KR20120052609A - Water-soluble magnetic nanoparticles functionalized with photosensitizer and the use therof - Google Patents

Abstract

PURPOSE: A magnetic nanoparticle which is conjugated with photosensitizer by covalent bond is provided to improve decomposition efficiency and to completely remove toxic organic materials. CONSTITUTION: A magnetic nanoparticle has a photosensitizer which generates reactive oxygen on the surface. The photosensitizer is a compound of chemical formula 1. The photosensitizer is conjugated on the surface of the magnetic nanoparticles. A method for modifying the surface of the magnetic nanoparticles comprises a step of reacting the photosensitizer which generates active oxygen.

Description

Water-soluble magnetic nanoparticles functionalized with photosensitizer and the use therof}

The present invention can be used as a photocatalyst capable of decomposing toxic organic substances, magnetic nanoparticles covalently coupled with photosensitive molecules generating active oxygen in the ultraviolet and visible region, which are easy to recover and reuse the photocatalyst, and uses thereof. It is about.

In recent decades, efforts have been made to purify wastewater and groundwater by chlorinated compounds. Chlorophenol among chlorinated organic compounds has been widely used in compounds for wood preservatives, pesticides, herbicides, insecticides, and fungicides. Also, they are present in the paper mill waste. Chlorophenol is toxic, hardly biodegradable and difficult to remove from the environment. Thus, chlorophenol has become one of the major environmental pollutants and has been selected by the US EPA as a major pollutant. Due to their toxicity to human and animal organisms, strict limits on the concentration of these compounds in wastewater are increasingly imposed for safe discharge. Therefore, it is very important to find innovative and inexpensive methods for the safe and complete disposal of chlorophenols such as 2,4,6-trichlorophenol and pentachlorophenol.

Several physical, chemical and biological techniques have been applied to remove chlorophenol, such as activated carbon uptake, incineration, membrane filtration, ion exchange, electrochemical oxidation and biodegradation. These techniques have the disadvantage that the removal efficiency is significantly reduced at trace levels. In addition, these techniques are expensive to process and potentially secondary pollution.

Photocatalytic oxidation, an advanced oxidation process, is one of the inexpensive techniques for the decomposition of chlorophenols. The main principle of photocatalytic oxidation lies in the formation of reactive oxygen species, which is the main oxidant for organic pollutants. Free radical species attack organic pollutants in water and convert them into carbon dioxide, water and inorganic acids. However, this photocatalytic oxidation method is limited in the separation and recovery of the catalysts used for reuse.

On the other hand, as a technique for decomposing chlorophenol using photosensitive molecules, research on photodegradation of toxic molecules such as chlorophenol and dimethylphenol using photosensitive molecules has been conducted, but this is simply photodegradation between photosensitive molecules and toxic molecules. It was only a local study of the reaction ( Photochem. Photobiol. Sci . 2005, 4, 617-624). In addition, photosensitive molecules were introduced into mesoporous silica nanoparticles having a very large surface area, and a study on the photooxidation reaction of trichlorophenol was performed, but it is difficult to recover or reuse the photodegradant ( Chem. Mater . 2007, 19, 1452-1458). Research has been carried out to introduce photosensitive molecules into very small organic nanoparticles based on polyacrylamide, to confirm the production efficiency of free radicals, and to explore the potential as photodynamic therapeutic agents ( Angew. Chem. Int . Ed. 2007, 46, 2224-2227), a study on the preparation of wastewater treatment using magnetic nanoparticles / polymeric core-cell nanoparticles that can be used as a nano-fenton system has been reported. There is a possibility of the formation of by-products as a reaction requiring hydrogen peroxide rather than a photooxidation reaction (Korean Patent Publication No. 2010-0078936).

Therefore, it is necessary to develop an improved photocatalyst capable of completely decomposing toxic organic substances without by-products through powerful photooxidation reactions and easily recovering and reusing photocatalysts.

It is an object of the present invention to provide an improved photocatalyst which is capable of decomposing toxic organic substances without by-products through a strong photooxidation reaction and which is easy to recover and reuse.

In order to achieve the above object, the present invention provides a magnetic nanoparticle in which a photosensitive molecule that generates active oxygen in the ultraviolet and visible light region is bonded to the surface.

In one embodiment, the photosensitive molecule may be a compound represented by the following formula (1):

[Formula 1]

Where

M represents a transition metal of Groups 7 to 12,

R ₁ and R ₄ are each independently C _5-12 aryl or _5-12 reduced heteroaryl substituted with a carboxyl group,

R ₂ and R ₃ are each independently

Hydrogen;

C _1-6 alkyl; C _1-6 alkoxy; Amines; And C _5-12 aryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy; or

C _1-6 alkyl; C _1-6 alkoxy; Amines; And 5-12 membered heteroaryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy,

C _5-12 aryl or _5-12 reduced heteroaryl substituted by carboxyl group.

The present invention also provides a method for surface modification of magnetic nanoparticles comprising the step of reacting the magnetic nanoparticles and photosensitive molecules generating active oxygen in the ultraviolet and visible region.

The present invention also provides a photocatalyst comprising the surface-modified magnetic nanoparticles according to the present invention.

The present invention also provides a method of recovering the photocatalyst of the present invention using a magnet.

The present invention also provides a wastewater purification method comprising the step of reacting the photocatalyst and wastewater of the present invention under ultraviolet or visible light.

The photofunctional magnetic nanoparticles of the present invention start the reaction using light without any other conditions to improve the decomposition efficiency compared to the conventional photocatalyst, and easy to recover and reuse using the huge surface area and magnetic properties of the magnetic nanoparticles. In addition, powerful photo-oxidation reactions using photosensitive molecules can completely remove not only chlorophenol but also many other toxic organic substances.

