KR100471376B1 - Nano particles of MBAN and preparation method thereof - Google Patents

Abstract

The present invention relates to a method for forming nanoparticles of fluorescent organic compounds under certain conditions, and to nanoparticles prepared by the method. Specifically, the present invention relates to a method of forming nano-sized particles according to precipitation method by forming a fluorescent organic compound such as MBAN in a specific mixed solvent, for example, a solubility difference in each solvent in a THF / water mixed solvent. The nanoparticles of the fluorescent organic compound thus formed improve the fluorescence efficiency by approximately 2-10 times than when dissolved in a single solvent.

In this case, the size and number of nanoparticles are determined by the type of solvent used, the mixing ratio thereof, and the stirring speed, and the fluorescent organic compound nanoparticles have different absorption wavelengths according to their sizes. In addition, it is possible to control the size of the nanoparticle aggregate by adjusting the stirring speed during precipitation formation.

The nanoparticles of the fluorescent organic compound prepared according to the present invention may be utilized as an organic light emitting device, a biosensor or a storage medium.

Description

Nanoparticles of MNP and preparation method

The present invention relates to a method for nanoparticle-forming a fluorescent organic compound in order to increase the fluorescence efficiency of the fluorescent organic compound, and to nanoparticles prepared by the method. Specifically, after dissolving the fluorescent organic compound in the first solvent, by adding a second solvent that is miscible with the first solvent but insoluble in the fluorescent organic compound to form a mixed solvent of the single phase, the first solvent and The present invention relates to a method for forming nanoparticles by precipitation of a fluorescent organic compound due to a difference in solubility of the fluorescent organic compound in a mixed solvent.

In general, it is reported that the nanoparticles of organic compounds obtained by the precipitation method are greatly reduced in their fluorescence efficiency. This is because the fluorescence efficiency is reduced when the organic compound becomes crystalline while forming a precipitate than when present in solution. However, when the diameter of the particles is reduced to nanometer level, the gap of the energy band, which is the quantum state energy level structure of the electrons in the crystal, becomes large, so that the light emission wavelength has high energy and thus the luminous efficiency is high. It is known to improve.

Jindong Luo et al., "Aggregation-induced emmission of 1-methyl-1,2,3,4,5-pentaphenylsilole (silole)" (Chemcomm communication, 2001, pp. 1740-1741), also found that water and ethanol Despite the formation of aggregates in solvents, the formation of aggregates (agglomerates) has been reported to increase the fluorescence intensity due to the planar structure of the material. However, the prior art is a paper on a material having a chemical structure different from the present invention, and the material used in the present invention is easier to modify the chemical structure for use as an organic light emitting device, a biosensor, or a storage medium. Do. The paper also describes a similar phenomenon but does not consider the possibility of use as nanoparticles.

Meanwhile, Korean Laid-Open Patent Publication No. 1998-059343 discloses a mixture of an aqueous solution of a phosphor raw material and an aqueous solution of a compound containing a luminescent center metal in the presence of a solvent in order to prevent aggregation of nanoparticle phosphors and to add a luminescent center. In the technology of adding a luminescent center by heat-treating and reacting with the gas phase phosphor raw material, in order to solve the problem of the use of toxic solvents, the use of expensive raw materials and the risk of explosion, the general formula A ₂ S A method for producing phosphor nanoparticles by adding an alkali compound represented by is disclosed.

However, in the prior art, there is no known method for improving the fluorescence efficiency of the fluorescent organic compound by forming the nanoparticles of the phosphor by precipitation by the difference in solubility between the first solvent and the mixed solvent as in the present invention.

The present invention dissolves MBAN in a first solvent and improves the fluorescence efficiency of MBAN (2,3-bis (4'-methyl-biphenyl-4-yl) -acrylonitrile), an organic compound exhibiting excellent fluorescence. The present invention provides a novel method for preparing nanoparticles by precipitation of MBAN due to the difference in solubility in the first solvent and mixed solvent of MBAN, and the fluorescent organic compound nanoparticles prepared by the method.

