KR102408347B1 - Gold nanocluster and method for producing the same and optical sensor comprising the same - Google Patents

Abstract

The present invention relates to a gold nanocluster and a method for manufacturing the same, and to provide a high-emission optical sensor capable of improving fluorescence including the same.

Description

Gold nanocluster and method for manufacturing same, and optical sensor including same

The present invention relates to a gold nanocluster, a method for manufacturing the same, and an optical sensor including the same.

Nanoclusters or superatoms composed of a certain number of metal atoms and ligands follow the macroatomic orbital theory, in which the valence electrons of particles are newly defined, It's a theory.

Nanoclusters have optical and electrochemical properties completely different from nanoparticles because they are more stable than single atoms or nanoparticles, and have stronger molecular properties than metallic properties. In particular, as optical, electrical and catalytic properties of nanoclusters are sensitively changed according to the number of metal atoms, types of metal atoms, ligands, etc., research on nanoclusters is being actively conducted in a wide variety of fields.

Conventionally, it was difficult to control the number of materials to be bound when bonding gold nanoclusters that are only soluble in water, because the reaction was not smooth to induce a terminal group binding reaction in an organic solvent. In particular, when the reaction of the gold nanoclusters was performed in water, it was not possible to bind as much as the number of ligands due to low activity and stability, but also had a remarkably low yield.

In addition, even when the reaction is induced in a mixed solvent in which water and an organic solvent are mixed, the problems of low yield and difficult to control the number of bonds as described above still occurred.

As a similar prior document, Korean Patent No. 10-1845153 has been proposed.

Accordingly, there is a need for development capable of easily binding various materials to the ligands of gold nanoclusters stably in an organic solvent and implementing various luminescence and fluorescence properties by precisely controlling the number of bonds.

Republic of Korea Patent Publication No. 10-1845153 (2018.04.06)

In order to solve the above problems, an object of the present invention is to provide a gold nanocluster capable of controlling the number of substances bound to an amino group, which is a terminal group, a method for manufacturing the same, and an optical sensor including the same.

Another object of the present invention is to provide a method for preparing gold nanoclusters in which a binding reaction to an amino group, which is a terminal group, is performed in an organic solvent.

One aspect of the present invention relates to gold nanoclusters satisfying the following formula (1).

[Formula 1]

(In Formula 1 above

L ₁ is a trivalent linking group, and the trivalent linking group includes or does not include any one or two or more selected from -O-, -C(=O)-, -COO-, -NH- and -CONH- a hydrocarbon skeleton, each R ₁ is independently hydrogen or -R ₁₁ -Ar ₁ , at least one of R ₁ in the y unit is -R ₁₁ -Ar ₁ , wherein R ₁₁ is an alkylene group having 1 to 6 carbon atoms. and Ar ₁ may be an aryl group having 6 to 50 carbon atoms, x is 18, 22, 25, 38, 67, 102, 144 or 333, and y is 14, 18, 24, 35, 44, 60 or 79 to be.)

In one aspect, the hydrocarbon skeleton in Formula 1 may have any one or two or more substituents selected from -OH, -COOH and -NH ₂ .

또는

이며, R₁₁은 탄소수 2 내지 6의 알킬렌기이고, 상기 Ar₁은 탄소수 6 내지 30의 아릴일 수 있다.In one aspect, in Formula 1, L ₁ is

or

and R ₁₁ may be an alkylene group having 2 to 6 carbon atoms, and Ar ₁ may be an aryl group having 6 to 30 carbon atoms.

Another aspect of the present invention relates to an optical sensor including the above-described gold nanoclusters.

Another aspect of the present invention is a step of a) reacting a compound represented by the following formula (2) and a quaternary ammonium salt to first bond a quaternary ammonium salt to the carboxyl group of the compound represented by formula (2), b) the primary bonded Gold represented by the following formula (1), including a step of secondarily bonding a compound represented by the following formula (3) to an amino group of the compound, and c) removing a quaternary ammonium salt first bound to a carboxyl group from among the secondary bonded compounds It relates to a method for manufacturing a nanocluster.

[Formula 1]

[Formula 2]

[Formula 3]

(In Formulas 1 to 3,

L ₁ is a trivalent linking group, and the trivalent linking group includes or does not include any one or two or more selected from -O-, -C(=O)-, -COO-, -NH- and -CONH- a hydrocarbon skeleton, each R ₁ is independently hydrogen or -R ₁₁ -Ar ₁ , at least one of R ₁ in the y unit is -R ₁₁ -Ar ₁ , wherein R ₁₁ is an alkylene group having 1 to 6 carbon atoms. and Ar ₁ may be an aryl group having 6 to 50 carbon atoms, R ₂ is hydrogen or a leaving group, x is 18, 22, 25, 38, 67, 102, 144 or 333, y is 14, 18, 24, 35, 44, 60 or 79).

In one aspect, the steps b) and c) may be performed in an organic solvent.

Preferably, in Formulas 1 to 3 according to an embodiment of the present invention, the hydrocarbon backbone may have any one or two or more substituents selected from -OH, -COOH and -NH ₂ , and the primary bonded compound and the following The molar ratio of the compound of Formula 3 may be 1:5 to 25.