Figure 1 shows the manufacturing process of the optical functional magnetic nanoparticles of the present invention.
Figure 2 is a TEM photograph of the magnetite nanoparticles (a) and the photofunctional magnetic nanoparticles (b) of the present invention, the internal photograph thereof is a high-resolution TEM photograph of each nanoparticle, (c) is a magnetite nanoparticles Histogram for particle size distribution, (d) shows the XRD pattern of magnetite nanoparticles.
Figure 3 shows the solubility of the magnetic nanoparticles of the present invention before and after surface modification, (a) are synthetic nanoparticles in hexane, (b) are nanoparticles modified with t-PtCP in water, (c ) Is a nanoparticle modified with t-PtCP in the presence of an external magnetic field.
Figure 4 shows the room temperature magnetic hysteresis loop of the magnetite nanoparticles and the photofunctional magnetic nanoparticles of the present invention.
Figure 5 shows the FT-IR spectrum of t-PtCP and photofunctional magnetic nanoparticles of the present invention.
Figure 6 shows the absorption spectrum (a) and emission spectrum (b, excitation wavelength: 510 nm) of t-PtCP and the photofunctional magnetic nanoparticles of the present invention in THF.
7 shows phosphorescent decay by relaxation of singlet oxygen from standard H ₂ TPP (a), t-PtCP (b) and the photofunctional magnetic nanoparticles (c) of the present invention. At 1270 nm and fitted to a single exponent (solid line).
FIG. 8 shows UV-Vis spectra according to reaction time of DPBF in the presence of photofunctional magnetic nanoparticles photoexcited in THF solution by irradiating a 510 nm laser beam, and an internal view shows H ₂ TPP (a And absorption absorbance of DPBF at 435 nm per irradiation time for the dispersed photofunctional magnetic nanoparticles (b) of the present invention.
Figure 9 shows the change in absorption spectrum of 2,4,6-TCP aqueous solution of pH 10 according to the photocatalytic reaction time using the photo-functional magnetic nanoparticles of the present invention, the internal view is 2,4,6- by irradiation time The rate of change between the reaction absorbance (C) and the initial absorbance (Co) of TCP.

EMBODIMENT OF THE INVENTION Hereinafter, the structure of this invention is demonstrated concretely.

The present invention relates to magnetic nanoparticles in which photosensitive molecules that generate free radicals in the ultraviolet and visible light regions are bonded to the surface.

Magnetic nanoparticles of the present invention is characterized in that the photosensitive molecules that generate singlet oxygen with high efficiency are chemically bonded to the surface of the nanoparticles. Preferably, it may be bound through covalent bonds such as asterislation, imine reaction, coordination bond, and the like.

The photosensitive molecule is not particularly limited as long as it can generate free radicals in the ultraviolet and visible region, and the terminal functional group can covalently bond with metal ions on the surface of the magnetic nanoparticle having the surface complex structure.

Preferably, the photosensitive molecules may be a compound represented by the following formula (1):

[Formula 1]

Where

M represents a transition metal of Groups 7 to 12,

R ₁ and R ₄ are each independently C _5-12 aryl or _5-12 reduced heteroaryl substituted with a carboxyl group,

R ₂ and R ₃ are each independently

Hydrogen;

C _1-6 alkyl; C _1-6 alkoxy; Amines; And C _5-12 aryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy; or

C _1-6 alkyl; C _1-6 alkoxy; Amines; And 5-12 membered heteroaryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy,

C _5-12 aryl or _5-12 reduced heteroaryl substituted by carboxyl group.

The terms used in the substituent definitions of the compounds of the present invention are as follows.

"Alkyl" refers to a straight or branched chain or cyclic saturated hydrocarbon having 1 to 30 carbon atoms unless otherwise stated. Examples of C _1-30 alkyl groups are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isopropyl, isobutyl, sec-butyl and tert-butyl, isopentyl, neopentyl, isohexyl , Isoheptyl, isooctyl, isononyl and isodedecyl, but is not limited thereto. The alkyl also includes "cycloalkyl". The cycloalkyl includes a monocyclic and fused ring as a non-aromatic, saturated hydrocarbon ring having 3 to 12 carbon atoms, unless otherwise specified. Representative examples of C _3-12 cycloalkyl include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.

"Alkoxy" means an alkyl group having 1 to 6 carbon atoms, such as 1 to 4 carbon atoms, bonded to an oxygen atom unless otherwise specified. Examples of C _1-4 alkoxy groups include, but are not limited to, methoxy, ethoxy, propoxy, and butoxy.

"Aryl" refers to 5 to 12-reduced aromatic cyclic compounds unless otherwise stated. Examples of aryl groups include, but are not limited to, phenyl, biphenyl, naphthyl and anthracenyl.

"Heteroaryl" refers to a 5 to 12-reduced aromatic cyclic compound containing at least one nitrogen, oxygen, or sulfur atom, unless otherwise noted. Examples of heteroaryl groups include, but are not limited to, pyridinyl, pyridazinyl, pyrimidyl, pyrazyl, triazinyl, pyrrolyl, pyrazolyl, imidazolyl, and the like.

Compound of Formula 1 is specifically

M represents Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu or Zn,

R ₁ and R ₄ are phenyl or pyridinyl substituted with a carboxyl group,

R ₂ and R ₃ are each independently

Phenyl unsubstituted or substituted with amines; or

C _1-4 alkyl; Or pyridinyl unsubstituted or substituted with benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-4 alkoxy,

Phenyl or pyridinyl substituted with a carboxyl group.

The compound of Formula 1 is more specifically

M represents Ni, Pd, or Pt,

R ₁ and R ₄ are phenyl or pyridinyl substituted with a carboxyl group,

R ₂ and R ₃ are each independently

Phenyl unsubstituted or substituted with amines; or

C _1-4 alkyl; Or pyridinyl unsubstituted or substituted with benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-4 alkoxy.

