KR101255255B1 - Rhodamine derivative and synthesis of the derivative - Google Patents

Abstract

The present invention relates to a rhodamine derivative of formula (1), which can be used as a fluorescent chemical sensor, and can be applied to a signal off-on FRET system capable of detecting specific ions.

Description

Rhodamine derivative and its preparation method {Rhodamine derivative and synthesis of the derivative}

FIELD OF THE INVENTION The present invention relates to rhodamine derivatives and to rhodamine derivatives that can be applied to signal off-on fluorescence resonance energy transfer (FRET) systems for detecting specific cations and methods for their preparation.

In fields such as environmental measurements or clinical diagnostics, it is necessary to quickly and accurately analyze the concentration of various ions in a particular solution. In this analysis, various kinds of chemical sensor materials using materials that are selective for specific ions are used. The general sensing signal of the sensor uses electrical properties such as electricity, resistance, and potential difference, or optical properties such as color and fluorescence. Among these, color change and fluorescence change can be easily distinguished by the naked eye, so it is one of the easy methods to measure even without special equipment. The sensor for observing the fluorescence change is called a fluorescence chemical sensor.

The design of fluorescence chemical sensors generally involves photoinduced electron / energy transfer (PET), metal-ligand charge transfer (MLCT), and intramolecular charge transfer. , ICT), excimer / exciplex formation, imine isomerization, chelation-enhanced fluorescence (CHEF) and fluorescence resonance energy transfer (FRET) Is made on the basis of Of these methods, fluorescence resonance energy transfer (FRET) is the most actively studied in recent years because it has a selective and high sensitivity to the target molecule or ionic species, as well as potential practicality in cell physiology and optical therapy.

Fluorescence resonance energy transfer (FRET) is one of the energy transfer mechanisms by which energy is transferred between different fluorophores. In this mechanism, donor phosphors deliver the excited energy to acceptor phosphors. Due to this action, the fluorescent material is changed to the electron bottom state, and light is emitted from the received fluorescent material. In this case, the luminous efficiency depends on the distance between the donor and the receiver and the spectral overlap of the donor emission spectrum and the receiver absorption spectrum. Figure 1 shows the overlap of the emission spectrum of Rhodamine 6G and absorption spectrum of Nile Red.

Rhodamine 6G (rhodamine 6G) is a water-soluble fluorescent substance, and has been used as a binding site with fluorescent substances that detect various kinds of cations. The opening of the spirolactam ring in the group of rhodamines induced by the binding of a specific cation is colorless and changes the non-fluorescent state to colored and strong fluorescence, and the "fluorescence off-on system." Form. This phenomenon makes it possible to design signal off-on FRET systems rather than racertric FRET systems by the mediation of specific guest cations. The inventors use a 'signal off-on FRET' using an N- tripodal molecule consisting of two branched calixarene units and a rhodamine B (sub) adjacent to the pyrenyl group. He has published research results on. PET systems induced by N- positional lone pair electrons of ligands dissipate fluorescence in the free ligand state, which enables a 'signal off-on FRET system.

Since Sharpless and Meldal, the 1,3-dipolar cycloaddition of alkyne and azide using copper (I) catalysts has been described as 1,2,3-triazole (1). , 2,3-triazole), in particular 1,4-disubstituted stereoisomers, are available for click chemistry. Simple linking strategies using 1,2,3-triazole have been studied in various fields such as bioconjugation, drug design and material chemistry. In addition, the triazole rings formed in the coupling reaction are known per se as good binding motifs.

The problem to be solved by the present invention is to provide a novel rhodamine derivative and a method for producing the same can be applied to a signal off-on fluorescence resonance energy transfer (FRET) system for detecting a specific cation.

In order to achieve the above technical problem, the present invention provides a rhodamine derivative represented by the following formula (1).

In the present invention, the rhodamine derivative of the formula (1) may be prepared according to the following scheme (1).

Scheme (1)

In addition, the compound of formula (2) may be prepared according to the following scheme (2).

Scheme (2)

In addition, the compound of formula (3) may be prepared according to the following scheme (3).

Scheme (3)

Rhodamine derivatives according to the present invention have a selective and high sensitivity to the target molecule or ionic species and thus can be applied to signal off-on fluorescence resonance energy transfer (FRET) systems capable of detecting specific cations.

Figure 1 shows the overlap of the emission spectrum of Rhodamine 6G and absorption spectrum of Nile Red.

Hereinafter, the present invention will be described in more detail.

