Gold nanoparticles

ES 2 222 348 T3

DESCRIPTION

Gold nanoparticles.

The present invention relates to a novel gold material which has advantageous characteristics in compositions comprising such material. The uses and methods of the preparation of such material are also developed.

Liquid gold compositions have been known in the art and are used for decoration and gilding substrates for a long time. Traditional liquid gold compositions contain gold sulfo-resinates in combination with natural resinous materials (by Boudnikoff, Comp. Rend., 196, 1898 (1933) and by Chemnitius, J. Prakt. Chem., 117, 245 (1927) ). Gold sulfo-resinates are prepared by reacting a gold chloride solution with a sulfurized terpene. These are then diluted with natural oils such as lavender, rosemary, and pine oils. Asphalt and rosin resins are added to thicken the compositions so that they are suitable for decoration, gilding and printing applications. In addition, small amounts of salts or resinates of metals such as rhodium, bismuth, chromium etc., are also added as fluxes to improve the shine of the gold in the cupellation product and also improve the adhesion of the applied gold. to the substrate after cupellation. In the preparation of other compositions, various gold mercaptides have been used. For example, US-A-2490399 describes the use of the gold mercaptides of cyclic terpenes but does not provide any structure for the resulting mercaptide. Also, the gold mercaptide prepared from thio-borneol has been described in the Joural of the society of the chemical Industry, Japan, 38, supplement 617B (1935) by Nakatsuchi although this reference does not mention the possibility of using such compounds in decoration or gilding compositions. According to US-A-3163665, gold thiolates derived from cyclic terpenes have the disadvantages of requiring relatively high cupellation temperatures, thereby limiting their use on substrates such as glass, ceramics, etc. And consequently the use of non-terpenoid secondary gold mercaptides is recommended.

Similarly, US-A-3245809 claims and describes the use of a liquid gold decoration composition comprising a gold substituted aryl mercaptide wherein sulfur is directly attached to the aryl nucleus which is already substituted by an alkyl group. in solution in an organic vehicle and a gold flux. Specific aryl mercaptides developed include gold p-tert-butylphenyl mercaptide prepared from p-tert-butylbenzenethiol and aurous chloride.

Due to environmental awareness and potential legislative activity to remove hazardous organic material from these gold ink-based organic materials a series of water-diluted gold (I) thiolates have been produced as described in EP-A 0514 073. Additionally, EP 0668 265 describes the preparation and use of water-soluble monooro dithiolates (I) for the production of decorations on refined surfaces that produce highly glossy pore-free and mark-free decorations.

In the US patent. 5,639,901 water soluble gold materials contain a gold content of 60-90% by weight and an atomic ratio of gold to sulfur of no greater than 0.71 to 4: 1 which are described and which are produced by a process pathway. Specific using a monooro (I) dimercaptocarbixilic acid compound. Specific synthetic details involve adding acid to a solution of the gold material at pH-2 or lower and then isolating the resulting material. There are problems with the use of these compounds, however for example the water solubility of this gold material prevents its use in traditional water displaceable decal technology. Gold materials which do not dissolve in water are therefore required. This is the problem of the present invention that is mentioned to solve.

Nanoparticles have been known for decades. In the past five years, the synthesis of nanoparticles with increased stability has been achieved (Schmidt and A. Lehnert, Angew. Chem. Int. Ed. Engl. 1989, 28, 780). For example, thiol-derived gold nanoparticles have been prepared by a two-phase reaction (Brust, M Walker, D. Bethell, DJ Shiffrin and C. Kiely, J. Chem. Soc. Common Chem., 1994, 801) . These particles range from 1-10 nm and are made of a crystalline metal core protected by a layer of ligands. This protective layer prevents agglomeration through electrostatic and steric barriers and thus imparts greater stability to these nanoparticles compared to those previously generated. They can also be isolated as dark solid materials and then redissolved in a wide range of solvents that depend on the stabilizers that form the protective monolayer.

Metal nanoparticles possess a characteristic plasmon resonance absorption (Creigton in Surface Enhanced Raman Scattering Eds. RK Chang, TE Furtak), Plenum, New York 1982, 315-337). A characteristic plasmon resonance absorption can also be observed for stabilized nanoparticles. This phenomenon of the surface plasmon is a collective excitation of free electrons at the interface between a metallic nucleus and the insulating layer of the ligands. In the case of small nanoparticles, the resonance absorption of the plasmon can often be very weak as reported by Brust et al. (Bethell, M. Brust, DJ Scriffin and C. Kiely, J. electroanalytical Chem., 1996, 409, 137-143).

The present invention provides a water insoluble gold material specifically designated for decorative uses comprising gold nanoparticles stabilized by thiol ligands.

ES 2 222 348 T3

In this material the gold forms a central metallic nucleus which is stabilized by the thiol groups. This new group of gold materials possess a number of advantages over previously described gold compounds.

