CN102154004A - Application of mon-carbonyl curcumin compound-based visual PH fluorescent probe - Google Patents

Abstract

The invention discloses an application based on a monocarbonyl curcumin compound as a visualized pH fluorescent probe. The visualized pH fluorescent probe has a structure as shown in formula I. The fluorescence characteristics of this series of monocarbonyl curcumin are very sensitive to pH detection. High, strong selectivity to hydrogen ions, and little interference from other metal ions; this type of probe has broad prospects as a reagent for measuring pH; Formula I The groups represented by R ₁ , R ₂ R ₃ , and R ₄ in Formula I are: OH, H, OCH ₃ , one of the Br substituents; X is CH ₂ , CH ₂ -O-CH ₂ , one of CH ₂ -S-CH ₂ ; n=0~2.

Description

Application of Monocarbonyl Curcumin Compounds as Visual pH Fluorescent Probes

technical field

The invention belongs to the technical field of detection, and in particular relates to the application of a monocarbonyl curcumin-based compound as a visualized pH fluorescent probe.

Background technique

The pH value is an important parameter in systems such as physiology, pharmacology, and environment. The conduct or completion of chemical reactions, and many important physiological processes of cells and organelles are closely related to its changes. Therefore, the determination of pH value is of great significance. The existing pH testing methods mainly include spectroscopic method, electrode method and indicator method. The electrode method is not used in the pH measurement of the living body due to the existence of electrochemical interference, possible mechanical wear and other defects. Fluorescence spectroscopy is a detection method based on optical signals, which has the advantages of high sensitivity, high selectivity, fast reflexivity and reversible performance. It makes up for the above-mentioned deficiencies of the electrode method, and has been greatly developed. Among the reported fluorescent probes, some probe molecules change in molecular form with the change of acidity and alkalinity of the solution, which is manifested as a significant change in the color of the solution. The characteristic of this type of probe is that it can not only judge the pH value of the solution qualitatively through the color change of the solution, but also measure the pH accurately through the fluorescence performance.

Curcumin (curcumin) is the main active ingredient of the traditional Chinese medicine turmeric, which has many medicinal activities and optical properties. Curcuminoids have a special D-π-P dienone fluorophore structure, and the isomerization transformation between the ketone form and the enol form of the dienone structure also endows it with many unique photochemical properties. In addition, the phenolic hydroxyl group in the curcumin structure can deprotonate under alkaline conditions, and the molecular shape changes, resulting in a significant change in the color of the solution. Recent studies have shown that curcumin can change the fluorescence properties by complexing with metal ions, and can also be used as a visual probe for metal ions. In addition, monocarbonyl curcuminoids have a stable structure and are not easily decomposed under acid-base conditions. Therefore, using dienone as fluorophore and phenolic hydroxyl group as deprotonated group, a structurally stable monocarbonyl curcumin compound was designed and synthesized, which was applied as a visual pH fluorescent probe.

Contents of the invention

One of the purposes of the present invention is to provide a highly selective, highly sensitive visualized pH fluorescent probe; the second purpose is to provide a method for synthesizing the visualized fluorescent probe with simple technology; the third purpose is to provide the visualized fluorescent probe The purpose of the needle.

One of purpose of the present invention is achieved through the following technical solutions:

The visualized fluorescent probe of the present invention has the following structural formula:

The fluorescent properties of this series of monocarbonyl curcumin have high sensitivity to pH detection, strong selectivity to hydrogen ions, and little interference from other metal ions; this type of probe is used as a reagent for measuring pH.

Two of the object of the present invention can be realized by following technical measures:

Dissolve a certain proportion of aldehydes and ketones in ethanol or glacial acetic acid, add a certain amount of saturated HCl in glacial acetic acid, and stir at room temperature (25-30°C). After the reaction is complete, add water, filter the precipitate to obtain the crude product, and recrystallize it with ethanol.

Three of the object of the present invention can be realized by following technical measures:

The visualized pH fluorescent probe of the present invention is applied to the detection of pH in an environmental system.

The beneficial effects of the visualized pH fluorescent probe of the present invention:

1. The excitation wavelength of the probe molecule is in the range of 350-600 nm, and the emission wavelength is in the range of 450-700 nm. It has good stability and can be stored and used for a long time. It is suitable for a variety of environmental systems, especially cell and organelle systems.

2. In the range of pH 7.00 to 10.00, the ultraviolet absorption and fluorescence spectra of probe molecules are strongly dependent on pH.

3. The probe molecule has good light resistance and good selectivity to hydrogen ions, metal ions (Mg ²⁺ , Ca ²⁺ , Ag ⁺ , Ba ²⁺ , Cu ²⁺ , Mn ²⁺ , Fe ²⁺ , Pb ²⁺ ) had no effect on detection. It has good selectivity, and common metal ions have little interference to the fluorescent signal of the molecule.