In the present invention, a new compound in which Nile Red is combined with Rhodamine 6G and 1,2,3-triazole ring spacer was synthesized, and thereby, a signal off-on FRET system was implemented. The present invention provides a rhodamine derivative represented by the following formula (1).

To synthesize the compound represented by Formula 1, rhodamine 6G was functionalized with an alkyne, and treated with azide-nile red to form an 1,2,3-triazole linker in the molecule.

First, the propargyl derivative (Formula 2) was synthesized according to the following Reaction Scheme (2). To insert the reporter unit through the triazole ring, propargyl derivatives (Formula 2) were synthesized in a simple synthetic sequence from commercially available rhodamine 6G (Formula 2a) and propargylamine hydrochloride, Pink solid was obtained in 26% yield. The compound of formula (2) is a derivative of rhodamine 6G, but this compound forms a colorless solution in CH ₃ CN / H ₂ O solution (1: 1) or acetonitrile, in which the spirolatamtam is mainly present in the form of a ring Inform them. The fact that a significant peak is observed around 65.0 ppm in the ¹³ C NMR spectrum for the compound of formula (2) supports this fact.

Scheme (2)

The synthetic route of the Nile Red derivative (Formula 3) is as shown in Scheme (3). Compound of formula (3b) by reacting nile red (formula 3a), monotosylated ethylene glycol and K ₂ CO ₃ (acting as a base) in dimethylformamide / ethylacetate solution (1: 1) Was obtained in 37% yield. The compound of formula (3b) was then tosylated with tosyl chloride to give the compound of formula (3c) in 64% yield. The compound of formula (3c) was then reacted with excess sodium azide to give an azido-Nile Red compound (Formula 3) in a yield of 23%.

Scheme (3)

"Click reaction" was carried out with the compound (2) and the compound (3) to produce the compound (1) in 18% yield as shown in the following scheme (1). When the copper iodide (CuI) catalyst was used for the dimethylformamide solvent and stirring was performed at 90 degreeC, the compound (1) was not produced. Instead, the compound of formula (1) could be synthesized in high yield when the solvent was changed to CH ₂ Cl ₂ / tetrahydrofuran (1: 1) to allow the reaction to be sufficiently dissolved. The hydrogen signal of triazole was observed in single peak at 7.23 ppm in ¹ H NMR analysis. In the present invention, NMR ( ¹ H and ¹³ C) analysis and fast atom bombardment (FAB) mass spectrum analysis of each compound were performed to confirm the structure of the compound.

Scheme (1)

As such, in the present invention, a novel compound (Formula 1) including Rhodamine 6G and Nile red bonded to a triazole ring spacer was synthesized, and the novel compound (Formula 1) was used to detect a specific cation. Applied to an on-fluorescence resonance energy transfer (FRET) system. The synthesis route of the compound according to the present invention may be applied to the synthesis of chemical sensors for FRET systems using various fluorescent materials.

Example  1: Synthesis of Compound of Formula 2

In a nitrogen atmosphere, Rhodamine 6G (solution (500 mg, 1.044 mmol, formula 2a), propargylamine hydrochloride (96 mg, 1.044 mmol) and triethylamine (5 mL, act as a base) were dissolved in methanol (30 mL) and 80 ° C. After refluxing for 24 hours, the solvent in the resulting solution was volatilized by rotary evaporation and dissolved in a CH ₂ Cl ₂ (200 mL) solvent The organic layer was washed with distilled water (2 × 300 mL). And dried over anhydrous Na ₂ S0 ₄ and filtered The residue was purified by silica gel column chromatography and dissolved in ethyl acetate-hexane (1: 3) to give 125 mg of a pale pink solid. 1 was obtained in a yield of 27. The melting point of the compound of formula 2 was measured at 254 ° C.

¹ H NMR (300 MHz) and ¹³ C NMR (100 MHz) analysis and FAB weight spectrum analysis were performed. ¹ H NMR analysis showed d 7.96-7.94 (1H, m), 7.46-7.42 (2H, m), 7.08-7.03 (1H, m), 6.36 (2H, s), 6.29 (2H, s), 3.93 ( 2H, d, J = 2 Hz), 3.54 (1H, br), 3.21 (4H, q, J = 7 Hz), 1.90 (6H, s), 1.32 (6H, t, J = 7.1 Hz), ¹³ C NMR analysis results were the same as d 14.7, 16.7, 28.6, 38.4, 64.9, 70.1, 78.3, 96.5, 105.3, 117.7, 123.1, 123.7, 128.0, 128.8, 130.2, 132.7, 147.4, 151.8, 154.0, 167.6. The FAB gravimetric analysis showed peaks at m / z (M ⁺ ) calcd 451.56, 452.3.