- Most of the known gold (I) thiolate compounds used for decorative purposes have poor solubility in common organic solvents. This poor solubility prevents the use of most of the known gold (I) thiolate compounds (without further modification) in traditional organic liquid gold formulations. A limited number of sterically bound compounds which show high organic solubility such as AuS-tC₁₂H₂₅, Aus-tC₉H₁₉, AuSCHMeC₆H₅, AuSC₆H₄-p-CMe₃They have been patented (US Patent 889,912, US Patent 3,163,665, US Patent 3,245,809) for use in liquid gold formulations. The gold nanoparticles of the present invention have been found to show a significant increase in solubility over their molecular gold thiolate analogs. This increase in solubility means that the formulator has a significantly increased selection of the thiol that can be used to stabilize the gold nanoparticles in the compositions. The formulator also has a significant increase in the selection of the suitable solvents for the dissolution of the gold nanoparticles, varying from the traditional non-polar organic solvents through the more polar ones, and importantly, less the solvents of the ether type of Hazardous glycol, which are increasingly being used in the formulations industry.

- They can be used in the production of decals: the phenomenon of bleeding and purple discoloration is significantly reduced when the gold composition of the present invention is used compared to its molecular gold thiolate analog.

- The nanoparticles of the present invention form a stable metallic film when applied to a surface of a substrate followed by heating from as low as 100 ° C to as high as 1200 ° C. In addition, metal films can be produced without heating, by conducting an appropriate post-treatment on a solvent cast film. Examples of post-treatments can include acid washes and irradiation with UV light. This makes a gold composition of the present invention particularly suitable for use on unrefined substrates such as plastic and paper.

In a first aspect of the present invention, it provides the use of a gold material for decorative purposes characterized in that the material comprises the gold nanoparticles stabilized by the thiol groups described by the general formula shown below, this compound has a plasmon frequency between 480 and 600 nm:

HSR

Where:

R = is a C3-C60 alkyl, aryl, benzyl or an alicyclic or heterocyclic group which may be substituted or unsubstituted, branched or unbranched.

In a preferred embodiment of the invention R is a C3-C30 alkyl, aryl, benzyl group or an alicyclic or heterocyclic group which may be branched or unbranched, substituted or unsubstituted. Substitution groups are preferably carboxylate groups, esters, thioethers, ethers, amines, hydroxyamines and / or amides.

Where R is an alkyl group, then preferably the substituted groups are any of one or more of the following:

-C (O) -OR "where R" is C alkyl₁- C₁₅ which can be branched or unbranched,

-COR "or CSR" where R "is an alkyl of C₁- C₁₅ which can be branched or unbranched,

-C-NR'R "where R 'and / or R" = Ho is an alkyl of C₁- C₁₅ which can be branched or unbranched,

-C (O) -N-R'R "where R 'and / or R" = H or is C alkyl₁- C₁₅ which can be branched or unbranched,

- the aryl group

- the -SH group.

In an alternative embodiment, R is an aryl. Preferably the aryl group is benzene, which may be substituted at any one or more positions around the ring structure or may be unsubstituted. Substituents can be but are not limited to C-alkyl₁- C₁₅, aryl, benzyl, alicyclic or heterocyclic groups which can be branched or unbranched. Where the substituents are the alkyl groups of C₁ - C₁₅ these may be substituted as described herein for the case where R is an alkyl group.

In a preferred embodiment R is a benzyl group in which the aromatic moiety can be substituted at

ES 2 222 348 T3 any of one or more positions around the o-ring structure may be unsubstituted. Substituents may be, but are not limited to, C1-C15 alkyl, aryl, benzyl groups, alicyclic or heterocyclic groups which may be branched or unbranched. Wherein the substituents are C₁ - C₁₅ they may be substituted as described herein for the case where R is an alkyl group. Alternatively or in addition to the benzyl carbon it may be branched or unbranched, unsubstituted or substituted as described herein for the case where R is alkyl.

In a further embodiment R is nitrogen, phosphorus, sulfur, or oxygen containing the heterocyclic group in which the thio group is attached to a carbon group within the heterocyclic ring structure.

Suitable thiol groups for use in preparing the nanoparticles used in the present invention include but are not limited to:

HSCe H₅, HSC6H₄-p-CMe₃, IISCI bo-CMc., HSCeH₃2-CMe₃-4-CMe₃, HSC6H₃-2CH₃-5-CMe₃, HSCeH₄-2-CH₃4-CMe₃, HSCeH4-o-CH3, HSCeH-oC₂H₅, HSCe ^ -p-CH, HSCeH-pC₂H₅, HSCeH4-o-C3H₇, HSCeH-p-C3H₇, HSCeH4-o-OCH3, HSCeH4-p-OCH3, HSCeH4-p-OH, HSCe ^ -p-NHCOC ^, HSC6H3-5-CH₃, HS-pinenyl, HSCH2 CO2C8H17, HSCH2CO2CH3, HSCH2CO2C2H5, HSCH2CO2C4H₉, HSCHMeCO2CH3, HSCHMeCO2C2H₅, HSCMe2 CH₂NH₂, HSC₂N₂S-SH, HSC₆H₁₁, HSC_1stH₇, HSCH₂C₆H₅, HSCHMeC₆H₅, HSCH₂C₆H₂-2-CH₃-4-CH₃-6-CH₃, HSC₆H4-o-CO2Me, HSC12H25, HSC₉H₁₉HS (CH2)₉SH, HSC6H4-2-SH, HSC6H4-3-SH.

