Process for dual-layer coating of metal-containing material for corrosion protection

Abstract

The present invention relates to a process for dual-layer coating of a metal-containing material to thereby protect said material from corrosion; and to a metal-organic complex comprising a A-heterocyclic carbene (NHC) linked via the carbene to a metal atom, and via a nitrogen atom thereof, i.e., at least one of the nitrogen atoms of said A-heterocyclic carbene, to a crosslinked polymer network made of monomers polymerizable via thermal or radical polymerization.

Description

PROCESS FOR DUAL-LAYER COATING OF METAL-CONTAINING MATERIAL FOR CORROSION PROTECTION

[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 relates to a process for dual-layer coating a metal-containing material to thereby protect said material from corrosion; and to a metal-organic complex comprising a A-hctcrocyclic carbene (NHC) linked via the carbene to a metal atom, and via a nitrogen atom thereof to a polymer network, more specifically a polymer made of monomers polymerizable via thermal or radical polymerization.BACKGROUND ART

[0003] The widespread use of iron in industry and manufacturing, along with its high susceptibility to corrosion, makes it essential to develop effective and sustainable strategies for corrosion mitigation on iron surfaces (Thompson et al., 2007; Cole and Marney, 2012; Wasim et al., 2018; Du et al., 2023). One common approach involves the use of coatings to prevent the access of corrosive substances to the metal surface (Zhu et al., 2017; Kokalj, 2021).

[0004] Methods for iron surface coating for corrosion mitigation include using inorganic or organic monolayers, primarily based on thiols and diazonium salts (Ramachandran et al., 1996; Nozawa et al., 1997; Tsuji et al., 2000; Combellas et al., 2005; Liu et al., 2006; Shimura and Aramaki, 2006; Rajkumar and Sethuraman, 2014; Kokalj, 2022; Grandy et al., 2023). However, monolayers on metal films, especially on iron, are characterized by limited chemical and thermal stability and provide inadequate long-term protection against environmental factors. For example, thiol-based monolayers suffer from oxidation and degrade over time, especially under oxidative conditions, which limit their long-term protection efficiency (Mani et al., 2008; Schoenfisch and Pemberton, 1998). Diazonium salts, while initially effective, undergo hydrolysis and decomposition under acidic or basicconditions, compromising their protection functionality (Marshall et al., 2018; Piel et al., 2008).

[0005] To further restrict the access of corrosive substances to iron surfaces, thin polymer films have been grafted either by using polymers with reactive end groups or by directly growing polymer chains from a pre-functionalized surface (Nozawa and Aramaki, 1999; Richards et al., 2009; Lu et al., 2010). The effectiveness of polymeric coatings towards corrosion mitigation has been hindered by relatively poor adhesion and low surface density of the polymer on iron, leading to deteriorated stability under harsh conditions. Dual-layer coatings for improved corrosion mitigation have been prepared by attaching polymers to monolayers, mainly based on diazonium salt precursors that can be covalently attached to iron substrates. Nevertheless, the instability of such monolayers under environmental conditions deteriorates their adhesion strength and effectiveness as primers in dual-layer coatings.

[0006] The aforementioned limitations of current methods for iron coatings necessitate a new approach for corrosion mitigation.

[0007] The high surface density and covalent anchoring of A-hctcrocyclic carbene (NHC)- based self-assembled monolayers (SAMs) to coinage metals have led to their utilization in various applications (Wang et al., 2017), including the use of polymer-NHC as surface ligands (Wei et al., 2022; Nguyan et al., 2023). As shown, NHCs can bind to metal-oxide surfaces, and NHC deposition can mitigate copper oxidation (Berg et al., 2022). As further shown, NHC -based SAMs may be deposited on iron film (Amit et al., 2024); however, the utilization of NHC monolayers on iron for corrosion mitigation has not yet been demonstrated.SUMMARY OF INVENTION

[0008] It has now been found, in accordance with the present invention, that a self- assembled monolayer (SAM) of N-hctcrocyclic carbene (NHC) (Smith et al., 2019), electrodeposited on iron foil as a primer in a dual-layer coating, more specifically as a binder for a secondary, crosslinked polymer network coating, induces a highly stable dual-layer coating that effectively prevents corrosion formation with a protective efficiency of 99.6+0.2%, as determined by polarization measurements in 3.5 wt.% NaCl solution.Spectroscopic analysis identified the formation of a chemical interaction between the NHC monolayer and the polymer film. The strong anchoring of NHC to iron along with its chemical interaction with the polymer film induced high stability and durability of the dual- layer coating to effectively protect the coated iron from corrosion formation.

[0009] In one aspect, thus disclosed herein is a process for coating a surface of a metal- containing material with a polymeric layer to thereby protect said material from corrosion, said method comprising:(i) exposing said surface to either:(a) compounds each independently of formula II: in the presence of a base, or under applied voltageor heat treatment; or(b) compounds each independently being an adduct of formula 12: under heat treatment capable of deprotonating saidadduct and consequently releasing CO2therefrom, wherein:X is (C2-C4) alkylene or (C2-C4)alkenylene, which together with thegroup 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, (C2-C6)alkynyl, and -O-(C1-C6)alkyl, and / or fused with a carbocyclic or aromatic ring to form a bicyclic or polycyclic heterocyclic group; andY and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, 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-, thereby converting said compounds to carbene compounds each independently of formula II:which consequently binds or coordinates to a metal atom in said surface of said metal-containing material, to thereby form a monolayer consisting of compounds each independently of formula III: coating said material; and(ii) exposing the coated material thus obtained to monomers polymerizable via thermal or radical polymerization, optionally in the presence of a photo - initiator, followed by thermal or photo -polymerization of said monomers, to thereby form a crosslinked polymer composed of said monomers, that is linked to a nitrogen atom of at least one of the compounds of the formula III.

[0010] In certain embodiments exemplified herein, said process comprises exposing a surface of a metal-containing material to compounds each independently of the formula II, wherein X is ethenylene, and together with the group form imidazol-3-ium-1,3-diyl, optionally fused with benzene to form benzoimidazol-3-ium-1,3-diyl; and Y andY’ each independently is (C1-C4)alkyl, preferably wherein Y and Y’ each is methyl. In particular such embodiments, the exposure of said material to said compounds is carried out under applied voltage of, e.g., from about -0.9 volt to about 1.3 volt, to thereby initiate electrochemical reduction of water molecules that are present in the medium in which the reaction is conducted, and consequently form hydroxide ions acting as a base. Such electrochemical reduction may be carried out in the presence of any suitable electrolyte, such as TEATFB. The material coated with the compounds of the formula III thus obtained, is then exposed to monomers capable of undergoing radical polymerization, e.g., compounds comprising at least one acrylate group such as a BPA-EDA, optionally in the presence of a photo-initiator such as TPO, to thereby form a crosslinked polymer composed of said monomers, e.g., in the form of a nanolayer having a thickness of at least about 0.5 nm, that is linked to a nitrogen atom of at least one of the compounds of the formula III.

[0011] The process disclosed results in a dual-layer coating, consisting of a primer made of compounds each independently of the formula III, and a secondary crosslinked polymer network made of monomers polymerizable via thermal or radical polymerization, that is linked to at least one of the compounds of the formula III via a nitrogen atom thereof, i.e., a nitrogen atom of the A-heterocyclic carbene. In certain embodiments, said at least one compound of the formula III is linked to such a crosslinked polymer network via one of said nitrogen atoms, and in other embodiments, said at least one compound of the formula III is linked to such a crosslinked polymer network via each one of said nitrogen atoms.

[0012] In another aspect, disclosed herein is a metal-containing material having a surface coated with a polymeric layer, obtained by the process defined above.

[0013] In a further aspect, disclosed herein is a metal-organic complex of formula V:M is 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), and platinum (Pt);X is (C2-C4) alkylene or (C2-C4)alkenylene, which together with thegroup 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, (C2-C6)alkynyl, and -O-(C1-C6)alkyl, and / or fused with a carbocyclic or aromatic ring to form a bicyclic or polycyclic heterocyclic group; andZ and Z’ each independently is either:(a) (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, 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-; or(b) a group of the formula -(CH2)2-C(O)-O-R, wherein R represents a remainder of an optionally crosslinked polymer composed of monomers polymerizable via thermal or radical polymerization, provided that at least one of Z and Z’, i.e., Z, Z’, or each one of Z and Z’, is a group of the formula -(CH2)2-C(O)-O-R.

