CN113527257B - Indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye and preparation method and application thereof - Google Patents

Abstract

The invention discloses an indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye and a preparation method and application thereof, wherein the chemical structure of the compound is shown as (I), 2-formyl-8-benzyloxy quinoline (II) is used as a starting material to perform Knoevenagel condensation reaction with iodinated 2,3, 3-trimethyl-1-propyl-3H-indole salt (III) to obtain an indolyl 8-hydroxyquinoline derivative (IV), and then the indolyl 8-hydroxyquinoline derivative shown as the formula (I) is obtained through boron tribromide debenzylation reaction. The compound has the advantages of simple preparation method, mild reaction conditions and simple and convenient operation, the maximum fluorescence emission wavelength of the compound in different solvents is more than 650nm, and the compound has large Stokes shift (more than 200 nm). In addition, the fluorescent probe has excellent cell permeability and biocompatibility, and can be used for near-infrared bioluminescence probes and bioluminescence imaging.

Description

A kind of indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye and its preparation method and application

technical field

The invention belongs to the technical field of organic small molecule synthesis and the field of near-infrared fluorescent dyes, and relates to a preparation method and application of an indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye.

Background technique

Benzindole derivatives are an important class of nitrogen-containing organic heterocyclic compounds with a large π-conjugated system, which have important applications in biomedicine, biological detection, fluorescent dyes, etc. 2,3,3-Trimethyl-1H-benzo[e]indole is an important intermediate in the synthesis of biological detection reagent indocyanine green. And benzoindole is also an important constituent group of cyanine dyes. Indole cyanine dyes have high photothermal stability, good solubility, large molar extinction coefficient, and large tunable range of maximum absorption wavelength. It has been widely used in photographic sensitization, optical disc recording media, tumor detection, near-infrared fluorescent dyes, photodynamic therapy, optical nonlinear materials and biological macromolecular fluorescent labels. However, the currently available indole-based near-infrared fluorescent dyes are still very limited, and many of them fail to reach the near-infrared region and suffer from problems such as poor photostability.

8-Hydroxyquinoline and its derivatives are a very important class of aromatic heterocyclic compounds, which are widely used in the field of fluorescent probes. They have a π-conjugated system that makes it easy to undergo electronic transitions to generate fluorescence. The nitrogen atom on the heterocyclic ring and the oxygen atom on the hydroxyl group can also participate in the coordination reaction. It is these characteristics that enable the quinoline derivatives to recognize different ions and generate fluorescence. In addition, 8-hydroxyquinoline is one of the important categories in medicinal chemistry, and is widely used in pharmaceutical preparations such as neuroprotective agents, anticancer agents, enzyme inhibitors, metalloprotein chelators, anti-HIV drugs, and antifungal drugs. In addition, its application in optoelectronic functional molecular materials has also received more and more attention.

The present invention designs and synthesizes indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dyes based on indole salts and 8-hydroxyquinoline compounds. The 8-hydroxyquinoline group was functionalized with the iodide indole group to increase its recognition group and increase the Stokes shift. While improving its physical and chemical properties, the increase in molecular mass is minimized, and the advantages of small molecular compounds that cause less interference to biological tissues and cells and are not prone to precipitation. The invention designs and develops a simple, novel, and further modifiable low-molecular-weight near-infrared fluorescent dye, which has good biocompatibility and cell membrane permeability, and is of great significance in terms of synthesis and application research.

SUMMARY OF THE INVENTION

Purpose of the invention: The purpose of the present invention is to provide a preparation method and application of an indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye.

Technical scheme: In order to realize the above-mentioned purpose of the invention, the technical scheme adopted in the present invention is:

The structure of an indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye involved in the present invention is as follows:

The synthetic route of a kind of indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye involved in the present invention is:

The preparation process of an indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye involved in the present invention comprises the following steps:

Step 1: Dissolve 2-formyl-8-benzyloxyquinoline (II) and 2,3,3-trimethyl-1-propyl-3H-indole iodide (III) in absolute ethanol In the solution, piperidine was added dropwise to the solution, and the reaction was refluxed at 80 °C for 12 h under an argon atmosphere. After the reaction is completed, it is cooled to room temperature, and the filtrate is removed by filtration to obtain a dark red solid, which is separated and purified by silica gel column chromatography to obtain indolyl 8-hydroxyquinoline derivative (IV);

Step 2: Dissolve the indolyl 8-hydroxyquinoline derivative (IV) in dry dichloromethane, slowly add boron tribromide dropwise under the protection of argon and under ice cooling, stir for 15 minutes and then remove In an ice bath, the mixture was slowly raised to room temperature and stirred for 6 h. After the reaction, the reaction solution was cooled in an ice bath and quenched with water, extracted with dichloromethane, the combined organic phases were washed with saturated brine, and then the organic phase was dried over anhydrous sodium sulfate and filtered, and the solvent was spin-dried and the crude product was obtained. The indolyl 8-hydroxyquinoline near-infrared fluorescent dye (I) was obtained by silica gel column chromatography.