The nanoparticles defined in the present invention are specifically designated for decorative uses. They can be applied alone to the surface of the substrate, in powder or liquid form. Alternatively they can be applied to the surface of the substrate in the form of a preparation comprising them.

In a further aspect, the present invention provides a gold material suitable for decorative purposes which is described by the general formula as described herein and is:

HSC6H4 - pCMe3

Where H is hydrogen, S is sulfur, C is carbon, Me is methyl.

In another aspect, the present invention provides a gold material suitable for decorative purposes which is described by the general formula described herein and is:

HS pinanil

In another aspect, the present invention provides a gold material suitable for decorative purposes, which is described by the general formula herein and is:

HS (CH2) 11CH3

In another aspect, the present invention provides a gold material suitable for decorative purposes, which is described by the general formula herein and is:

HSCH (Me) CÜ2CH2CH3

Therefore, in a further aspect, the present invention provides a composition comprising the gold material as described herein and at least one solvent.

Typically a composition of the present invention comprises from 0.01% to 50% by weight of gold. The selection of suitable solvents will be dependent on the chemical composition of the thiol ligand selected to stabilize the gold nanoparticles. Properties such as solvent viscosity, evaporation rate and surface tension will also need to be considered, depending on the manner in which the composition is to be applied to the substrate. Suitable solvents include but are not limited to aldehydes, cohols, ketones, aliphatic hydrocarbons, aromatic hydrocarbons, alkyl acetates, glycol ethers, terpenes, natural oils, and waxes.

More specifically, these may include one or more of the following: methyl ethyl ketone, cyclohexanone, isophorone, ethyl acetate, ethyl lactate, butyl lactate, amyl acetate, cyclohexanol, propylene glycol butyl ether, propylene glycol phenyl ether, dipropylene glycol dimethyl ether, dipropylene glycol methyl ether, propylene glycol methyl ether, propylene glycol methyl ether, propylene acetate methyl ether, toluene, xylene, terpenes such as pinene, dipentene oxide, natural oils, such as lavender, rosemary, lemon balm, fenchone oil, cyclohexylethanol, trimethylcyclohexanone and alkyldimethoxy benzene.

Furthermore, the addition of the non-polymeric solids, for example camphor, tert-butyl cyclohexanone, cyclohexanedi

ES 2 222 348 T3 methanol, isomenthol may be beneficial to the composition, as they act as solvents for the gold nanoparticles during cupellation procedures.

The composition may further comprise minor amounts of metal additives. These are small amounts of the metal salts, compounds or resinates which are present in the composition to improve the adhesion of the gold metallic film to the substrate in the cupellation through the formation of the metal oxides. Careful selection of the minor amounts of metal additives in the composition depends on the substrate used, which makes it possible to achieve good chemical and abrasion resistance.

They are also used to influence the refining color of the gold film. Suitable minor amounts of metal additives include but are not limited to the salts, compounds or resinates of antimony, bismuth, boron, cerium, chromium, cobalt, copper, iridium, rhodium, silicon, silver, tin, titanium, Vanadium, Palladium, Platinum, Zirconium, Selenium and Indium. The amount of the metal additives in minor amounts that are added to the composition is suitably in the range of about 0.01 to 10% by weight, preferably about 0.05 to 5.0% by weight. The percentage is the total amount of the minor amounts of the metal additives in the present invention.

The composition may additionally comprise at least one polymer or mixture of polymers. The function of such polymers is to alter the viscosity and viscoelastic nature of the composition such that the composition can be applied to the substrate. An additional function of the polymer is to provide raw material strength to the applied composition, prior to heat treatment to produce the metallic film. An additional function may be to protect the gold nanoparticles from attack by organic solvents when the gold-containing film is overprinted with commercially available coatings as part of the decal production process. With careful selection of the polymer or mixture of polymers, bleeding and purple discoloration that can be observed in the purification of conventional gold inks suitable for decals is significantly reduced or eliminated.

One skilled in the art will appreciate that it is the particular combination of the polymer with the gold material that is crucial. For example Scripset 540 resin and stabilized pt-butylthiophenol (HSC₆H₄-pCMe₃) produce particularly favorable results.

Examples of the polymers which can be used include, poly (acrylates), poly (methacrylates), polycarbonates, cellulose derivatives, poly (styrene-co-maleic anhydride) polymers both partially esterified and non-esterified, poly (vinylpyrrolidone ), poly (styrenes), poly (ketones), poly (vinyl alcohols), poly (vinyl acetate), poly (vinyl butyral), poly (esters), polyurethanes.

In addition, materials derived from rosin such as hydrogenated rosins, rosin dimers, maleate rosin, and rosin esters, and their sulfide derivatives, can additionally be used and can be combined with the above polymers.

Additional materials which can be added to the compositions are surfactants such as polysiloxane based wetting agents; viscosity modifiers, such as hydrogenated castor oils, binding agents, such as micas and talcs; and precious metal pigments, colorants, fluxes, powders and particles.

In a further aspect of the present invention, there is provided a method for the production of the gold material as described herein, comprising the steps of:

- The transfer of an aqueous gold source into the organic layer using the phase transfer agent.

