KR20120119934A - Silica Nanotubes, Manufacturing method for the same and Their Applications as Multi-Chemosensors - Google Patents

Abstract

PURPOSE: A silica nanotube, a manufacturing method of the same, and a multi-sensor including the same are provided to improve selectivity to metal ions and to separate mercury or lead ions from drinking water. CONSTITUTION: A silica nanotube includes a cylindrical template containing silica. The outer side of the cylindrical template is saturated with azobenzen groups; the inner side of the cylindrical template is saturated with boron dipyrromethene groups. A azobenzen group is derived from a compound represented by chemical formula 1. In chemical formula 1, R1 is C1-5 alkyl group; R2 is C1-10 alkoxy group; R3 is a heteroatom and is non-cyclic host containing one or more oxygen and one or more nitrogen. A boron dipyrromethene group is derived from a compound represented by chemical formula 3. In chemical formula 3, X is O or S; and R3 is respectively selected from C1-7 alkyl groups.

Description

 Silica Nanotubes, Manufacturing method for the same and Their Applications as Multi-Chemosensors}

The present invention relates to nanoparticles that introduce significantly different chemical functionalities into and out of silica nanotubes as multi-sensors, and to a method and application thereof. Specifically, the present invention relates to high sensitivity of mercury and lead ions from drinking water contaminated with mercury and lead. It is a multi-sensor that can detect and separate mercury and lead from contaminated drinking water through chemical and physical adsorption. The present invention relates to an optical sensor and a water purifying device using the nanotubes.

Nanomaterials with a variety of functionalities have many advantages in modern environments, biomedical, biological applications, catalysts, filters, separations, molecular separations, reservoirs, medical imaging, drug delivery, and sensors. Unlike spherical nanoparticles, nanotubes can use template synthesis to introduce desired functional groups independently on the other side. Smart multifunctional silica nanotubes are now being made for monomolecular sensing, bioseparation and drug / protein delivery. The Matin group described the extraction of lipophilic groups from aqueous solutions by introducing different functionalities into the inner and outer surfaces of silica nanotubes.

However, the general method for the selective introduction of different functional groups into the inner and outer surfaces of silica nanotubes remains a challenge.

In order to solve the above problems, the present invention provides a silica nanotube that can be applied as a multi-sensor capable of detecting and separating mercury and lead from contaminants containing mercury and lead, and to provide a method and application thereof have.

The above object is that the outer surface of the cylindrical mold is saturated with an azobenzene group, the inner surface of the mold is saturated with a boron-dipyrromethene group (hereinafter referred to as BODIPY group), and the mold includes silica. Is achieved from silica nanotubes.

In such a silica nanotube, the azobenzene group which saturated the outer surface of a template is derived from the compound represented by following formula (1).

Formula 1

In Formula 1, R ¹ is an alkyl of (C1-C5), R ² is a (C1-C10) alkoxy group, R ³ is a heterocyclic host containing at least one oxygen, at least one nitrogen as a hetero atom.

In a more specific embodiment, the azobenzene group saturating the outer surface of the template is derived from a compound represented by the following formula (2).

(2)

In the silica nanotubes according to one embodiment of the present invention, the BODIPY group saturating the inner surface of the template is derived from the compound represented by the following formula (3).

(3)

In Formula 3, X is selected from an oxygen atom (O) or a sulfur atom (S);

R ¹ and R ² are independently hydrogen, (C1-C7) alkyl group, halogen element, nitro group, nitrile group, (C6 ~ C20) aryl group, (C6 ~ C20) ar (C1 ~ C7) alkyl group or (C1 ~ C20) is an alkoxy group, the alkyl of the alkyl group or aralkyl group may include an unsaturated bond, the carbon atom of the alkyl group, aryl group or aralkyl group may be substituted with a hetero element selected from N, O, S, Alkyl group, aryl group or aralkyl group is nitro group, nitrile group, halogen element, (C1-C7) alkyl group, (C6-C20) aryl group, (C6-C20) ar (C1-C7) alkyl group or (C1-C20) May be further substituted with a substituent selected from an alkoxy group;

R ³ is independently selected from a (C1-C7) alkyl group;

a, a ', b, and b' are independently integers from 0 to 4, and c, c ', d, and d' are independently integers from 0 to 10;

n and m are integers from 1 to 3.

In a more specific embodiment, the BODIPY group saturating the inner surface of the template is derived from a compound represented by the following formula (4).

Formula 4

Another embodiment of the present invention comprises the steps of preparing a glass gel fiber using a gel former; Adding tetraethoxysilane to the organic gel fibers and reacting to prepare a cylindrical silica nanotube template; Fixing the azobenzene group to the outer surface of the silica nanotube template; And fixing the BODIPY group to the inner surface of the silica nanotube template in which the azobenzene group is fixed to the outer surface.

In the method for producing silica nanotubes according to an embodiment of the present invention, the fixing of the azobenzene group on the outer surface of the silica nanotube template may be performed by a method of reacting the silica carbon nanotubes with the compound represented by Chemical Formula 1 above. have.

In a more specific embodiment, the step of fixing the azobenzene group on the outer surface of the silica nanotube template may be carried out by a method of reacting the silica carbon nanotubes with the compound represented by the formula (2).