In the above reaction step 1, the substance of 2-formyl-8-benzyloxyquinoline (II) and 2,3,3-trimethyl-1-propyl-3H-indole iodide (III) The ratio of quantity is 1:1;

In the above reaction step 1, the amount of catalyst piperidine is 5-10% of the amount of the reactant raw material;

In the above reaction step 2, the substance ratio of indolyl 8-hydroxyquinoline derivative (IV) to boron tribromide is 1:10.

Beneficial effects of the present invention:

Compared with the prior art, the advantages of the indole-conjugated 8-hydroxyquinoline near-infrared fluorescent dye and the preparation method of the present invention are as follows: (1) indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye It has a significant solvent effect, the maximum fluorescence emission wavelength is above 650nm, and has a large Stokes shift; (2) It can be used for HeLa cell fluorescence imaging research, has good cell permeability and biocompatibility, and can be It can be used as a near-infrared biofluorescence probe and biofluorescence imaging; (3) the synthetic route is simple, the reaction conditions are mild, the reaction selectivity is good, the separation method is simple, and has universality, and can be applied to the synthesis of similar near-infrared fluorescent dyes.

Description of drawings

Fig. 1 is the ultraviolet-visible absorption spectrum of indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) of the present invention in different solvents;

Fig. 2 is the fluorescence emission spectrum of indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) of the present invention in different solvents;

FIG. 3 is a confocal laser fluorescence imaging image of the indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) of the present invention after co-incubating with HeLa cells.

Detailed ways

The present invention is further explained below in conjunction with specific examples, which do not limit the present invention in any way.

The structures of the compounds were characterized by UV-Vis spectroscopy and fluorescence spectroscopy and the photophysical properties of the compounds were studied. The instrument used for detection was: Shimadzu UV-3100 UV-Vis spectrophotometer (scanning range 300-900 nm, optical path slit 2 nm), and the fluorescence spectrum was tested with American Amico Bowman Series 2 Luminescence Spectrometer.

Example 1

2-Formyl-8-benzyloxyquinoline (II) (265 mg, 1 mmol) and 2,3,3-trimethyl-1-propyl-3H-indole iodide (III) (330 mg, 1 mmol) was dissolved in 15 mL of absolute ethanol, 50 μL of piperidine was added dropwise to the solution, and the reaction was refluxed for 12 h under an argon atmosphere. After the reaction, it was cooled to room temperature, and the filtrate was removed by filtration to obtain a dark red solid, which was separated and purified by silica gel column chromatography using dichloromethane-methanol (v:v=20:1) as the eluent to obtain indolyl 8-hydroxyl Quinoline derivative (IV), 74% yield. ¹ H-NMR (600 MHz, CDCl ₃ , ppm): δ=8.94 (d, J=8.4 Hz, 1H), 8.67 (d, J=16.2 Hz, 1H), 8.43 (d, J=16.2 Hz, 1H) , 8.37(d, J=8.4Hz, 1H), 7.71-7.70(m, 1H), 7.64-7.61(m, 3H), 7.58(d, J=7.8Hz, 2H), 7.53(t, J=7.8 Hz, 1H), 7.48-7.43(m, 3H), 7.39(t, J=7.2Hz, 1H), 7.16(d, J=7.2Hz, 1H), 5.40(s, 2H), 5.00(t, J =7.2Hz, 2H), 2.04(q, J=7.2Hz, 2H), 1.97(s, 6H), 1.03(t, J=7.8Hz, 3H).