The fluorescent organic compound whose fluorescence efficiency is improved by the method for forming nanoparticles of the present invention is MBAN (2,3-bis (4′-methyl-biphenyl-4-yl) -acrylonitrile) having the following formula.

MBAN is soluble in organic solvents such as, for example, THF (Tetrahydrofuran), but insoluble in water or alcohol. Thus, for example, when a certain amount of water is added (about 60% or more) to the MBAN solution dissolved in THF, an organic solvent, nanoparticles are formed by the difference in solubility, which is superior to the MBAN itself. Seems.

This phenomenon results in the coplanar structure of MBAN when the structure is distorted (twisted structure) in the solution and becomes nanoparticles, and the fluorescence efficiency is caused by the interaction by the π-electron clusters caused by this. It can be explained that this is increased. Unlike other organic materials, this MBAN has increased its fluorescence efficiency when forming nanoparticles, and thus, its application potential can be obtained.

In addition, the nanoparticle size can be adjusted by adjusting the mixing ratio of the mixed organic solvent used in forming the fluorescent nanoparticles, thereby adjusting the absorption wavelength.

According to the present invention, the nanoparticles formed by the difference in solubility in the solvent mixture solution form nanoparticles having excellent fluorescence according to the type and mixing ratio of the solvents. On the other hand, the stability in the solution of the nanoparticle aggregate formed by selection of a suitable solvent and mixing ratio, temperature, and stirring speed is different.

The first solvent used in the method of forming MBAN nanoparticles of the present invention may be any organic solvent that dissolves MBAN. Examples of suitable first organic solvents are THF, chloroform, toluene, acetone, benzene and NMP (1-Methyl-2-pyrrolidinone).

The second solvent that may be used in the MBAN nanoparticle formation method of the present invention may be any solvent that is miscible with the first solvent but does not dissolve MBAN. Examples of suitable second solvents are water, methanol, ethanol and the like.

The mixing ratio of the first solvent and the second solvent varies depending on the solvent pairs, but in the case of THF / water, the volume fraction of water is preferably 60% or more for MBAN.

The precipitation temperature depends on the solvent pair used, but can generally be at or below the boiling point of each solvent at room temperature. When using a THF / water solvent pair, the 20-60 ° C. range is suitable.

The stirring speed is suitably in the range of 200-600 rpm.

The size of the nanoparticles can be adjusted by adjusting the type and mixing ratio of the first solvent and the second solvent, and the stirring speed. In general, the nanoparticles of a small size can be obtained by increasing the stirring speed, and the nanoparticles having a larger size can be obtained as the difference in solubility between the first solvent and the second solvent or at a higher temperature.

Hereinafter, the present invention will be described through examples. However, the following examples are merely illustrative of the method for embodying the technical idea of the present invention, and are not intended to limit the protection scope of the present invention to the following. In addition, various modifications may be made by those skilled in the art to which the present invention pertains, and all of them are included in the claims of the present patent.

Example

Example 1

Nanoparticle formation of MBAN in THF / water mixed solvent with 60% by volume of water

In a 50 ml flask equipped with a stirrer and a thermometer, 4 ml of THF and 0.000385 g of MBAN were added at a temperature of 25 ° C. under normal pressure, and MBAN was dissolved while operating the stirrer at 300 rpm. Then, 6 ml of water was added to the solution using a micro syringe. Was slowly added dropwise and stirred. The formation of nanoparticles was visually observed while the stirrer was kept running. FE-SEM photographs were taken of the formed nanoparticles and are shown in FIG. 1, and the fluorescence phenomenon during ultraviolet irradiation was confirmed (FIG. 2).

Comparative Example 1

MBAN Solution Preparation in THF Single Solvent

In a 50 ml flask equipped with a stirrer and a thermometer, 10 ml of THF was added at a temperature of 25 ° C. under normal pressure, and 0.000385 g of MBAN was slowly added while dissolving the stirrer at 200 rpm. About the solution, the fluorescence phenomenon at the time of ultraviolet irradiation was confirmed and shown in FIG. 2 (FIG. 2).