[0014] In certain embodiments, disclosed herein is a metal-organic complex as defined above, wherein said metal atom is contained within a metal-containing material comprising said metal atom or an oxide thereof, e.g., a film having a thickness in the range of from about 1 nm to about 200 nm, a bulk material, or a conductive- or semi-conductive material, such as silicon (Si), tin (Sn), titanium (Ti), aluminum (Al), and graphite, comprising metal atoms dispersed thereon.

[0015] Thus, and as shown herein, disclosed herein is a metal-containing material, such as a film having a thickness in the range of from about 1 nm to about 200 nm, a bulk material, or a conductive- or semi-conductive material comprising metal atoms dispersed thereon, which is coated with a monolayer made of an N-heterocyclic carbene (NHC) and with a crosslinked polymer film, as primary and secondary coating layers, respectively, providing highly effective protection that prevents corrosion.BRIEF DESCRIPTION OF DRAWINGS

[0016] Fig. 1 shows FIB-SEM analysis of polymer-coated iron foils before (upper panels) and after (lower panels) their immersion in NaCl solution and exposure to potentiodynamic polarization measurements. The iron foils were coated with a crosslinked polymer network (CPN) with (left panels) and without (right panels) benzNHC monolayer as a binder. A protective layer of iridium (Ir) was deposited on the polymer prior to FIB extraction.

[0017] Fig. 2 shows potentiodynamic polarization curves of a bare iron foil, CPN-coated iron foil, benzNHC-coated iron foil and an iron foil that was coated with a dual-layer (CPN on benzNHC) coating. All samples were immersed in 3.5 wt% NaCl solution at 25°C.

[0018] Figs. 3A-3B show Nls XPS (3 A) and SERS (3B) signals of iron foil coated with benzNHC monolayer. Measurements were acquired before and after exposure of the supported benzNHC monolayer to TPO and methyl acrylate and their illumination ((i) and (ii) spectra, respectively).

[0019] Fig. 4 shows SERS signals of Fe foil that was coated with benzNHC monolayer (lower (i) spectrum), after exposure to TPO and illumination (middle (ii) spectrum) and exposure to TPO, methyl acrylate and illumination (upper (iii) spectrum). The SERS spectra was interpreted and assigned by using previously reported data (Table 2) (Crudden et al., 2016; Chowdhury et al., 2024). The benzNHC molecules on Fe film revealed vibrational signatures that are assigned to both ‘Flat’ and ‘Vertical’ configurations, based on previously published normal mode analysis (see Table SI). 8-9 Following expo-sure to TPO and illumination, the vibrational signatures that were correlated to flat-lying geometry were mostly unchanged while the vibrational signatures that were correlated to standing configurations were quenched, which can be correlated either to rearrangement of themolecules into a preferred flat-lying position or to higher reactivity of the standing molecules.

[0020] Fig. 5 shows LDI signals of benzNHC on Au film that was coated with benzNHC monolayer before (lower (i) spectrum), and after exposure to TPO and methyl acrylate (upper (ii) spectrum).DETAILED DESCRIPTION

[0021] In one aspect, the present invention relates to a process for coating a surface of a metal-containing material with a polymeric layer to thereby protect said material from corrosion, said method comprising:(i) exposing said surface to either:(b) compounds each independently of the formula II: in the presence of a base, or under applied voltageor heat treatment; or(c) compounds each independently being an adduct of the formula 12:under heat treatment capable of deprotonating said adduct and consequently releasing CO2therefrom, wherein:X is (C2-C4) alkylene or (C2-C4)alkenylene, which together with thegroup 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, (C2-C6)alkynyl, and -O-(C1-C6)alkyl, and / orfused with a carbocyclic or aromatic ring to form a bicyclic or polycyclic heterocyclic group; andY and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, 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-, thereby converting said compounds to carbene compounds each independently of the formula II:which consequently binds or coordinates to a metal atom in said surface of said metal-containing material, to thereby form a monolayer consisting of compounds each independently of the formula III: coating said surface of said metal-containing material; and(ii) exposing the coated material thus obtained to monomers polymerizable via thermal or radical polymerization, optionally in the presence of a photo- initiator, followed by thermal or photo-polymerization of said monomers, to thereby form a crosslinked polymer composed of said monomers, that is linked to a nitrogen atom of at least one of the compounds of the formula III.

[0022] The term “surface” as used herein with respect to a metal -containing material refers to the outer surface of said metal-containing material, i.e., to the overall surface of said material exposed to the environment.

[0023] 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, zr-propyl, isopropyl, «-butyl, sec -butyl, isobutyl, tert-butyl, «-pentyl, isopentyl, neopentyl, 2,2-dimethylpropyl, n-hcxyl, 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-.

[0024] 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-.

[0025] 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 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.

[0026] 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.

[0027] The term “cycloalkyl” means a univalent mono- or bicyclic 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-C12)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-.

[0028] 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-C8)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-.

[0029] 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, dihydrotriazole, tetrahydro triazole, 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 atomfrom any of the ring atoms. Said univalent group may be substituted, at any position thereof, with one or more groups each independently selected from (C1-C6)alkyl, (C1-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1-C6)alkyl.

[0030] The term “divalent heterocyclic group” generally refers to a divalent group derived from a heterocyclic ring by removal of two hydrogen atoms from any of the ring atoms, but more particularly each from a different ring atom. The divalent heterocyclic group specifically referred to herein is a 5-7-membered positively charged nitrogen atom- containing monocyclic ring, formed by the group linked via each one of thenitrogen atoms to a different carbon atom of group X ((C2-C4)alkylene, preferably linear (C2- C4)alkylene, or (C2-C4)alkenylene, preferably linear (C2-C4) alkenylene). Said divalent heterocyclic group may be substituted, at any one of its carbon atoms except for the one bridging the two nitrogen atoms, with one or more groups each independently selected from (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, and -O-(C1-C6)alkyl, and / or fused with a carbocyclic or aromatic, but preferably aromatic, ring to form a [positively charged nitrogen atom-containing] bicyclic or polycyclic divalent heterocyclic group. As would be clear from formulae II and 12, the compounds of said formulae are in fact based on said divalent heterocyclic group linked, via the nitrogen atoms thereof, to the groups Y and Y’ .

[0031] 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.

[0032] 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.

[0033] In certain embodiments, disclosed herein is a process as defined above, wherein X is (C2-C4) alkylene or (C2-C4)alkenylene, and together with the group form a5-7-membered divalent heterocyclic group, optionally fused with an aromatic ring to form a bicyclic or polycyclic heterocyclic group. In particular such embodiments, X is (C2- C4)alkenylene such as ethenylene, propenylene, and butenylene, and together with thegroup form the divalent heterocyclic group of formula 1 (imidazol-3-ium-1,3-diyl), formula 2 (4H -3λ2-pyrimidin-l-ium-1,3-diyl), and formula 3 or 4 (4,5-dihydro-1,3λ2-diazepin-l-ium-1,3-diyl or 4,7-dihydro-1,3λ2-diazepin-l-ium-1,3-diyl), respectively, which is optionally fused with benzene to form the bicyclic heterocyclic group of formula 1-fb (benzoimidazol-3-ium-1,3-diyl, exemplified herein), formula 2-fb (3H-3λ2-quinazolin- l-ium-1,3-diyl), and formula 3-fb or 4fb (4,5-dihydro-3H -benzo[d][1,3]diazepin -l-ium-1,3- diyl or 2,5-dihydro-lH -benzo[e][1,3]diazepine-4-ium-2,4-diyl), respectively (Table 1). More particular such embodiments are those wherein X is ethenylene, and together with thegroup form imidazol-3-ium-1,3-diyl, optionally fused with benzene to form benzoimidazol-3 -ium- 1 ,3 -diyl.