Example 2

The indolyl 8-hydroxyquinoline derivative (IV) (114.8 mg, 0.2 mmol) was dissolved in 30 mL of dry dichloromethane, and under the protection of argon, boron tribromide (0.19 mL, 2 mmol), stirred for 15 min, removed the ice bath, slowly raised to room temperature and stirred for 6 h. After the reaction was completed, the reaction solution was cooled in an ice bath and quenched with water, extracted with dichloromethane, washed with saturated brine, the organic phase was dried over anhydrous sodium sulfate and filtered, the solvent was spin-dried, and the mixture was washed with dichloromethane-methanol. (v:v=40:1) is the eluent, and the indolyl 8-hydroxyquinoline near-infrared fluorescent dye (I) is obtained by separation and purification by silica gel column chromatography, and the yield is 76%. ¹ H-NMR (600 MHz, CDCl ₃ , ppm): δ=9.08 (s, 1H), 8.79 (d, J=15.6 Hz, 1H), 8.572-8.514 (m, 2H), 8.14 (d, J=7.8 Hz, 1H), 7.68 (s, 1H), 7.59-7.56 (m, 3H), 7.39 (t, J=7.8Hz, 1H), 7.20 (d, J=7.2Hz, 1H), 7.02 (d, J =7.2Hz, 1H), 3.41(s, 1H), 2.03(d, J=6.6Hz, 2H), 1.91(s, 6H), 1.05(t, J=7.2Hz, 3H).

Example 3 UV-Vis absorption spectra of indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) in different solvents

The indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) was dissolved in dichloromethane, ethyl acetate, and methanol, respectively, and prepared into a solution with a concentration of 1×10 ^-5 mol/L. - Visible absorption spectrum. Fig. 1 is the ultraviolet-visible absorption spectrum of the fluorescent dye (I) prepared in Example 2 of the present invention in different solvents.

Example 4 Fluorescence of indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) in different solvents

The indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) was dissolved in dichloromethane, ethyl acetate and methanol, respectively, and prepared into a solution with a concentration of 1×10 ^-5 mol/L, and its fluorescence was measured. ll. Figure 2 is the solution fluorescence spectrum of the fluorescent dye (I) prepared in Example 2 of the present invention in different solvents.

Example 5 Indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) for tumor cell fluorescence imaging

Imaging pictures of HeLa cells were observed under a confocal fluorescence microscope after indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) was co-incubated with HeLa cells. Figure 3 is a photo of confocal fluorescence imaging of HeLa cells after co-incubation with fluorescent dye (I). The excitation wavelength of Hoechst 33342 is 352nm; the excitation wavelength of mHoney Dew is 487nm; Merged is in superposition state. After the fluorescent dye (I) was added to the HeLa cells for co-incubation, the fluorescent dye entered the inside of the HeLa cells for clear imaging. Indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I) can be used for biological cell imaging.

Claims (4)

1. a preparation method of indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye, is characterized in that, the chemical structure of indolyl-conjugated 8-hydroxyquinoline near-infrared fluorescent dye is shown in (1):

The preparation method of the indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye is as follows: using 2-formyl-8-benzyloxyquinoline (II) as the starting material and 2,3,3-trimethyl iodide Base-1-propyl-3H-indole salt (III) undergoes Knoevenagel condensation reaction to obtain indolyl 8-hydroxyquinoline derivative (IV), which is then debenzylated by boron tribromide to obtain formula (I) Indolyl 8-hydroxyquinoline near-infrared fluorescent dye shown;

2. preparation method according to claim 1, is characterized in that, described preparation method comprises the following steps: Step 1: Dissolve 2-formyl-8-benzyloxyquinoline (II) and 2,3,3-trimethyl-1-propyl-3H-indole iodide (III) in absolute ethanol In the solution, piperidine was added dropwise to the solution, and the reaction was refluxed at 80 °C for 12 h under an argon atmosphere; after the reaction was completed, it was cooled to room temperature, and the filtrate was filtered to obtain a dark red solid, which was separated and purified by silica gel column chromatography to obtain indolyl 8-hydroxyl Quinoline derivatives (IV); Step 2: Dissolve the indolyl 8-hydroxyquinoline derivative (IV) in dry dichloromethane, under argon protection, slowly add boron tribromide dropwise in an ice bath, stir for 15min and remove the ice bath , slowly raised to room temperature and stirred for 6 h; after the reaction was over, the reaction solution was cooled in an ice bath and quenched with water, then extracted with dichloromethane, the combined organic phases were washed with saturated brine, and the organic phase was washed with anhydrous After drying and filtration over sodium sulfate, the solvent is removed, and the solution is separated and purified by silica gel column chromatography to obtain an indolyl conjugated 8-hydroxyquinoline near-infrared fluorescent dye (I). 3. preparation method according to claim 2 is characterized in that in described step 1, 2-formyl-8-benzyloxyquinoline (II) and iodide 2,3,3-trimethyl-1 -Propyl-3H-indole salt (III) has a substance amount ratio of 1:1, and the amount of the catalyst piperidine is 5-10% of the amount of the reactant raw material. 4. preparation method according to claim 2, is characterized in that in described step 2, indolyl 8-hydroxyquinoline derivative (IV) and the material amount ratio of boron tribromide (V) are 1: 10.

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