The compound of Formula 1 is more specifically

이고, R ₁ and R ₄

ego,

,

,

,

,

,

, 또는

를 나타낼 수 있다.
R ₂ and R ₃ are each independently

,

,

,

,

,

, or

Can be represented.

The compound of Formula 1 is most specifically

M represents Pt,

R ₁ and R ₄ are phenyl substituted with a carboxyl group,

R ₂ and R ₃ may represent phenyl.

The photophysical properties of the compound of Formula 1 are as follows.

The compound of Formula 1 exhibits a B band in the ultraviolet region and a Q band in the visible region, and the Q band exhibits two peaks at 510 nm and 538 nm. No fluorescence spectra of this compound were observed, and the phosphorescence spectra showed peaks at 660 nm and 725 nm.

In addition, the quantum yield of singlet oxygen under aeration conditions is measured to be 0.65 ± 0.05, and this high value is achieved by efficient energy transfer from triplet oxygen to ground triplet oxygen in triplet state. It is considered to be.

The photofunctional magnetic nanoparticles with surface modification of the present invention have no significant difference in terms of morphology and crystal structure of the magnetic nanoparticles before surface modification. That is, it shows a spherical shape, the average particle size is about 4 to 6 nm, and shows a single crystal structure.

In the surface-modified magnetic nanoparticles of the present invention, the metal ions of the magnetic nanoparticles and the functional groups of the photosensitive molecules are covalently bound to each other.

According to one embodiment, in the IR spectrum of the photosensitive molecule, t-PtCP, a strong peak corresponding to the stretching frequency of the carbonyl double bond (υ _{c = O} ) at 1689 cm ⁻¹ and carbon—at 1421 cm ⁻¹ Oxygen Single Bond (υ _cO ) Peak corresponding to the stretching frequency of, at the binding strain of the hydroxyl group at 1290 cm ^-1 (υ _c-OH ) Peaks are observed. These characteristic peaks suggest that the t-PtCP photosensitive molecule contains a carboxyl group including a proton. After surface modification, the characteristic peaks indicating the presence of the carboxyl groups of the t-PtCP photosensitive molecules disappear, and the asymmetric stretching mode of carboxylate COO ⁻ at 1559 cm ⁻¹ and the symmetric stretching mode of carboxylic acid at 1408 cm ⁻¹ A new band is created. Therefore, it can be seen that the surface-modified photo-functional magnetic nanoparticles have a dicarboxylic acid bonded to the surface of the magnetic nanoparticles.

In view of the photophysical properties of the surface modified photofunctional magnetic nanoparticles of the present invention, the absorption spectrum of the photofunctional magnetic nanoparticles is the same as that of the photosensitive molecules.

In one embodiment, the peak at 400 nm is the Soret band of t-PtCP and the peaks of the Q band are located at 510 nm and 538 nm. At an excitation wavelength of 408 nm, t-PtCP produces two strong emission peaks at 660 nm and 725 nm, while the photofunctional magnetic nanoparticles show a slightly blue shifted peak at 651 nm and 715 nm. The shifted peak in blue is due to the strong binding between t-PtCP and the surface of the magnetic nanoparticles.

In one embodiment, the lifetime of the singlet oxygen of the surface modified photofunctional magnetic nanoparticles is 20 kPa or less, and the quantum yield of the singlet oxygen is 0.47 ± 0.03.

In addition, the magnetic nanoparticles before the surface modification may be dispersed in water or an organic solvent depending on the type of the structural stabilizer on the particles, the surface-modified magnetic nanoparticles are mostly photosensitive molecules of the structural stabilizer on the nanoparticles Substitution may vary the solvent dispersion. Preferably, the photofunctional magnetic nanoparticles whose surface is modified are characterized as having water dispersibility.

In addition, the surface-modified photo-functional magnetic nanoparticles of the present invention have superparamagnetic properties with a saturation magnetization value of 28.5 emu / g.

In addition, the surface-modified photo-functional magnetic nanoparticles of the present invention can be easily recovered through a magnetic medium, for example, a magnet.

In one embodiment, contacting a magnet from the outside of a cuvette containing a surface-modified photo-functional magnetic nanoparticle collects the nanoparticle toward the magnet, and the collected particles can be dispersed again in water with moderate shaking. When the surface-modified photo-functional magnetic nanoparticles of the present invention are used as a photocatalyst, recovery is easy, and in particular, there is no possibility of secondary contamination, and thus reuse is possible.

In addition, the surface-modified photo-functional magnetic nanoparticles of the present invention generates a high yield of singlet oxygen, which is capable of photocatalytic decomposition with singlet oxygen, for example, 2,4, under visible light or ultraviolet light. Chlorinated compounds including chlorophenols such as 6-trichlorophenol and pentachlorophenol; Alternatively, it is possible to effectively decompose environmentally harmful substances having aromatic rings, such as phenol, dioxin-based environmental hormones, or dyes.

According to one embodiment, the photofunctional magnetic nanoparticles of the surface-modified the present invention upon visible light irradiation decomposes 2,4,6-trichlorophenol to absorb 2,4,6-trichlorophenol The corresponding peak gradually decreases and the peak corresponding to the decomposition product 2,4-dichlorobenzoquinone tends to increase gradually.

The present invention also relates to a method for surface modification of magnetic nanoparticles comprising reacting magnetic nanoparticles and photosensitive molecules that generate free radicals in the ultraviolet and visible region.

The surface modification method of the magnetic nanoparticles of the present invention may be performed through a simple process of mixing the magnetic nanoparticles and the photosensitive molecular solution and stirring them at room temperature.

The magnetic nanoparticles may be made of an alloy such as Ni, Co, Fe, MFe _x O _y , or FePt, but is not particularly limited thereto.