[0034] In certain embodiments, disclosed herein is a process as defined above, 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-. In particular such embodiments, Y and Y’ each independently is (C1-C6)alkyl or (C2- C6)alkenyl, optionally substituted as defined above, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-. In yet more particular such embodiments, Y and Y’ each independently is (C1-C4)alkyl or (C2-C4)alkenyl, preferably (C1-C4)alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec- butyl, isobutyl, and tert-butyl. According to the present invention, preferred embodiments are those wherein Y and Y’ are identical, e.g., wherein Y and Y’ each is methyl, ethyl, n- propyl, isopropyl, n-butyl, sec -butyl, isobutyl, or tert-butyl.-N — CH=N-Table 1. Divalent heterocyclic groups formed by group X and the1I group, specifically referred to herein

[0035] In certain embodiments, disclosed herein is a process as defined above, wherein X is (C2-C4) alkylene or (C2-C4)alkenylene, and together with the group form a5-7-membered divalent heterocyclic group, optionally fused with an aromatic ring to form a bicyclic or polycyclic heterocyclic group; and 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-. In particular such embodiments, X is (C2- C4)alkenylene such as ethenylene, propenylene, and butenylene, which together with the group form the divalent heterocyclic group of formula 1 (imidazol-3-ium-1,3-diyl), formula 2 (4H -3λ2-pyrimidin-l-ium-1,3-diyl), and formula 3 or 4 (4,5-dihydro-1,3λ2-diazepin-l-ium-1,3-diyl or 4,7-dihydro-1,3λ2-diazepin-l-ium-1,3-diyl), respectively, which is optionally fused with benzene to form the bicyclic heterocyclic group of formula 1-fb (benzoimidazol-3-ium- 1,3-diyl), formula 2-fb (3H -3X2-quinazolin-l-ium-1,3-diyl), and formula 3-fb or 4fb (4,5-dihydro-3H -benzo[d][1,3]diazepin-l-ium-1,3-diyl or 2,5-dihydro- lH -benzo[e][1,3]diazepine-4-ium-2,4-diyl), respectively (Table 1); and Y and Y’ each independently is (C1-C6)alkyl or (C1-C6)alkenyl, optionally substituted as defined above, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-. In more particular such embodiments, X is ethenylene, and together with the group form imidazol-3-ium-1,3-diyl, optionally fused withbenzene to form benzoimidazol-3-ium- 1,3-diyl; and Y and Y’ each independently is (C1- C4)alkyl or (C2-C4)alkenyl, preferably (C1-C4)alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec -butyl, isobutyl, and tert-butyl. In still more particular embodiments, Y and Y’ are identical, e.g., methyl.

[0036] The process disclosed herein is aimed at coating a surface of a metal-containing material, i.e., a material containing a metal atom or an oxide thereof, with a polymeric layer to thereby protect said material from corrosion, and starts by exposing said surface to compounds of formula II or 12, as defined above, under conditions which enable converting said compounds to carbene compounds of formula II as defined above, wherein each one of said carbene compounds consequently binds or coordinates to a metal atom in the surface of said metal-containing material, forming first a monolayer consisting of compounds each independently of formula III, coating said surface.

[0037] In certain embodiments, the process disclosed, according to any one of the embodiments above, starts by exposing said surface to compounds each independently of the formula II, in the presence of a base. In certain particular such embodiments, said base is an aqueous base, such as hydroxide ions obtained by electrochemical reduction of an aqueous medium such as water, e.g., by applying voltage to said aqueous medium. Such electrochemical reduction may be carried out in the presence of any suitable electrolyte, e.g., tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate (TEATFB), tetrabuthylammonium tetrafluoroborate, and tetrabutylammonium perchlorate. In otherparticular such embodiments, said base is an inorganic or organic base. Examples of such bases include, without being limited to, the organic bases potassium tert-butoxide (KtBuO), sodium tert-butoxide (NatBuO), sodium bis(trimethylsilyl) amide (NaHMDS), and potassium bis(trimethylsilyl)amide (KHMDS); and the inorganic bases sodium hydride (NaH), and potassium hydride (KH).

[0038] In other embodiments, the process disclosed, according to any one of the embodiments above, starts by exposing said surface to compounds each independently of the formula II, under applied voltage. In particular such embodiments, said surface is exposed to said compounds under a voltage of from about -0.9 volt to about 1.3 volt. The application of voltage initiates electrochemical reduction of water molecules that are present in the medium in which the reaction is conducted, and results in the formation of hydroxide ions acting as a base.

[0039] In yet other embodiments, the process disclosed, according to any one of the embodiments above, starts by exposing said surface to compounds each independently of the formula II, under heat treatment. In particular such embodiments, said surface is exposed to said compounds at a temperature of up to 100°C, such as from about 40°C, 50°C, or 60°C to about 80°C, 90°C, or 100°C.

[0040] In further embodiments, the process disclosed, according to any one of the embodiments above, starts by exposing said surface to compounds (adducts) each independently of the formula 12, under heat treatment capable of deprotonating said adduct and consequently releasing CO2therefrom. In particular such embodiments, said heat treatment is carried out at a temperature equal to or higher than about 40°C or 50°C, such as in the range of from about 60°C to about 100°C, e.g., at about 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C.

[0041] According to the method disclosed, once a monolayer consisting of compounds of formula III and coating the surface of said metal-containing material is formed, said coated surface is exposed to monomers polymerizable via thermal or radical polymerization, i.e., capable of undergoing thermal or radical polymerization, optionally in the presence of a photo-initiator, followed by thermal or photo -polymerization of said monomers, to thereby form a crosslinked polymer composed of said monomers, wherein said crosslinked polymer is linked to a nitrogen atom of at least one of the compounds of the formula III.

[0042] In certain embodiments, disclosed herein is a process as defined in any one of the embodiments above, wherein the surface coated with said monolayer is exposed to monomers capable of undergoing thermal polymerization, optionally in the presence of a photo-initiator. Such monomers include, without limiting, compounds each having at least one polymerizable functional group facilitating polymerization through the formation of free radicals at elevated temperatures, such as vinyl group, acrylate group, methacrylate group, and olefinic bond.

[0043] In other embodiments, disclosed herein is a process as defined in any one of the embodiments above, wherein the surface coated with said monolayer is exposed to monomers capable of undergoing radical polymerization, optionally in the presence of a photo-initiator. Such monomers include, without being limited to, compounds each having at least one functional group facilitating polymerization through the formation of free radicals under UV light, such as styrene, vinyl acetate, vinyl chloride, acrylonitrile, vinylidene chloride, ethylene, propylene, vinyl toluene, methyl methacrylate, ethyl acrylate, and derivatives thereof. In particular embodiments, said monomers polymerizable via radical polymerization are compounds comprising at least one acrylate group. Examples of compounds comprising at least one acrylate group include, without being limited to, a bisphenol A ethoxylate diacrylate (BPA-EDA) of formula IV:wherein n each independently is an integer of at least one, preferably 1-6, more preferably 1, 2 or 3.

[0044] The term “photo-initiator” as used herein refers to a molecule capable of absorbing photons upon irradiation with UV-Vis light, i.e., with a wavelength in the range of 100-800 nm, and consequently forming reactive species out of the excited state, which initiate consecutive reaction. Examples of photo-initiators include, without limiting, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO).

[0045] The method of the present invention is aimed at coating a surface of a metal- containing material with a polymeric layer to thereby protect said surface from corrosion, i.e., from oxidation, e.g., due to exposure to external environment. In certain embodiments, disclosed herein is a process as defined in any one of the embodiments above, wherein said metal-containing material comprises a metal atom selected from an alkali metal atom such as Li, Na and K; an alkali-earth metal atom such as Mg; and a transition metal atom such as Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, W, Re, Os, Ir, and Pt. In other embodiments, said metal-containing material comprises a metal oxide, e.g., an oxide of a metal as defined hereinabove. In particular embodiments, said metal-containing material comprises Cu or Fe, or an oxide thereof.

[0046] In certain embodiments, disclosed herein is a process as defined in any one of the embodiments above, wherein the metal-containing material protected against corrosion is a film having a thickness of up to 0.5, 1.0, 1.5, or 2.0 mm, e.g., in the range of from about 1 nm to about 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 650, 700, 750, or 800 nm; a bulk material; or a conductive- or semi-conductive material comprising metal atoms dispersed thereon. In some particular embodiments, said material comprises a metal- containing article exposed to external environment, such as pipeline, railway, car shielding, and ship. In other particular embodiments, said material composes 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), titanium (Ti), aluminum (Al), and graphite.

[0047] In other embodiments, disclosed herein is a process as defined in any one of the embodiments above, wherein the polymeric layer formed on- and coating said metal- containing material is a nanolayer having a thickness of at least about 0.5 nm, e.g., in the range of from about 0.5 or 1.0 nm to about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 nm.

[0048] In another aspect, the present invention relates to a polymer-coated material comprising a metal-containing material coated with a polymeric layer, obtained by the process disclosed herein, according to any one of the embodiments above.