Example  2: Synthesis of Compound of Formula 3

Example  2-1: Synthesis of Compound of Formula 3b

30 ml of DMF in Nile Red (240 mg, 0.711 mmol, Formula 3a), monotosylated ethylene glycol (53 mg, 0.711 mmol) and K ₂ CO ₃ (100 mg, 0.723 mmol) in a nitrogen atmosphere / Ethyl acetate (1: 1) and heated to 80 ° C. After refluxing for 12 hours, the solvent in the resulting solution was volatilized on a rotary evaporator and dissolved in ethyl acetate (200 mL). The organic layer was washed with distilled water (2 × 300 mL), dried over anhydrous MgSO ₄ and filtered. The residue was purified by column gel column chromatography, dissolved in ethyl acetate-hexane (1: 2) and separated to give 100 mg of a dark purple solid compound (Formula 3b) in 37% yield. .

¹ H NMR (300 MHz) and ¹³ C NMR (100 MHz) analysis and FAB weight spectrum analysis were performed. ¹ H NMR analysis results show d 8.23 (1H, d, J = 8.7 Hz), 8.06 (1H, d, J = 2.6 Hz), 7.58 (1H, d, J = 9.1 Hz), 7.19 (1H, dd, J ₁ = 8.7 Hz, J ₂ = 2.7 Hz), 6.66 (1H, dd, J ₁ = 9.1 Hz, J ₂ = 2.7 Hz), 6.45 (1H, d, J = 2.7 Hz), 6.31 (1H, s), 4.52 (2H, t, J = 4.5 Hz), 4.39 (2H, t, J = 4.5 Hz), 3.47 (4H, q, J = 7.1 Hz), 1.26 (6H, t, J = 7.1 Hz), ¹³ C NMR analysis results were as follows: d 12.9, 45.3, 61.6, 69.8, 96.5, 105.4, 106.9, 109.8, 118.4, 124.9, 126.2, 128.1, 131.3, 134.3, 140.0, 147.1, 151.0, 152.3, 161.5, 183.4. The FAB gravimetric analysis showed peaks at m / z (M ⁺ ) calcd 378.42, 379.1.

Example  2-2: Synthesis of Compound of Chemical Formula 3c

In a nitrogen atmosphere, compound 3b (100 mg, 0.264 mmol), TsCl (55 mg, 0.288 mmol) and NaOH (15 mg, 0.375 mmol) were dissolved in 10 ml of THF and stirred for 12 hours. In the resulting solution the solvent was volatilized on a rotary evaporator and dissolved in CH ₂ Cl ₂ (200 mL). The organic layer was washed with distilled water (2 × 300 mL), dried over anhydrous MgSO ₄ and filtered. The residue was purified by column gel column chromatography, dissolved in ethyl acetate-hexane (1: 3) and separated to yield 90 mg of dark purple solid Compound 3 in 64% yield. Melting point of the compound (Formula 3c) was measured at 184 ℃.

¹ H NMR analysis showed d 8.18 (1H, d, J = 8.6 Hz), 7.94 (1H, d, J = 2.6 Hz), 7.84 (2H, d, J = 8.4 Hz), 7.60 (1H, d, J = 9.2 Hz), 7.34 (2H, d, J = 8.4 Hz), 7.01 (1H, dd, J ₁ = 8.8 Hz, J ₂ = 2.6 Hz), 6.67 (1H, dd, J ₁ = 9.2 Hz, J ₂ = 2.8 Hz), 6.46 (1H, d, J = 2.8 Hz), 6.30 (1H, s), 4.47 (2H, m), 4.37 (2H, m), 3.48 (4H, q, J = 7.2 Hz), 2.43 (3H, s), 1.27 (6H, t, J = 7.2 Hz), and ¹³ C NMR analysis showed d12.6, 21.7, 45.1, 65.6, 68.0, 96.2, 105.2, 106.3, 109.6, 118.3, 124.7, 126.1, 127.8, 128.0, 129.9, 131.1, 132.8, 134.0, 145.1, 146.9, 150.8, 152.1, 160.5, and 183.1. The FAB gravimetric analysis showed peaks at m / z (M ⁺ ) calcd 532.61 and 533.3.

Example  2-3: Synthesis of Compound of Formula 3

In a nitrogen atmosphere, compound 3c (330 mg, 0.620 mmol) and sodium azide (60 mg, 0.929 mmol) were dissolved in DMF and heated to 90 ° C. After refluxing for 24 hours the solvent in the resulting solution was volatilized on a rotary evaporator and dissolved in ethyl acetate (300 mL). The residue was purified by silica gel column chromatography, dissolved in ethyl acetate-hexane (1: 3) and separated to yield 59 mg of a dark purple solid compound (Formula 3) in a yield of 24%. The melting point of the compound was measured at 144 ° C.