The manufacturing method of the magnetic nanoparticles is not particularly limited, for example, J. Am. Chem. Soc . 2004. 126, p273.

The photosensitive molecule is not particularly limited as long as it can generate free radicals in the ultraviolet and visible region, particularly in the long wavelength region, and the terminal functional group can covalently bond with metal ions on the surface of the magnetic nanoparticle having the surface complex structure. Preferably, the compound of Formula 1 may be used.

Method for preparing a compound of Formula 1

Preparing a compound of Formula 3 by mixing a porphyrin compound represented by Formula 2 and a metal precursor; And

It may include the step of preparing a compound of Formula 1 by substituting a carboxyl group CO ₂ CH ₃ group of the compound of Formula 3:

[Formula 2]

(3)

[Formula 1]

Where

M represents a transition metal of Groups 7 to 12,

R ₁ and R ₄ are each independently C _5-12 aryl or _5-12 reduced heteroaryl substituted with a carboxyl group,

R ₂ and R ₃ are each independently

Hydrogen;

C _1-6 alkyl; C _1-6 alkoxy; Amines; And C _5-12 aryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy; or

C _1-6 alkyl; C _1-6 alkoxy; Amines; And 5-12 membered heteroaryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy,

C _5-12 aryl or _5-12 reduced heteroaryl substituted by carboxyl group,

Ar represents C _5-12 arylene or _5-12 reduced heteroarylene.

Hereinafter, each step of the method for preparing the compound of Formula 1 according to the present invention will be described in detail.

The preparing of the compound of Formula 3 according to the present invention is a step of providing structural stability by mixing the compound of Formula 2 and the metal precursor in a solvent so that the metal is positioned at the center of the compound of Formula 2.

The compound of Formula 2 may be prepared by mixing a compound represented by Formula 4 to 6 under a catalyst and a solvent:

[Formula 4]

[Chemical Formula 5]

[Formula 6]

Where

Ar represents C _5-12 arylene or _5-12 reduced heteroarylene,

R is hydrogen;

C _1-6 alkyl; C _1-6 alkoxy; Amines; And C _5-12 aryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy; or

C _1-6 alkyl; C _1-6 alkoxy; Amines; And 5-12 membered heteroaryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy,

C _5-12 aryl or _5-12 reduced heteroaryl substituted by carboxyl group.

2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) may be used as the catalyst, but is not particularly limited thereto.

BF _{3 ~} OEt ₂ may be used as the solvent, but is not particularly limited thereto.

In one embodiment, the compound of formula 2 according to the present invention is concentrated in a BF ₃ ? OEt ₂ solution of methyl-4-formylbenzoate, benzaldehyde and pyrrole, and then catalyzed by 2,3-dichloro-5,6- It can be prepared by reacting the mixture by adding dicyano-1,4-benzoquinone (DDQ).

The compound of Formula 2 and the metal precursor may be suspended in a solvent, purged with nitrogen gas, heated and refluxed to prepare a compound of Formula 3.

Benzenitrile and the like may be used as the solvent, but is not particularly limited thereto.

PtCl ₂ , PtCl ₄ , PtCl, PtCl ₃ , PtO, or PtO ₂ may be used as the metal precursor, but is not particularly limited thereto.

The heating conditions may be carried out at room temperature to 200 ℃, but is not particularly limited thereto.

The reflux may be carried out under nitrogen gas and may be carried out until no free base remains.

Terminal group substitution of the compound of Formula 3 of the preparation method according to the present invention is a step of allowing the CO ₂ CH ₃ group to be covalently bonded to the nano-bulk structure by esterification or imine reaction by imparting hydrophilicity .

Substitution of the carboxyl group may be performed by mixing the compound of Formula 3 and KOH with a mixed solution of tetrahydrofuran (THF), ethanol and water, and then acidifying the mixture.

The tetrahydrofuran (THF), ethanol and water may be mixed in a weight ratio of 1: 1: 0.05 to 1: 1: 0.5, but is not particularly limited thereto.

According to one embodiment, the substitution with a carboxyl group may be carried out by mixing the compound of Formula 3 and KOH with a mixed solution of tetrahydrofuran (THF), ethanol and water, refluxing, cooling the mixture to room temperature and acidifying with HCl. Can be.

An example of the preparation method according to the present invention as described above is shown in Scheme 1 below.

Scheme 1

The invention also relates to a photocatalyst comprising the surface-modified magnetic nanoparticles according to the invention.

The photofunctional magnetic nanoparticles whose surface has been modified include photosensitive molecules capable of generating high yields of singlet oxygen under UV or visible light, thereby photooxidizing compounds capable of photocatalytic decomposition with singlet oxygen. It can be completely removed through the decomposition reaction.

Therefore, it is characterized by having a photocatalytic activity that effectively decomposes a compound capable of photocatalytic reaction with singlet oxygen, for example, a chlorinated compound, or an environmentally harmful substance having an aromatic ring.

According to one embodiment, the photofunctional magnetic nanoparticles of the surface-modified the present invention upon visible light irradiation decomposes 2,4,6-trichlorophenol to absorb 2,4,6-trichlorophenol The corresponding peak gradually decreases and the peak corresponding to the decomposition product 2,4-dichlorobenzoquinone tends to increase gradually.

The present invention also relates to a method for recovering the photocatalyst of the present invention using a magnet.

The photofunctional magnetic nanoparticles whose surface is modified can be easily recovered through a magnetic medium, for example, a magnet.

In one embodiment, contacting a magnet from the outside of a cuvette containing a surface-modified photo-functional magnetic nanoparticle collects the nanoparticle toward the magnet, and the collected particles can be dispersed again in water with moderate shaking. When the surface-modified photofunctional magnetic nanoparticles of the present invention are used as a photocatalyst, recovery and reuse may be easy.

