylammonium perchlorate. [0057] In other embodiments, the article of the present invention, according to any one of the embodiments above, is obtained by exposing said metal-containing- or carbon-based- material to said plurality of compounds, in the presence of an inorganic or organic base. Examples of such bases include, without limiting, potassium ZerZ-butoxide (KzBuO), sodium ZerZ-butoxide (NazBuO), sodium bis(trimethylsilyl)amide (NaHMDS), potassium bis(trimethylsilyl)amide (KHMDS), sodium hydride (NaH), and potassium hydride (KH). [0058] Study 2 herein shows that 2 nm thick NHC-nanolayer can be prepared on copper films by using electrochemically assisted deprotonation of alkyne-functionalized imidazolium salt and show that nanolayer-coating provides surface passivation that mitigates copper oxidation. In the electrochemical nanolayer formation process, hydroxide ions are electrochemically formed on a copper electrode by water reduction. The localized base formation enabled deprotonation of the imidazolium salt precursors and NHCs’ anchoring on copper electrodes. Alkyne groups were deprotonated by the localized basic environment, leading to on-surface polymerization and nanolayer formation. NHC-nanolayer was characterized by a self-limiting growth mechanism that induced nanolayer thickness of 2.0+0.5 nm. The high spatial and temporal proximity between the deprotonation, surface- anchoring and polymerization steps enabled the formation of NHC nanolayer on the copper electrode and circumvented the solution-phase polymerization. The pKa differences between the imidazolium and alkyne groups provided the capability to discriminate between the surface-anchoring and polymerization step and to form a highly-dense monolayer, with strong surface affinity. It is plausible that strong carbene-metal interactions and NHC interconnections in the encapsulating nanolayer provided the high thermal and chemical stability and mitigated copper oxidation in air under elevated temperature (100°C) and alkaline environment. The oxidation mitigation capabilities of NHC-nanolayer outperformed that of NHC monolayers. The ease of preparation and well-controlled growth process of electrochemically-induced NHC nanolayer makes it an easily-applicable method for large-scale coating to provide thin and effective passivation layer for copper surfaces. Moreover, the electro -induced mechanism of NHC-nanolayer formation makes it possible to selectively deposit the protective layer on conducting copper wires without changing the optical properties of the entire device. These advantages make the presented technology highly suitable for applications that require high transparency, such as solar cells and electroluminescence devices.

[0059] In another aspect, disclosed herein is a method for coating a surface of a metal- containing- or carbon-based- material with a polymeric layer, said method comprising exposing said surface, in the presence of a base, to a plurality of compounds each independently of formula I’ :

I’ wherein:

X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or more groups each independently selected from -NH-, =N-, -O-, -S-, and -CO-, which together with the - - moiety form a divalent heterocyclic group, said heterocyclic group being

optionally substituted by one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, and -O-(C1-C6)alkyl, and/or fused with a carbocyclic, heterocyclic, aromatic, or heteroaromatic ring to form a bicyclic or polycyclic heterocyclic group; and

[0060] According to the method of the present invention, the polymeric layer coating the metal-containing- or a carbon-based material of the article prepared results from polymerization, in the presence of a base, of a plurality of, i.e., identical or different, compounds each independently of the formula I’ . Said compounds each consists of a divalent + heterocyclic group formed by a group X as defined herein and the moiety -N— c— N-, linked via the two nitrogen atoms to the groups Y and Y’ each as defined herein. Said heterocyclic group may optionally be substituted as defined herein, and/or fused with a carbocyclic, heterocyclic, aromatic, or heteroaromatic ring to form a bicyclic or polycyclic heterocyclic group.

[0061] In certain embodiments, X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or two groups each independently selected from -NH- and =N-, and together with the - moiety form a 5-9-membered divalent heterocyclic group. In

particular such embodiments, X is (C2-C4)alkenylene, optionally interrupted by the group -

NH- or =N-, and together with the - moiety form a 5-8-membered divalent

heterocyclic group. More particular such embodiments are those wherein X is ethenylene, and together with the - moiety form the divalent heterocyclic group (1H-

imidazol-3 -ium- 1 ,3 -di-yl) .

[0062] In certain embodiments, Y and Y’ each independently is (C1-C6)alkyl, (C2- C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more groups each independently selected from (C1-C3)alkyl, (C2-C3)alkenyl, (C2-C3)alkynyl, and -O-(C1- C3)alkyl, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group ). In particular such embodiments, Y

and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

). In more particular such embodiments, Y and Y’ each independently is (C1- C6)alkyl or (C2-C6)alkenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

( ). In yet more particular such embodiments, Y and Y’ each independently is (C1-C4)alkyl substituted with acetylenyl group According to the present invention, preferred embodiments are those wherein Y and Y’ are identical. [0063] In specific such embodiments, each one of Y and Y’ is 2-propyn-l-yl, and the polymeric layer formed is represented by the formula

wherein W represents the divalent heterocyclic ring; n is the number of repeating units comprised within said polymeric layer; and said polymeric layer is either coordinated to a metal atom of said metal-containing material or linked to a carbon atom of said carbon-based material, via a carbene-carbon atom thereof.

[0064] In certain embodiments, (i) X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or two groups each independently selected from -NH- and =N-, and together with the moiety form a 5-9-membered divalent heterocyclic group; and

(ii) Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more groups each independently selected from (C1-C3)alkyl, (C2-C3)alkenyl, (C2-C3)alkynyl, and -O-(C1-C3)alkyl, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

)•

[0065] In particular such embodiments, (i) X is (C2-C4)alkenylene optionally interrupted by the group -NH- or =N-, and together with the -

moiety form a 5-8-membered divalent heterocyclic group; and (ii) Y and Y’ each independently is (C1-C6)alkyl, (C2- C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

In more particular such embodiments, (i) X is ethenylene, and together with the

moiety form the divalent heterocyclic group

and (ii) Y and Y’ each independently is (C1-C6)alkyl or (C2-C6)alkenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group In yet more particular such

embodiments, Y and Y’ each independently is (C1-C4)alkyl substituted with acetylenyl group

[0066] In specific such embodiments, each one of Y and Y’ is 2-propyn-l-yl, and the polymeric layer formed is represented by the formula

wherein W represents the divalent heterocyclic ring, e.g.,

n is the number of repeating units comprised within said polymeric layer; and said polymeric layer is either coordinated to a metal atom of said metal-containing material or linked to a carbon atom of said carbon-based material, via a carbene-carbon atom thereof.

[0067] In certain embodiments, the method disclosed herein comprises exposing said metal-containing- or carbon-based- material to said plurality of compounds, according to any one of the embodiments above, in the presence of an aqueous base, e.g., hydroxide ions obtained by electrochemical reduction of an aqueous medium such as water.