In the method for producing silica nanotubes according to an embodiment of the present invention, the step of fixing the azobenzene group on the inner surface of the silica nanotube template is a silica nanotube and the compound represented by the formula (3) having the azobenzene group fixed on the outer surface It may be carried out by a reaction method.

In a more specific embodiment, the step of fixing the azobenzene group on the inner surface of the silica nanotube template may be performed by a method of reacting the compound represented by Formula 4 with the silica nanotubes fixed with the azobenzene group on the outer surface.

In one exemplary embodiment of the present invention can provide a multi-sensor comprising the silica nanotubes according to the embodiments.

Such a multisensor may be to detect that the azobenzene group saturated in the nanotubes reacts with mercury, and may also be a multisensor to detect that the BODIPY group saturated in the nanotubes reacts with lead to emit light.

The silica nanotubes substituted with the azobenzene group and the BODIPY group of the present invention are surprisingly excellent chemical sensors and adsorbents of mercury ions and lead ions, and have the effect of separating and removing mercury or lead from drinking water. The silica nanotubes substituted with the azobenzene group and the BODIPY group of the present invention are colored and luminescent materials, and when mercury binds to the azobenzene organic receptor in close proximity to the nanoparticles, color development occurs, and lead binds to the BODIPY organic receptor in proximity to the nanoparticles. In this case, light emission is exhibited.

Figure 1 shows an example of a process for producing a multi-functional silica nanotube according to the present invention, (a) gel fiber, (b) pre-dissolution SNT, (c) receptor based on azobenzene on the outer surface of SNT Introduction of 1 (A-SNT), (d) Removal of gel fiber of SNT 1 introduced by washing with ethanol, (e) Introduction of receptor 2 based on BODIPY inside SNT (A-SNT-B) Indicates.
Figure 2 is an XPS spectrum, XPS spectrum of (a) SNT, (b) A-SNT, (c) A-SNT-B.
3 is a photograph of (a) A-SNT-B. SEM of A-SNT-B and TEM image of A-SNT-B.
In Figure 4 A is the UV-vis spectrum of A-SNT-B (10 mM), (a) before the addition of Hg ²⁺ (10 equivalents) to the aqueous solution (pH = 7.4) (a) and after (b). (c) and (d) show separation from curve (b) by curve correction, B is (a) Hg ²⁺ (10 equivalents) and Pb ²⁺ (10 equivalents) in A-SNT-B. Photograph before addition of aqueous solution, (b) Photograph after addition of Hg2 ⁺ to A-SNT-B, and (c) Photograph after addition of Pb ²⁺ to A-SNT-B.
5 is a fluorescence spectrum of A-SNT-B (10 mM) with addition of aqueous metal ion solution (pH = 7.4).
6 are pellet photographs prepared with A-SNT-B by UV lamp irradiation, (a) A-SNT-B, (b) Li ⁺ , (c) Ca ²⁺ , (d) Sr ²⁺ , ( e) Co ²⁺ , (f) Cd ²⁺ , (g) Zn ²⁺ , (h) Pb ²⁺ , (i) Hg ²⁺ , (j) Cu ²⁺ , (k) Fe ²⁺ , (l ) Fe ³⁺ .
7 is a flow chart for detection of Pb ²⁺ and Hg ²⁺ by using A-SNT-B.
8 is FT IR spectrum of A-SNT.
9 is FT IR spectrum of A-SNT-B.
10 is the TOF-SIMS spectrum of A-SNT-B.
11 is a UV-vis spectrum of A-SNT-B dispersed in an aqueous solution.
Figure 12 is a solid photograph of (A) A-SNT and (B) a solution photograph of A-SNT dispersed, before the addition of Hg ²⁺ (a) and (b).
13 is a fluorescence spectrum of A-SNT.
Figure 14 is a fluorescence spectrum of A-SNT-B (10 mM), (a) before addition of Pb ²⁺ , (b) after addition of Pb ²⁺ , and (c) HCl (0.01 N) / NaOH (0.01 N). adding.

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

The present invention provides a silica nanotube comprising an outer surface of a cylindrical template saturated with an azobenzene group, an inner surface of the template saturated with a boron-dipyrromethene (BODIPY) group, and the template containing silica.

An example of the structure of such silica nanotubes may be represented by the following formula (5).

Formula 5

In Chemical Formula 5, A is a support selected from silica nanotubes, silica nano spheres, silica particles (silicagel 60) and silica mesoporous (SBA-15, MCM-41); R ³ is an acyclic host containing at least one oxygen, at least one nitrogen as a heteroatom.

Silica nanotubes are a type of inorganic structure that, due to their biocompatibility, are expected to be widely used in fields such as bioseparation, drug delivery, imaging and biomedical medicine.

The present invention is to introduce different chemical functional groups on the inner and outer surfaces of the silica nanotubes to be applied as a multi-sensor for detecting mercury and lead, specifically to be used to detect and separate mercury contained in drinking water When the azobenzene group was saturated on the outer surface of the silica nanotube template, the azobenzene group reacted with mercury to develop color.

Specifically, it may be preferable that the azobenzene group saturated in the silica nanotube template is derived from the compound represented by the following Chemical Formula 1.