The present invention also relates to a wastewater purification method comprising the step of reacting the photocatalyst and wastewater of the present invention under ultraviolet or visible light.

The photocatalyst of the present invention can completely remove the toxic substances present in the wastewater by initiating a strong photooxidation reaction of the photosensitive molecules using light without other conditions.

More specifically, the photocatalyst of the present invention includes a photosensitive molecule capable of generating a high yield of singlet oxygen, which is capable of photocatalytic reaction with singlet oxygen, for example, 2,4,6-trichloro Chlorinated compounds containing chlorophenols such as phenol and pentachlorophenol; Alternatively, environmentally harmful substances having aromatic rings, such as phenols, dioxins-based environmental hormones, or dyes, may be completely removed through photocatalytic decomposition.

The photocatalyst can be easily recovered through a magnet, and the recovered photocatalyst can be easily dispersed and reused in water to remove harmful environmental pollutants at a very low cost.

Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention, but the scope of the present invention is not limited by the following Examples.

Preparation Example 1 Synthesis of 1,5-bisphenyl-10,20-bis (4-Methoxycarbonylphenyl) -porphyrin [FB-Por]

Methyl-4-formylbenzoate (Fluka, 1.5 g, 9.137 mmol), benzaldehyde (0.97 g, 9.147 mmol) and pyrrole (1.27 mL, 18.26 mmol) were mixed to prepare BF ₃ -OEt ₂ (1.39 mL, 10.96 mmol). Concentrated chloroform (913 mL) at room temperature for 1 hour. Then DDQ (6.22 g, 27.41 mmol) was added. The mixture was stirred at rt for 1 h and then the solvent was removed via reduced pressure. The residue was taken up in CHCl ₃ and passed through a short silica column to remove non-porphyrin based compounds from the reaction mixture. The mixture was purified by secondary column (silica, CHCl ₃ ) to give FB-por compound (86 mg, 1.4%).

¹ H-NMR: (CDCl ₃ , 300 MHz) [ppm]: δ 8.87-8.81 (m, 8H, β-pyrrole), 8.46-8.43 (d, 4H, Ar-H), 8.32-8.29 (d, 4H, Ar-H), 8.29-8.23 (d, 4H, Ar-H), 7.78-7.61 (d, 4H, Ar-H), 4.12 (s, 6H, -OCH ₃ ), -2.78 (s, 2H , -NH);

FT-IR (KBr pellet, cm ⁻¹ ): 1720 (ester, C═O), 3315 (amine, —NH :);

FAB-MS (m / z): Calcd. C ₄₈ H ₃₄ N ₄ O ₄ 730.81, Found 731.0

Preparation Example 2 Synthesis of [5,15-bisphenyl-10,20-bis (4-methoxycarbonylphenyl) -porphyrin] Platinum [Pt (II) -por]

FB-por (0.5 g, 0.68 mmol) and PtCl ₂ (0.46 g, 1.71 mmol) were suspended in benzonitrile anhydride. The mixture was purged with nitrogen gas and heated slowly to 160 ° C. When developed in TLC, the mixture was refluxed under nitrogen gas until no free base remained. The mixture was cooled at room temperature and the solvent was removed by vacuum distillation. The final product was dried completely and purified on column (silica, CH ₂ Cl ₂ ) to give Pt (II) -por compound (400 mg, 86%).

¹ H-NMR: (CDCl ₃ , 300 MHz) [ppm]: 8.78-8.68 (m, 8H, β-pyrrole), 8.43-8.41 (d, 4H, Ar-H), 8.25-8.22 (d, 4H, Ar-H), 8.15-8.12 (d, 4H, Ar-H), 7.75-7.31 (d, 4H, Ar-H), 4.10 (s, 6H, -OCH ₃ );

FT-IR (KBr pellet, cm ⁻¹ ): 1720 (ester, C═O);

FAB-MS (m / z): Calcd. C ₄₈ H ₃₂ N ₄ O ₄ Pt 923.87, Found 924.0

Preparation Example 3 Synthesis of [5,15-bisphenyl-10,20-bis (4-carboxyphenyl) -porphyrin] Platinum [Pt (II) -por-COOH]

Pt (II) -Por (0.6 g, 0.65 mmol) and KOH (0.36 g, 6.49 mmol) are dissolved in THF-EtOH-H ₂ O (1: 1: 0.1, volume ratio, 50 mL) and the solution is 12 h. Reflux for a while. The mixture was cooled to room temperature and neutralized with HCl. Then extracted with CH ₂ Cl ₂ . The organic phase was washed with aqueous sodium bicarbonate solution and dried over sodium sulfate. Solvent was removed to give Pt (II) -por-COOH (500 mg, 85.9%).

¹ H-NMR: (DMSO, 300 MHz) [ppm]: 8.74 (s, 8H, β-pyrrole), 8.37-8.34 (d, 4H, Ar-H), 8.30-8.27 (d, 4H, Ar-H ), 8.17-8.15 (d, 4H, Ar-H), 7.82-7.80 (d, 4H, Ar-H);

FT-IR (KBr pellet, cm ^-1 ): 1690 (carboxylic acid, C = O), 2400-3400 (carboxylic acid, -COOH);

FAB-MS (m / z): Calcd. C ₄₆ H ₂₈ N ₄ O ₄ Pt 895.82, Found 896.0

Example 1 Preparation of Photofunctional Magnetic Nanoparticles

A similar method previously reported was applied to prepare magnetite (Fe ₃ O ₄ ) nanoparticles covered with oleylamine ( J. Am. Chem. Soc. 2004, 126 , 273). Fe (acac) ₃ , 1,2-hexadecanediol, oleylamine and phenyl ether were mixed and magnetically stirred under nitrogen gas. The mixed solution was heated at 200 ° C. for 30 minutes and refluxed for an additional 30 minutes at the same temperature under a nitrogen atmosphere. The dark brown mixture solution was cooled at room temperature. Under atmospheric conditions, ethanol was added to the mixture. Black compound precipitated and was separated by centrifugation. Redispersed with hexane.