[0068] In other embodiments, the method disclosed herein comprises exposing said metal- containing- or carbon-based- material to said plurality of compounds, according to any one of the embodiments above, in the presence of an inorganic or organic base as defined above. [0069] Unless otherwise indicated, all numbers expressing, e.g., amounts and sizes, used in this specification, are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification are approximations that may vary by up to plus or minus 10% depending upon the desired properties to be obtained by the present invention.

[0070] The invention will now be illustrated by the following non-limiting Examples.

EXAMPLES

Study 1. Electrochemical deposition of V-heterocyclic carbene monolayers on metal surfaces

Methods

[0071] Electrochemical (EC) deposition. Au films (100 nm) were evaporated on a highly doped n-type Si wafer. The Au-coated Si wafers (2x1 cm) were thoroughly rinsed and dried under nitrogen prior to deposition of NHCs. EC depositions were conducted with a potentiostat (CHI-630, CH Instruments). The EC-deposition setup consists of a conventional three-electrode cell, with the metal -coated Si wafer as the working electrode, Ag/AgBr as a quasi-reference electrode and a platinum wire was used as a counter electrode, 5 mM solution of 1,3-bis(2,4-dinitrophenyl)-imidazolium bromide salt (prepared as previously disclosed) (Wu et al., 2017) in acetonitrile along with 0.1 M of a supporting electrolyte (tetrabutylammonium tetrafluoroborate) and 50 mM triple-distilled water at room temperature. A voltage of -1 V was applied for five minutes. After this step, the Au coated Si wafer was rinsed by three cycles of acetonitrile, triple-distilled water, and ethanol, following 5 min flow of N2. Similar procedure was performed for EC-deposition of NO2- NHCs on Ag, Pd and Pt films and for EC-deposition of 1,3-dimethyl-benzimidazolium iodide on Au films.

[0072] Base-induced deposition. 1,3-bis(2,4-dinitrophenyl)-imidazolium bromide was prepared and activated in a glove box according to a previously published protocol (Wu et al., 2017). The freshly prepared carbene solution was transferred into a vial in which the Au- coated Si wafers were deposited. After 18 h, the wafer was removed from the glove box and rinsed three times with tetrahydrofuran (THF) (5 ml) and distilled water (5 ml), intermittently. The sample was flushed with N2 for 5 minutes.

[0073] XPS measurements. X-ray photoelectron spectroscopy (XPS) measurements were performed using Kratos AXIS Supra spectrometer (Kratos Analytical Ltd., Manchester, U.K.) with Al Ka monochromatic X-ray source (1486.6 eV). The XPS spectra were acquired with a takeoff angle of 90° (normal to analyzer); vacuum condition in the chamber was 2x10" ⁹ Torr. High-resolution XPS spectra were acquired with pass energy of 20 eV and step size of 0.1 eV. The binding energies were calibrated according to the Au4/?/2 XPS peak position (B.E. = 84.0 eV). Data were collected and analyzed by using ESCApe processing program (Kratos Analytical Ltd.) and Casa XPS (Casa Software Ltd.).

[0074] Linear sweep voltammetry (LSI⁷) measurements. LSV measurements were conducted with a potentiostat (CHI-630, CH Instruments) using a three-electrode glass cell. Ag/AgCl (KC1 1 M) was used as a reference electrode and platinum wire was used as a counter electrode. The samples were immersed in 0.1 M HC1 (aqueous) during LSV measurements, and the voltage was scanned from 0.15 to -0.5 V at 0.1 V/sec.

[0075] AFM-IR measurements. Au films (100 nm) were evaporated on a highly doped n- type Si wafer and annealed under nitrogen to 300°C for 10 h for the formation of patchy Au films. These conductive Au films were prepared without exposure to exogenous source of carbon or the use of an adhesive layer. Tapping-mode AFM-IR measurements were performed using a nanoIR3 system (Bruker) equipped with Bruker Hyperspectral QCL laser source (800-1800 cm^-1). AFM-IR measurements were performed using gold-coated Si probes with a nominal diameter of ~25 nm, resonance frequency values of 75±15 kHz and spring constant values of 1 -7 N/m. Averaged spectral acquisition time was 5 sec/spectra with resolution of 4 cm^-1. All spectra were averaged and smoothed using Savitzky-Golay filter.

Results and discussion

[0076] Spectroscopic analysis of EC-deposited monolayer of NHCs on Au film. Nitro- functionalized NHCs (NO2-NHCs) were electrochemically deposited on Si-supported Au film. In the EC-deposition process, hydroxide ions were formed in proximity to the Au- coated Si electrode by applying a negative potential (-1 V) that led to water reduction (Fig. 1). The hydroxide ions function as a base for deprotonation of the imidazole cations, enabling active carbenes formation in proximity to the electrode surface. These carbenes were self-assembled on the electrode’s surface as identified byN1s XPS measurements (Fig. 2A).

[0077] The N1s XPS signal of EC-deposited NCL-NHCs (Fig. 2A) was constructed of two distinctive peaks, located at 405-408 and 397-403 eV and correlated to NO2 and C-NH_X species, respectively. The low energy N1s XPS peak was fit by two Gaussians, centered at 399.4 and 401.3 eV, which were assigned to the amine (N-H) and carbene nitrogen, respectively (Dery etal., 2019b). TheNO2:NHx peaks area ratio was 1.5:1, which is smaller than the stoichiometric 2: 1 ratio of NO2-NHC and indicates that a fraction of the nitro groups were reduced upon their deposition. This conclusion is validated by the presence of an amine-correlated feature in the XPS signal (centered at 399.4 eV).

[0078] Electroreduction of the nitro groups in surface-anchored NCE-NHCs provides a chemical handle for quantitative analysis of the surface density of NHCs, based on the well- documented mechanism of electroreduction of aromatic nitro compounds . Linear sweep voltammetry (LSV) of EC-deposited NCE-NHCs revealed a reduction peak at -0.05 to -0.40 V, correlated to reduction of -NO2 groups (Fig. 2B). Similar electroreduction patterns were previously reported for molecules that were functionalized with di- and tri-nitro groups. The electroreduction peak was not detected in a consecutive LSV measurement (Fig. 2B), indicating that the -NO2 groups were fully reduced during the first electroreduction cycle.

[0079] The nitro-to-amine electroreduction was identified as well in the N1s XPS signal (Fig. 2A). The high binding energy peak (405.5 eV), which was correlated to NO2 species, was not probed after the first LSV cycle. The elimination of this peak was coupled with an increase in the area of the low-binding energy Gaussian in the XPS signal, which was correlated to amine. The noticeable changes in the NG XPS spectrum and LSV voltammogram following one cycle of LSV indicate that nitro-to-amine electroreduction was facilitated in NO2-NHCS that were deposited on the Au surface.

