阅读说明：本技术 一种对酸碱有关-开-关-开转换信号的分子探针及应用 (Molecular probe for acid-base related-on-off-on switching signals and application ) 是由 王芳 李春辉 王爱丽 王文强 杨敏 李玉美 刘明成 李凌雪 高敏 王筱冰 于 2021-09-29 设计创作，主要内容包括：本发明提供了一种对酸碱有关-开-关-开转换信号的分子探针及应用,涉及有机化合物检测性能技术领域；本发明提供的分子探针是以2,3-二羟基苯甲醛和2,7二氨基芴为反应原料,通过一步聚合反应制备。由于该分子探针同时含有对质子敏感的亚胺基团、对碱性环境敏感的邻二酚羟基作用位点,其对酸碱性环境变化呈现出显著的“关-开-关-开”四转换荧光检测响应,具有显著的应用价值；且其制备方法具有产率高、制备工艺简单,易于实施等优点,适合工业化推广,为本二酚羟基芴希夫碱分子探针的推广应用创造了有利条件。(The invention provides a molecular probe for acid-base related-on-off-on switching signals and application thereof, relating to the technical field of organic compound detection performance; the molecular probe provided by the invention is prepared by taking 2, 3-dihydroxy benzaldehyde and 2, 7-diaminofluorene as reaction raw materials through one-step polymerization reaction. Because the molecular probe simultaneously contains imine groups sensitive to protons and catechol hydroxyl action sites sensitive to alkaline environments, the molecular probe presents obvious 'off-on' four-conversion fluorescence detection response to acid-alkaline environment change and has obvious application value; the preparation method has the advantages of high yield, simple preparation process, easy implementation and the like, is suitable for industrial popularization, and creates favorable conditions for the popularization and application of the diphenol hydroxyfluorene Schiff base molecular probe.)

1. A molecular probe related to acid-base on-off-on switching signals has a molecular structure as follows:

。

2. the application of the molecular probe capable of switching signals between acid and alkali according to claim 1, wherein the acceptor unit of the molecular probe simultaneously contains an imine group sensitive to protons and an o-diphenol hydroxyl site sensitive to an alkaline environment, and the molecular probe shows an off-on four-conversion fluorescence detection response to the change of the acid and alkaline environments and has sensitive dynamic detection performance to the acid and alkali environments.

Technical Field

The invention relates to the technical field of organic compound function detection, in particular to a diphenol hydroxyfluorene Schiff base molecular probe which presents a sensitive off-on-off-on fluorescent four-conversion detection signal along with the change of an acid-base environment and an application thereof.

Background

Industrial processes often require specific acid, alkaline environments. However, when the industrial wastewater with too high acidity or alkalinity is discharged into the nature, the industrial wastewater can cause serious pollution to the whole water system and soil, and bring great harm to the ecological system and the human living environment. After polluted water with over-high acidity or alkalinity is used in the industrial and agricultural production process, not only industrial equipment is damaged, but also the product quality is seriously influenced; and the chemical components of the soil are changed, the fertility is reduced, and the crop is reduced in yield and even dies. When people drink water with high acidity or alkalinity, a series of diseases such as low immunity, dysfunction, cancer and the like of the organism can be caused, and even the life is threatened. For example, people who drink acid or alkali polluted water have a much higher incidence of cancers such as liver cancer and stomach cancer than people who drink clean water. Therefore, the development of a sensitive and convenient method for monitoring the acidity and the alkalinity of the environment has very important significance in the fields of industrial and agricultural production, chemical industry, environmental science and the like.

The fluorescent molecular probe converts the recognition effect in the microscopic world into an optical signal easy to observe through ingenious design, realizes the in-situ and real-time detection process on the molecular level, has the characteristics of high sensitivity, good selectivity, quick response, easy real-time field detection and the like, and has received more and more attention. Based on different detection principles, a large number of functionally diverse pH fluorescent molecular probes have been developed. However, most of the currently reported detection signals of the pH fluorescent molecular probe change in a single direction, namely, the fluorescence changes in a single signal of 'off-on' or 'on-off' along with the increase/decrease of acid and alkaline environments; molecular probes that exhibit sensitive "off-on" four-conversion of fluorescence signal intensity as the solution acidic and basic environment changes have been reported. With the development of society, people have higher and higher requirements on sensitive detection of changes of acid-base environments around the work and life of people. Therefore, the development of a pH fluorescent molecular probe which is fast, sensitive, simple to operate, easy to prepare and the like is urgently needed in various monitoring fields at present.