 [Formula 1]

In Formula 1, R ¹ is an alkyl of (C1-C5), R ² is a (C1-C10) alkoxy group, R ³ is a heterocyclic host containing at least one oxygen, at least one nitrogen as a hetero atom.

인 화합물(하기 화학식 2 화합물) 유래의 것이다.More preferably, in the azobenzene group, in Formula 1, R ¹ is a propyl group, R ² is an ethoxy group, and R ³ is

It is derived from a phosphorus compound (Compound 2).

 [Formula 2]

In addition, the silica nanotubes of the present invention have a BODIPY group substituted on the inner surface of the mold so as to be used for detecting and separating lead contained in drinking water, and such functional groups react with lead to emit light. Preferably, the BODIPY group derived from the compound represented by the following formula (3) is substituted.

 (3)

In Formula 3, X is selected from an oxygen atom (O) or a sulfur atom (S);

R1 and R2 are independently hydrogen, (C1-C7) alkyl group, halogen element, nitro group, nitrile group, (C6 ~ C20) aryl group, (C6 ~ C20) ar (C1 ~ C7) alkyl group or (C1 ~ C20) Alkoxy group, alkyl of the alkyl group or aralkyl group may include an unsaturated bond, the carbon atom of the alkyl group, aryl group or aralkyl group may be substituted with a hetero element selected from N, O, S, the alkyl group, The aryl group or aralkyl group is a nitro group, a nitrile group, a halogen element, a (C1-C7) alkyl group, a (C6-C20) aryl group, a (C6-C20) ar (C1-C7) alkyl group or a (C1-C20) alkoxy group May be further substituted with a substituent selected from;

R 3 is independently selected from a (C 1 -C 7) alkyl group;

a, a ', b, and b' are independently integers from 0 to 4, and c, c ', d, and d' are independently integers from 0 to 10; n and m are integers from 1 to 3.

In Formula 3, R ¹ is more preferably independently selected from hydrogen, a (C1-C3) alkyl group or a halogen element.

 [Formula 4]

As the silica support according to the present invention, silica nanotubes may be used, and the more porous and the surface area is, the more preferable the binding force between the chromophore and the light-emitting receptor compound is.

The silica nanotubes of the present invention preferably use nanocrystals having an average diameter of 10 to 200 nm, and silica nanotubes can be produced by a known production method.

For example, silica nanotubes can be made by using an organic fiber as a template. The gelator (gelling agent) is dissolved in ethanol by heat, and TEOS (tetraethoxysilane), water and benzylamine are added to the gel. Heat until a clear solution is obtained. The reaction is then left at room temperature under stable conditions for 3-7 days. Finally, the resultant is washed with toluene to give a white solid.

At this time, a well-known thing may be used as a gelator, and examples thereof include carboxypolymethylene, carboxymethyl cellulose, carboxysipropyl cellulose, polyxamer, carrageenan, beegum, carboxyvinyl, karaya rubber, Products such as xan rubber, guar gum, gum arabic and tragacanth rubber may be used, but the present invention is not limited thereto.

In a specific embodiment of the present invention, a compound represented by the following Chemical Formulas 6 (Compound 7) to 7 (Compound 8) is mixed and used as a gelling agent.

6

Formula 7

Referring to the process of manufacturing a silica nanotube substituted with azobenzene group and BODIPY group of the present invention as shown in FIG.

Referring to FIG. 1, compounds 7 and 8 are mixed to prepare a gel sample (a), and then reacted by adding TEOS thereto to obtain a template (a) of cylindrical silica nanotubes.

The silica nanotube template thus formed has a cylindrical shape and a hollow structure thereof.

Next, in order to fix the azobenzene group on the silica nanotubes, an azobenzene group-containing compound such as Compound 1 is reacted with the silica nanotubes to fix the azobenzene group on the outer surface of the mold. Since the template of the silica nanotubes has a non-empty structure, the azobenzene group is fixed to the outer surface of the silica nanotubes ((c)).

Next, the inside of the silica nanotube template is washed (d) and a BODIPY-based receptor (e.g. Compound 2) is introduced on its inner side. Alcohol-based solvents such as ethanol may be used to clean the inside of the mold, but the present invention is not particularly limited thereto.

The resulting silica nanotube has a structure (A-SNT-B) in which an azobenzene group is saturated on the outer side of the mold and a BODIPY group is saturated on the inner side.

The silica nanotubes substituted with the azobenzene group and the BODIPY group of the present invention are surprisingly excellent chemical sensors and adsorbents of mercury ions and lead ions, and have the effect of separating and removing mercury or lead from drinking water.

 The silica nanotubes substituted with the azobenzene group and the BODIPY group according to the present invention are characterized in that they are colored and luminescent materials. When bound to the BODIPY organic receptor, luminescence is shown.

Due to these characteristics, in an exemplary embodiment of the present invention, a multisensor may be manufactured using the silica nanotubes of the present invention as described above.

The multi-sensor manufactured as described above reacts to mercury, and the color sensor detects the presence of mercury in the sample and the degree of its content.

In addition, it reacts with lead, and it is possible to grasp the presence and absence of lead in the sample while emitting light by this reaction.