Preferably, step c) according to an embodiment of the present invention may be performed with tetraalkylammonium (C1-C20)alkylcarboxylic acid or trialkylammonium (C1-C20)alkylcarboxylic acid.

The gold nanoclusters according to the present invention have the advantage of remarkably increasing fluorescence due to excellent light emission characteristics and stability.

In addition, the method for preparing gold nanoclusters according to the present invention has the advantage that the gold nanoclusters soluble only in water can be reacted in an organic solvent, and the number of bonds of materials bound to an amino group, which is a terminal group, can be easily controlled.

1 illustrates a method for manufacturing gold nanoclusters according to Example 1 of the present invention.
2 is a graph showing the electrospray ionization mass spectrometry (ESI-MS) results of the gold nanoclusters (Au ₂₂ GS ₁₈ ) prepared in Preparation Example 1 of the present invention.
Figure 3 is a view showing a ¹ H-NMR graph of the Au ₂₂ GS ₁₈ BPy ₁₈ material prepared in Example 1 of the present invention.
4 is a result of measuring the absorbance of the gold nanoclusters of an embodiment and a comparative example of the present invention.
5 is a PL characteristic result for a wavelength band measured after excitation of 350 nm gold nanoclusters of one embodiment and a comparative example of the present invention.
6 is a PL characteristic result for the number of end group bonds measured at wavelengths of 380 nm, 480 nm, and 650 nm of the gold nanoclusters of an embodiment of the present invention.
7 is a PL characteristic result for the number of terminal group bonds measured at wavelengths of 380 nm, 480 nm and 650 nm of the gold nanoclusters of Example 11 of the present invention.

Hereinafter, a gold nanocluster according to the present invention, a method for manufacturing the same, and an optical sensor including the same will be described in detail with reference to the accompanying drawings. The drawings introduced below are provided as examples so that the spirit of the present invention can be sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. Also, like reference numerals refer to like elements throughout.

At this time, if there is no other definition in the technical terms and scientific terms used, it has the meaning commonly understood by those of ordinary skill in the art to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings Descriptions of known functions and configurations that may be unnecessarily obscure will be omitted.

In addition, in describing the components of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms.

As used herein, the term “alkyl” refers to a monovalent straight-chain or branched saturated hydrocarbon radical composed of only carbon and hydrogen atoms, and may have 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Examples of such alkyl radicals include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, and the like. The term “alkylene” means a divalent organic radical derived from a saturated hydrocarbon.

As used herein, the term “aryl” is an organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, and is preferably a single or fused ring containing 4 to 7, preferably 5 or 6 ring atoms in each ring. It includes a system, and includes a form in which a plurality of aryls are connected by a single bond. Specific examples include, but are not limited to, phenyl, naphthyl, biphenyl, anthryl, indenyl, fluorenyl, pyrenyl, chrysenyl, and the like.

As used herein, the term “arylene” refers to an aromatic ring divalent organic radical derived from an aromatic hydrocarbon.

As used herein, the term “halo” or “halogen” refers to a halogen element, and includes, for example, fluoro (F), chloro (Cl), bromo (Br), and iodo (I).

The present inventors have provided a gold nanocluster capable of stably binding various materials to the ligand of the gold nanoclusters in an organic solvent, as well as finely controlling the number of bonds to realize various luminescence and fluorescence properties, a method for preparing the same, and An object of the present invention is to provide an optical sensor including the same.

In detail, the present invention relates to gold nanoclusters satisfying the following Chemical Formula 1, and by satisfying the following Chemical Formula 1, excellent light emitting properties and stability may be obtained.

[Formula 1]

(In Formula 1 above

L ₁ is a trivalent linking group, and the trivalent linking group includes or does not include any one or two or more linking groups selected from -O-, -C(=O)-, -COO-, -NH- and -CONH- and R ₁ is each independently hydrogen or -R ₁₁ -Ar ₁ , at least one of R ₁ in y units is -R ₁₁ -Ar ₁ , and R ₁₁ is an alkyl having 1 to 6 carbon atoms. Rene group, wherein Ar ₁ may be an aryl group having 6 to 50 carbon atoms, x is 18, 22, 25, 38, 67, 102, 144 or 333, y is 14, 18, 24, 35, 44, 60 or 79.)

The gold nanocluster according to the present invention includes gold (Au), has a shape in which gold (Au) is coordinated with sulfur (S) in the y unit as a ligand, and satisfies Chemical Formula 1 above.

In one embodiment of the present invention, the gold nanocluster (Au _x (GS) _y ) is a core composed of a core composed of gold (Au) atoms and the GS ligand surrounding the core composed of a shell. - It can have a shell structure. In this case, GS is an abbreviation for the y unit in Formula 1.

More specifically, in an example of the present invention, the gold nanoclusters have gold (Au) atoms centered as a core (nucleus), and around the core [GS-Au-GS-Au-GS-Au-GS Two chains such as ] and two chains such as [GS-Au-GS-Au-GS-Au-GS-Au-GS] form a ring with each other to form a cluster in a structure surrounding the core (shell). have.