4. Stokes displacement is large. Fluorescent background interference is small, and the signal-to-noise ratio is good.

5. The color of the solution changes significantly with the change of pH.

6. When the solution changes from acidic to alkaline, the red shift of the ultraviolet absorption spectrum is large, and the color of the solution changes significantly.

The visualized pH fluorescent probe of the present invention has very important application value, and the probe of the present invention can

As an acid-base indicator, the pH value of the environment can be judged simply and quickly by the color change of the solution, and the pH value of the environment can be detected by the change of the fluorescence performance.

Description of drawings

Fig. 1 The UV absorption spectrum of the probe as a function of pH.

Fig. 2 The fluorescence spectrum of the probe as a function of pH.

Figure 3. Changes of fluorescence intensity with time.

Fig. 4 Effect of metal ions (Mg ²⁺ , Ca ²⁺ , Ag ⁺ , Ba ²⁺ , Cu ²⁺ , Mn ²⁺ , Fe ²⁺ , Pb ²⁺ ) on the fluorescence intensity of the probe.

Detailed ways

The present invention will be further described by the following examples, but the present invention is not limited thereto.

Example 1:

Put 0.01 mol of 4-hydroxy-3-methoxy-benzaldehyde and 0.005 mol of acetone in a round bottom flask, add 20 mL of saturated HCl in glacial acetic acid solution, and stir at room temperature (25-30 ℃) for 30 min Leave it for 2 days. After the reaction was complete, 20 mL of water was added to the reaction flask, and the precipitate was filtered to obtain a crude product, which was recrystallized with ethanol and dried in vacuo to obtain an orange-yellow powder. 1,5-Bis(4-hydroxy-3-methoxy)-1,4-pentadien-3-one Yield 98%. mp 99–100 °C. ¹ H NMR (DMSO-d6, 300 MHz) δ (ppm): 9.60 (brs, 2H, –OH), 7.63 (d, J = 15.9 Hz, 2H, –CH=C–), 7.35 (s, 2H, ArH), 7.18 (d, J = 8.1 Hz , 2H, ArH), 7.12 (d, J = 15.9 Hz, 2H, –C=CH–), 6.81 (d, J = 8.1 Hz, 2H, ArH), 3.84 (s, 6H, –OCH ₃ ). ESI –MS (m/z): 325[M-1] ^- . Anal. Calc. for C ₁₉ H ₁₈ O ₅ : C 69.93, H 5.56. Found: C 69.79, H 5.67.

Example 2:

Put 0.01 mol of 4-hydroxy-3-methoxy-benzaldehyde and 0.005 mol of cyclopentanone in a round-bottomed flask, add 20 mL of saturated HCl in glacial acetic acid, and stir at room temperature (25-30 °C) for 30 Leave it for 2 days after min. After the reaction was complete, 20 mL of water was added to the reaction flask, and the precipitate was filtered to obtain a crude product, which was recrystallized with ethanol. 2,5-Bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone Yield 94%. mp 212–214 °C. 1H NMR (DMSO-d6, 300 MHz) δ (ppm): 9.64 (brs, 2H, –OH), 7.34 (s, 2H, –CH=), 7.23 (s, 2H, aroma), 7.15 (d, J = 8.1 Hz, 2H, ArH), 6.87 (d, J = 8.1 Hz, 2H, ArH), 3.83 (s, 6H, –OCH ₃ ), 3.06 (s, 4H, –H ₂ C–CH ₂ –). ESI–MS (m/z): 351[M-1] ^- Calc. for C ₂₁ H ₂ 0O ₅ : C 71.58, H 5.72. Found: C 71.50, H 5.88.

Example 3:

Put 0.01 mol of 4-hydroxy-3-methoxy-benzaldehyde and 0.005 mol of cyclopentanone in a round-bottomed flask, add 20 mL of saturated HCl in glacial acetic acid, and stir at room temperature (25-30 °C) for 30 Leave it for 2 days after min. After the reaction was complete, 20 mL of water was added to the reaction flask, and the precipitate was filtered to obtain a crude product, which was recrystallized with ethanol. Yield 98%. mp 178–179 °C. ¹ H NMR (DMSO-d6, 300 MHz) δ (ppm): 9.48 (brs, 2H, –OH), 7.53 (s, 2H, –CH=), 7.08 ( s, 2H, ArH), 7.01 (d, J = 8.1 Hz, 2H, ArH), 6.82 (d, J = 8.1 Hz, 2H, ArH), 3.79 (s, 6H, –OCH ₃ ), 2.87 (t, J = 6.7 Hz, 4H, –H ₂ C–C–CH ₂ –), 1.71 (q, J = 6.7 Hz, 2H, –C–CH ₂ –C–). ESI–MS (m/z): 365 [M-1] ^- . Anal. Calc. for C ₂₂ H ₂₂ O ₅ : C 72.12, H 6.05. Found: C 72.03.48, H 6.02.