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

Evaluation in the following Examples was carried out in the following manner.

(1) structural characterization

¹ H and ¹³ C NMR spectra were measured with a Bruker ARX 300 MHz spectrometer. Mass spectrometry was performed using JEOL JMS-700 mass spectrometer. Transmission electron microscopy (TEM) images were measured at 50 keV using JEOL JEM-2100 F. Image is Fuji Photo Film Co. LTd. The FDL5000 system was used. All fluorescence spectra were recorded on an RF-5310PC spectrometer.

(2) optical spectroscopic characterization

Fluorescence emission spectrum was used for Shimadzu RF-5310-PC equipment, and the mother liquor (0.01M) of the metal hydroxide and chlorine solution using water of pH 7. All measurements were measured with excitation conditions 350 nm and excitation, emission slick thickness 1.5 nm. pH value was adjusted using 0.2 MOPS. Fluorescence quantum yield was predicted with reference to rhodamine 6G (Φ = 0.76).

[Example]

Referring to FIG. 1, silica nanotubes having different chemical functional groups introduced thereinto were prepared in the following manner.

end. Synthesis of Organic Gel Forming Agent

Gelators 7 and 8 are described in J. H. Jung, Y. Ono, and S. Shinkai, Chem. Eur. J. 2000, 6, 4552 prepared by the method reported in the literature, summarized in the following scheme 1.

Scheme 1

I. Preparation of Silica Nanotubes

As a gel-generator, 30 mg of the organics of the compounds 7 and 8 were added to 2 ml of ethanol and warmed until the solution became clear. It was allowed to stand for 1 hour at room temperature and static conditions, and then 40 mg of TEOS 120 mg water and 40 mg of benzylamine were added, which were then warmed up to a clear solution. It was left for 5 days at room temperature and static conditions. 240 mg of TEOS (tetraethoxysilane) and 120 mg of water were added sequentially, and the mixture was stirred to mix well, and then stored at room temperature and static condition for 5 days. The material was washed with toluene to give a white solid (illustrated in FIG. 1 (b)).

All. Synthesis of Receptor 1 Based on Azobenzene

This is summarized in Scheme 2 below.

Scheme 2

(1) Synthesis of Compound 4

O-anisidine was added to a solution of potassium dihydrogen phosphate and ethyl bromoacetate in 10 ml acetonitrile. The reaction solution was kept at 60 ° C. for 10 hours. After cooling to room temperature, the mixture was extracted with chloroform and water, and the organic layer was removed using anhydrous magnesium sulfate. Compound 4 was obtained by performing a column using 7: 3 hexanes: ethyl acetate.

m.p. 78-80 ° C .;

¹ H-NMR (300 MHz, CDCl ₃ , TMS) δ = 6.87 (d, ² J (H, H) = 12.3 Hz, 1H; Ar-H), 4.20 (d, ² J (H, H) = 7.2 Hz , 1H; Ar-H), 3.80 (s, 3H; CH ₃ ) 1.26 (t, ³ J (H, H) = 7.2 Hz, 6H; CH ₃ );

¹³ C NMR (CDCl ₃ , TMS) δ = 171,151,122,120,119,111,77,77,77,76,60,55,53,30,14;

IR (KBr): ν = 3393,3090,2931,2853,1740,1653,1373,1032,751 cm ⁻¹ ;

High resolution masss pectrum (HRMS) (FAB ⁺ ) m / z 295.14 [(M + H) ⁺ calcd for C ₁₅ H ₂₁ NO ₅ : 295.16]. Anal. Cald for C ₁₅ H ₂₂ NO ₅ : C, 61.00; H, 7. 17; N, 4.74. found: C, 60.68; H, 7. 23; N, 4.69.

(2) Synthesis of Compound 3

1.047 g o-amino benzoic acid was added to a solution of 0.5261 g NaNO2 in 20 ml THF and 20 ml water. Maintain 0 ° C. and add HCl slowly. It was slowly added dropwise to a solution containing the appropriate ester in 40 ml THF and 40 ml water. This solution was maintained at 0 ° C. for about 2 hours. Then, the mixture was stirred at room temperature for one day. Extracted with chloroform and water, the organic layer was removed using anhydrous magnesium sulfate. The column was performed using 7: 3 hexanes: ethyl acetate to obtain light red Compound 3.

m.p. 101-103 ° C .;

¹ H-NMR (300 MHz, CDCl ₃ , TMS) δ = 8.10 (d, ² J (H, H) = 7.75 Hz, 1H; Ar-H), 7.59 (d, ² J (H, H) = 7.2 Hz, 1H; Ar-H), 7.48 (t, ³ J (H, H) = 7.8 Hz, 1H; Ar-H), 6.9 (d, ² J (H, H) = 4.5 Hz, 1H; Ar- H), 4.18 (m, 8H), 3.8 (s, 3H; CH ₃ ), 1.26 (t, ³ J (H, H) = 7.2 Hz, 6H; CH ₃ );

¹³ C NMR (300 MHz, CDCl ₃ , TMS) δ = 187, 182, 154, 144, 135, 134, 134, 133, 133, 127, 127, 125, 120, 116, 58, 43, 42, 23, 18 ,;

IR (KBr): ν = 3414, 3270, 2940, 2856, 1870, 1735, 1637, 968, 804 cm ⁻¹ ;

HRMS (FAB ⁺ ) m / z 443.17 [(M + H) ⁺ calcd for C ₂₂ H ₂₅ N ₃ O ₇ : 443.20]. Anal. Cald for C ₂₂ H ₂₅ N ₃ O ₇ : C, 59.59; H, 5.68; N, 9.48. found: C, 60.11; H, 5.80; N, 9.35.