[0080] Spectroscopic analysis of NHC monolayer prepared by base induced deprotonation. The properties of EC-deposited NO2-NHCS were compared to those of NO2- NHC SAMs that were prepared using an inorganic base (KO^tBu) for deprotonation of the imidazolium salt under inert conditions, following the teaching of the prior art. The N1s XPS signal of Au-anchored NO2-NHCS, prepared by base-induced deprotonation, showed two distinctive peaks (Fig. 2C); however, the ratio of the two peaks, correlated to NCGCNHx ratio, was 0.07. This value is more than an order of magnitude smaller than the value measured for EC-deposited NO2-NHCS and indicates that most of the nitro groups were reduced during the base-induced deposition process. The deteriorated NCGCNHx ratio is consistent with the highly reactive nature of the base-induced deposition approach (Dery et al., 2019a).

[0081] LSV measurement of NO2-NHCS that were surface-anchored by base-induced deprotonation showed a much shallower electroreduction peak (Fig. 2D) in comparison to the peak detected for EC-deposited NO2-NHCS. The presence of a shallower electroreduction peak correlates with the XPS results and shows that most of the nitro groups were reduced during the deposition process.

[0082] The high-energy peak in the NG XPS signal of NO2-NHCs that were prepared by base-induced deprotonation was eliminated after one LSV cycle (Fig. 2C). Additionally, the low-energy peak in the N G XPS signal became wider, and a dominant feature was identified at 398.9 eV. The detection of a peak at this energy, which is at lower energy than the expected amine peak position, signals that the electroreduction was coupled with partial decomposition of surface-anchored NHCs. Similar decomposition pattern was previously identified for NO2-NHCS that were prepared by base-induced deprotonation and anchored on Pt (111) (Dery et al., 2019a). The detection of a decomposition peak in a monolayer that was prepared by base-induced deprotonation and exposed to electroreducing conditions shows its deteriorated chemical stability in comparison to that of EC-deposited monolayer. [0083] Comparative analysis of SAMs prepared by the two deposition techniques. The surface density of EC-deposited NO2-NHCs was quantified by analysis of the electroreduction peak of the -NO2 groups and was determined to be (2.3±0.7)x10^-11 molxcm" ². Thus, the average surface area for a single surface-anchored NO2-NHC molecule was determined to be 7±2 nm²/molecule. Analysis of the influence of EC-deposition duration on the surface density of NO2-NHCS showed that a maximum surface density is reached after 5 minutes of deposition (data not shown). Extending the electrodeposition duration beyond this point did not noticeably change the surface density of NO2-NHCS.

[0084] The surface density of NO2-NHCS that were prepared by base-induced deprotonation was 3.8x1 O^-12 mol cm'², as quantified by analysis of the electroreduction peak that was detected in LSV measurements. However, this analysis is biased by the fact that most of the nitro groups in NO2-NHCS that were prepared by base-induced deprotonation were already reduced upon their deposition (Fig. 2C). A comparison of the N1s/Au4/XPS peaks area ratios revealed threefold higher values for EC-deposited NHCs than that of NHCs that were prepared by base-induced deprotonation. Based upon this ratio it can be calculated that the surface density of NO2-NHCs that were prepared by base-induced deprotonation was (0.8±0.2)x10^-1 mol cm^-2.

[0085] The higher surface density of EC-deposited NO2-NHCS was connected with lower surface concertation of competitive adsorbates, as identified by XPS measurements. XPS analysis of Au surfaces on which NO2-NHCS were prepared by EC-deposition and base- induce deprotonation showed N:Br:K atomic ratios of 1 :0.3:0 and 1 : 1.25:0.4, respectively. An inverse correlation was therefore identified between the surface density of NHCs and that of bromide and potassium, indicative of a competitive surface-adsorption process between these species. XPS measurements did not detect F1s signals on the Au surface on which NO2-NHCS were EC-deposited, demonstrating that electrolyte residues were not adsorbed on the Au surface during EC-deposition (data not shown).

[0086] DFT simulations identified that the optimal surface density of NO2-NHCs in a closely packed monolayer was 1.2x 10^10- mol cm'² (data not shown). Thus, the calculated surface density was 5-fold higher than that of the experimental value. The difference between the experimental and calculated surface density can be linked with the competitive adsorption of bromide and carbene on the Au surface and to the strong interaction of NO2- NHCs with the Au surface that hindered the formation of a dense monolayer in which all surface-anchored molecules are well aligned. [0087] Thus, integration of XPS and LSV results identified that higher surface density and improved chemical stability were achieved by EC-deposition of NO2-NHCS. The higher surface density and improved chemical stability of EC-deposited monolayer were attributed to the following factors: (i) milder deprotonation conditions; and (ii) formation of small and constant concentration of carbenes in proximity to the metal surface. These two factors minimized the competitive adsorption of bromide on the surface and the deformation of NHCs upon their surface-anchoring.

[0088] The EC-deposition mechanism of NHCs. Various control experiments were conducted to validate the EC-deposition mechanism. Reduction and oxidation cycles of Fe(CN)6³-/Fe(CN)6⁴' on the bare and NO2-NHC coated Au electrode showed that no passivation of the electrode was induced following EC-deposition (data not shown), thus excluding multilayer formation by EC-deposition. Spectro-electrochemistry measurements demonstrated that imidazolium deprotonation is facilitated only once negative potential (-1 V) is applied and H2O was added to the solution (data not shown). Similarly, XPS measurements revealed that surface-anchoring of NO2-NHCS was not achieved without water addition or with a lower voltage of -0.5 V (data not shown).

[0089] The influence of water concentration on the EC-deposited yield was studied (data not shown). It was identified that the surface density of NHCs was fourfold lower once water concentration was decreased from 50 to 5 mM. The surface density of NHCs was not changed once water concertation was increased to 150 mM, demonstrating the self-limited process of monolayer formation by EC-deposition. However, higher water concertation induced undesired oxidation reactions within the surface-anchored NHCs. The results of these experiments validate our hypothesis that water reduction led to the formation of a basic environment that facilitated imidazolium deprotonation and the following surface-anchoring of carbene.

[0090] The feasibility for EC-deposition is based on the fact that hydroxide ions, which are formed by water electroreduction, will function as a base for deprotonation of the imidazolium salt (Fig. 1). The pK_a of 2,4 dinitrophenyl-imidazolium was measured and was found to be equal to pK_a = 10.49+0.02. The pH in the vicinity of electrode during EC deposition was estimated to be pH = 12.54. Thus, the pK_a of the imidazolium salt is lower than the pH on the electrode, enabling deprotonation of the imidazolium salt by water reduction. [0091] The stability of the EC-deposited NO2-NHCs was studied following exposure to 25 and 50 cycles of cyclic voltammetry (-0.5 V to 1 V vs Hg/Hg2SO4). N1s XPS measurements did not reveal noticeable changes in the surface density of NO2-NHCs after 25 cycles (data not shown). However, the surface density was fivefold lower after 50 cycles, indicating that electro-induced desorption has occurred.