In one embodiment of the present invention, in Formula 1, L ₁ is a trivalent linking group consisting of three bonds, preferably -CONH-, it may be a hydrocarbon skeleton including or not including any one or two or more selected from . More preferably, it may have any one or two or more substituents selected from -OH, -COOH and -NH ₂ in the hydrocarbon backbone. More preferably, it may have a -COOH substituent in the hydrocarbon backbone.

More specifically, it may have a stable cluster structure, and in Formula 1, L ₁ may be a glutathione skeleton, and the glutathione skeleton has two carboxyl groups (-COOH) as terminal groups and It is derived from a compound represented by the following formula (4) having one amino group (—NH ₂ ).

[Formula 4]

More preferably, any one or two or more selected from the skeletons represented by the following Chemical Formulas 5 and 6 may be used.

[Formula 5]

[Formula 6]

In one embodiment of the present invention, the gold nanoclusters can easily bind various materials to the terminal groups, thereby increasing the luminescence intensity and yield, and the number of bonds can be finely controlled to realize various luminescence intensities. have. In particular, in the prior art, it was very difficult to bind a material to a terminal group as much as the number of ligands, and there was a disadvantage that the yield was significantly low. It has the advantage of being able to combine.

The above-described various materials refer to materials bonded to R ₁ in Formula 1, and will be described in more detail below.

In an embodiment of the present invention, each of R ₁ is independently hydrogen or -R ₁₁ -Ar ₁ , and at least one of R ₁ in y units is -R ₁₁ -Ar ₁ . Preferably, in the y unit, at least two of R ₁ may be -R ₁₁ -Ar ₁ . Specifically, in Formula 1, R ₁₁ is an alkylene group having 1 to 6 carbon atoms, Ar ₁ may be an aryl group having 6 to 50 carbon atoms, preferably, R ₁₁ is an alkylene group having 2 to 6 carbon atoms, The Ar ₁ may be an aryl group having 6 to 50 carbon atoms. More preferably, R ₁₁ is propylene, isopropylene, butylene, pentylene, or hexylene, and Ar ₁ may be a polycyclic aromatic group, specifically phenyl, naphthyl, biphenyl, anthryl, pyrenyl or cre It may be cenyl. When R ₁₁ is a direct bond, energy transfer disappears, whereas when an end-group bond as described above is formed, more energy transfer occurs and excellent fluorescence can be realized.

As described above, the gold nanoclusters according to the present invention can impart fluorescence when at least one of R ₁ among y units is bonded to -R ₁₁ -Ar ₁ , and as the number of bonds increases, strong fluorescence can be realized. have. Furthermore, when all of the R ₁ in the y unit are combined with -R ₁₁ -Ar ₁ , the fluorescence intensity of three wavelength bands of 380 nm, 480 nm and 650 nm is remarkably increased, and white light may be realized. As described above, the combination of all of R ₁ among the y units is an effect that cannot be realized by the conventional manufacturing method.

In one embodiment of the present invention, the gold nanocluster has a number of ligands capable of binding depending on the number of gold atoms, specifically, x in Formula 1 is 18, 22, 25, 38, 67, 102, 144 or 333, , y is 14, 18, 24, 35, 44, 60 or 79. For example, when (x,y), (18,14), (22,18), (25,18), (38,24), (67,35), (102,44), (144) ,60) or (333,79) is satisfied. In order to finely control the number of end group bonds, x is preferably 18, 22 or 25, and y may be 14 or 18, for example, when (x, y), (18, 14), ( 22,18) or (25,18) may be satisfied, but is not limited thereto.

In an example of the present invention, the gold nanoclusters may have an average size of 10 nm or less, preferably 0.1 to 5 nm, more preferably 0.5 to 3 nm, but limited thereto it is not going to be

The gold nanoclusters according to the present invention have the above-described configuration, and thus can implement remarkably excellent fluorescence and achieve a maximized fluorescence effect even with a small amount.

In addition, the gold nanoclusters according to the present invention can realize water solubility because the carboxyl group is present as it is. By having water solubility in this way, it can be variously applied in bio fields such as biodiagnosis.

Another aspect of the present invention relates to an optical sensor including the above-described gold nanoclusters. The optical sensor refers to a sensor having optical properties capable of expressing light emission and fluorescence properties, and specifically, may be a fluorescent sensor or a light emitting sensor. Depending on the intended use, for example, it may be selected from a biosensor, an energy harvesting sensor, and a gas sensor, and more specifically, it may be applied in fields selected from bioimaging, biodiagnosis, disease diagnosis and gas detection, etc. However, the present invention is not limited thereto.

In an example of the present invention, the gold nanoclusters may be used as an optical sensor by themselves, and may be used in combination with various parts, materials, systems, etc., but is not limited thereto.