(3) Synthesis of Compound 1

Compound 3 was added to a solution of 1.0 g aminopropyltriethoxysilane dissolved in 10 ml ethyl acetate. The reaction mixture was stirred for 2 minutes under nitrogen atmosphere and cooled to 0 ° C. 68 mg 1-hydroxybenzotriazole and 1.870 g dicyclohexyl carbodiimide were added as a mixture of solids and stirred at room temperature for 24 hours. The residue was removed with a filter using an aqueous sodium carbonate solution and an aqueous sodium sulfate solution. Water was removed using anhydrous magnesium sulfate, and the organic solvent was removed using a rotary vacuum evaporator. The impure product was dissolved in methanol again and stirred for 10 hours before adding sodium bicarbonate to the reaction mixture and removing the solvent. Pure columnar 1 was obtained by performing a column using 1: 1 hexane: ethyl acetate.

mp 115-117 ^o C; ¹ H NMR (300 MHz, DMSO) δ = 7.5, 7.5, 7.4 (m, 3H) 6.9, 6.8, 6.8, 6.7 (m, 4H), 4.17 (t, ³ J (H, H) = 6.9 Hz, 1H Ar-H), 3.79 (s, 3H), 1.73 (t, ³ J (H, H) = 2.4 Hz, 1H; Ar-H) 1.24 (m, 15H);

IR (KBr): ν = 3414, 3270, 2940, 2856, 1870, 1735, 1637, 1121, 968, 804 cm ⁻¹ ;

HRMS (FAB ⁺ ) m / z 646.30 [(M + H) ⁺ calcd for C ₂₈ H ₄₃ N ₄ O ₈ Si: 591.29]. Anal. Cald for C ₂₈ H ₄₃ N ₄ O ₈ Si: C, 56.83; H, 7. 32; N, 9.47. found: C, 56.75; H, 7. 34; N, 9.50.

la. Synthesis of Receptor 2 based on BODIPY

This is summarized in Scheme 3 below.

Scheme 3

(1) Synthesis of Compound 2

40 mg compound 6 , 0.054 ml 3-triethoxysilyl propyl isocyanate, 0.03 ml triethylamine was added to 30 ml THF, and refluxed for 12 hours, and then maintained at room temperature. After the solvent was removed using a rotary vacuum evaporator, pure compound 2 was obtained by performing a column using 1: 1 hexane: ethyl acetate.

¹ H NMR (300 MHz, CDCl ₃ ): δ = 7.07 (d, 2H, J = 8.7 Hz), 6.85 (d, 2H, J = 8.4 Hz), 5.97 (s, 2H), 5.26 (s, 2H) , 4.27 (t, 4H, J = 6.0 Hz), 3.85 (q, 12H, J = 7.0 Hz), 3.66 (t, 4H, J = 5.9 Hz), 3.22 (q, 4H, J = 5.9 Hz), 2.54 (s, 6H), 1.68 ?? 1.58 (m, 4H), 1.48 (s, 6H), 1.25 (t, 18H, J = 7.1 Hz), 0.66 (t, 4H, J = 8.3 Hz);

¹³ C NMR (75 MHz, CDCl ₃ ): δ = 156.4, 154.8, 147.8, 143.2, 142.8, 132.1, 129.1, 122.6, 120.9, 112.0, 61.4, 60.4, 58.4, 50.5, 43.5, 23.3, 21.0, 18.3, 14.7 , 14.5, 14.2, 7.6;

IR (KBr, cm ⁻¹ ): 3448, 2919, 1709, 1607, 1469, 1303, 1197, 1108;

MS (EI): [M + H] ⁺ m / z = 922 (calcd Mw = 921.47); Anal. Calcd for C ₄₃ H ₇₀ BF ₂ N ₅ O ₁₀ Si ₂ : C, 56.01; H, 7.65; N, 7.60. Found: C, 55.81; H, 7.56; N, 7.60.

hemp. Introduction of Compound 1 into Silica Nanotubes (A-SNT)

100 mg of the azobenzene compound 1 obtained in C. was dissolved in 10 ml of anhydrous toluene, and 100 mg of the silica nanotubes obtained in B. was added thereto, and stirred in a reflux condenser for 24 hours under nitrogen gas. After the reaction was completed, the solid obtained was washed with Compound 1 remaining in toluene and dried in vacuo.

Finally, washed with ethanol to prepare a silica nanotube in which Compound 1 was introduced outside the silica nanotube.

bar. Introduction of Compound 2 to A-SNT

100 mg of BODIPY compound 2 obtained in D. was dissolved in 10 ml anhydrous toluene, and 100 mg of A-SNT obtained in E. was added thereto, and stirred in a reflux condenser for 24 hours under nitrogen gas. After the reaction was completed, the solid obtained was washed with Compound 2 remaining in toluene and dried in vacuo. Finally, washing with ethanol to prepare a silica nanotube (A-SNT-B) in which Compound 2 was introduced into the A-SNT.