Next, the precipitated magnetic nanoparticles (1.5 mg) were mixed with a t-PtCP / THF (1.8 × 10 ⁻² mM) solution. The mixed solution was stirred for 24 hours at room temperature. After the reaction was completed the product was washed several times with THF solution. The concentration of t-PtCP bound to the magnetic nanoparticles was detected by measuring the absorbance of the characteristic absorption peak at 510 nm corresponding to the Q band of t-PtCP.

Experimental Example 1 Characterization of Photofunctional Magnetic Nanoparticles

A transmission electron microscope (TEM, JEOL JEM-2100F) was used to measure the size and shape of the photofunctional magnetic nanoparticles. Crystalline properties and nanostructures of the composite nanoparticles were investigated using an X-ray diffractometer (XRD, PANalytical, X 'Pert Pro MPD) operating on Cu Kα radiation. Vibrating sample magnetometry (VSM, Lakeshore 7300) was used to measure the magnetization of the magnetic field loop at room temperature to H = 10 kOe. Infrared spectra were obtained using a PerkinElmer FT-IR spectrum 100 spectrometer. For IR measurements, samples were ground in a mortar and prepared in the form of compressed wafers (ca. 1% samples in KBr). Absorption and emission spectra were obtained on UV-Vis spectrophotometers (Hitachi, U-2800) and spectrofluorometers (Hitachi, F-4500), respectively.

As shown in FIG. 1, photofunctional magnetic nanoparticles were prepared through surface modification of magnetic nanoparticles using t-PtCP, which is a photosensitive molecule. The terminal carboxyl group of t-PtCP chemically bonds with Fe ions on the surface of the magnetic nanoparticle having the surface complex structure.

The morphology and crystal structure of magnetic nanoparticles and photofunctional magnetic nanoparticles were investigated using TEM and XRD. Both magnetic nanoparticles and photofunctional magnetic nanoparticles are spherical and are well dispersed on the TEM grid (FIGS. 2A and B). There was no significant change in their size and shape after surface modification.

2C shows a histogram of the size distribution of magnetic nanoparticles, which was evaluated using 300 particles in different regions of the TEM micrograph. The average particle size showed a uniform size of 5.2 ± 0.4 nm. In the high resolution TEM photographs, both nanoparticles showed a single crystal state (see also the internal photographs of FIGS. 2A and 2B). The distance between two neighboring planes is approximately 2.98 mm 3, which is consistent with the distance between the (220) planes of the magnetite nanoparticles of inverse spinel structure.

Powder XRD pattern results of magnetite nanoparticles (FIG. 2D), strong Bragg reflection peaks (2q = 30.0, 35.6, 43.3, 53.7, 57.0, 62.8 °) show standard Fe ₃ O ₄ powder diffraction data (JCPDS, card 19-0629) From their Miller indices (220), (311), (400), (422), (511), and (440), they were characteristic peaks of magnetite crystals of cubic form of inverse spinel structure. . The average particle diameter of 5.0 nm estimated from the Scherrer equation was consistent with the value measured by statistical analysis of the TEM photograph. This means that each individual particle is a single crystal. The Scherrer equation can be written as

Where λ is the wavelength used, B is the full width at half maximum (FWHM) measured in radians on the 2θ scale, and θ _B is the Bragg angle with respect to the measured hkl peak.

Figure 3 shows the solubility of the magnetic nanoparticles before and after the surface modification with t-PtCP, the magnetite nanoparticles before the modification reaction is well dispersed in hexane because there is an oleylamine group acting as a structural stabilizer on the particles (Fig. 3a) . On the other hand, surface-modified photofunctional magnetic nanoparticles are dispersed only in water, and the upper and lower layers are phase separated like hexane and water (FIG. 3B).

The results indicate that the water dispersibility of the photofunctional nanoparticles is that most of the oleylamine on the nanoparticles is substituted with t-PtCP.

As in Figure 3c, the photofunctional magnetic nanoparticles are collected by magnets on the outer surface of the cuvette. When the external magnets are removed, the collected particles are dispersed again in water with moderate shaking.

Magnetic properties of magnetite nanoparticles and photofunctional magnetic nanoparticles were measured using VSM at room temperature.

As shown in FIG. 4, the magnetization curve indicates no hysteresis and no residual magnetization even at the maximum magnetic field, which means the superparamagnetic properties of the nanoparticles. The magnetite nanoparticles showed a high saturation value of 32.2 emu / g, while the high saturation value of the surface modified photofunctional magnetic nanoparticles was 28.5 emu / g. The difference in saturation magnetization is due to the diamagnetic provision of t-PtCP molecules chemically bound to the surface of the nanoparticles.

Next, in order to confirm the binding between the carboxyl group and the metal ion, the FT-IR spectrum of the t-PtCP and the photofunctional magnetic nanoparticles was measured.

As shown in Figure 5, the major peak position of the photofunctional nanoparticles was in good agreement with the main peak of t-PtCP. This means that the t-PtCP molecule is present on the surface of the photofunctional magnetic nanoparticles even after several washings with a THF solvent.

In the t-PtCP IR spectrum, a strong peak corresponding to the stretching frequency of the carbonyl double bond (υ _{c = O} ) at 1689 cm ⁻¹ and a carbon-oxygen single bond (υ _cO ) at 1421 cm ⁻¹ Peak corresponding to the stretching frequency of, at the binding strain of the hydroxyl group at 1290 cm ^-1 (υ _c-OH ) Peaks are observed. These characteristic peaks suggest that the t-PtCP photosensitive molecule contains a carboxyl group containing a proton. After surface modification, the characteristic peaks indicating the presence of the carboxyl group of the t-PtCP photosensitive molecule disappeared, the asymmetric stretching mode of the carboxylate COO ⁻ at 1559 cm ⁻¹ and the symmetric stretching of the carboxylic acid at 1408 cm ⁻¹ A new band of modes is created. Based on these observations, it was concluded that FT-IR could not provide quantitative information by content on the particle surface, but bound dicarboxylic acid to the surface of magnetite nanoparticles.