Another aspect of the present invention relates to a method for preparing the above-described gold nanoclusters, and specifically relates to a method for preparing gold nanoclusters represented by the following Chemical Formula 1, a) a compound represented by the following Chemical Formula 2 and a quaternary ammonium salt a step of first bonding a quaternary ammonium salt to the carboxyl group of the compound represented by Formula 2 by reacting with b) secondary bonding of the compound represented by Formula 3 to the amino group of the primary bonded compound, and c) the above and removing the quaternary ammonium salt first bound to the carboxyl group in the secondary bound compound.

[Formula 1]

[Formula 2]

[Formula 3]

(In Formulas 1 to 3,

L ₁ is a trivalent linking group, and the trivalent linking group includes or does not include any one or two or more linking groups selected from -O-, -C(=O)-, -COO-, -NH- and -CONH- and R ₁ is each independently hydrogen or -R ₁₁ -Ar ₁ , wherein R ₁ is at least one of the y units is -R ₁₁ -Ar ₁ , wherein R ₁₁ is an alkyl having 1 to 6 carbon atoms. Rene group, wherein Ar ₁ may be an aryl group having 6 to 50 carbon atoms, R ₂ is hydrogen or a leaving group, x is 18, 22, 25, 38, 67, 102, 144 or 333, and y is 14, 18 .

Existing gold nanoclusters have problems in that the yield is remarkably low due to remarkably low reaction activity and stability, and it is difficult to control the number of reaction bonds by performing the reaction under conditions that necessarily include water. In contrast, in the method for preparing gold nanoclusters according to the present invention, steps b) and c), which are reaction steps of binding a material to a ligand terminal group, can be performed in an organic solvent without water, and the reaction activity and stability are excellent. The number of bonds in the short-term bonding reaction can be precisely controlled as desired, and the yield of gold nanoclusters in the reaction performed in an organic solvent condition is 3 times or more in excellent yield compared to the reaction performed in the condition containing water. can do.

In the method for preparing gold nanoclusters according to the present invention, steps a) to c) may be sequentially performed, and specifically, the steps are as follows.

In an example of the present invention, in step a), the compound represented by Formula 2 includes a carboxyl group and an amino group as terminal groups, and may be primary bonded by reacting a quaternary ammonium salt with the carboxyl group.

In one embodiment of the present invention, the compound represented by Formula 2 is a material soluble only in water, but after step a) as described above, it loses solubility in water and has solubility in organic solvents, so that subsequent A hostile reaction may proceed. By carrying out the reaction in the organic solvent as described above, the number of bonds during the end-group bonding reaction can be precisely controlled as desired with excellent reaction activity and stability, and gold nanoclusters can be obtained in excellent yield. In addition, the compound represented by the formula (3) may be more stably bonded to the amino group of the compound represented by the formula (2).

In a specific example, in step a), a solution obtained by dispersing or dissolving a quaternary ammonium salt in an organic solvent is added to an aqueous solution in which the compound represented by Formula 2 is dispersed or dissolved in water, and the product is first bound to an organic solvent. It may be to induce a phase movement to the phase. This makes it possible to induce a subsequent reaction in the organic solvent as described above.

In an example of the present invention, the primary bonding in step a) may be performed under basic conditions, and may preferably be reacted under conditions of pH 8 to 10. By adjusting the pH as described above, it is possible to smoothly induce phase movement. The primary bond may have the form of an ionic complex of the carboxyl group of the compound represented by Formula 2 and a quaternary ammonium salt. By having the form of the ionic complex, it is preferable because it loses solubility in water and has solubility in organic solvents, and can easily separate the quaternary ammonium salt from the gold nanoclusters again in step c).

In an example of the present invention, the organic solvent may be a non-water-miscible, non-polar solvent. Specifically, it may be selected from an aliphatic alkyl solvent, a substituted alkyl solvent, and an aromatic solvent. For example, toluene, xylene, benzene, dichloromethane, dichlorobenzene, chloroform, cyclohexane, methylcyclohexane, heptane, hexane, octane, decane, undecane, dodecane, tetradecane, pentadecane and hexadecane ) may be any one or a mixture of two or more selected from the like.

In one embodiment of the present invention, the compound represented by Formula 2: quaternary ammonium salt may be carried out in a weight ratio of 1: 1.5 to 3.

In one embodiment of the present invention, the quaternary ammonium salt may be an ammonium salt having a tetraalkyl-substituted structure, specifically, a tetra(C4-C20)alkylammonium salt. For example, tetrabutyl ammonium bromide (TBACl, Tetrabutylammonium bromide), tetrapentyl ammonium bromide (TPABr, Tetrapentylammonium bromide), tetrahexyl ammonium bromide (THXABr, Tetrahexylammonium bromide), tetraheptylammonium bromide (THTABr), tetraheptylammonium bromide (THTABr) Octyl ammonium bromide (TOABr, Tetraoctylammonium bromide), tetrahexadecyl ammonium bromide (THDABr, Tetrahexadecylammonium bromide), tetraoctadecyl ammonium bromide (TODABr, Tetraoctadecylammonium bromide), tetrabutyl ammonium chloride (TBACl) TPACl, Tetrapentylammonium chloride), Tetrahexylammonium chloride (THXACl, Tetrahexylammonium chloride), Tetraheptylammonium chloride (THTACl, Tetraheptylammonium chloride), Tetraoctylammonium chloride (TOACl, Tetraoctylammonium chloride), Tetrahexadecylammonium chloride (THDACl, Tetrahexadecylammonium chloride) And it may include any one or two or more selected from tetraoctadecyl ammonium chloride (TODACl, Tetraoctadecylammonium chloride). By binding the quaternary ammonium salt as described above, it is possible to effectively induce a phase transfer of the gold nanoclusters from water to an organic solvent, thereby stably performing secondary bonding in the organic solvent.