The methodology of the above embodiments prepares silica nanotubes by first using organic fibers as a template, as shown in FIG. 1. Before removal of the organogel fibers, silica nanotubes (SNTs) and receptor 1 could be reliably introduced to the outside of the SNTs by vigorous stirring for one day in toluene. In this process, receptor 1 into which azobenzene was introduced was introduced to the outer surface of the SNTs as a receptor colored for Hg ²⁺ . Then, after removing the organic gel from the empty portion inside the SNTs, in addition to the silica nanotubes, synthesized azobenzene-receptor 1 (A-SNT) was confirmed by SEM, TEM, FTIR, UV-vis spectroscopy, XPS spectroscopy.

To verify the structural evidence that receptor 1 was introduced into or outside of A-SNTs, IRs of SNT and A-SNT were compared. IR peaks of SNT showed strong peaks at 3450, 1658, and 1084 cm-1. IR peaks of A-SNT showed strong peaks at 3382, 2976, 2884, 1626, 1615, 1570, 1471, 1446, 1428, and 1382 cm-1. New peaks from receptor 1 introduced with acyclic azobenzene, which provides clear evidence, demonstrate that receptor 1 was certainly introduced to the outer surface of the SNT. In addition, the elements of A-SNT were confirmed by XPS (FIG. 2). XPS spectrum of the A-SNT showed C1s, N1s, O1s, Si2p binding energy (Fig. 2 (b)). In the SNT (FIG. 2 (a)) no N1s peak for nitrogen was shown, whereas in A-SNT (FIG. 2 (b)) the N1s derived from the nitrogen atom of receptor 1 based on azobenzene were shown. In addition, the UV-vis spectrum of A-SNT dispersed in aqueous solution showed a maximum absorption wavelength at 320 nm, indicating that an azobenzene-receptor was introduced on the outer surface of the SNT.

In order to selectively introduce A-SNT inside, Receptor 2, which exhibits fluorescence based on BODIPY, was reacted for 24 hours by adding A-SNT to toluene as described above. Since the outer surface of the A-SNT is completely filled by the receptor 1, which is already colored, receptor 2 could be selectively attached to the inside of the A-SNT. After cooling to room temperature the pink solid product was filtered off, washed with THF and dried (FIG. 3 (a)). This was confirmed by Fig. 3 (incorporation of BODIPY derivative 2 (A-SNT-B) by IR and TOF-SIMS. In the IR spectrum of A-SNT-B, (Fig. Rather, strong peaks appearing at 2750, 1990, 1704, 1473, 1210 cm ⁻¹ originating from receptor 2 indicate that receptor 2 is (FIG. 3 (introduced (FIG. 9)). TOF-SIMS spectrum of A-SNT-B Showed cleavage confirming that receptor 2 is covalently immobilized inside of Figure 3. (Figure 10) In addition, the absorption spectra of A-SNTs are 320 nm and 505 from receptors 1 and 2 Two visible light absorption bands were shown at nm (Fig. 11), in addition, the XPS spectra of A-SNT showed C1s, N1s, O1s, Si2p, F1s binding energies (Fig. 2 (c)), characteristically F1s The binding energy was from BODIPY-based receptor 2. These results indicated that fluorescent receptor 2 was internal to A-SNTs. Indicates that the fixing to the surface. A-B of the SNT-SEM (Fig. 3 (b)) and TEM (FIG. 3 (c)) pictures are shown of a nanotube structure having a diameter of 120 nm.

On the other hand, in order to confirm the application of the silica nanotubes prepared as a color and fluorescence chemical sensor for the detection of two different metal ions, Li ⁺ , Na ⁺ , K ⁺ , Mg ^{2 in} aqueous solution (pH = 7.4) A-SNT-B ⁺ , Ba ²⁺ , Ca ²⁺ , Sr ²⁺ , Co ²⁺ , Cd ²⁺ , Pb ²⁺ , Zn ²⁺ , Fe ³⁺ , Cu ²⁺ , Hg ²⁺ The characteristic which shows the color of was investigated. As a result, absorption bands of A-SNT-B excluding metal ions were observed at 320 nm and 505 nm, respectively (FIG. 4A (a)). Interestingly, the addition of Hg ²⁺ to the water suspension of A-SNT-B results in two absorption bands for receptor 1 based on azobenzene and receptor 2 based on BODOPY by curve correction (Fig. 4A (c). A new absorption band appears around 480 nm consisting of) and (d)) (Fig. 4A (b)) and a color change from pink to grey-brown (Fig. 4B (b)). The absorption band at 320 nm shifted to 480 nm, which is due to the electron charge transfer from the end of the electron donor to the end of the electron acceptor in the chromophore. Thus, the observed color change explains the formation of the complex as a strong coordination bond between the nitrogen atom of receptor 1 and Hg ²⁺ . Other metal ions except Hg ²⁺ did not show a significant color change (FIG. 4B (c)). These results confirm that A-SNT-B can be used as a sensing material that displays color for the selective detection of Hg ²⁺ among several metal ions.