[0092] High spatial resolution IR mapping of NO2- NHCs monolayers. AFM-IR measurements were performed to complement the ensemble-based measurements and provide high spatial resolution analysis of the distribution and chemical properties of NO2- NHCs monolayers that were prepared by EC-deposition and base-induced deprotonation. AFM-IR measurements provide both structural and chemical information at the nanoscale with a spatial resolution of ~20 nm. These capabilities make it a superb technique for analysis of the averaged distribution and chemical functionality ofNHCs on surfaces. The AFM-IR measurements were conducted on a patchy Au film that was evaporated on a Si wafer in order to map the averaged distribution of NHCs on the Au surface and probe leaching of NHCs onto the Si surface.

[0093] Fig. 3A shows a topographic map of the Si substrate (brown-colored) and the patchy Au film (50-70 nm height, gold-colored) on which NO2-NHCs were EC-deposited. AFM-IR measurements were conducted on several points across the Au film and the bare Si surface. Dots in Fig. 3A mark the locations in which AFM-IR measurements were performed, and the measured IR spectra are shown in Fig. 3B respectively. The spectra measured on the gold surface (dots Nos. 1 and 2 in Fig. 3A, and spectra Nos. 1 and 2 in Fig. 3B, respectively) show signals at 1533 and 1603 cm^-1, correlated to asymmetric N-0 and aromatic C=C vibrations, respectively (Wu et al., 2017). Vibrational signals were not detected on the bare Si substrate (spectrum No. 3 in Fig. 3B), demonstrating the selective adsorption of NHCs on the Au surface. Interestingly, stronger vibrational signals were identified on flatter areas, correlated to higher surface density of NO2-NHCs on these sites (data not shown).

[0094] The AFM-IR spectrum of surface-anchored NO2-NHCs was compared with the ATR-IR spectrum of the imidazolium salt precursor (data not shown). Three main peaks were detected in the ATR-IR spectrum of the salt precursor, located at 1340, 1536 and 1608 cm^-1 and correlated to the symmetric and asymmetric N-0 vibrations and aromatic C=C vibration, respectively. IR spectrum of the imidazolium salt was also deduced by DFT calculations and showed peaks at similar positions to those detected in the ATR-IR spectrum (data not shown). Infrared reflection absorption spectrum of surface-anchored NO2-NHCS showed peaks at similar positions to those detected by ATR-IR (Dery et al., 2019b).

[0095] The asymmetric N-0 vibration and aromatic C=C vibration were detected in both the ATR-IR and AFM-IR spectra with relatively small shifts of up to 5 cm^-1 in the peak position. The absence of the symmetric N-0 vibration in the AFM-IR spectrum can be connected with the fact that AFM-IR measurements are more sensitive to vibrations that are perpendicular to the surface. Thus, the lack of a symmetric N-0 vibration can indicate that the -NO2 groups in EC-deposited NO2-NHCS were not oriented in a standing position, as identified in DFT calculations (data not shown) and in other addressable NHC monolayers (Dery et al., 2019b; Dery et al., 2020).

[0096] AFM topography image along with the corresponding AFM-IR mapping at 1533 cm^-1 are shown in Figs. 3C and 3D, respectively. The AFM-IR map reveals homogeneous distribution of the vibrational signal at 1533 cm^-1 across the Au surface. No signal was detected on the bare Si surface. AFM-IR mapping at 1603 cm^-1 showed a uniform distribution of the vibrational signals on the same area (data not shown). These results suggest that there is a uniform chemical functionality of surface-anchored NHCs in the mapped surface. It should be noted that the AFM-IR measurements provide averaged nanoscale information about the chemical properties of surface-anchored NHCs over an area of 1 μm². Analysis of the distribution and chemical functionality of NHCs on metal surfaces at this scale cannot be easily achieved by conducting STM measurements.

[0097] The AFM topography image (Fig. 3C) showed randomly distributed structures in the size range of 10-70 nm, which were scattered on both the Au film and Si substrate and were higher by 10-15 nm from their surrounding environment. These structures did not show the indicative IR absorption at 1533 cm^-1 (Fig. 3D). AFM phase image revealed differences between the phase of the randomly distributed structures and their surrounding environment (data not shown). These structures can be attributed to bromide residues, which were detected by XPS measurements (data not shown), and locally blocked the NHCs’ adsorption on the Au film.

[0098] SAM of NO2-NHCS was also prepared on a patchy Au film by base-induced deprotonation and characterized by AFM-IR measurements (Fig. 4). The dots in the AFM topography image (Fig. 4A) represent the sites in which localized IR measurements were performed, and the corresponding IR spectra were plotted in Fig. 4B. [0099] AFM-IR spectra showed significant vibrational features at 1346 and 1533 cm^-1 that correspond to the symmetric and asymmetric N-0 vibrations, respectively (Fig. 4B) (Dery et al., 2019b). A signal at 1466 cm^-1 was detected and assigned to a C-NH vibration. Vibrational signature was also probed at 1603 cm^-1 and correlated to aromatic C=C vibrations. No vibrational signature was identified on the bare Si surface, indicating that NO2-NHCs were solely anchored on the Au surface. The selective adsorption of NCE-NHCs on Au surfaces, following base-induced deprotonation, was also previously identified by synchrotron-based IR nanospectroscopy measurements (Wu et al., 2017).

[00100] ATR-IR spectrum of the nitro -functionalized imidazolium salt precursor showed similar peaks to those detected in the AFM-IR spectra. However, the peak at 1466 cm^-1, which was detected in the AFM-IR spectra and correlated to C-NH vibration, was not probed in the ATR-IR spectra. This result validates that this peak was obtained due to reduction of -NO2 groups.

[00101] The IR peaks at 1346 and 1466 cm^-1 , correlated to symmetric N-O and C-NH vibrations, respectively, which were detected in the AFM-IR spectra of NO2-NHCS that were prepared by base-induced deposition (Fig. 4B), were not detected in the AFM-IR spectra of EC-deposited NO2-NHCS (Fig. 3B). The presence of a vibrational signal at 1466 cm^-1, which presumably results from reduction of nitro-groups to amines, demonstrates the reductive nature of base-induced deprotonation deposition, as identified by XPS and LSV measurements (Figs. 2C-2D). The detection of both the symmetric and asymmetric N-0 vibrations in base-induced deposited NHCs can be correlated to the random orientation of the -NO2 groups. Comparison of the AFM-IR amplitudes revealed that EC-deposited NO2- NHCs has two-fold higher signals than NO2-NHCS that were prepared by base-induced deprotonation (data not shown). This variation reflects the higher surface density of EC- deposited NHCs.