- Mix the gold source with the thiol groups and then,

- Reduce the resulting mixture to produce the stabilized nanoparticles.

A standard method has been developed by the present inventors, which solve most of the problems of the method previously known in the art. Additionally, it provides some surprising advantages over previously used methods. A detailed description of the procedure is detailed in Example 1. Nanoparticles are typically characterized by a 78.2 ± 1.0% assay but this can be increased or decreased by varying the reaction conditions. Factors influencing the particle pore test include variation in molar ranges, temperatures, addition rates, concentration, and reaction time.

The method of the present invention is a modification of a method described by Brust, M. Walker, D Bethell, DJ Shiffrin and C. Kiely, J. Chem. Soc. Chem. Común., 1994, 801, which is found which has the following problems:

- On a large scale basis, the literature method causes foam which is very difficult to control.

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- On a large scale basis the same method causes a large increase in temperature, which is also difficult to control.

Both of these problems prevent the use of this method for large-scale preparations of the nanoparticles. The inventors of the present invention, however, have found if one of the steps is reversed: such that it is the mixture of organic phase for example AuCl₄ / ammonium salt / thiol that is added to the reducing agent, then surprisingly the problems of the prior art are solved.

Preferably, the phase transfer reagent is an ammonium salt with long alkyl chains (for example aliquat'336- | CHjCIl ·) · | A'CH / Cl, adogen®336- [CH₃(CH₂) „| .NCH.'Cl with n = 8-10, or [CH₃(CH₂)_n]₄N⁺X^- with n = 5-12 and X = halogen, NO₃ , HSO₄ ). Preferably the reducing agent is an aqueous solution of sodium borohydride. Other suitable reducing agents include but are not limited to R-type aluminum hydrides.₂AlH, RAIH₂, ER₃AlH, with E = Li or Na and R = an alkyl group (for example LiAlH₄ or LiAl [OC (Me)₃]₃H; borane derivatives of the EBH type_4-nL_n where n = 0-4, E = organic cation, tetra-ammonium cations, Na, Li and K and L = alkyl, alkoxy, amine, amide, phosphine, etc., (for example [CH₃(CH₂)₃]₄NBH₃CN or NaB [OOCMe]₃H).

The present inventors have found of particular importance when performing this method is the ratio of AuCl₄^-/ thiol for gold assay control. It has generally been found that the solubility and therefore the stability of stabilized gold nanoparticles decreases with increasing gold assay.

The gold nanoparticles of the present invention can also be reacted with molecular silver compounds such as silver thiolates, silver dithiocarbonates, silver nitrate, and silver carboxylates. The simplicity of the reaction results in heating and stirring of the two components in a suitable organic solvent such as toluene. The incorporation of the molecular silver compounds results in the agglomeration of the individual gold nanoparticles into longer particles, presumably due to the inter-reactions between the silver and a single pair of electrons available in the thiol stabilizing the gold nanoparticles. This increase in agglomeration is reflected by a change in the color of the nanoparticles in solution from coffee (gold only) to purple-red (gold and silver). An increase in the intensity of the surface plasmon band is also clearly evident in the uv-visible spectrum, again indicating an increase in the size of the nanoparticles.

The gold-silver materials obtained can be used for decorative purposes such as gold nanoparticles, but with the conviction that it is known to those skilled in the art as a lemon gold film after refining.

Once the nanoparticles have been prepared using the method described herein, they can be applied to the surface of the substrate for decorative uses.

Therefore, in a further aspect, the present invention provides a method for decorating a substrate surface, which method comprises the steps of applying a gold material or gold composition as described herein. to a surface of the substrate and treating the substrate to adhere the gold material or gold composition to the surface of the substrate to produce a decorative effect.

Suitable treatments include but are not limited to heating from temperatures as low as 100 ° C to as high as 1200 ° C. additionally the execution of an appropriate post-treatment on a solvent cast film, for example by washing with the acid and / or irradiation with UV light which produces the metallic films exhibiting a decorative effect.

The substrate can be but is not limited to one or more of the following: glass, earthenware, phosphate porcelain, porcelain, silicate materials, metals, quartz, carbon, mica, plastics, laminates, wood, paper, textiles, and leathers . The cupellation temperature used will depend to some degree on the composition of the formulation containing the nanoparticles, but more importantly it will depend on the surface of the substrate on which the decoration is applied. Low temperatures (<300 ° C) are required for cupellating on plastics, laminates, wood, paper and leather. Temperatures of 400 to 700 ° C are typically used for glass gold film cupellation, while phosphatic porcelain or porcelain cupelation develops cupellation temperatures between 700 and 1100 ° C, typically between 700 and 900 ° C. In addition, a combination of the gold material or the gold composition with special sintering agents may be required for high temperature applications.

The gold material or gold composition of the present invention can be applied to the substrate by any one or more of the following methods: brush coating, ink jet printing, stenciling, spraying, stippling, screen printing, spin coating, screen coatings, dip coatings, pad coatings, thermoplastic coatings, web roll, decal or electrostatic coatings.