[0049] In a further aspect, the present invention provides a metal-organic complex of the formula V :wherein:M is a metal atom selected from an alkali metal atom such as Li, Na and K; an alkali-earth metal atom such as Mg; and a transition metal atom such as Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, W, Re, Os, Ir, and Pt;X is (C2-C4) alkylene or (C2-C4)alkenylene, which together with thegroup 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, (C2-C6)alkynyl, and -O-(C1-C6)alkyl, and / or fused with a carbocyclic or aromatic ring to form a bicyclic or polycyclic heterocyclic group; andZ and Z’ each independently is either:(a) (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, 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-; or(b) a group of the formula -(CH2)2-C(O)-O-R, wherein R represents a remainder of an optionally crosslinked polymer composed of monomers polymerizable via thermal or radical polymerization, provided that at least one of Z and Z’ is a group of the formula -(CH2)2-C(O)-O-R.

[0050] In certain embodiments, disclosed herein is a metal-organic complex as defined above, wherein X is (C2-C4) alkylene or (C2-C4)alkenylene, and together with thegroup form a 5-7-membered divalent heterocyclic group, optionally fused with an aromatic ring to form a bicyclic or polycyclic heterocyclic group. In particular such embodiments, X is (C2-C4) alkenylene such as ethenylene, propenylene, and butenylene, and together with the group form the divalent heterocyclic group of formula 1(imidazol-3-ium-1,3-diyl), formula 2 (4H -3λ2-pyrimidin-l-ium-1,3-diyl), and formula 3 or 4 (4,5-dihydro-1,3λ2-diazepin-l-ium-1,3-diyl or 4,7-dihydro-1,3λ2-diazepin-l-ium-1,3- diyl), respectively, which is optionally fused with benzene to form the bicyclic heterocyclic group of formula 1-fb (benzoimidazol-3-ium-1,3-diyl, exemplified herein), formula 2-fb (3H -3λ2-quinazolin-l-ium-1,3-diyl), and formula 3-fb or 4fb (4,5-dihydro-3H -benzo[d] [ 1, 3 ] diazepin- 1-ium- 1,3 -diyl or 2,5-dihydro-1H-benzo[e][1,3]diazepine-4-ium-2,4-diyl), respectively (Table 1). More particular such embodiments are those wherein X is ethenylene, and together with thegroup form imidazol-3-ium-1,3-diyl, optionally fused with benzene to form benzoimidazol-3-ium-1,3-diyl.

[0051] In certain embodiments, disclosed herein is a metal-organic complex as defined above, wherein Z and Z’ each independently is either (a) (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-; or (b) a group of the formula -(CH2)2-C(O)-O-R. In particular such embodiments, Z and Z’ each independently is either (a) (C1-C6)alkyl or (C2-C6)alkenyl, optionally substituted as defined above, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-; or (b) a group of the formula -(CH2)2-C(O)-O-R. In yet more particular such embodiments, Z and Z’ each independently is either (a) (C1-C4)alkyl or (C2-C4)alkenyl, preferably (C1-C4)alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec -butyl, isobutyl, and tert-butyl; or (b) a group of the formula -(CH2)2-C(O)-O-R.

[0052] In certain embodiments, disclosed herein is a metal-organic complex as defined above, wherein X is (C2-C4) alkylene or (C2-C4)alkenylene, and together with thegroup form a 5-7-membered divalent heterocyclic group, optionally fused with an aromatic ring to form a bicyclic or polycyclic heterocyclic group; and Z and Z’ each independently is either (a) (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-; or (b) a group of the formula -(CH2)2-C(O)-O-R. In particular such embodiments, X is (C2- C4)alkenylene such as ethenylene, propenylene, and butenylene, which together with the group form the divalent heterocyclic group of formula 1 (imidazol-3-ium-1,3-diyl), formula 2 (4H -3λ2-pyrimidin-l-ium-1,3-diyl), and formula 3 or 4 (4,5-dihydro-1,3λ2-diazepin-l-ium-1,3-diyl or 4,7-dihydro- 1,3λ2-diazepin-l-ium-1,3-diyl), respectively, which is optionally fused with benzene to form the bicyclic heterocyclic group of formula 1-fb (benzoimidazol-3-ium-1,3-diyl), formula 2-fb (3H -3λ2-quinazolin-l-ium-1,3-diyl), and formula 3-fb or 4fb (4,5-dihydro-3H -benzo[d][1,3]diazepin-l-ium-1,3-diyl or 2,5-dihydro- 1H -benzo[e][1,3]diazepine-4-ium-2,4-diyl), respectively (Table 1); and Z and Z’ each independently is either (a) (C1-C6)alkyl or (C2-C6)alkenyl, optionally substituted as defined above, and further optionally interrupted by one or more groups each independently selected from -O-, -NH-, -CO-NH-, and -NH-CO-; or (b) a group of the formula -(CH2)2-C(O)-O-R. In more particular such embodiments, X is ethenylene, and together with thegroup form imidazol-3-ium-1,3-diyl, optionally fused with benzene to form benzoimidazol- 3-ium-1,3-diyl; and Z and Z’ each independently is either (a) (C1-C4)alkyl or (C2-C4)alkenyl, preferably (C1-C4)alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec -butyl, isobutyl, and tert-butyl; or (b) a group of the formula -(CH2)2-C(O)-O-R. In still more particular embodiments, Z and Z’ each independently is either methyl or a group of the formula -(CH2)2-C(O)-O-R.

[0053] In certain embodiments, disclosed herein is a metal-organic complex as defined in any one of the embodiments above, wherein said monomers polymerizable via thermalpolymerization are compounds as defined above, each independently having at least one polymerizable functional group facilitating polymerization through the formation of free radicals at elevated temperatures; or said monomers polymerizable via radical polymerization are compounds as defined above, each independently having at least one functional group facilitating polymerization through the formation of free radicals under UV light. In particular embodiments, said monomers polymerizable via radical polymerization are compounds comprising at least one acrylate group, e.g., a BPA-EDA of the formula IV as defined above.

[0054] In certain embodiments, disclosed herein is a metal-organic complex as defined in any one of the embodiments above, wherein said metal atom is Cu or Fe. In particular metal- organic complexes as disclosed herein, the metal atom is contained within a metal-containing material comprising said metal atom or an oxide thereof, e.g., a film having a thickness in the range of from about 1 nm to about 200 nm, a bulk material, or a conductive- or semi- conductive material comprising metal atoms dispersed thereon.

[0055] Unless otherwise indicated, all numbers expressing, e.g., temperature or thickness, 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.

[0056] The invention will now be illustrated by the following non-limiting Examples.EXAMPLESStudy 1. Self-assembled monolayer of N-heterocyclic carbene as a primer in a dual- layer coating for corrosion protection on ironMaterials and Methods

[0057] Fe foils (0.025 mm thick, purity of 99.5%) were purchased (Goodfellow) and stored in a vacuum chamber. 1,3-Dimethyl-lH-benzimidazolium iodide (DMBI) was purchased from Sigma-Aldrich. Bisphenol A ethoxylate diacrylate (BPA-EDA, Scheme 1) and methyl acrylate were purchased from Sigma-Aldrich, and diphenyl(2,4,6- trimethylbenzoyl) -phosphine oxide (TPO) was purchased from IGM resins.Scheme 1. Bisphenol A ethoxylate diacrylate (BPA-EDA) (n is 1-3)

[0058] Electrochemical (EC) deposition was conducted in a conventional three-electrode cell, with the Fe foil as the working electrode, Ag / Ag+ (CH instruments) as a non-aqueous quasi-reference electrode, and a platinum wire as a counter electrode. 5 mM of DMBI in acetonitrile along with 0.1 M of tetraethylammonium tetrafluoroborate (TEATFB) as a supporting electrolyte and 5 mM triple-distilled water at room temperature were used in the electrodeposition. A voltage of -1.3 V vs. Ag / Ag+ was applied for five minutes. After this step, the iron foil was rinsed with three cycles of acetonitrile and isopropyl alcohol, then dried under N2 flow.

[0059] Tafel measurements were performed in a dedicated electrochemical cell, in which the iron foil was used as a working electrode with an area of 0.63 cm2, a carbon electrode as a counter electrode, and an aqueous Ag reference electrode was used with a 3.5 wt% NaCl solution, prepared using purified water (18.2 MQxcm). Before the measurements, the corrosion cell was allowed to rest for 2 hours to achieve equilibrium. The scan rate for the Tafel measurements was set at 10 mV / sec with a potential range of ±200 mV. Corrosion current values were calculated using the EC-LAB software.