6 (a) shows that the absorption spectrum of the photofunctional magnetic nanoparticles has the same characteristics as that of t-PtCP in THF. At 400 nm the peak is the Soret band of t-PtCP and the Q band peaks are located at 510 nm and 538 nm. At an excitation wavelength of 408 nm, t-PtCP produces two strong emission peaks at 660 nm and 725 nm, while the photofunctional magnetic nanoparticles show a slightly blue shifted peak at 651 nm and 715 nm. The blue shifted peak was thought to be due to the strong binding between t-PtCP and the surface of the magnetic nanoparticles.

Experimental Example 2 Direct Detection of Singlet Oxygen Generated by Photofunctional Magnetic Nanoparticles

Phosphorescence emitted from the photoexcited t-PtCP bound to the nanoparticles was directly detected to confirm the generation of singlet oxygen from the photofunctional magnetic nanoparticles.

The quantum yield of singlet oxygen (φ _Δ ( ¹ O ₂ )) and its lifetime were determined by detecting near infrared phosphorescence emission peaks at 1270 nm. Phosphorescent signals were collected using germanium photodiodes (EG & G, Judson) at normal angles to the excitation beam (<1000 nm, CVI) and the interference filter (1270 nm, spectrogon) passing through the cut-off. Nd-YAG pumped OPO laser (BM Industries, OP901-355, 5 ns FWHM pulse) was used as the excitation source. The signal collected by the 500 MHz digital oscilloscope was passed for data analysis. The singlet oxygen phosphorescent signal over time is shown in FIG. 7.

As shown in FIG. 7, the lifetime of the singlet oxygen of H ₂ TPP, t-PtCP, and bound t-PtCP in THF solution was all ˜20 μs, which is consistent with the values reported in the literature.

The quantum yield (φ _Δ ) of singlet oxygen of the sample was measured by comparing the phosphorescence intensity at 1270 nm with respect to the sample and H ₂ TPP as a standard in THF solution. Singlet oxygen quantum yield of photofunctional magnetic nanoparticles was estimated to be 0.47 ± 0.03, whereas t-PtCP was estimated to be 0.65 ± 0.05. The low φ _Δ value of 0.47 compared to 0.65 is likely due to the closed contact between more existing t-PtCP molecules bound to the surface of the nanoparticles than the free molecules in solution. Such interactions between molecules with high dense densities and the limitation of t-PtCP molecules due to binding to magnetic nanoparticles were thought to be due to the spectral shift of the emission band and the low occurrence of singlet oxygen. In addition, the aggregated form of photosensitive molecules and photosensitive molecules bound to the silica matrix have been reported.

Experimental Example 3 Indirect Measurement of Singlet Oxygen

In order to evaluate the release efficiency of singlet oxygen into solution, the decomposition method of DPBF was used. As a specific singlet oxygen quencher, DPBF gradually undergoes a 1,4-cyclic reaction with singlet oxygen to form endoperoxides. It is then decomposed into an irreversible product of 1,2-dibenzoylbenzene. Therefore, the emission of singlet oxygen can be monitored by observing a decrease in optical density of DPBF absorption at 435 nm.

5, 10, 15, 20-tetraphenyl-21H, 23H-porphine (H ₂ TPP) (1.42 × 10 ^-5 M) and DPBF (1.0 × 10 ^-5 M) 3.5 mL aliquots containing THF solution were injected into 1 cm quartz cells in the dark. The experiment was performed by irradiating a sample with a laser beam (λ = 510 nm, 7.5 mW / cm ² ) using a nanosecond pulsed Nd-YAG pumped OPO laser.

Photolysis of DPBF was monitored by recording the absorbance of the absorption peak at 435 nm. Absorbance change was measured for each irradiation time. Singlet oxygen emission efficiency (η _Δ ) of the photofunctional magnetic nanoparticles was measured according to the following equation using a H ₂ TPP solution in THF standard.

Where t _H2TPP is the time constant of the first exponential decay to decrease in the absorption peak of DPBF during the photocatalytic decomposition reaction with free H ₂ TPP / THF solution, and t _particle is the time In the presence of the mean time constant as described above for the reduction of absorption of DPBF, φ _H2TPP refers to the singlet oxygen quantum yield of free H ₂ TPP in THF solution provided to be 0.62.

Figure 8 shows the change in absorbance of the absorption peak of DPBF in THF in the presence of photofunctional magnetic nanoparticles, which is reaction time dependent under laser irradiation at 510 nm. The release efficiency (η _Δ ) of singlet oxygen from the photofunctional magnetic nanoparticles was determined to be 0.42 ± 0.04, very similar to the singlet oxygen quantum yield evaluated by direct detection of phosphorescence.

Example 2 Photocatalytic Reaction Using Photofunctional Magnetic Nanoparticles

To check the applicability to wastewater purification, the photofunctional magnetic material prepared in Example 1 was subjected to photocatalytic oxidation of a 2,4,6-TCP aqueous solution at pH 10 under visible light irradiation (> 450 nm) of an Xe lamp. The photocatalytic activity of the nanoparticles was evaluated.