[00102] AFM topography image at higher magnification showed that the Au surface became decorated with nanoparticles in the size range of 10-50 nm following base-induced deposition of NO2-NHCS (Fig. 4C). AFM-IR mapping at 1533 cm^-1 (Fig. 4D) revealed that while the flat areas on the Au film were characterized with strong vibrational signal, no vibrational signature was detected on areas that were decorated by nanoparticles. This observation is consistent with the hypothesis that the nanoparticles blocked the NHCs’ adsorption sites. These nanoparticles may be constructed of potassium and bromide residues, which their presence on the surface was probed by XPS measurements (data not shown). AFM phase imaging identified as well differences in the properties of the nanoparticles and their surrounding Au surface (data not shown).

[00103] AFM topography (Fig. 5A) and AFM-IR measurements (Fig. 5B) of EC-deposited NO2-NHCS were conducted after one LSV cycle (0.15 to -1 V at 0.1 V/sec) in order to identify the influence of electroreduction on the vibrational properties of the SAM. AFM-IR measurements showed IR spectra with a single peak at 1463 cm^-1, corresponding to N-H vibration (Fig. 5B). The lack of N-0 signatures in the IR spectra demonstrates the high efficiency of the electroreduction process. No vibrational signatures were detected on the bare Si surface, indicating that electroreduction did not lead to diffusion of NHCs into the Si substrate. The absence of aromatic C=C signal at 1603 cm^-1 can either reflect that the molecules have changed their orientation into a more flat-lying position or can be the result of the deteriorated surface-density of NHCs due to electrodesorption.¹⁷ AFM topography measurement at higher magnification (Fig. 5C) and AFM-IR mapping of the same area at 1460 cm^-1 (Fig. 5D) revealed that areas that were adjacent to the Si substrate showed weaker vibrational signals. This result indicates that partial NHCs’ desorption from the Au surface, which was facilitated by electroreduction, has mostly occurred on sites that were located in proximity to the Si substrate.

[00104] EC-deposition of NO 2-NHCs on various metal films. One of the advantages in the EC-deposition approach is that it can be widely utilized for deposition of NHCs on various conductive substrates. To demonstrate this feasibility, NO2-NHCS were EC-deposited, in addition to Au, on Pt, Pd and Ag films. N1s XPS measurements identified that SAMs of NO2-NHCS were formed by EC-deposition on the various metal films (Fig. 6). Interestingly, an inverse correlation was detected between the atomic ratio of Br and that of N on the various metal surfaces (data not shown). This result demonstrates the competitive adsorption of bromide and carbene on the metal surface. The variation in the NO2/NHx peaks area ratio among the different metals was correlated to differences in their affinity for dissociate chemisorption of H2, which is formed during EC deposition. Thus, a more inert surface toward H2 dissociation, such as Au, led to higher NO2/NHx ratio.

[00105] It should be noted that SAM formation of NHCs on Ag films was not previously reported while using imidazolium salts as precursors. In previous reports the deposition of NHCs on Ag required highly controlled environment (ultra-high vacuum conditions and cryogenic temperature) and using NHC-CO2 adduct as precursor (Jiang et al., 2017). The challenges in surface-anchoring of NHCs on Ag surfaces can be related to the presence of oxidized Ag or to the strong interaction of Ag with halides. It is postulated that the reductive conditions of the EC-deposition and the presence of a relatively small concentration of halides during the deposition enabled the formation of a SAM of NHCs on the Ag film by this deposition method.

[00106] EC-deposition of dimethyl-benzimidazole monolayer on Au film. In order to show the wide applicability of the EC-deposition approach we have expanded our NHCs scope and demonstrate that dimethyl-benzimidazole can be EC-deposited on Au surfaces. N1s XPS spectra were acquired following EC-deposition of 5 mM dimethyl-benzimidazolium iodide with 50 mM H2O at -1 V. The successful EC-deposition of dimethyl-benzimidazole on Au was identified by the presence of a single peak in the N1s XPS spectrum (Fig. 7). No significant changes were detected in the peak area once the concentration of dimethyl- benzimidazolium iodide in the EC-deposition was increased by fivefold to 25 mM (Fig. 8). This result demonstrates that an optimize coverage was already achieved at lower concentration and validates the self-limited EC-deposition process that led to monolayer formation.

Study 2. V-heterocyclic carbene nanolayer for copper film oxidation mitigation

[00107] Alkyne-functionalized imidazolium salt (1,3-di(prop-2-yn-l-yl)-lH-imidazolium iodide) was synthesized (Johnson and Gimeno, 2017) and electrochemically deposited on copper film. During the electrochemical deposition, hydroxide ions were formed near the copper electrode by applying a negative potential (-1.3 V vs. Ag/Ag⁺) that led to water reduction. The hydroxide ions function as a base for deprotonation of imidazolium cations (pK_a = 22), enabling active carbene formation in proximity to the electrode surface that led to self-assembly of NHC monolayer. In addition to deprotonation of the imidazolium proton, the alkyne groups (pK_a = 25) of surface-anchored NHCs were deprotonated by the hydroxide ions thus enabling on-surface polymerization between surface-anchored and solvated NHCs, resulting in NHC-nanolayer formation on copper film.

[00108] NHC nanolayer was characterized byN1s X-ray photoelectron spectroscopy (XPS) measurement (Fig. 8A, spectrum i). TheN1s XPS spectrum showed a broad peak that was fit by two Gaussians, centered at 399.4 eV and 401.4 eV and assigned to C-N=C and N-C bonds, respectively (Dery et al., 2021b). For comparison, dimethyl-benzimidazolium iodide (DMBI) was used as a precursor for monolayer formation on copper film due to its ability to form densely -packed NHC monolayers (Crudden et al. , 2016) . N 1 s XPS signal of copper- supported NHC monolayer, prepared by using DMBI as a precursor, was measured (Fig. 8A, spectrum ii). TheN1s XPS peak area of the alkyne-NHC was four- fold higher than that of DMBI monolayer. Thus, on average, the alkyne-NHC nanolayer contains four layers of NHCs.

[00109] A lamella was extracted from NHC-nanolayer coated copper film using focused ion beam and the nanolayer thickness was assessed by scanning transmission electron microscopy energy dispersive X-ray spectroscopy (STEM-EDS) analysis. A protective iridium layer was deposited on the nanolayer before its extraction in order to prevent beam damage. Cross-sectional STEM-EDS analysis of the extracted lamella (Fig. 8B) revealed a 2.0+0.5 nm thick organic layer between the copper film and the protective iridium layer. Since NHC monolayer thickness is ~ 0.5 nm, the measured thickness of the NHC nanolayer indicates that it is constructed of four layers of NHC. This result nicely matches the XPS results (Fig. 8A) that showed a 4-fold increase in theN1s XPS peak area of NHC nanolayer in comparison to DMBI monolayer.