In an example of the present invention, in step b), the compound represented by Formula 3 may be secondary bonded to the amino group of the primary bonded compound. For example, the secondary bond may induce a coupling reaction between the carboxyl group of the compound represented by Formula 3 and the amino group of the compound represented by Formula 2 through a DCC/NHS coupling reaction as an example of a coupling reagent. . Specifically, the compound represented by Formula 3 is treated with dicyclohexylcarbodiimide (DCC) to form an unstable intermediate ester, and then N-hydroxy succinimide (NHS, N-hydroxy succinimide) ), the carboxyl group can be converted into an amine-reactive NHS ester intermediate in a metastable state. The amine-reactive NHS ester intermediate reacts with the amino group of the compound represented by Formula 2 to form an amide bond. A leaving group according to an embodiment of the present invention is a compound fragment that comes out with an electron pair when a compound is disproportionately decomposed in a chemical reaction. The ability to break away from the original molecule is important. The leaving group according to an embodiment of the present invention may be any functional group that can be recognized by those skilled in the art, but may be, for example, a halogen group, an N-succinylimide group, or the like.

In one embodiment of the present invention, the dicyclohexylcarbodiimide and N-hydroxysuccinimide may be included in a molar ratio of 1:0.1 to 1:5, preferably 1:1 to smooth secondary bonding. It may be included in a molar ratio of 1:4, but is not limited thereto.

In an example of the present invention, the secondary bonding in step b) may be performed under a basic catalyst. The basic catalyst may further include any one or a mixture of two or more selected from, for example, pyridine, pyrimidine, triethylamine, diethylamine, diisopropylamine, diisopropylethylamine and dimethylaminopyridine. can By adjusting the reaction solution to a basic condition by adding the basic catalyst as described above to the reaction solution, the secondary bonding reaction can be performed more effectively.

As the secondary bonding reaction as described above is performed in an organic solvent, the compound represented by Formula 3 can be stoichiometrically covalently bonded to the gold nanoclusters very uniformly. In addition, according to the uniform and stoichiometric reaction characteristics, the number of moles of the compound of Formula 3 to be secondary bonded according to the number of moles of reaction of the compound represented by Formula 3 can be precisely controlled, so that the luminescence intensity suitable for the purpose can be realized.

The molar ratio of the primary bound compound and the compound of Formula 3 may be adjusted according to the light emission intensity that meets the purpose, but may be preferably 1: 5 to 25, more preferably 1: 10 to 20. have.

In an example of the present invention, in the compound represented by Formula 3, R ₁₁ may be an alkylene group having 2 to 6 carbon atoms, and Ar ₁ may be an aryl group having 6 to 50 carbon atoms. More preferably, R ₁₁ is propylene, isopropylene, butylene, pentylene, or hexylene, and Ar ₁ may be a polycyclic aromatic group, specifically phenyl, naphthyl, biphenyl, anthryl, pyrenyl or cre It may be cenyl. When the end group bond as described above is formed, excellent fluorescence can be realized.

In one embodiment of the present invention, the secondary bond may bind one or more of the y units of the compound represented by Formula 1, thereby conferring fluorescence, and increasing the number of bonds to achieve stronger fluorescence. can be implemented Moreover, when all of the y units are secondary bonded, the fluorescence intensity of three wavelength bands of 380 nm, 480 nm and 650 nm is remarkably increased, and white light can be realized. The combination of all y units as described above is an effect that cannot be realized by the conventional manufacturing method.

In one embodiment of the present invention, step c) is a step of again removing the quaternary ammonium salt primarily bonded to the carboxyl group among the secondary bonded compounds. Specifically, an ammonium salt of an alkylcarboxylic acid may be used to remove the quaternary ammonium salt bound to the primary, and specifically, tetraalkylammonium (C1-C20)alkylcarboxylic acid or trialkylammonium (C1-C20)alkylcarboxylic acid acid, preferably tetra(C1-C5)alkylammonium(C1-C20)alkylcarboxylic acid or tri(C1-C5)alkylammonium(C1-C20)alkylcarboxylic acid. Specifically, the ammonium salt of the alkyl carboxylic acid may be a tetraammonium salt of the alkyl carboxylic acid, preferably R ₃ COO ^- N ⁺ (R ₄ R ₅ R ₆ R ₇ ) may be satisfied. R ₃ is an alkyl group having 1 to 20 carbon atoms, and R ₄ to R ₇ are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms. More preferably, R ₃ may be an alkyl group having 10 to 20 carbon atoms, and R ₄ to R ₇ may each independently be hydrogen or an alkyl group having 1 to 3 carbon atoms. By removing the quaternary ammonium salt as described above, a carboxyl group is formed in the final gold nanoclusters to lose solubility in an organic solvent and to have water solubility again. By having water solubility in this way, it has compatibility with the living environment in which water exists, and thus can be used in the bio field. In addition to this, it can be applied in various fields requiring excellent fluorescence.