¹ H NMR analysis results show d 8.24 (1H, d, J = 8.7 Hz), 8.06 (1H, d, J = 2.7 Hz), 7.60 (1H, d, J = 9.0), 7.21 (1H, dd, J ₁ = 8.7 Hz, J ₂ = 2.7 Hz), 6.66 (1H, dd, J ₁ = 9.0 Hz, J ₂ = 2.8 Hz), 6.46 (1H, d, J = 2.8 Hz), 6.31 (1H, s), 4.38 (2H, t, J = 4.9 Hz), 3.70 (2H, t, J = 4.9 Hz), 3.48 (4H, q, J = 7.1 Hz), 1.27 (6H, t, J = 7.1 Hz), ¹³ C The results of NMR analysis were d 12.6, 45.1, 50.1, 67.2, 96.2, 105.2, 106.3, 109.6, 118.4, 124.7, 126.1, 127.9, 131.1, 134.0, 139.6, 146.9, 150.8, 152.1, 160.8, and 183.1. The FAB gravimetric analysis showed peaks at m / z (M ⁺ ) calcd 404.43 and 404.0.

Example  3: Synthesis of Compound of Formula 1

In a nitrogen atmosphere, copper iodide (15 mg) was added to propargyl rhodamine 6G (Formula 2, 15 mg, 0.0372 mmol) and Nile red azide (Formula 3, 16.7 mg, 0.0372 mmol) and 10 mL of CH ₂ It was dissolved in Cl ₂ / THF (1: 1) solvent and heated to 60 ° C. for 4 hours. In the resulting solution the solvent was volatilized on a rotary evaporator and dissolved in CH ₂ Cl ₂ (50 mL). The organic layer was washed with distilled water (300 mL), dried over anhydrous Na ₂ SO ₄ , and filtered. The residue was purified by eluent gel gel column chromatography, dissolved in CH ₂ Cl ₂ -methanol (20: 1) and separated to yield 6 mg of a dark purple solid compound (Formula 1) in 19% yield. Melting point of the compound (Formula 1) was measured at 174 ℃.

¹ H NMR analysis showed d 8.21 (1H, d, J = 8.7 Hz), 8.01 (1H, d, J = 2.8 Hz), 7.97 (1H, dd, J ₁ = 5.6 Hz, J ₂ = 2.2 Hz), 7.60 (1H, d, J = 9.1 Hz), 7.46-7.43 (2H, m), 7.23 (1H, s), 7.14 (1H, dd, J ₁ = 8.9 Hz, J ₂ = 2.6 Hz), 7.04 (1H , dd, J ₁ = 6.1 Hz, J ₂ = 2.6 Hz), 6.65 (1H, dd, J ₁ = 9.1 Hz, J ₂ = 2.8 Hz), 6.45 (1H, d, J = 2.8 Hz), 6.32 (2H , s), 6.30 (1H, s), 6.10 (2H, s), 4.57 (2H, t, J = 5.5 Hz), 4.50 (2H, s), 4.41 (2H, t, J = 5.5 Hz), 3.47 (4H, q, J = 7.0 Hz), 3.18 (4H, m), 1.82 (6H, s), 1.27 (12H, m), and ¹³ C NMR analysis showed d 12.8, 14.97, 16.88, 35.2, 38.6, 45.3, 49.1, 65.2, 66.6, 96.5, 96.8, 105.5, 105.9, 106.5, 109.9, 117.8, 118.8, 123.2, 123.7, 124.0, 124.9, 126.5, 128.2, 128.3, 128.7, 130.9, 131.3, 132.9, 134.3, 139.7, 144.3, 147.1, 147.5, 151.1, 151.9, 152.3, 153.9, 160.6, 168.2, and 183.3. In addition, the FAB gravimetric analysis showed peaks at m / z (M ⁺ ) calcd 854.99 and 855.7.

Claims (4)

Rhodamine derivative represented by following General formula (1).

A process for preparing the rhodamine derivative of claim 1 according to the following scheme (1):
Scheme (1)

(2) (3) (1) The method of claim 2,
Method for preparing a rhodamine derivative, characterized in that the compound of formula (2) is prepared according to the following scheme (2):

The method of claim 2,
Method for preparing a rhodamine derivative characterized in that the compound of formula (3) is prepared according to the following scheme (3):
Scheme (3)

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