[0060] X-ray photoelectron spectroscopy (XPS) measurements were performed using Kratos AXIS Su-pra spectrometer (Kratos Analytical) with Al Ka monochromatic X-ray source (1486.6 eV). The XPS spectra were acquired with a takeoff angle of 90° (normal to analyzer), pass energy of 20 eV and step size of 0.1 eV, vacuum condition in the chamber was 2x1 O'9Torr. The binding energies were calibrated according to the Cis XPS peak position (B.E. = 285.0 eV). Data were collected and analyzed by using ESCApe processing program (Kratos Analytical) and Casa XPS.

[0061] Laser desorption ionization mass-spectrometry (LDLMS) measurements were performed by following a recently published procedure. Experiments were conducted using a Bruker autoflex MALDI-TOF instrument equipped with a frequency smartbeam-II solidstate laser (repetition rate up to 2 kHz) for excitation. Using conductive carbon tape, Au films were immobilized on a MALDI steel sample target. At 80% laser strength, a minimum of 2000 laser shots were collected for each spectrum. Mass spectra were acquired using either a reflectron or a linear accelerator in the positive ion mode. FlexControl was used for data acquisition, and flexAnalysis was used for data analysis.

[0062] Surface Enhanced Raman Spectroscopy (SERS) measurements were conducted following a published procedure. Raman measurements were performed using InVia Confocal Raman Mi-croscope (Renishaw) equipped with a 785 nm laser (300 mW). The samples were exposed to 10% laser intensity for 10 seconds. Three drops (30 pL) of citrate- capped gold nanoparticles were drop-cast onto the NHC-coated Fe film and dried under a high vacuum for 3h.

[0063] The chronoamperometry experiment was carried out using a modified literature approach. BenzNHC was electrodeposited on the Fe foil, and a SERS experiment was performed before applying chronoamperometry. All measurements were carried out in IM NaCICU solution in water with a typical three-electrode cell setup consisting of benzNHC deposited on Fe foil as a working electrode, a platinum wire counter electrode, and an Ag / AgCl (3M KC1) reference electrode. In a two-voltage step for 30 seconds each, a total of three chronoamperometry pulses were applied, initially at 0 V and followed by relative potentials.

[0064] General procedure for polymerization . A mixture of BPA-EDA monomers (468.0 mg, 1 eq, 1 mmol) and ~0.1 wt% of TPO (0.45 mg, 0.0013 mmol) was placed in a 10 mL glass vial and heated to 40°C for 30 minutes while being covered with aluminum foil. To create a uniform coating, the solution was drop-casted onto the NHC-coated Fe foil and spin- coated (5000 rpm, 40 seconds). The samples were exposed to UV light (405 nm) under a nitrogen environment for 15 minutes. The coated samples were then rinsed with three cycles of triple distilled water, ethanol, and isopropanol and then dried under N2 flow for 5 minutes.

[0065] Methyl acrylate was used as a monomer homolog in the XPS, SERS, and EDI-MS experiments. In these experiments, methyl acrylate (1 mmol) was mixed with 0.1 wt% of TPO at room temperature and drop-casted on a clean Fe foil. The Fe foil was directly exposed to UV light under N2 atmosphere for 15 minutes. The samples were then rinsed withthree cycles of triple distilled water, ethanol, and isopropanol and then dried under N2 flow for 5 minutes.Results and Discussion

[0066] In the present study, NHC -based SAM was employed as a chemical binder between an iron surface and a polymer film, demonstrating its effectiveness as an adhesion promoter in a dual-layer coating. The integration of NHC monolayer and polymer film, as primary and secondary coating layers, respectively, provided a highly effective dual-layer protection that prevented corrosion formation on iron under harsh conditions.

[0067] 1,3-dimethylbenzimidazolylidene (benzNHC) was self-assembled on an iron foil by electrodeposition (Amit et al., 2020; Kang et al., 2023), using 0.1 M of TEATFB as a supporting electrolyte and 5 mM of triple-distilled water (Scheme 2). In this process, deprotonation of DMBI into benzNHC was induced via its exposure to hydroxide ions, which were formed near an iron electrode by electrochemical water reduction reaction (Amit et al., 2020; Schotten et al., 2021).

[0068] In the second step of the coating process, the benzNHC -coated iron foil was spin- coated with BPA-EDA monomers mixed with TPO. A crosslinked polymer network (CPN) was prepared by photopolymerization of the BPA-EDA (Richards et al., 2009). In this process, TPO functions as a photo -initiator for a radical polymerization reaction, leading to the formation of a three-dimensional (3D) crosslinked network. Spectroscopic analysis of the benzNHC monolayer properties and its interaction with the CPN will be discussed in detail below.Scheme 2. Dual-layer coating formation on iron foil

[0069] The evaluation of anti-corrosive efficacy typically employs potentiodynamic polarization measurements in a saline environment, with 3.5 wt.% NaCl solution being a common choice (Zhang et al., 2022). This simulates a harsh corrosive environment wherethe anodic reaction involves iron oxidation to iron ions, and the cathodic reaction includes the reduction of water and oxygen (Sherif et al., 2010). The presence of Cl’ ions further exacerbates the corrosion process by strongly adsorbing to the metal surface and accelerating the formation of corrosive intermediates (Sherif et al., 2010; Darwish et al., 1973; Song et al., 2017). In the current work, we analyzed the effectiveness of the benzNHC-CPN dual- layer coating in a saline environment to ensure a direct and meaningful evaluation of its corrosion mitigation effectiveness.

[0070] Polymer-coated iron samples were extracted using a focused ion beam (FIB) to identify the polymer film thickness and its stability following exposure to a saline environment. Iridium was deposited on the polymer film to protect it during the milling process. Scanning electron microscope (SEM) imaging identified a film thickness of 11.8 and 6.6 pm for the CPN fdm with and without the benzNHC monolayer, respectively (Fig. 1, upper and right panels, respectively). It is hypothesized that the high surface density of benzNHCs, which function as active sites for on-surface polymerization, as will be discussed below, enabled the formation of a thicker film on the metal surface, in comparison to the film that was prepared on the bare iron foil.

[0071] Potentiodynamic polarization measurements were employed to evaluate the anti- corrosive efficacy of the developed dual-layer coatings. Fig. 2 presents Tafel plots of four distinct samples: bare iron foil, CPN- and benzNHC-coated iron foil, and a sample with a dual-layer coating that includes benzNHC and CPN, as a primer and a secondary coating, respectively. The potentiodynamic polarization measurements were conducted in a 3.5 wt% NaCl solution maintained at 25°C, simulating a saline corrosive environment.

[0072] Fig. 2 shows that iron foil with benzNHC monolayer coating exhibits a corrosion current density (icon-) that is similar to that of the bare iron (icorr= 0.35±0.03 and 0.32±0.03 pA / cm2for the bare and benzNHC coated iron foil, respectively). The measured icon- values for bare iron are comparable to previously published data in NaCl solutions (Liu etal., 2021). BenzNHC monolayer coatings slightly reduced the corrosion potential (Ecorr= -644 mV) compared to the bare iron foil (Ecorr= -701 mV) indicating that the coating increased the threshold at which corrosion is initiated. CPN fdms were less effective in corrosion protection than the benzNHC monolayer, with Ecorr= -706 mV, which is similar to the bare iron foils and demonstrates the weak adhesion of CPN films to iron.

[0073] Conversely, iron foils that were coated with a dual-layer of benzNHC and CPN demonstrated a substantial decrease in both anodic and cathodic currents, indicative of a more effective barrier against both cathodic and anodic reactions. This is quantitatively confirmed by a significant reduction of more than two orders of magnitude in corrosion currents (icorr= 0.0012±0.0003 pA / cm2) in comparison to the bare iron foil. In addition, the Tafel plots exhibit a notable shift toward more noble corrosion potentials (Ecorr= -226 mV) for the dual-layer coated sample.