Hereinafter, a gold nanocluster according to the present invention, a method for manufacturing the same, and an optical sensor including the same will be described in more detail through examples. However, the following examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Also, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein is for the purpose of effectively describing particular embodiments only and is not intended to limit the invention. In addition, the unit of additives not specifically described in the specification may be weight %.

[Preparation Example 1] Synthesis of Au ₂₂ GS ₁₈ Cluster

0.25 mmol of HAuCl ₄ .3H ₂ O dissolved in 12.50 ml of water and 0.37 mmol of glutathione (GS) dissolved in 7.50 ml of water were simultaneously added to 230 ml of water, followed by vigorous stirring for 2 minutes. Then, when the color of the solution changed to turbid yellow, 1 M NaOH was added to increase the pH to 12. To the solution, 0.1 ml of NaBH ₄ having a concentration of 3.5 mM was slowly added dropwise to the solution. Then, after stirring for 30 minutes, the pH of the solution was lowered to 2.5 using 1 M HCl, followed by further stirring at room temperature for 6 hours. After completion of the reaction, the solvent was completely removed by rotary evaporation, dissolved in 10 ml of water, and 12 ml of isopropanol was added to precipitate the solid formed by using a centrifugal separator to separate Au ₂₂ GS ₁₈ nanoclusters through recrystallization. A solid formed by adding 2 ㎖ of isopropanol to the supernatant was separated through a centrifuge, and this process was continued until the supernatant became transparent. The separated solid was washed with excess isopropanol and methanol to remove unreacted impurities to obtain gold nanoclusters (Au ₂₂ GS ₁₈ ), which are Au ₂₂ clusters protected with glutathione ligand (GS).

2 shows the mass spectrometry results of the gold nanoclusters (Au ₂₂ GS ₁₈ ) prepared in Preparation Example 1. From this, it can be seen that gold nanoclusters (Au ₂₂ GS ₁₈ ) were synthesized.

[Preparation Example 2] Synthesis of Au ₁₈ GS ₁₄ cluster

0.25 mmol of HAuCl ₄ 3H ₂ O dissolved in 12.0 ml of water and 0.37 mmol of glutathione (GS) dissolved in 8.0 ml of water were simultaneously added to 230 ml of water, and stirred vigorously for 2 minutes. Then, when the color of the solution changed to turbid yellow, 1 M NaOH was added to increase the pH to 10. Thereafter, carbon monoxide gas was purged at 1 atm for 2 minutes, followed by vigorous stirring for 16 hours. When the reaction is complete, after the reaction is completed, half of the solvent is evaporated by rotary evaporation, the solution is placed in an ion removal column with 3000 Da cut off as a filter, and the solution is rotated at 4000 rpm for 7 minutes with a centrifuge to remove unreacted impurities and glutathione ligand. Gold nanoclusters (Au ₁₈ GS ₁₄ ), which are Au ₁₈ clusters protected with (GS), were obtained.

[Preparation Example 3] Synthesis of Au ₂₅ GS ₁₈ cluster

0.394 g of HAuCl ₄ .3H ₂ O dissolved in 80 ml of methanol and 1.23 g of glutathione (GS) dissolved in 40 ml of water were simultaneously mixed, stirred vigorously for 30 minutes, and the color of the solution When it turned cloudy white, 0.374 g NaBH ₄ dissolved in 10 ml of water was added and vigorously stirred for 1 hour and 30 minutes. After evaporating all the solvents, 10 ml of water was added and dissolved. Each 5 ml each was transferred to a Falcon tube, 1 ml of methanol was added thereto, shaken, and centrifuged. The supernatant was transferred to another falcon tube and a solid that fell below was obtained. The centrifugation method was repeated after adding methanol until the supernatant became transparent. The separated solid was washed with excess isopropanol and methanol to remove unreacted impurities to obtain gold nanoclusters (Au ₂₅ GS ₁₈ ), which are Au ₂₅ clusters protected with glutathione ligand (GS).

[Example 1] Au ₂₂ GS ₁₈ Bpy ₁₈

After dissolving 10 mg of Au ₂₂ GS ₁₈ of Preparation Example 1 in 10 ml of water, a solution obtained by dissolving 20 mg of tetraoctylammonium bromide (TOABr) in 1 ml of toluene was additionally added. Then, after raising the pH to 9 using 1 M NaOH, and stirring the entire solution, Au ₂₂ GS ₁₈ dissolved in water was strongly ionically bound to tetraoctylammonium cation (TOA) to form an ionic complex. The product, the ionic complex, lost its solubility in water and all phase transferred to the toluene layer. Thereafter, the toluene layer was separated in a vial, and 15 ml of water was added to remove excess tetraoctylammonium bromide (TOABr) and other impurities that did not react with Au ₂₂ GS ₁₈ to prepare TOA-Au ₂₂ clusters.