In the case where the method of application to the substrate is by decal it is found that the resulting decal exhibits minimal surface bleeding when compared to the molecular gold thiolate analog.

The invention will now be described by the following examples in which:

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Figure 1: (a) Shows a transmission electron micrograph of the gold nanoparticles produced according to Example 1 of the present invention. (b) The particle size distribution of the nanoparticles produced according to example 1. The vertical axis shows the percentage of particles and the horizontal axis shows the average diameter of the particles in nm.

Examples

Example 1

General procedure for the preparation of stabilized gold thiol nanoparticles

A 600 cm aqueous solution³ of IIAuCl4 (50g, 0.1057 mol) is mixed with 600 cm³ of a toluene solution of the phase transfer reagent, aliquat®336 (170.9g, 0.4228 mol). The two-phase system is stirred at room temperature until the AuCl4 anion transfer is complete, for example colorless aqueous phase. The orange organic phase is then isolated and washed twice with an appropriate amount of water. In the addition of the HSC₆H₄p-CMe₃ (35.08g, 0.2113 moles), the mixture turns green and finally orange in 15 minutes. The mixture is added to a freshly prepared 2000cm solution.³ of sodium borohydride (79.96g, 2.113 moles), with vigorous stirring while the reaction is cooled in a water bath to keep the reaction temperature below 40 ° C during the addition. A dark brown organic layer is obtained instantly and after stirring at room temperature it is left for 15 minutes, after the addition. The organic phase is separated and washed twice with an appropriate amount of water. The addition of large volumes of methanol lead to the precipitation of a black powder, which is isolated by filtration, washed with methanol and recrystallized with toluene / MeOH.

It is found that the sub-compounds in the reaction conditions can result in a variation of up to +/- 1.0% in the gold assay when the same procedure is repeated.

Product characteristics

Color: black powder

Yield: 87%

Gold Assay: 78.2%

Elemental analysis; C, 16.00; H, 1.88; S 4.31;

Particle size (nm): most are between 1 and 2.5 nm.

TGA analysis: exotherm at 223 ° C

UV-vis spectrum: surface plasmon at 500 nm

1H NMR spectrum: broad resonances (br) with the given shift in the center, 1.1 (br, 9H), and 7.2 (s, 4H) ppm.

Example 2

Preparation of stabilized thiol nanoparticles

As for example 1 with the following quantities: HAuCl₄ (50g, 0.1057 mol), aliquat®336 (58g, 0.143 mol), HSC₆H₅-p-CMe₃ (17.54g, 0.1057 mol) and NaBH₄ (20g, 0.528 moles). The two-phase system develops: 200 ml of toluene is used for the organic phase to mix AuCl₄^-, aliquat®336 and HSC₆H₅-p-CMe₃ and NaBH₄ dissolves in 500 ml of H₂Or demineralized to form the aqueous phase.

Product characteristics

Color: black powder

Yield: 86%

Gold Assay: 77.5%

Elemental analysis: C 16.06; H, 1.7; S, 4.2;

TGA analysis: exotherms at 218.05 and 276.8 ° C.

UV-vis spectrum: surface plasmon at 500 nm

1H NMR spectrum: broad resonances with given shift in center, 1.1 (s, 9H) and 7.2 (s, 4H) ppm.

ES 2 222 348 T3

Example 3

Preparation of stabilized thiol nanoparticles

As for the general procedure with the following amounts: HAuCl₄ (50g, 0.1057 moles), aliquat®336, (58g, 0.143 moles), HSC₆H₅-p-CMe₃ (8.77g, 0.528 mole) and NaBH₄ (20g, 0.528 moles). The two-phase system develops: 200 ml of toluene is used for the organic phase to mix AuCl₄, aliquat®336 and HSC₆H₅-p-CMe₃ and NaBH₄ dissolves in 500 ml of H₂Or demineralized to form the aqueous phase.

Product characteristics

Color: black powder

Yield: 88%

Gold Assay: 81%

Elemental analysis: C, 13.53; H, 1.03; S, 3.8;

TGA analysis: exotherm at 223 ° C

UV-vis spectrum: surface plasmon at 500 nm

1H NMR spectrum: broad resonances with given shift in center, 1.1 (s, 9H), and 7.2 (s, 4H) ppm.

Example 4

Preparation of stabilized thiol nanoparticles

As for the general procedure with the following amounts: HAuCl₄ (50g, 0.1057 mol), aliquat®336 (58g, 0.143 mol), HSC₆H₅-p-CMe₃ (8g, 0.048 moles) and NaBH₄ (20g, 0.528 moles). The two-phase system develops: 200 ml. of toluene that is used for the organic phase to mix AuCl₄ , aliquat®336 and HSC₆H₅-p-CMe₃ and NaBH₄ dissolves in 500 ml of H₂Or demineralized to form the aqueous phase.

Product characteristics

Color: black powder

Yield: 91%

Gold Assay: 83%

Elemental Analysis: C, 12.2; H, 1; S, 3.64;

TGA analysis: exotherm at 220 ° C

UV-vis spectrum: surface plasmon at 500 nm

1H NMR spectrum: broad resonances with given shift in center, 1.1 (s, 9H) and 7.2 (s, 4H) ppm.