[00110] The influence of EC-deposition duration on nanolayer thickness was examined by analysis of theN1s XPS signal as a function of the applied-voltage duration. It was identified that the polymerization rate decreases with the EC-deposition duration (data not shown). Growth deceleration was attributed to the deteriorated conductivity of copper film coated with an insulating polymer layer (data not shown), which hinders the formation of hydroxide ions. The growth of an insulating nanolayer was validated by probing the continuous decrease in the current during on- surface polymerization (data not shown). The influence of water concentration on nanolayer formation was analyzed and a reduction of up to 20% in nanolayer formation yield was probed as water concertation was gradually decreased (data not shown).

[00111] Resistivity measurements demonstrated that the presence of NHC nanolayer increased the Cu film resistivity by 6%, in comparison to Cu film that was exposed to the reducing deposition conditions, but without the imidazolium precursor (data not shown). Thus, the surface-anchoring of NHC nanolayer had a relatively minor impact on the bulk electronic properties of Cu.

[00112] Spectroscopic measurements were conducted in order to shed light on the molecular properties of NHC-nanolayer and its formation mechanism. Raman spectra of the imidazolium salt precursor revealed a single peak at 1560 cm^-1 (Fig. 9A, spectrum i), correlated to the symmetric stretching vibration of the imidazolium ring. An additional peak was detected at 2130 cm ^-1 (Fig. 9B, spectrum i), matching the symmetric C=C stretching vibration. Attenuated total reflection infrared (ATR-IR) spectra of the imidazolium salt precursor revealed a sharp peak at 3290 cm^-1, correlated to the =C-H vibration (data not shown).

[00113] Raman spectra of the nanolayer-coated sample showed a broad peak at ~ 1600 cm' ^x, correlated to surface-anchored carbene ring (Fig. 9A, spectrum ii) (Dery et al., 2019b; Dery et al., 2020). It is hypothesized that the basic environment of the electrochemical deposition induced polymerization of solvated alkyne-NHCs with surface- anchored NHCs under anionic reaction conditions for polyacetylene formation. Polyacetylenes are well known to be susceptible to oxidation and the presence of a carbonyl-related peak at 1780 cm^-1 (Fig. 9A, spectrum ii) indicates that the unsaturated bonds in the nanolayer were oxidized. No peak was detected in the C=C bond region of the nanolayer-coated copper film (Fig. 9B, spectrum ii), indicating that alkyne concentration was diminished following deposition. IR spectrum of the nanolayer showed as-well the diminish of the C=C vibration amplitude following surface-anchoring along with the presence of various carbonyl-related signatures (data not shown). The NHC-nanolayer oxidation was also probed in Cis XPS measurements that showed threefold higher CO_X related features in the nanolayer spectrum in comparison to DMBI monolayer (data not shown).

[00114] NHC polymerization was also induced by exposure of alkyne-functionalized imidazolium salt to potassium tert-butoxide. However, in contrast to on-surface electro- polymerization, the solution phase polymerization was not self-limited and led to precipitation. ATR-IR spectrum of the precipitated polymer did not identify the strong =C- H signal that was detected in the imidazolium precursor (data not shown). In addition, it was observed that the IR alkene signal in the nanolayer was an order of magnitude higher than that of alkyne (data not shown). The formation of NHC oligomers with 3-4 repeating units should have led to higher alkyne to alkene signals ratio and should not have fully quenched the =C-H signal. The spectroscopic results can therefore indicate that the polymerization process was not restricted to short oligomers formation and can lead to formation of longer chains in solution phase or interconnected oligomers on the Cu surface.

[00115] The polymerization mechanism was studied by monitoring the influence of TEMPO ((2,2,6,6-tetramethylpiperidin-l-yl)oxyl), which is a radical scavenger (Niki, 1991), addition on NHC-nanolayer formation. XPS measurements revealed that TEMPO addition did not influence the nanolayer formation (data not shown), thus indicating that the polymerization does not involve a radical-based formation mechanism. Electrodeposition of alkyne-NHC in the presence of ascorbic acid, which functions as acid and radical scavenger (Berg et al., 2021), prevented the polymerization process and exclusively led to NHC monolayer formation, as identified by a 4-fold decrease in the N1s XPS peak area (data not shown). This result can be rationalized by the higher pKa value of the alkyne groups compared to the imidazole cations, leading to efficient quenching of the alkyne -based polymerization process. Monolayer formation was still achieved even in the presence of ascorbic acid due to the lower pKa value of the imidazolium cation and the high proximity between deprotonated NHCs and copper surface, which enabled surface anchoring. Nanolayer formation was also quenched once the alkyne group was protected with triisopropylsilyl (TIPS) group. (Berg et al., 2021). This result demonstrates the crucial role of alkyne deprotonation in initiating nanolayer formation. Based on the spectroscopic measurements, a hypothesized scheme for on-surface anchoring and polymerization was suggested (Fig. 10).

[00116] The oxidation state of nanolayer-coated copper film was detected by XPS and Auger spectra (Figs. 11A and 11B, respectively). Cu2p XPS spectrum of nanolayer-coated copper film showed a dominant peak at 932.7 eV, correlated to Cu°/Cu¹⁺ (Fig. 11A, spectrum i). No indication for Cu²⁺ species (-942.5 eV) was detected on the nanolayer-coated surface (Espinos et al., 2002). Since Cu° and Cu¹⁺ cannot be differentiated in XPS measurement, X- ray-induced Auger electron spectroscopy measurements were performed to distinguish between these oxidation states. Auger spectrum of nanolayer-coated copper film (Fig. 11B, spectrum i), showed a noticeable peak at 918.5 eV, indicative of the presence of Cu° species. Another peak was detected at 916.5 and was correlated to Cu¹⁺ species (Veinot et al., 2020). [00117] The nanolayer-coated copper film was exposed to oxidizing conditions (100°C, air, 4 h) to assess the functionality of the organic layer for corrosion inhibition. The XPS spectrum of nanolayer-coated copper film did not noticeably change after exposure to oxidizing conditions (Fig. 11A, spectrum ii). Changes in the Auger spectrum following exposure to oxidizing conditions indicated that partial oxidation from Cu° to Cu¹⁺ was induced. However, a dominant Cu° peak was still detected and demonstrated that the nanolayer-coated copper surface did not lose its metallic character.

[00118] Exposure of a bare copper film to identical oxidizing conditions led to the appearance of a noticeable XPS peak at 942.5 eV, correlated to Cu²⁺ species (Fig. 11A, spectrum iii). This peak was not detected prior to exposure of the non-coated copper film to oxidizing conditions (data not shown). Auger spectra of the bare surface after exposure to oxidizing conditions showed no indication for a peak at ~ 918.5 eV, which is indicative of complete oxidation of Cu° to Cu¹⁺ and Cu²⁺ (Fig. 11B, spectrum iii). Longer exposure duration of the nanolayer-coated sample to oxidizing conditions had some influence on copper oxidation (data not shown). However, exposure of the nanolayer-coated copper film to elevated temperatures (150 and 200°C) led to noticeable copper oxidation, as indicated by the Cu²⁺ signature appearance in the XPS spectra (data not shown).