79 mg of 1-pyrenvaleric acid (BPy) was dissolved in 5 ml of dichloromethane, and 2 mg of 4-dimethylaminopyridine was added thereto. Then, 282 mg (1.35 mmol) of dicyclohexylcarbodiimide (DCC) was dissolved in 1 ml of dichloromethane, dicyclohexylcarbodiimide was added in a molar ratio of 5-fold that of 1-pyrene valeric acid (BPy), and the mixture was stirred. . After dissolving 315 mg (2.7 mmol) of N-hydroxysuccinimide (NHS) in 6 ml of acetone, it was sequentially added to the reaction solution in a molar ratio 10 times that of 1-pyrene valeric acid (BPy). After stirring for 24 hours, impurities were removed to obtain a reaction intermediate (NHS-BPy) in which N-hydroxysuccinimide was bound to 1-pyrene valeric acid.

0.015 mmol of the reaction intermediate (NHS-BPy) dissolved in 1 ml of dichloromethane was added to the TOA-Au ₂₂ cluster dissolved in 5 ml of dichloromethane at 0.001 mmol, and the mixture was stirred for 16 hours. After that, 0.07 mmol of 0.1M tetraethylammonium decanoic acid dissolved in methanol was added to remove tetraoctylammonium cation (TOA) to prepare gold nanoclusters, which were obtained by polyacrylamide gel electrophoresis (Polyacrylamide gel electrophoresis, PAGE) through Au ₂₂ GS ₁₈ BPy ₁₈ material, Au ₂₂ GS ₁₈ BPy ₁₇ material (Example 2), Au ₂₂ GS ₁₈ BPy ₁₆ material (Example 3), Au ₂₂ GS ₁₈ BPy ₁₅ material (Example 4) , Au ₂₂ GS ₁₈ BPy ₁₁ material (Example 5), Au ₂₂ GS ₁₈ BPy ₁₁ material (Example 6) and Au ₂₂ GS ₁₈ BPy ₁₀ material (Example 7) were obtained by separating, respectively.

¹ H-NMR of the Au ₂₂ GS ₁₈ BPy ₁₈ material prepared in Example 1 is shown in FIG. 3 , and it can be seen that Au ₂₂ GS ₁₈ BPy ₁₈ of Example 1 was prepared as shown in FIG. 3 .

[Example 8] Au ₂₂ GS ₁₈ Bpy ₇

In Example 1, 0.007 mmol of the reaction intermediate (NHS-BPy) dissolved in 1 ml of dichloromethane was added to the TOA-Au ₂₂ cluster dissolved in 5 ml of dichloromethane at 0.001 mmol. Gold nanoclusters obtained in the same manner as in Example 1 were obtained by separating Au ₂₂ GS ₁₈ BPy ₇ materials through polyacrylamide gel electrophoresis (PAGE).

[Example 9] Au ₂₂ GS ₁₈ Bpy ₆

Gold obtained by adding 0.007 mmol of the reaction intermediate (NHS-BPy) dissolved in 1 ml of dichloromethane to the TOA-Au ₂₂ cluster dissolved in 5 ml of dichloromethane in Example 1 at 0.001 mmol Nanoclusters were obtained by separating Au ₂₂ GS ₁₈ BPy ₆ materials through polyacrylamide gel electrophoresis (PAGE).

[Example 10] Au ₁₈ GS ₁₄ Bpy ₁₄

In Example 1, Au ₁₈ GS ₁₄ prepared in Preparation Example 2 was used instead of Au ₂₂ GS ₁₈ to obtain a gold nanocluster Au ₁₈ GS ₁₄ Bpy _14. The same procedure was performed.

[Example 11] Au ₂₅ GS ₁₈ Bpy ₁₈

A gold nanocluster Au ₂₅ GS ₁₈ Bpy ₁₈ was obtained in the same manner as in Example 1 except that Au ₂₅ GS ₁₈ prepared in Preparation Example 3 was used instead of Au ₂₂ GS ₁₈ in Example 1.

[Comparative Example 1]

Au ₂₂ GS ₁₈ prepared in Preparation Example 1 was used as it is.

[Comparative Example 2]

Au ₂₅ GS ₁₈ prepared in Preparation Example 1 was used as it was.

[Result analysis]

Luminescence characteristics

As shown in FIG. 4 , the absorbance of the gold nanoclusters of Examples 1 to 11 and Comparative Example 1 was observed. Through the absorbance, it was confirmed that the peak intensity increased as the number of pyrene groups (BPy) bonded to the gold nanoclusters increased.

As shown in FIG. 5 , the PL characteristics of the gold nanoclusters of Examples 1 to 11 and Comparative Example 1 were observed. Compared to Comparative Example 1, when measured at an excitation wavelength of 350 nm, it was confirmed that the emission peaks were expressed at 380 nm, 480 nm, and 650 nm. As the number of pyrene groups (BPy) increased, energy transfer became more active, and it was confirmed that fluorescence was improved. Moreover, in the case of Example 1 in which 18 pyrene groups were combined, it was observed that the light emission intensity of 380 nm, 480 nm, and 650 nm was remarkably improved while emitting white light.