Example 5

Preparation of stabilized thiol nanoparticles

The method as for the general procedure uses the following amounts: HAuCl₄ (40g, 0.0846 mole), aliquat® 336 (34.2 g, 0.169 mole), HSC₆H₅-p-CMe₃ (3.5g, 0.0211 moles) and NaBH₄ (32g, 0.846 moles). The two-phase system develops: 240 ml of toluene that is used for the organic phase to mix AuCl₄^-, aliquat®336 and HSC₆H₅-pCMe₃ and NaBH is dissolved in 800 ml of H₂Or demineralized to form the aqueous phase.

Product characteristics

Color: black powder

Yield: 90%

Gold Assay: 91%

Elemental Analysis: C, 6.6, H, 0.42; s, 2;

ES 2 222 348 T3

TGA analysis: exotherm at 233 ° C

UV-vis spectrum: surface plasmon at 500 nm

1H NMR spectrum: broad resonances with the given shift in the center, 1.1 (s, 9H), and 7.2 (s, 4H) ppm.

Example 6

Preparation of stabilized thiol nanoparticles

The method as for the general procedure using the following quantities: HAuCl₄ (50g, 0.1057 mol), aliquat®336 (58g, 0.143 mol), HSC₆H₅-p-CMe₃ (8.77g, 0.053 mole) and NaBH₄ (20g, 0.528 moles). The two-phase system develops: 200 ml of xylene that is used for the organic phase to mix AuCl₄, aliquat®336 and HSC₆H₅p-CMe₃ and NaBH₄ it is dissolved in 500 ml of demineralized water to form the aqueous phase.

Product characteristics

Color: black powder

Yield: 92%

Gold Assay: 79.5%

Elemental Analysis: C, 14.97; H, 1.6; S, 3.29;

TGA analysis: exotherm at 222 ° C

UV-vis spectrum: surface plasmon at 500 nm

1H NMR spectrum: broad resonances with the given shift in the center, 1.1 (s, 9H) and 7.2 (s, 4H) ppm.

Example 7

Preparation of stabilized thiol nanoparticles

To a 20 cm solution of toluene³ of [CH3 (CH2) 7] 4N⁺Br^- (20.6 g, 0.037 mol), HAuCl4 diluted in 50 cm³of demineralized water (5g, 0.0105 mol) is added to allow phase transfer of AuCl4 in the organic layer. Subsequently, the HS pinenyl thiol (2.98 g, 0.037 mol) is added to the stirred mixture for 15 minutes. Finally 20 cm³ 40 of a freshly prepared aqueous solution of NaBH4 (3.78g, 0.100 mol) is added in portions to give a dark brown mixture which is stirred at room temperature for 3 hours after the addition. The organic layer is then isolated and concentrated under vacuum. Ethanol is added and the mixture is stored at -15 ° C for 48 hours. A dark solid is obtained, filtered, and washed with MeOH. The black material is finally dried under vacuum for 24 hours.

Product characteristics

Color: black powder,

Yield: 86%

Gold Assay: 78.6%

Elemental Analysis: C, 14.55; H, 1.92; S, 4.44

Example 8

Preparation of stabilized thiol nanoparticles

As for example 1, but using the following quantities: HAuCl₄ (0.849 g, 0.9 mmol), [CH₃(CH₂)₇]₄60 N⁺Br^-(4.37g, 4mmol), HS (CH₂)₁₁CH₃ (0.34g, 1.68mmol) and NaBH₄ (0.756 g, 0.010 moles).

Product characteristics

Color: black powder

Yield: 86%

Gold Assay: 73.5%

ES 2 222 348 T3

Elemental Analysis: C, 18.74; H, 13.28; S, 4.58

Example 9

Preparation of stabilized thiol nanoparticles

A 200 cm aqueous solution³ by HAuCl₄ (25g, 0.0529 mol) is mixed with a 250ml toluene solution of the phase transfer reagent, aliquat®336 (79.07 g, 0.195 mol). The two-phase system is stirred at room temperature until the transfer of the AuCl anion is complete.₄ , for example colorless aqueous phase. In the addition of the HSCH (Me) CO₂CH₂CH₃ (12.78g, 0.095 moles), the mixture turns green and finally orange within 15 minutes. This is added to a freshly prepared 200 cm solution.³ of sodium borohydride (79.96 g, 2.113 moles), with vigorous stirring while the reaction is cooled in a water bath, to keep the reaction temperature below 40 ° C during the addition. A dark purple organic layer is obtained instantly and is further stirred at room temperature leaving it for 6 hours after the addition. The organic layer is then isolated and concentrated under vacuum. MeOH is added and the mixture is stored at -15 ° C for 48 hours. A dark solid is obtained, filtered, and washed with MeOH. The black material is finally dried under vacuum for 24 hours.