As a reference experiment, a color change experiment of A-SNT to which Hg ²⁺ was added was performed as shown in FIG. 12. A-SNT also showed a color change from yellow to pink by the addition of Hg ²⁺ in aqueous solution (Fig. 12A (b)). This result means that Hg ²⁺ ions are coordinated to receptor 1 introduced on the outer surface of A-SNT-B. Then, in an aqueous solution (pH = 7.4), Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ba ²⁺ , Ca ²⁺ , Sr ²⁺ , Co ²⁺ , Cd ²⁺ , Pb ²⁺ , Zn ²⁺ The change in fluorescence of A-SNT-B according to, Fe ³⁺ , Cu ²⁺ , Hg ²⁺ metal ions was observed. As expected, A-SNT-B without metal ions was certainly free of fluorescence, and efficient photoinduced electron transfer (PET) was shown by quenching of the fluorophore by unshared electron pairs of nitrogen atoms in the benzoyl moiety. Interestingly, the addition by increasing the concentration of Pb ^{2 +,} the emission spectrum of the A-B-SNT showed fluorescence (CHEF) enhanced effectiveness to a large chelation due to blocking of the PET process. At luminescence (λ _em = 510 nm) ca. Global fluorescence changes of 10-fold (Φ = 0.019, figure 4) were observed for Pb ²⁺ . On the other hand, Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ba ²⁺ , Ca ²⁺ , Sr ²⁺ , Co ²⁺ , Cd ²⁺ , Zn ²⁺ , Fe ³⁺ , Cu ²⁺ , Hg ^{2 In an} equivalent experiment with ⁺ No characteristic change in fluorescence was seen (FIG. 5). From these fluorescence changes, it was found that A-SNT-B showed high selectivity for Pb ²⁺ in various metal cations. These results also indicate that BODIPY-based receptor 2 introduced on the inner surface of A-SNT-B recognizes high selectivity and only Pb ²⁺ ions.

In addition, in order to evaluate the further usefulness of A-SNT-B with a probe that selectively colors and fluoresces for Hg ²⁺ and Pb ²⁺ ions, Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ba in aqueous solution A-SNT-B with the addition of various biological and environmentally related metal ions such as ²⁺ , Ca ²⁺ , Sr ²⁺ , Co ²⁺ , Cd ²⁺ , Zn ²⁺ , Fe ³⁺ , Cu ²⁺ Competitive color and fluorescence changes were investigated (Fig. 14). As expected, Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ba ²⁺ , Ca ²⁺ , Sr ²⁺ , Co ²⁺ , Cd ²⁺ , Zn ²⁺ , Fe ³⁺ , Cu ²⁺ to Hg2 + , The color and fluorescence changes of A-SNT-B were observed with the addition of Pb2 +, and A-SNT-B was found to be able to detect Hg ²⁺ and Pb ²⁺ selectively in excess of various metal ions. It is a promising substance. On the other hand, the color and fluorescence of A-SNT-B were completely reversible by addition of strong base (0.01 N NaOH) to acidic solution (0.01 N HCl) (FIG. 14). In addition, color and fluorescence changes could be reproduced in multiple detections and separations.

In addition, to apply as a portable chemical sensor tool, A-SNT-B disk-shaped pellets were prepared in an easy and convenient way (Fig. 6). The luminescence of the disc-shaped pellets of A-SNT-B was dramatically increased. In addition, disc-shaped pellets of pink A-SNT-B immediately turned grayish when wet with Hg ²⁺ solution. Li ⁺ , Na ⁺ , K ⁺ , Mg ²⁺ , Ba ²⁺ , Ca ²⁺ , Sr ²⁺ , Co ²⁺ , Cd ²⁺ , Zn ²⁺ , Fe ³⁺ , except Hg ²⁺ and Pb ²⁺ When the metal, such as Cu ²⁺ , was wetted to the disc, the fluorescence and color change of A-SNT-B did not appear. These results suggest that disc-shaped pellets prepared with A-SNT-B can be applied as portable chemical sensors for the detection of Hg ²⁺ and Pb ²⁺ in the environmental and biological fields.

Figure 7 shows the visual color and fluorescence change with the addition of metal ions to the dispersed solution of A-SNT-B. Based on the visual color and fluorescence changes mentioned above, qualitative analysis of unknown samples was performed in two steps. (1) Subsamples of unknown samples are dispersed in A-SNT-B aqueous solution. If both color and fluorescence change, both Hg ²⁺ and Pb ²⁺ are present in unknown samples. (2) If fluorescence changes, unknown samples should contain Pb ²⁺ . On the other hand, if the fluorescence does not change and only the visual color changes, Hg ²⁺ should be present in unknown samples.

The present invention describes the selective introduction of two different receptors into the inner and outer surfaces of SNTs by a simple sol-gel grafting reaction. SNT-A-B sensor could be successfully applied to the Hg ^{+ 2} and Pb ^{2 +} ion very selective detection. In addition, the new multifunctional nanostructure could be easily recycled by chemical treatment. Simple and convenient methods for different functionalization of the inner and outer surfaces will be very efficient for the recognition and separation of specific target molecules. Control of internal and external surface chemistry can be assured that a wide range of influences for the study and application of porous materials are achieved.