Moreover, when the emission intensity of 380 nm, 480 nm and 650 nm emission peaks was observed with the gold nanoclusters of Examples 1 to 11 as shown in FIG. 6, the number of pyrene groups (BPy) bonded to the gold nanoclusters It was confirmed that the luminescence intensity increased as the .

In addition, as shown in FIG. 7 , the PL characteristics of the gold nanoclusters of Example 11 were observed. Compared to Comparative Example 2, when measured at an excitation wavelength of 350 nm, emission peaks were expressed at 380 nm, 480 nm, and 650 nm, and it was observed that the emission intensity was significantly improved while emitting white light.

In addition, it was observed that the gold nanoclusters of Example 10 also had the same pattern as Examples 1 and 11, exhibited emission peaks at 380 nm, 480 nm, and 650 nm, and emitted white light while the emission intensity was remarkably improved. did

The gold nanoclusters according to the present invention can not only easily control the number of end-group bonds, but also induce end-group bonds as much as the number of ligands, so that they can have strong luminescence intensity. It can be applied to various optical sensors due to its excellent luminescence and fluorescence characteristics, and the final material has water solubility, so it is excellent in application to bio fields such as living body.

Although the present invention has been described with reference to specific matters and limited examples as described above, these are only provided to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and the present invention pertains to Various modifications and variations are possible from these descriptions by those of ordinary skill in the art.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and not only the claims described below, but also all of the claims and all equivalents or equivalent modifications to the claims will be said to belong to the scope of the spirit of the present invention. .

Claims (9)

Gold nanoclusters satisfying the following formula (1).
[Formula 1]

(In Formula 1 above
L ₁ is a trivalent linking group, and the trivalent linking group is a hydrocarbon backbone that may include any one or more selected from -O-, -C(=O)-, -COO-, -NH-, and -CONH-; ,
R ₁ is each independently hydrogen or -C(=O)-R ₁₁ -Ar ₁ , wherein at least one of R ₁ in y units is -C(=O)-R ₁₁ -Ar ₁ , and R ₁₁ is an alkylene group having 1 to 6 carbon atoms, and Ar ₁ is an aryl group having 6 to 50 carbon atoms,
x is 18, 22, 25, 38, 67, 102, 144 or 333;
y is 14, 18, 24, 35, 44, 60 or 79.) The method of claim 1,
In Chemical Formula 1, the hydrocarbon backbone is -OH, -COOH, and -NH ₂ Gold nanoclusters having one or more substituents selected from the group consisting of. The method of claim 1,
The L ₁ is

or

is,
R ₁₁ is an alkylene group having 2 to 6 carbon atoms, and Ar ₁ is aryl having 6 to 30 carbon atoms. An optical sensor comprising the gold nanoclusters of any one of claims 1 to 3. a) reacting a compound represented by the following formula (2) and a quaternary ammonium salt to first bond a quaternary ammonium salt to a carboxyl group of the compound represented by formula (2);
b) forming an amide bond by secondary bonding a compound represented by the following Chemical Formula 3 to the amino group of the primary bonded compound; and
c) removing the quaternary ammonium salt primarily bonded to the carboxyl group among the secondary bonded compounds
A method for preparing gold nanoclusters represented by the following formula (1), including:
[Formula 1]

[Formula 2]

[Formula 3]

(In Formulas 1 to 3,
L ₁ is a trivalent linking group, and the trivalent linking group is a hydrocarbon backbone that may include any one or more selected from -O-, -C(=O)-, -COO-, -NH-, and -CONH-; ,
R ₁ is each independently hydrogen or -C(=O)-R ₁₁ -Ar ₁ , and at least one of R ₁ in y units is -C(=O)-R ₁₁ -Ar ₁ , wherein R ₁₁ is an alkylene group having 1 to 6 carbon atoms, and Ar ₁ is an aryl group having 6 to 50 carbon atoms,
R ₂ is hydrogen or a leaving group,
x is 18, 22, 25, 38, 67, 102, 144 or 333;
y is 14, 18, 24, 35, 44, 60 or 79.) 6. The method of claim 5,
Steps b) and c) are a method for preparing gold nanoclusters that are performed in an organic solvent. 6. The method of claim 5,
In Formulas 1 to 3, the hydrocarbon backbone is -OH, -COOH, and -NH ₂ A method for producing a gold nanoclusters having any one or two or more substituents selected from the group consisting of. 6. The method of claim 5,
The molar ratio of the primary bound compound to the compound of Formula 3 is 1: 5 to 25. A method for producing a gold nanocluster. 6. The method of claim 5,
Step c) is a method for preparing gold nanoclusters that is carried out with tetraalkylammonium (C1-C20)alkylcarboxylic acid or trialkylammonium (C1-C20)alkylcarboxylic acid.

Images