Product characteristics

Color: black powder

Yield: 80%

Gold Assay: 89%

Example 10

General preparative method for the Reaction of Gold nanoparticles (prepared as in example 1) with silver compounds

The gold nanoparticles (as for example 1, test 78.5%) are dissolved in a suitable organic solvent and shaken. The desired silver compound is added to the reaction vessel (typically in a molar ratio of 1: 0.2 Au: Ag) and the reaction is stirred and heated at 60 ° C for 30 minutes, before it is allowed to cool down. room temperature. A change in the visible color of brown to red-purple is observed, remaining at rest with an increase in the size of the colloid. The solution is then filtered to remove any small amount of insoluble material before evaporation of the reaction solvent. The dried material is either washed with or recrystallized with a suitable solvent, filtered and dried.

Example 11

Reaction of gold nanoparticles with silver nitrate

The reaction is carried out according to the general procedure above using the following reagents:

<td>Gold nanoparticles (as in example 1) Assay 78.5%</td><td>5.0g, (3.92 g Au, 0.02 mole)</td>

<td>Silver nitrate</td><td>0.616 g, (0.392 g, Ag, 0.0036 mole)</td>

<td>Solvents - Reaction - Washed.</td><td>Toluene (20cm ') / Ethanol (20cm³) Water (100 cm³)</td>

Example 12

Reaction of gold nanoparticles with AgSC₆H₄-p-CMe₃

The reaction is carried out according to the general procedure above using the following reagents:

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<td>Gold nanoparticles (as in example 1) test 78.5%</td><td>10.Og (7.85 g Au, 0.04 mole)</td>

<td>AgSC₆H₄-p-CMe₃</td><td>1.99 g (0.785 g Ag, 00073 moles).</td>

<td>Solvent- Reaction - Washed</td><td>Xylene (50 cm³) Methanol (100 cm³)</td>

Example 13

Reaction of gold nanoparticles with AgSC₆H₄-p-CMe₃

The reaction is carried out according to the general procedure above using the following reagents:

<td>Gold nanoparticles (as in example 1) Assay 78.5%</td><td>10.0 g (7.85 g. Au, 0.04 moles)</td>

<td>AgSC₆H₄-p-CMe₃</td><td>1.49 g (0.59 g. Ag, 0.0055 mol)</td>

<td>Solvent - Reaction - Washed</td><td>Xylene (50 cm³) Methanol (100 cm³)</td>

The reaction products are characterized by their assay, the uv-visible spectrum and the 1H NMR spectrum.

<td></td><td>Example 11</td><td>Example 12</td><td>Example 13</td>

<td>Essay (theoretical)</td><td> 77.9 (80.0)</td><td> 72.3 (72.0)</td><td> 73.4 (73.4)</td>

<td>Plasmon of surface</td><td>Wide band a</td><td>Wide band a</td><td>Wide band a</td>

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<td>Band position</td><td>from</td><td colspan="2">-520 nm</td><td colspan="2">-540 nm</td><td colspan="2">-540 nm</td>

<td>1H NMR</td><td></td><td>Like in</td><td>the</td><td>Like in</td><td>the</td><td>Like in</td><td>the</td>

<td></td><td></td><td>Example 1</td><td></td><td>example</td><td> 1,</td><td>example</td><td> 1,</td>

<td></td><td></td><td></td><td></td><td>but</td><td>with</td><td>but</td><td>with</td>

<td></td><td></td><td></td><td></td><td>resonances</td><td></td><td>resonances</td><td></td>

<td></td><td></td><td></td><td></td><td>sharp to 1</td><td> • 2,</td><td>sharp to 1</td><td> • 2,</td>

<td></td><td></td><td></td><td></td><td>1.3 ppm</td><td>Y</td><td>1.3 ppm</td><td>Y</td>

<td></td><td></td><td></td><td></td><td>multiplets</td><td></td><td>multiples</td><td></td>

<td></td><td></td><td></td><td></td><td>sharp in</td><td>the</td><td>sharp in</td><td>the</td>

<td></td><td></td><td></td><td></td><td>region</td><td></td><td>region</td><td></td>

<td></td><td></td><td></td><td></td><td>aromatic.</td><td></td><td>aromatic.</td><td></td>

Compositions that demonstrate the use of nanoparticles

The compositions are prepared by combining the thiol stabilized gold nanoparticles with the solvents and resins, followed by the addition of the additives in minor amounts of metal. Adequate heating and stirring is carried out to ensure homogeneous and uniform compositions are obtained. The formulations are allowed to stand overnight and then printed on a 120T mesh polyester screen (not otherwise mentioned in the examples). Prints are coated with OPL500 thix (available from Johnson Matthey Colors and Coatings Division) then dry for a minimum of 3 hours. Once dry, the transformed compounds are applied to the phosphate porcelain and porcelain utensils. Compositions are tested for refined film quality by cupelling at 840 ° C for 1 hour and cooling.

The data for all compositions are given in% by weight, with the% of the gold nanoparticles adjusted to have an approximate concentration of 10% by weight of Au in the formulation. The brand names Scripset 540 and Scripset 550 are poly (styrene-co-maleic acid), partial butyl ester resins of molecular weight 180,000 and 105,000 respectively. These are commercially available from Hercules Inc. The chrome 5 vanadium and nuosyn preparation are available from Johnson Matthey Colors and Coatings Division.