Examples 2 to 8

Formation of MBAN Nanoparticles According to Composition Change of Mixed Solvent

The same experiment as in Example 1 was repeated except that a solvent was added to have a composition as shown in the following table.

Example number THF input amount (ml) Water input amount (ml) Fraction of water (% by volume) Fluorescence efficiency (%) Comparative Example 1 10 0 0 0.1 2 9 One 10 0.1 3 8 2 20 0.1 4 7 3 30 0.1 5 6 4 40 0.1 6 5 5 50 0.1 One 4 6 60 10.0 7 3 7 70 35.0 8 2 8 80 69.0

Fluorescence efficiency of the MBAN nanoparticles obtained in Examples 1 to 8 and Comparative Examples was measured and the results are shown in Table 1 and FIG. 3.

Hereinafter, the effects of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an image by scanning electron microscopy (SEM) of MBAN nanoparticles formed under a 20 vol% THF and 80 vol% water mixed solvent. FIG. It shows that uniform nanoparticles of about 30 nm size were formed.

FIG. 2 compares the fluorescence phenomenon when the MBAN nanoparticles formed under the 20 vol% THF and 80 vol% water mixed solvent is irradiated with ultraviolet light to the MBAN fluorescence phenomenon in THF solvent alone. When dissolved in THF solvent alone (left vial), the fluorescence is very weak, whereas MBAN nanoparticles (right vial) formed according to the method of the present invention show very bright sky blue fluorescence. Can be.

3 is a graph showing the fluorescence efficiency of MBAN according to the mixing ratio of THF and water. In the graph, the x-axis represents the volume fraction of water in the mixed solvent, and the y-axis represents the fluorescence efficiency. In the graph, the fluorescence efficiency of the MBAN nanoparticles formed at a water fraction of 60 vol% or more was increased by 2-10 times per unit concentration.

On the other hand, MBAN used in the present invention is a compound that is completely different from the silol-based compound described in Jindong Luo et al., And the chemical structure for the application of the organic light emitting device, etc. The nanoparticles of MBAN prepared according to the method can be utilized as an organic light emitting device, a biosensor, or a storage medium because their fluorescence efficiency is dramatically increased.

The present invention has been described in detail by way of examples, but the present invention is only illustrated to understand the present invention, and the protection scope of the present invention is defined by the appended claims, and is not limited to the above embodiments. . Therefore, one of ordinary skill in the art within the scope of the technical idea of the present invention can be implemented in various modifications and equivalent ranges from the above embodiment, but all of them are within the protection scope of the technical idea of the present invention. Will be understood.

1 is 2,3-bis (4'-methyl-biphenyl-4-yl) -acrylonitrile (MBAN: 2,3-bis (4'-methyl-biphenyl-4) prepared according to the method of the present invention. -yl) -acrylonitrile) FE-SEM picture of nanoparticles.

Figure 2 is a photograph showing the results of the test of the luminescence under ultraviolet light of MBAN nanoparticles prepared according to the method of the present invention.

Figure 3 is a graph of the increase in fluorescence efficiency of MBAN nanoparticles prepared according to the method of the present invention.

Claims (4)

Preparing a first solution by dissolving MBAN (2,3-bis (4′-methyl-biphenyl-4-yl) -acrylonitrile) in a first solvent; Preparing a second solution by adding a second solvent that is miscible with the first solvent but insoluble for MBAN to the first solution; And MBAN nanoparticles manufacturing method comprising the step of precipitating the nanoparticles of MBAN from the second solution. The method of claim 1, wherein the first solvent is tetrahydrofuran (THF) and the second solvent is water. The method of claim 2, wherein the water is 60 vol% or more in the total mixed solvent. MBAN nanoparticles prepared by the method of any one of claims 1 to 3.