[00119] In order to compare the effectiveness of NHC-nanolayer vs. NHC-monolayer in mitigating copper oxidation, the properties of DMBI-coated copper film were measured following exposure to oxidizing conditions (100°C, air, 4 h). Oxidation mitigation functionality of DMBLcoated copper film was inferior in comparison to NHC-nanolayer (data not shown). Moreover, N1s XPS measurements of DMBLcoated copper film did not detect any nitrogen signal following exposure to oxidizing conditions, demonstrating its limited stability. It should be noted that in a similar way to DMBI, both benzotriazole and alkanethiols, which have been used as corrosion inhibitors (Fox et al., 1979) showed inadequate thermal stability with noticeable deformation following exposure to 100°C under atmospheric conditions.

[00120] The nanolayer-coated and bare copper films were exposed to NaOH (0.1 M, 2 h) and then characterized by XPS and Auger measurements (Figs. 12A and 12B, respectively). Exposure to NaOH led to partial surface oxidation as identified by detection of Cu²⁺ peak in the XPS spectra of the nanolayer-coated and bare copper films (spectra i and ii, respectively). Cu²⁺ peak area (937-947 eV) in the XPS spectrum of the bare copper sample was four-fold higher than that of the nanolayer-coated sample. Auger spectrum of nanolayer-coated copper film showed a peak in the range of Cu¹⁺/ Cu²⁺ and a shoulder at 918.5 eV, which was correlated to Cu° species (Fig. 12B, spectrum i). Auger spectrum of the bare copper following its exposure to NaOH showed a dominant peak at 917.5 eV (correlated to Cu²⁺ species) with no signature at -918.5 eV that can be correlated to Cu° (Fig. 12B, spectrum ii).

[00121] Integration of the XPS and Auger data indicates that following exposure to NaOH the bare copper film was fully oxidized to Cu²⁺ and Cu¹⁺ with no indication for Cu°. The nanolayer-coated Cu film was less oxidized and Cu° species was still detected after exposure to NaOH. The oxidation mitigation ability of NHC-nanolayer was also observed visually as the nanolayer-coated copper film maintained a metallic copper color even after exposure to 0.1 M NaOH, while the non-coated copper film was characterized with a darker color, indicative of surface oxidation.

[00122] It is postulated that the improved thermal and chemical stability of NHC-nanolayer, in comparison to NHC- and thiol-based monolayers, are linked with the strong metal-carbene bond (Koy et al., 2021) and the ability to construct interconnections between neighboring NHCs in the encapsulating nanolayer. The encapsulating nature of NHC-nanolayer can be further utilized for coating and protecting rough surfaces, which cannot be easily achieved while using organic monolayers such as benzotriazole, alkanethiols, and formate (Peng et al., 2020).

[00123] The electrodeposition of NHC-nanolayer is comparable to electrografting of aryldiazonium salts, which are surface-anchored and polymerized in a radical process under reducing conditions. However, the radical-based mechanism of aryldiazonium polymerization and the fact that the surface anchoring and polymer forming groups are identical, make it challenging to control their surface-polymerization process. Our mechanistic study suggests that in alkyne-functionalized NHC, the carbene group functions as the surface anchoring group while the alkyne group induces the polymerization step. The lower pKa value of the carbene group compared to the alkyne group, increased the surface- anchoring rate compared to the polymerization step, thus leading to high density of surface- anchored NHCs and preventing solution-phase polymerization. In addition, the presence of two nitrogen atoms in NHC led to 7t-electron donation characteristics that further increased the interaction between the NHC and copper surface compared to the aryl-metal interactions. The improved stability of the NHC nanolayer, compared to aryldiazonium-based multilayers, can be therefore attributed to stronger surface interactions and high density of surface-anchored NHCs.

[00124] The presented results show that NHC nanolayer can mitigate Cu film oxidation. It is hypothesized that the functionality of this layer can be further improved by increasing the density of surface anchored molecules and by enhancing the crosslinking between neighboring oligomers toward the formation of a dense nanolayer network. These aims can be achieved by tuning the chemical structure of alkyne-NHC to enable higher surface density and improved crosslinking capabilities. Exposure of the sample to irradiation can also be utilized for nanolayer network formation, as demonstrated in topochemical polymerization of diacetylenes. REFERENCES

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Claims

1. An article comprising a metal-containing- or a carbon-based- material, having at least one surface coated with a polymeric layer comprising a plurality of repeating units each independently of formula I or I’

I I wherein:

wherein the dot represents the point of attachment; and the wavy lines each independently represents H, OH, a repeating unit of 7 the formula I or I’, linked via a group

thereof, or a repeating unit of the formula I linked via the carbene carbon atom thereof, provided that at least one of the wavy lines represents a repeating unit, wherein at least one of said repeating units is of the formula I and is either coordinated to a metal atom of said metal-containing material or linked to a carbon atom of said carbon - based material, via the carbene-carbon atom thereof.

2. The article of claim 1, wherein X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or two groups each independently selected from -NH- and =N-, and together with the -

moiety form a 5-9-membered divalent heterocyclic group.

3. The article of claim 2, wherein X is (C2-C4)alkenylene optionally interrupted by the group -NH- or =N-, and together with the moiety form a 5-8-

membered divalent heterocyclic group.

4. The article of claim 3, wherein X is ethenylene, and together with the

moiety form the group ( 1H-imidazol-3-ium-1,3-di-yl) or

respectively.

5. The article of claim 1, wherein Y and Y’ each independently is (C1-C6)alkyl, (C2- C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more groups each independently selected from (C1-C3)alkyl, (C2-C3)alkenyl, (C2-C3)alkynyl, and -O-(C1- C3)alkyl, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ comprises the group

thereof, or a repeating unit of the formula I linked via the carbene carbon atom thereof, provided that at least one of the wavy lines represents a repeating unit.

6. The article of claim 5, wherein Y and Y’ each independently is (C1-C6)alkyl, (C2- C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ comprises the group

7. The article of claim 6, wherein Y and Y’ each independently is (C1-C6)alkyl or (C2- C6)alkenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and wherein at least one of Y and Y’ comprises the group

8. The article of claim 7, wherein Y and Y’ each independently is (C1-C4)alkenyl comprising the group

9. The article of claim 8, wherein Y and Y’ are each of the formula

, wherein the dot represents the point of attachment to the nitrogen atom of the heterocyclic group.