Example 14

Composition containing gold nanoparticles

12.8 Gold nanoparticles (as in example 1)

4.8 Silver sulforesinate (21% silver)

3.0 Ethyl rhodium hexanoate solution (10% by weight in cyclohexanone)

1.5 MeSi (OEt) 3 solution (5% by weight in cyclohexanone)

1.0 prep. vanadium

1.0 Chromium nuosyn 5

Scripset 540 solution (40% by weight in dipropylene dimethyl glycol ether)

Scripset 550's solution (30% by weight in cyclohexanone)

15.0 Phenyl Glycol Propylene Ether

10.9 4-tert-butyl cyclohexanone.

The formulations give refined films that are virtually free from undercoat bleed. Abrasion resistance and chemical durability is comparable to common commercially available products.

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Example 15

Composition containing gold nanoparticles

12.6 Gold nanoparticles from test 79.5% (prepared as in example 6)

50.0 Solution of Scripset 540 (40% by weight in dimethyl dipropylene glycol ether)

17.5 Ethyl lactate

6.0 Camphor

6.0 4-t-butylcyclohexanone

2.4 Silver sulforesinate (21% Ag)

3.0 Ethyl Rhodium Hexanoate (10% of the solution in cyclohexanone)

2.4 (EtO) 3SiMe (5% of the solution in cyclohexanone)

0.1 Special Byketol

The resulting gold film is bright and uniform with minimal coating interaction.

Example 16

Composition containing gold nanoparticles

15.2 Gold nanoparticles that react with silver nitrate (as in Example 11)

Ethyl rhodium hexanoate solution (10% by weight in cyclohexanone)

1.5 MeSi (OEt) 3 solution (5% by weight in cyclohexanone)

1.0 prep. vanadium

1.0 Chromium nuosyn 5

25.0 Solution of Scripset 540 (40% by weight of dimethyl dipropylene glycol ether)

25.0 Solution of Scripset 540 (40% by weight in dipropylene methyl glycol ether)

10.3 Phenyl Glycol Propylene Ether

5.0 Isophorone

7.0 4-tert-butyl-cyclohexanone

7.0 Camphor

The resulting gold film is shiny and uniform with a slight purple color at the edges of the print.

Example 17

Formulation for brushing

12.8 Gold nanoparticles (as in example 1)

4.8 Silver sulforesinate (21% silver)

3.0 Ethyl rhodium hexanoate solution (10% by weight in cyclohexanone)

1.5 MeSi solution (OEt)₃ (5% by weight in cyclohexanone)

20.0 Solution of Scripset 540 (40% by weight in cyclohexanone

40.0 Cyclohexanone

17.9 Alphapinene

Example 18

Formulation suitable for brushing or rotating

12.7 Gold nanoparticles (as in example 1)

75.5 Dipropylene Dimethyl Glycol Ether

8.4 Co-polymethacrylate resin, DRM-99095 (available from Lawter International)

3.4 Ethyl rhodium hexanoate (10% by weight in cyclohexanone

The formulation is rotated on a porcelain tile and cupelled at 840 ° C in a 1 hour cycle. The resulting film is reflective and shiny gold.

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Example 19

Formulation suitable for dip coating

The formulation with Au nanoparticles is stabilized with ethyl 2-mercaptopropionate.

37.5 Gold nanoparticles (89% Au assay, prepared as in Example 9)

62.5 Isoforane

The composition is dip coated onto a polyester foil (as used for overhead projectors) and heated to ca. 100 ° C. A shiny gold film forms.

Example 20

Composition containing gold nanoparticles

12.7 Gold nanoparticles from assay 78.0%

47.9 Solution of Scripset 540 (40% by weight in dimethyl dipropylene glycol ether)

20.0 Citronellol

6.0 4-t-butylcyclohexanone

6.0 Camphor

1.4 Silver sulforesinate (21% Ag)

2.0 Ethyl Rhodium Hexanoate (10% of the solution in cyclohexanone)

2.0 Byk 141

The resulting gold film is bright and uniform with minimal coating interaction.

Example 21

Composition containing gold nano-particles

1.9 Gold nanoparticles from assay 78.0%

1.1 Partial poly (styrene cometic acid) isobutyl ester with average Mw of 65000 (50% by weight in dimethyl dipropylene glycol ether)

1.8 Citronellol

1.8 Tixin R

1.4 Silver sulforesinate (21% silver)

2.0 Ethyl Rhodium Hexanoate (10% solution in cyclohexanone) prep. Vanadium (50% by weight in solution in xylene

1.0 prep. chromium (50% by weight in xylene solution)

2.0 Byk 141

The resulting gold film is shiny with no coating interaction.

Comparative examples

Example comparable with that of Molecular Gold Thiolate

18.3 AuSC6H4-p-CMe3

50.0 Scripset 540 solution (30% by weight in cyclohexanone)

2.0 Ethyl rhodium hexanoate solution (10% by weight in cyclohexanone)

0.2 Triphenyl bismuth

29.5 Isophorone

The formulations provide refined films (from the decals) which show interaction of the coating with slightly purple color around the edge of the print and an efflorescent surface on the gold. This efflorescence can be removed to leave a shiny gold film, but the slightly purple color cannot be removed. It will be apparent to those skilled in the art that modifications can be made to the invention described herein without departing from the inventive concept thereof.