[0074] The protective efficiency, Pi, of the coating was determined from the polarization curves by:where icorand i°cordenote the average corrosion current densities in the presence and absence of the coating, respectively (Aramaki, 1999). The value of Pi for the dual-layer coated iron foil was 99.6±0.2%. These results suggest that the CPN film that was polymerized on the benzNHC monolayer, forms a robust protective barrier, substantially limiting the metal’s exposure to corrosion. Furthermore, prolonged immersion tests demonstrated that the dual- layer coating induced low corrosion currents over an extended time duration of up to 24 h (data not shown). These results emphasize the enhanced efficacy and stability of the dual- layer coating, ensuring durable and reliable corrosion resistance over time. Changes in the electrolyte composition, such as varying the types of anions or adjusting the pH, have the potential to further improve the coating protection efficiency in other, more specific environments.

[0075] FIB-SEM measurements of the polymer-coated samples were conducted following their exposure to potentiodynamic polarization measurements. SEM measurements identified a polymer thickness of 6.7 pm for the dual-coated iron foil (Fig. 1, lower left panel), while a detachment of the polymer film was detected for the sample in which the polymer was directly deposited on the bare iron foil (Fig. 1, lower right panel). Exposure of the dual-layer coating to NaCl solution led to film shrinkage, correlated to ion-polymer interactions (Perera et al., 2021). The obtained results reveal the crucial role of benzNHC monolayer as a binder of the polymer film to the iron foil. NHC monolayer was found essential for the formation of a polymer film that is strongly anchored to the iron foil.

[0076] Spectroscopic measurements were conducted to identify the chemical properties of benzNHC and its interaction with the polymer film (Fig. 3). Nls X-ray photoelectron spectroscopy (XPS) measurements were conducted to assess the chemisorption and self- assembly of benzNHC on Fe foil (Fig. 3A, (i)). Nls XPS peak was identified at 399.7 eV, and the XPS signal was constructed of two Gaussians. The dominant Gaussian was centered at 399.6 eV, correlated to chemisorbed benzNHC, and was similar in its position to NHCs that were chemisorbed on Fe and Cu films (Amit et al., 2024). A minor Gaussian was centered at 401.0 eV and correlated to a nitrogen background signature that originated from nitrogen contamination in the iron foil. It cannot be excluded that some contribution to the high binding energy signal is due to the presence of a pyrrolic species (Jansen and Van Bekkum, 1995), commonly observed after partial decomposition of the imidazole ring. Fe2p XPS analysis showed an overall increase in the XPS signal correlated to the self-cleaning nature of NHC deposition, without noticeable changes in the oxidation state of Fe (data not shown).

[0077] Surface enhanced Raman spectroscopy (SERS) measurements of benzNHC on iron were conducted (Fig. 3B, (i)) following a recently developed protocol for NHC monolayer probing on surfaces. A detailed analysis of Raman mode assignments is included in Table 2. Diagnostic Raman signals were detected at 1370 cm-1, correlated to CC stretch, CN stretch, CH bending, and indicative of a vertical configuration of benzNHC, based on previously reported normal mode analysis. Bands at 795, 1010, and 1183 cm-1, correlated to aromatic CH wagging, ring -breathing, and in-plane aromatic CH bending, respectively (Table 2), and corroborate the population of flat-lying molecules, as recently identified by experimental and theoretical normal modes analysis. The overall Raman pattern was similar to that of benzNHC on Au surfaces (data not shown) thus indicating that most of the benzNHCs were chemisorbed on iron without fragmentation or chemical deformation. SERS measurements further revealed the electrochemical stability of benzNHC on the Fe surface in a voltage window of -0.3 to 0.5 V versus Ag / AgCl. (data not shown).

[0078] Spectroscopic measurements were conducted to elucidate the mechanism by which benzNHC functions as a chemical binder to the CPN film. In these experiments, methyl- acrylate was used as a monomer homolog in order to study the interaction between NHC and BPA-EDA, without masking the NHC signal due to polymer film growth.

[0079] Nls XPS signal was acquired following exposure of the chemisorbed benzNHC to methyl acrylate (with 0.1% TPO and following illumination). A single dominant feature was detected at 399.7 Ev (Fig. 3A, (ii)). The decrease in the overall amplitude of the Nls XPS signal was correlated to the presence of methyl acrylate, supported by the overall increase in the Cis XPS signal (data not shown). A more noticeable decrease was identified in the high binding energy component in the Nls XPS feature, in comparison to the lower binding energy component. This provides another indication that the high binding energy feature originates from deeper layers of nitrogen contamination, which are located in the iron foil.Table 2. Raman mode assignments

[0080] The exposure to methyl acrylate led to dominant changes in the SERS spectra (Fig. 3B, (ii), see Table 2 for vibrational assignments). Significantly, peaks at 840 and 1580 cm- \ correlated to C-O-C vibration and C-C stretch, respectively, along with a broad shoulderat 1730 cm-1, correlated to C=O vibration, were probed and assigned to the chemical signature of methyl ester. SERS signal at 997 cm-1along with the lack of a signal at 1373 cm-1, which is indicative of a vertical orientation, can potentially indicate a favorable flat- lying benzNHC signature. SERS measurements uncovered changes in the structure and orientation of benzNHC already after exposure to TPO and illumination, prior to exposure to methyl-acrylate, demonstrating the role of TPO in inducing chemical interaction between the surface-anchored NHC and methyl acrylate (Fig. 4) (Crudden et al., 2016). The spectroscopic measurements also demonstrate the stability of surface-anchored benzNHC, with no indication for desorption during the photo-induced reaction.

[0081] The similarity in the SERS spectra of benzNHC on Fe and Au foils, both before and after exposure to TPO and methyl acrylate (Fig. 3B), indicate that similar chemical changes in the benzNHC monolayer are induced on both surfaces. Based on this spectroscopic similarity, laser desorption ionization mass-spectrometry (LDI-MS) measurements were conducted on Au fdm to identify the chemical reactivity of benzNHC after exposure to TPO and methyl acrylate under illumination (Fig. 5). Following benzNHC deposition, the LDI-MS signal was detected at 147.1 m z-1, and correlated to (benzNHC -H)+. This signature was not probed after exposure to methyl acrylate and TPO, while a new signature was probed at 219.1 m z-1and was correlated to the formation of methyl-ester tethered benzNHC. These results can indicate that methyl ester tethered benzNHC via N- methyl bond activation.

[0082] In order to further assess the chemical role of the imidazole ring in polymer film stabilization, we have tested the efficiency of NHC (dimethyl-imidazolylidene) SAM as a primer in dual-layer coating for corrosion mitigation. The chemical difference between the benzNHC and NHC is in the lack of the benzyl ring. This comparative analysis therefore provides information about the role of the benzyl ring in surface-anchoring of NHC and its functionality as a chemical binder for the polymer film.

[0083] Tafel measurements identified that NHC SAM can function as well as a primer coating to mitigate corrosion formation on iron foil (data not shown), though at lower effectiveness than that of benzNHC SAM. These results demonstrate that surface anchoring and chemical coordination of the polymer film with the SAM are initiated via interactionwith the imidazolylidene ring, while the role of the benzylic group is to stabilize the surface anchored NHCs by intermolecular interactions.