10. The article of claim 9, wherein Y and Y’ are each of the formula

, wherein the dot represents the point of attachment to the nitrogen atom of the heterocyclic group; and the wavy lines each independently represents H, OH, or a repeating unit of the formula I or

I’, linked via a group

thereof.

11. The article of claim 1, wherein:

(i) X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or two groups each independently selected from -NH- and =N-, and together with the

- moiety form a 5-9-membered divalent heterocyclic group; and

(ii) Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more groups each independently selected from (C1-C3)alkyl, (C2-C3)alkenyl, (C2-C3)alkynyl, and -O-(C1- C3)alkyl, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ comprises the group

, wherein the dot represents the point of attachment; and the wavy lines each independently represents H, OH, a repeating unit of the formula I or I’, linked via a group > thereof, or a repeating unit of the formula I linked via the carbene

carbon atom thereof, provided that at least one of the wavy lines represents a repeating unit. The article of claim 11, wherein:

(i) X is (C2-C4)alkenylene optionally interrupted by a group selected from -NH- and =N-, and together with the

moiety form a 5-8- membered divalent heterocyclic group; and

(ii) Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of

Y and Y’ comprises the group

The article of claim 12, wherein:

(i) X is ethenylene, and together with the -

moiety form the ‘ group (1H-imidazol-3-ium-1,3-di-yl) or , respectively; and

(ii) Y and Y’ each independently is (C1-C6)alkyl or (C2-C6)alkenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and wherein at least one of

Y and Y’ comprises the group

14. The article of claim 13, wherein Y and Y’ each independently is (C1-C4)alkenyl comprising the group

15. The article of claim 14, wherein Y and Y’ are each of the formula

, wherein the dot represents the point of attachment to the nitrogen atom of the divalent heterocyclic group.

16. The article of claim 15, wherein Y and Y’ are each of the formula

, wherein the dot represents the point of attachment to the nitrogen atom of the heterocyclic group; and the wavy lines each independently represents H, OH, or a repeating unit of the

17. The article of any one of claims 1-16, comprising a metal-containing material.

18. The article of claim 17, wherein said metal-containing material comprises a metal atom selected from an alkali metal atom such as lithium (Li), sodium (Na) and potassium (K); an alkali-earth metal atom such as magnesium (Mg); and a transition metal atom such as titanium (Ti), vanadium (V), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), or platinum (Pt).

19. The article of claim 18, wherein the metal-containing material comprises Cu or Fe.

20. The article of claim 18 or 19, wherein the metal-containing material is either a film having a thickness in the range of from about 1 nm to about 200 nm, or a conductive- or semi-conductive material comprising metal atoms dispersed thereon.

21. The article of any one of claims 1-16, comprising a carbon-based material.

22. The article of claim 21, wherein said carbon-based material is graphene, graphite, or carbon nanotubes.

23. The article of any one of claims 1-22, wherein said polymeric layer is a nanolayer having a thickness in the range of from about 0.5 nm to about 100 nm, e.g., from about 1 nm to about 5 nm.

24. A method for coating a surface of a metal-containing- or carbon-based- material with a polymeric layer, said method comprising exposing said surface, in the presence of a base, to a plurality of compounds each independently of formula I’ :

wherein:

X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or more groups each independently selected from -NH-, =N-, -O-, -S-, and -CO-, which together with the moiety form a divalent heterocyclic group, said heterocyclic group being

thereby: (i) converting at least one of said compounds to carbene carbon atom- containing compounds thus enabling coordination or linkage of said at least one carbene carbon atom-containing compound, via the carbene-carbon atom thereof, to a metal atom in said surface of said metal-containing material, or a carbon atom in the surface of said carbon- based material, respectively; and (ii) polymerizing at least one of the coordinated/linked compounds obtained via the at least one acetylenyl group thereof with at least one of the non- coordinated/linked compounds via an acetylenyl group thereof or the carbene-carbon atom thereof, when present, to thereby form said polymeric layer on said surface of said metal- containing- or carbon-based- material.

25. The method of claim 24, wherein X is (C2-C4)alkylene or (C2-C4)alkenylene, optionally interrupted by one or two groups each independently selected from -NH- and =N-

, and together with the -

moiety form a 5-9-membered divalent heterocyclic group.

26. The method of claim 25, wherein X is (C2-C4)alkenylene optionally interrupted by the group -NH- or =N-, and together with the moiety form a 5-8-membered

divalent heterocyclic group.

27. The method of claim 26, wherein X is ethenylene, and together with the -

moiety form 1H-imidazol-3-ium-1,3-di-yl.

28. The method of claim 24, wherein Y and Y’ each independently is (C1-C6)alkyl, (C2- C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more groups each independently selected from (C1-C3)alkyl, (C2-C3)alkenyl, (C2-C3)alkynyl, and -O-(C1- C3)alkyl, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

29. The method of claim 28, wherein Y and Y’ each independently is (C1-C6)alkyl, (C2- C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

30. The method of claim 29, wherein Y and Y’ each independently is (C1-C6)alkyl or (C2-C6)alkenyl, optionally substituted by one or more (C2-C3)alkynyl groups, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

31. The method of claim 30, wherein Y and Y’ each independently is (C1-C4)alkyl substituted with acetylenyl group

32. The method of claim 31, wherein Y and Y’ each is 2-propyn-1-yl.

33. The method of claim 24, wherein:

moiety form a 5-9-membered divalent heterocyclic group; and

(ii) Y and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, or cycloakenyl, optionally substituted by one or more groups each independently selected from (C1-C3)alkyl, (C2-C3)alkenyl, (C2-C3)alkynyl, and -O-(C1- C3)alkyl, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-, and wherein at least one of Y and Y’ is substituted with at least one acetylenyl group

)•

34. The method of claim 33, wherein:

- moiety form a 5-8-membered divalent heterocyclic group; and

Y and Y’ is substituted with at least one acetylenyl group

35. The method of claim 34, wherein:

(i) X is ethenylene, and together with the

- moiety form l /7-imidazol-3- ium-1,3-di-yl; and

Y and Y’ is substituted with at least one acetylenyl group

36. The method of claim 35, wherein Y and Y’ each independently is (C1-C4)alkyl substituted with acetylenyl group

37. The method of claim 36, wherein Y and Y’ each is 2-propyn-l-yl.

38. The method of any one of claims 24-37, wherein said base is an aqueous base.

39. The method of claim 38, wherein said aqueous base is hydroxide ions obtained by electrochemical reduction of an aqueous medium such as water (e.g., by applying voltage to said aqueous medium).

40. The method of claim 39, wherein said electrochemical reduction of said aqueous medium is performed in the presence of an electrolyte such as tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate (TEATFB), tetrabuthylammonium tetrafluoroborate, and tetrabutylammonium perchlorate.

41. The method of any one of claims 24-40, wherein said base is an inorganic or organic base such as KtBuO, NatBuO, NaHMDS, KHMDS, NaH, add KH.