Specifically, the photocatalytic decomposition experiment of 2,4,6-TCP was performed by irradiating visible light in an aqueous solution in which the photofunctional magnetic nanoparticles were suspended. The suspension solution was prepared by adding 10 mg of photo-functional magnetic nanoparticles to 20 mL of 2,4,6-TCP aqueous solution so as to have an initial concentration of 7.5 × 10 ⁻⁵ M. Before irradiating visible light, the mixed solution was kept in equilibrium by stirring with a magnet for 1 hour in the dark state. Air was injected into the suspension solution for 30 minutes before visible light irradiation. Xe lamp (150 W, Abet Technologies, USA) was used as the irradiation light source. A 450 nm glass cut off filter was used to remove ultraviolet light so that only the Q band could be irradiated. The UV cut off also inhibits direct photolysis of 2,4,6-TCP from UV light irradiation. Every 20 minutes of irradiation, the absorption spectrum of the sample was observed with a UV-vis spectrophotometer.

Figure 9 shows the degree of photolysis of 2,4,6-TCP by irradiation time in the presence of photofunctional magnetic nanoparticles, the spectral change is the decrease in 2,4,6-TCP molecules and 2 when the photocatalytic reaction continues Means the formation of, 4-dichlorobenzoquinone, the absorption peaks corresponding to 2,4,6-TCP and 2,4-dichlorobenzoquinone at 312 nm and 273 nm, respectively.

In conclusion, magnetic nanoparticles introduced with t-PtCP through a simple reforming reaction have superparamagnetic properties with a saturation magnetization of 28.5 emu / g, excellent dispersibility and stability in water, and a singlet oxygen of 0.47 ± 0.03. It produces a quantum yield and is sufficient for use as a renewable photocatalyst activated by visible light excitation. Photocatalytic decomposition experiments have effectively decomposed 2,4,6-TCP, and the photocatalytic properties activated by the visible light of the photofunctional magnetic nanoparticles can be used to eliminate environmental hazards in water, especially nano The magnetic properties of the particle composite can provide for reuse of the photocatalyst while suppressing the possibility of secondary contamination.

Claims (16)

Magnetic nanoparticles in which photosensitive molecules that generate free radicals in the ultraviolet and visible region are bonded to the surface.
The method of claim 1,
The photosensitive molecule is a magnetic nanoparticle which is a compound represented by Formula 1 below:
[Formula 1]

Where
M represents a transition metal of Groups 7 to 12,
R ₁ and R ₄ are each independently C _5-12 aryl or _5-12 reduced heteroaryl substituted with a carboxyl group,
R ₂ and R ₃ are each independently
Hydrogen;
C _1-6 alkyl; C _1-6 alkoxy; Amines; And C _5-12 aryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy; or
C _1-6 alkyl; C _1-6 alkoxy; Amines; And 5-12 membered heteroaryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy,
C _5-12 aryl or _5-12 reduced heteroaryl substituted by carboxyl group.
The method of claim 2,
M represents Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Cu or Zn,
R ₁ and R ₄ are phenyl or pyridinyl substituted with a carboxyl group,
R ₂ and R ₃ are each independently
Phenyl unsubstituted or substituted with amines; or
C _1-4 alkyl; Or pyridinyl unsubstituted or substituted with benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-4 alkoxy,
Magnetic nanoparticles representing phenyl or pyridinyl substituted with carboxyl groups.
The method of claim 3,
M represents Ni, Pd, or Pt,
R ₁ and R ₄ are phenyl or pyridinyl substituted with a carboxyl group,
R ₂ and R ₃ are each independently
Phenyl unsubstituted or substituted with amines; or
C _1-4 alkyl; Or benzyl substituted or unsubstituted pyridinyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-4 alkoxy.
The method of claim 4, wherein
R ₁ and R ₄

ego,
R ₂ and R ₃ are each independently

,

,

,

,

,

, or

Magnetic nanoparticles representing.
The method of claim 4, wherein
M represents Pt,
R ₁ and R ₄ are phenyl substituted with a carboxyl group,
R ₂ and R ₃ are magnetic nanoparticles representing phenyl.
The method of claim 1,
Photosensitive molecules are magnetic nanoparticles that are covalently bonded to the surface of the magnetic nanoparticles.
The method of claim 1,
Magnetic nanoparticles are magnetic nanoparticles having water dispersibility.
A method for surface modification of magnetic nanoparticles comprising the step of reacting the magnetic nanoparticles and photosensitive molecules generating active oxygen in the ultraviolet and visible region.
10. The method of claim 9,
The photosensitive molecule is a surface modification method of the magnetic nanoparticles, which is a compound represented by Formula 1 below:
[Formula 1]

Where
M represents a transition metal of Groups 7 to 12,
R ₁ and R ₄ are each independently C _5-12 aryl or _5-12 reduced heteroaryl substituted with a carboxyl group,
R ₂ and R ₃ are each independently
Hydrogen;
C _1-6 alkyl; C _1-6 alkoxy; Amines; And C _5-12 aryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy; or
C _1-6 alkyl; C _1-6 alkoxy; Amines; And 5-12 membered heteroaryl unsubstituted or substituted with one or more substituents selected from the group consisting of benzyl unsubstituted or substituted with one or more substituents selected from the group consisting of nitro and C _1-6 alkoxy,
C _5-12 aryl or _5-12 reduced heteroaryl substituted by carboxyl group.
A photocatalyst comprising the magnetic nanoparticles of which the surface according to claim 1 is modified.
A method for recovering the photocatalyst of claim 11 using a magnet.
A wastewater purification method comprising the step of reacting the photocatalyst of claim 11 and wastewater under ultraviolet light or visible light.
The method of claim 13,
The reaction is a wastewater purification method in which the photocatalytic reaction of a chlorinated compound or an environmentally harmful substance having an aromatic ring by a photocatalyst is performed.
The method of claim 14,
A method for purifying wastewater, wherein the chlorinated compound comprises chlorophenol.
The method of claim 14,
Environmentally harmful substances having aromatic rings are phenol, dioxin-based environmental hormones, or dyes.

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