[0084] To conclude, in the present work, we show that a benzNHC monolayer can be self- assembled on iron foil and functions as a binder for a secondary coating of a cross-linked polymer network. The dual-layer coating, constructed of benzNHC monolayer and CPN film as a primer and a secondary coating, respectively, functions as an effective blocking layer and shows high efficiency in mitigating corrosion formation on iron foils.REFERENCESAmit, E.; Dery, L.; Dery, S.; Kim, S.; Roy, A.; Hu, Q.; Gutkin, V.; Eisenberg, H.; Stein, T.; Mandler, D.; Dean Toste, F.; Gross, E., Nat. Commun. 2020, 11, 5714Amit, E.; Mondal, R.; Berg, I.; Nairoukh, Z.; Gross, E., Langmuir 2024, 40, 10374- 10383Aramaki, K., Corros. Sci. 1999, 41, 1715-1730Berg, I.; Amit, E.; Hale, L.; Toste, F.D.; Gross, E., Angew. Chem. Int. Ed. 2022, 61, e202201093Chowdhury, S.; Hu, G.; Jensen, I.M.; Santos, A.V.; Jenkins, D.M.; Jensen, L.; Camden, J.P., The Journal of Physical Chemistry C. 2024, 128, 13550-13557Combellas, C.; Delamar, M.; Kanoufi, F.; Pinson, J.; Podvorica, F.I., Chem. Mater. 2005, 17, 3968-3975Cole, I.S.; Marney, D., Corros. Sci. 2012, 56, 5-16Crudden, C.M.; Horton, J.H.; Narouz, M.R.; Li, Z.J.; Smith, C.A.; Munro, K.; Baddeley, C.J.; Larrea, C.R.; Drevniok, B.; Thanabalasingam, B.; McLean, A.B.; Zenkina, O.V.; Ebralidze, LI.; She, Z.; Kraatz, H.B.; Mosey, N.J.; Saunders, L.N.; Yagi, A., Nat. Commun. 2016, 7, 12654Darwish, N.A.; Hilbert, F.; Lorenz, W.J.; Rosswag, H., Electrochim. Acta 1973, 18, 421-425Du, P.; Liu, D.X.; Chen, X.; Xie, H.W.; Qu, X.; Wang, D.H.; Yin, H.Y., Energy Storage Mater. 2023, 57, 371-399Fernandez, V.; Fairley, N.; Baltrusaitis, J., Applied Surface Science. 2021, 538, 148031-148036Godbold, P.; Johnson, G.; Obi, A.D.; Brown, R.; Hwang, S.; Gilliard, R.J.; Zhang, S., Journal of the American Chemical Society. 2021, 143, 2644-2648Grandy, L.; Chaniolleau, M.; Lacasse, R.; Mauzeroll, J., J. Electrochem. Soc. 2023, 170, 051502Jansen, R.J.J.; Van Bekkum, H., Carbon 1995, 33, 1021-1027Kang, H.; Jang, J.; Kong, G.D.; Jung, S.; Ohto, T.; Yoon, H.J., J. Mater. Chem. A 2023, 11, 16233-16242Kokalj, A., Corros. Sci. 2021, 193, 109650Kokalj, A., Corros. Sci. 2022, 196, 109939Li, L.; Ma, P.; Hussain, S.; Jia, L.; Lin, D.; Yin, X.; Lin, Y.; Cheng, Z.; Wang, L., Sustainable Energy & Fuels. 2019, 3, 1749-1756Liu, X.Y.; Chen, S.H.; Ma, H.Y.; Liu, G.Z.; Shen, L.X., Appl. Surf. Sci. 2006, 253, 814-820Liu, R.; Cui, Y.; Liu, L.; Wang, F., Acta. Mater. 2021, 203, 116467Lu, G.; Li, Y.M.; Lu, C.H.; Xu, Z.Z., Colloid Poly m. Sci. 2010, 288, 1445-1455Mani, G.; Johnson, D.M.; Marton, D.; Dougherty, V.L.; Feldman, M.D.; Patel, D.;Ayon, A.A.; Agrawal, C.M., Langmuir 2008, 24, 6774-6784Marshall, N.; Rodriguez, A.; Crittenden, S., RSCAdv. 2018, 8, 6690-6698Nozawa, K.; Nishihara, H.; Aramaki, K., Corros. Sci. 1997, 39, 1625-1639Nozawa, K.; Aramaki, K., Corros. Sci. 1999, 41, 57-73Perera, R.M.; Gupta, S.; Li, T.Y.; Bleuel, M.; Hong, K.L.; Schneider, G.J., Soft Matter 2021, 17, 4452-4463Rajkumar, G.; Sethuraman, M.G., Thin Solid Films 2014, 562, 32-36Ramachandran, S.; Tsai, B.L.; Blanco, M.; Chen, H.; Tang, Y.C.; Goddard, W.A., Eangmuir 1996, 12, 6419-6428Richards, J.J.; Danquah, M.K.; Kalakkunnath, S.; Kalika, D.S.; Kusuma, V.A.; Matteucci, S.T.; Freeman, B.D., Chem. Eng. Sci. 2009, 64, 4707-4718Schoenfisch, M.H.; Pemberton, J.E., J. Am. Chem. Soc. 1998, 120, 4502-4513Schotten, C.; Bourne, R.A.; Kapur, N.; Nguyen, B.N.; Willans, C.E., Adv. Synth. Catal. 2021, 363, 3189-3200Sethuraman, A.R.; Stencel, J.M.; Rubel, A.M.; Cavin, B.; Hubbard, C.R., Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 1994, 12, 443-451Shimura, T.; Aramaki, L., Corros. Sci. 2006, 48, 3784-3801Sherif, E.M.; Erasmus, R.M.; Comins, J.D., Electrochim. Acta 2010, 55, 3657-3663Smith, C.A.; Narouz, M.R.; Lummis, P.A.; Singh, I.; Nazemi, A.; Li, C.H.; Crudden, C.M., Chem. Rev. 2019, 119, 4986-5056Song, Y.; Jiang, G.; Chen, Y.; Zhao, P.; Tian, Y„ Sci Rep 2017, 7, 6865Thompson, N.G.; Yunovich, M.; Dunmire, D., Corros. Rev. 2007, 25, 247-262Tsuji, N.; Nozawa, K.; Aramaki, K., Corros. Sci. 2000, 42, 1523-1538Viel, P.; Le, X.T.; Hue, V.; Bar, J.; Benedetto, A.; Le Goff, A.; Filoramo, A.; Alamarguy, D.; Noel, S.; Baraton, L.; Palacin, S., J. Mater. Chem. 2008, 18, 5913-5920Wang, G.; Ruhling, A.; Amirjalayer, S.; Knor, M.; Ernst, J.B.; Richter, C.; Gao, H.J.; Timmer, A.; Gao, H.Y.; Doltsinis, N.L.; Glorius, F.; Fuchs, H., Nat. Chem. 2017, 9, 152- 156Wasim, M.; Shoaib, S.; Mubarak, N.M.; Inamuddin; Asiri, A.M., Environ. Chem. Lett. 2018, 16, 861-879Wei, Z.; Mullaj, K.; Price, A.; Wei, K.; Luo, Q.; Thanneeru, S.; Sun, S.; He, J., ACS Appl.Mater. Interfaces 2022, 14, 55227-55237Zhang, D.; Srinivasan, J.; Locke, J.S., Corrosion 2022, 78, 1229-1249Zhu, Y.K.;Free, M.L.; Woollam,R.; Durnie, W., Prog. Mater. Sci. 2017, 90, 159-223

Claims

CLAIMS1. A process for coating a surface of a metal-containing material with a polymeric layer to thereby protect said material from corrosion, said method comprising:(i) exposing said surface to either:(a) compounds each independently of formula II:, in the presence of a base, or under applied voltage or heat treatment; or(b) compounds each independently being an adduct of formula 12:, under heat treatment capable of deprotonating said adduct and consequently releasing CO2therefrom, wherein:X is (C2-C4) alkylene or (C2-C4)alkenylene, which together with thegroup 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, (C2-C6)alkynyl, and -O-(C1-C6)alkyl, and / or fused with a carbocyclic or aromatic ring to form a bicyclic or polycyclic heterocyclic group; andY and Y’ each independently is (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, 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 moregroups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-, thereby converting said compounds to carbene compounds each independently of formula II:which consequently binds or coordinates to a metal atom in said surface of said metal-containing material, to thereby form a monolayer consisting of compounds each independently of formula III: coating said material; and(ii) exposing the coated material thus obtained to monomers polymerizable via thermal or radical polymerization, optionally in the presence of a photo - initiator, followed by thermal or photo -polymerization of said monomers, to thereby form a crosslinked polymer composed of said monomers, that is linked to a nitrogen atom of at least one of the compounds of the formula III.

2. The process of claim 1, wherein X is (C2-C4)alkylene or (C2-C4)alkenylene, and together with the group form a 5-7-membered divalent heterocyclic group,optionally fused with an aromatic ring to form a bicyclic or polycyclic heterocyclic group.

3. The process of claim 2, wherein X is ethenylene, and together with thegroup form imidazol-3-ium-1,3-diyl, optionally fused with benzene to form benzoimidazol- 3-ium-1,3-diyl.

4. The process 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-.

5. The process of claim 4, wherein Y and Y’ each independently is (C1-C6)alkyl or (C2-C6)alkenyl.

6. The process of claim 5, wherein Y and Y’ each independently is (C1-C4)alkyl.

7. The process of claim 6, wherein Y and Y’ each is methyl.

8. The process of claim 1, wherein:X is (C2-C4) alkylene or (C2-C4)alkenylene, and together with thegroup form a 5-7-membered divalent heterocyclic group, optionally fused with an aromatic ring to form a bicyclic or polycyclic heterocyclic group; andY 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-.

9. The process of claim 8, wherein X is (C2-C4)alkenylene; and Y and Y’ each independently is (C1-C6)alkyl or (C2-C6)alkenyl.