Claims (13)

The outer surface of the cylindrical mold is saturated with an azobenzene group,
The inner surface of the mold is saturated with boron-dipyrromethene groups,
The template is a silica nanotube containing silica. The method of claim 1,
The azobenzene group which saturated the outer surface of a template is a silica nanotube derived from the compound represented by following formula (1).
Formula 1

In Formula 1, R ¹ is an alkyl of (C1-C5), R ² is a (C1-C10) alkoxy group, R ³ is a heterocyclic host containing at least one oxygen, at least one nitrogen as a hetero atom. The method according to claim 1 or 2,
The azobenzene group which saturated the outer surface of a template is a silica nanotube derived from the compound represented by following formula (2).
(2)

The method of claim 1,
The boron-dipyrromethene group which saturated the inner side of a template is a silica nanotube derived from the compound represented by following formula (3).
(3)

In Formula 3, X is selected from an oxygen atom (O) or a sulfur atom (S);
R ¹ and R ² are independently hydrogen, (C1-C7) alkyl group, halogen element, nitro group, nitrile group, (C6 ~ C20) aryl group, (C6 ~ C20) ar (C1 ~ C7) alkyl group or (C1 ~ C20) is an alkoxy group, the alkyl of the alkyl group or aralkyl group may include an unsaturated bond, the carbon atom of the alkyl group, aryl group or aralkyl group may be substituted with a hetero element selected from N, O, S, Alkyl group, aryl group or aralkyl group is nitro group, nitrile group, halogen element, (C1-C7) alkyl group, (C6-C20) aryl group, (C6-C20) ar (C1-C7) alkyl group or (C1-C20) May be further substituted with a substituent selected from an alkoxy group;
R ³ is independently selected from a (C1-C7) alkyl group;
a, a ', b, and b' are independently integers from 0 to 4, and c, c ', d, and d' are independently integers from 0 to 10;
n and m are integers from 1 to 3. The method according to claim 1 or 4,
The boron-dipyrromethene group which saturated the inner side of a template is a silica nanotube derived from the compound represented by following formula (4).
Formula 4

Preparing glass gel fibers using a gel former;
Adding tetraethoxysilane to the organic gel fibers and reacting to prepare a cylindrical silica nanotube template;
Fixing the azobenzene group to the outer surface of the silica nanotube template; And
A method for producing silica nanotubes comprising fixing a boron-dipyrromethene group to an inner surface of a silica nanotube template having an azobenzene group fixed to an outer surface thereof. The method according to claim 6,
Fixing the azobenzene group on the outer surface of the silica nanotube template is a method for producing silica nanotubes by a method of reacting the silica carbon nanotubes with a compound represented by the following formula (1).
Formula 1

In Formula 1, R ¹ is an alkyl of (C1-C5), R ² is a (C1-C10) alkoxy group, R ³ is a heterocyclic host containing at least one oxygen, at least one nitrogen as a hetero atom. The method according to claim 6 or 7,
Fixing the azobenzene group on the outer surface of the silica nanotube template is a method for producing silica nanotubes by a method of reacting the silica carbon nanotubes with a compound represented by the following formula (2).
(2)

The method of claim 7, wherein
Fixing the azobenzene group on the inner surface of the silica nanotube template is a method for producing a silica nanotube is carried out by reacting the compound represented by the following formula (3) with the silica nanotube fixed to the azobenzene group.
(3)

In Formula 3, X is selected from an oxygen atom (O) or a sulfur atom (S);
R ¹ and R ² are independently hydrogen, (C1-C7) alkyl group, halogen element, nitro group, nitrile group, (C6 ~ C20) aryl group, (C6 ~ C20) ar (C1 ~ C7) alkyl group or (C1 ~ C20) is an alkoxy group, the alkyl of the alkyl group or aralkyl group may include an unsaturated bond, the carbon atom of the alkyl group, aryl group or aralkyl group may be substituted with a hetero element selected from N, O, S, Alkyl group, aryl group or aralkyl group is nitro group, nitrile group, halogen element, (C1-C7) alkyl group, (C6-C20) aryl group, (C6-C20) ar (C1-C7) alkyl group or (C1-C20) May be further substituted with a substituent selected from an alkoxy group;
R ³ is independently selected from a (C1-C7) alkyl group;
a, a ', b, and b' are independently integers from 0 to 4, and c, c ', d, and d' are independently integers from 0 to 10;
n and m are integers from 1 to 3. 9. The method according to claim 7 or 8,
The fixing of the azobenzene group on the inner surface of the silica nanotube template is a method for producing silica nanotubes carried out by reacting the silica nanotubes fixed with the azobenzene group on the outer surface and the compound represented by the following formula (4).
Formula 4

A multisensor comprising the silica nanotubes of claim 1. 12. The multisensor of claim 11, which detects that azobenzene groups saturated in the nanotubes react with mercury to develop color. 13. The multi-sensor according to claim 11 or 12, wherein the boron-dipyrromethene group saturated in the nanotubes detects that light reacts with lead.

Images