Example 4:

Put 0.01 mol of 4-hydroxy-3-methoxy-benzaldehyde and 0.005 mol of cyclopentanone in a round-bottomed flask, add 20 mL of saturated HCl in glacial acetic acid, and stir at room temperature (25-30 °C) for 30 Leave it for 2 days after min. After the reaction was complete, 20 mL of water was added to the reaction flask, and the precipitate was filtered to obtain a crude product, which was recrystallized with ethanol. Yield 82%. mp 226–228 °C. ¹ H NMR (DMSO-d6, 300 MHz) δ (ppm): 9.54 (brs, 2H, –OH), 7.52 (s, 2H, –CH=), 7.07 ( s, 2H, ArH), 7.00 (m, 2H, ArH), 6.83((m, 2H, ArH), 3.98 (s, 4H, –CH ₂ –O–CH ₂ –), 3.81 (s, 6H, – OCH ₃ ). ESI–MS (m/z): 367[M-1] ^- . Anal. Calc. for C ₂₁ H ₂₀ S ₆ : C 68.47, H 5.47. Found: C 68.45, H 5.68.

Example 5:

Put 0.01 mol of 4-hydroxy-3-methoxy-benzaldehyde and 0.005 mol of cyclopentanone in a round-bottomed flask, add 20 mL of saturated HCl in glacial acetic acid, and stir at room temperature (25-30 °C) for 30 Leave it for 2 days after min. After the reaction was complete, 20 mL of water was added to the reaction flask, and the precipitate was filtered to obtain a crude product, which was recrystallized with ethanol. Yield 82%. mp 98–100 °C. ¹ H NMR (DMSO-d6, 300 MHz) δ (ppm): 9.64 (brs, 2H, –OH), 7.57 (s, 2H, –CH=), 7.00 ( s, 4H, ArH), 6.85 (m, 4H, ArH), 4.89 (s, 4H, –CH ₂ –S–CH ₂ –), 3.81 (s, 6H, –OCH ₃ ). ESI–MS (m/ z): 383[M-1] ^- . Anal. Calc. for C ₂₁ H ₂₀ O ₅ S: C 65.61, H 5.24. Found: C 65.60, H 5.44.

Embodiment 6:

A representative probe, 2,5-bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone, was selected to evaluate its dependence on pH. Quantitative compounds were added to buffer solutions with different pH values to make the final concentration 10 mM. After the solution was stable for 2 min, the ultraviolet absorption spectrum was scanned to study the relationship between the ultraviolet absorption spectrum and the pH value of the solution. The excitation wavelength of the fluorescence spectrum was determined according to the absorption spectrum of the compound, and then the fluorescence spectrum was scanned for the compound solution (final concentration: 10 mM) with different pH values to study the relationship between the fluorescence spectrum and the pH value of the solution. Figure 1 is the pH titration of ultraviolet absorption. It can be seen from the figure that ultraviolet absorption has good selectivity to pH. When changing from acidic to alkaline, the ultraviolet absorption spectrum undergoes a large red shift, and the color of the solution changes from yellow to red. . Figure 2 shows the fluorescence pH titration. It can be seen from the figure that the intensity of the fluorescence spectrum increases significantly in the range of pH 7.00 – 10.00, and the Stokes shift is large.

Embodiment 7:

A representative probe, 2,5-bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone, was selected to evaluate its photostability. FIG. 3 is a graph showing the relationship between the fluorescence spectrum intensity of the probe and time. It can be seen that the fluorescence spectrum intensity of the probe does not change much with the passage of time, and has good light resistance.

Embodiment 8:

A representative probe 2,5-bis(4-hydroxy-3-methoxybenzylidene)cyclopentanone was selected to evaluate its anti-interference ability of metal ions. Figure 4 shows the change of fluorescence intensity in the presence of metal ions. It can be seen that the effect of metal ions on the fluorescence intensity of the probe is not obvious.

Claims (1)

1. one kind based on the application of single carbonyl curcumine compound as visual pH fluorescent probe, it is characterized in that described visual fluorescent probe has the structure shown in the formula I:

?

Formula I

R among the formula I ₁, R ₂R ₃, R ₄The group of representative is: OH, H, OCH ₃, a kind of in the Br substituting group; X is CH ₂, CH ₂-O-CH ₂, CH2-S-CH ₂In a kind of; N=0 ~ 2.

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