10. The process of claim 9, wherein:X is ethenylene, and together with the group form imidazol-3-ium-1 ,3-diyl, optionally fused with benzene to form benzoimidazol-3-ium-1,3-diyl; andY and Y’ each independently is (C1-C4)alkyl.

11. The process of claim 10, wherein Y and Y’ each is methyl.

12. The process of any one of claims 1-11, comprising exposing said surface to compounds each independently of the formula II, in the presence of an aqueous base.

13. The process of claim 12, wherein said aqueous base is hydroxide ions obtained by electrochemical reduction of an aqueous medium such as water.

14. The process of claim 13, wherein said electrochemical reduction is carried out by applying voltage to said aqueous medium.

15. The process of claim 13 or 14, wherein said electrochemical reduction of said aqueous medium is performed in the presence of an electrolyte such as tetramethylammonium tetrafluoroborate, tetraethylammonium tetrafluoroborate (TEATFB), tetrabutylammonium tetrafluoroborate, and tetrabutylammonium perchlorate.

16. The process of any one of claims 1-11, comprising exposing said surface to compounds each independently of the formula II, in the presence of an inorganic or organic base such as KtBuO, NatBuO, NaHMDS, KHMDS, NaH, and KH.

17. The process of any one of claims 1-11, comprising exposing said surface to compounds each independently of the formula II, under applied voltage of -0.9 to 1.3 volt, or at a temperature of up to 100°C such as from about 60°C to about 100°C.

18. The process of any one of claims 1-11, comprising exposing said surface to compounds each independently of the formula 12, at a temperature in the range of from about 60°C to about 100°C.

19. The process of any one of claims 1-18, wherein: said monomers polymerizable via thermal polymerization are compounds each independently having at least one polymerizable functional group facilitating polymerization through the formation of free radicals at elevated temperatures, such as vinyl group, acrylate group, methacrylate group, and olefinic bond; or said monomers polymerizable via radical polymerization are compounds each independently having at least one functional group facilitating polymerization through the formation of free radicals under UV light, such as styrene, vinyl acetate, vinyl chloride,acrylonitrile, vinylidene chloride, ethylene, propylene, vinyl toluene, methyl methacrylate, ethyl acrylate, and derivatives thereof.

20. The process of claim 19, wherein the coated material obtained in step (i) is exposed in step (ii) to monomers polymerizable via radical polymerization, in the presence of a photo - initiator, followed by photo -polymerization of said monomers.

21. The process of claim 20, wherein said monomers polymerizable via radical polymerization are compounds comprising at least one acrylate group.

22. The process of claim 21, wherein said compounds comprising at least one acrylate group are each independently a bisphenol A ethoxylate diacrylate (BPA-EDA) of formula IV:wherein n each independently is an integer of at least one, preferably 1- 6, more preferably 1-3.

23. The process of any one of claims 20-22, wherein said photo-initiator is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), or phenyl bis(2,4,6- trimethylbenzoyl)phosphine oxide (BAPO).

24. The process of any one of claims 1-23, wherein said metal-containing material comprises a metal atom selected from an alkali metal atom such as Li, Na and K; an alkali- earth metal atom such as Mg; and a transition metal atom such as Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, W, Re, Os, Ir, and Pt, or an oxide thereof.

25. The process of claim 24, wherein the metal-containing material comprises Cu or Fe, or an oxide thereof.

26. The process of claim 24 or 25, wherein said metal-containing material is a film having a thickness in the range of from about 1 nm to about 200 nm, a bulk material, or a conductive- or semi-conductive material comprising metal atoms dispersed thereon.

27. The process of any one of claims 1-26, wherein said polymeric layer is a nanolayer having a thickness of at least about 0.5 nm, such as in the range of from about 0.5 nm to about 100 nm, or from about 1 nm to about 5 nm.

28. A metal-organic complex of formula V:wherein:M is a metal atom selected from an alkali metal atom such as Li, Na and K; an alkali- earth metal atom such as Mg; and a transition metal atom such as Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, W, Re, Os, Ir, and Pt;X is (C2-C4) alkylene or (C2-C4)alkenylene, which together with thegroup 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, (C2-C6)alkynyl, and -O-(C1-C6)alkyl, and / or fused with a carbocyclic or aromatic ring to form a bicyclic or polycyclic heterocyclic group; andZ and Z’ each independently is either:(a) (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, cycloalkyl, cycloakenyl, heterocycles, 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 oneor more groups each independently selected from -O-, -CO-, -NH-, -CO-NH-, -NH-CO-, and -S-; or(b) a group of the formula -(CH2)2-C(O)-O-R, wherein R represents a remainder of an optionally crosslinked polymer composed of monomers polymerizable via thermal or radical polymerization, provided that at least one of Z and Z’ is a group of the formula -(CH2)2-C(O)-O-R.

29. The complex of claim 28, wherein X is (C2-C4) alkylene or (C2-C4)alkenylene, and together with the group form a 5-7-membered divalent heterocyclic group,optionally fused with an aromatic ring to form a bicyclic or polycyclic heterocyclic group.

30. The complex of claim 29, wherein X is ethenylene, and together with thegroup form imidazol-3-ium-1,3-diyl, optionally fused with benzene to form benzoimidazol-3 -ium- 1 ,3 -diyl.

31. The complex of claim 28, wherein Z and Z’ each independently is either (a) (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-; or (b) a group of the formula -(CH2)2-C(O)-O-R.

32. The complex of claim 31, wherein Z and Z’ each independently is either (a) (C1- C6)alkyl or (C2-C6) alkenyl; or (b) a group of the formula -(CH2)2-C(O)-O-R.

33. The complex of claim 32, wherein Z and Z’ each independently is either (C1-C4)alkyl or a group of the formula -(CH2)2-C(O)-O-R.

34. The complex of claim 33, wherein Z and Z’ each independently is either methyl or a group of the formula -(CH2)2-C(O)-O-R.

35. The complex of claim 28, whereinX is (C2-C4) alkylene or (C2-C4)alkenylene, and together with thegroup form a 5-7-membered divalent heterocyclic group, optionally fused with an aromatic ring to form a bicyclic or polycyclic heterocyclic group; andZ and Z’ each independently is either (a) (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-; or (b) a group of the formula -(CH2)2-C(O)-O-R.

36. The complex of claim 35, wherein X is (C2-C4) alkenylene; and Z and Z’ each independently is either (a) (C1-C6)alkyl or (C2-C6) alkenyl; or (b) a group of the formula - (CH2)2-C(O)-O-R.

37. The complex of claim 36, whereinX is ethenylene, and together with thegroup form imidazol-3-ium-1 ,3-diyl, optionally fused with benzene to form benzoimidazol-3-ium-1,3-diyl; andZ and Z’ each independently is either (C1-C4)alkyl or a group of the formula -(CH2)2- C(O)-O-R.

38. The complex of claim 37, wherein Z and Z’ each is either methyl or a group of the formula -(CH2)2-C(O)-O-R.

39. The complex of any one of claims 28-38, wherein: said monomers polymerizable via thermal polymerization are compounds each independently having at least one polymerizable functional group facilitating polymerization through the formation of free radicals at elevated temperatures, such as vinyl group, acrylate group, methacrylate group, and olefinic bond; or said monomers polymerizable via radical polymerization are compounds each independently having at least one functional group facilitating polymerization through the formation of free radicals under UV light, such as styrene, vinyl acetate, vinyl chloride,acrylonitrile, vinylidene chloride, ethylene, propylene, vinyl toluene, methyl methacrylate, ethyl acrylate, and derivatives thereof.

40. The complex of claim 39, wherein said monomers polymerizable via radical polymerization are compounds comprising at least one acrylate group.

41. The complex of claim 40, wherein said compounds comprising at least one acrylate group are each independently a bisphenol A ethoxylate diacrylate (BPA-EDA) of formula IV:wherein n each independently is an integer of at least one, preferably 1- 6, more preferably 1-3.

42. The complex of any one of claims 28-41, wherein said metal atom is Cu or Fe.

43. The complex of any one of claims 28-42, wherein said metal atom is contained within a metal-containing material comprising said metal atom or an oxide thereof.

44. The complex of claim 43, wherein said metal-containing material is a film having a thickness in the range of from about 1 nm to about 200 nm, a bulk material, or a conductive- or semi-conductive material comprising metal atoms dispersed thereon.

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