In the construction process of the fluorescent molecular probe, the receptor generally selects a group containing N, O atoms with strong coordination capacity and the like as a binding site, and obtains the fluorescent molecular probe with specific detection performance through an optical signal induced after the group is complexed with a target to be detected. The imine-C = N-group has stronger proton complexing ability, and after the nitrogen atom is complexed with the proton, sensitive fluorescent signal change can be induced. Based on imine schiff base groups, a series of pH fluorescent molecular probes with different recognition properties were prepared [ t. Dhawa, a. Hazra, a. bama, k. Pal, p. karkakar, p. Roy,RSC Adv.,2020,10,15501; K. K. Sadhu, S. Mizukami, A. Yoshimura, K. Kikuchi, Org. Biomol. Chem., 2013, 11, 563]. However, no molecular probe constructed by imine groups and having sensitive 'off-on-off-on' fluorescence four-conversion detection signals for acid-base environment changes has been reported.

Disclosure of Invention

The invention aims to provide a diphenol hydroxyfluorene Schiff base molecular probe which has sensitive 'off-on-off-on' four-conversion fluorescence detection signals to the change of acid and alkali environments.

The invention also aims to provide a method for sensitively detecting the pH value of the water for work and life of people, which has the advantages of sensitivity, easy operation, low cost, easy popularization and the like.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

a diphenol hydroxyl fluorene Schiff base molecular probe with sensitive 'off-on-off-on' four-conversion fluorescence detection signals to acid-base environment changes has a molecular structure as follows:

a diphenol hydroxyl fluorene Schiff base molecular probe with sensitive 'off-on-off-on' four-conversion fluorescence detection signals to acid-base environment changes is prepared by the following steps:

in N₂Under the protection condition, sequentially putting alpha mmol of 2, 3-dihydroxybenzaldehyde and gamma mmol of 2,7 diaminofluorene into a round-bottom flask, dissolving with beta mL of anhydrous methanol, heating to 75 ℃, and reacting for 3 hours; filtering the mixture obtained by the reaction, washing the mixture by using anhydrous methanol, and drying the mixture to obtain a dark red diphenol hydroxyfluorene Schiff base fluorescent molecular probe; the ratio of alpha, beta and gamma is 2:1: 30.

A diphenol hydroxyl fluorene Schiff base molecular probe with sensitive 'off-on-off-on' four-conversion fluorescence detection signals to the change of acid and alkali environment is prepared by the following reaction formula:

the invention has the following technical effects: the diphenol hydroxyfluorene Schiff base fluorescent molecular probe acceptor unit simultaneously contains imine sensitive to proton and diphenol hydroxyl group sensitive to alkaline environment; along with the continuous enhancement of the acid environment of the solution, the maximum fluorescence emission intensity of the molecular probe at the position of 410 nm is firstly obviously increased and then reduced, and a sensitive 'off-on-off' double fluorescence detection signal is presented to the acid environment; along with the continuous enhancement of the alkaline environment of the solution, the maximum fluorescence emission intensity of the molecular probe at the position of 410 nm is obviously increased, so that the molecular probe presents a sensitive off-on four-conversion fluorescence detection signal along with the change of the alkaline environment, and has higher application value; the preparation process of the diphenol hydroxyfluorene Schiff base fluorescent molecular probe provided by the invention has the advantages of simple process, mild reaction conditions, high yield and the like, is suitable for industrial implementation, and creates favorable conditions for popularization and application of the fluorescent molecular probe.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of the compound obtained in example 1.

FIG. 2 shows fluorescence emission spectra of diphenol hydroxyfluorene Schiff base molecular probe added with HCl of different concentrations in 95% DMSO aqueous solution.

FIG. 3 shows fluorescence emission spectra of diphenol hydroxyfluorene Schiff base molecular probe added with NaOH of different concentrations in 95% DMSO aqueous solution.

FIG. 4 shows fluorescence emission spectra of diphenol hydroxyfluorene Schiff base molecular probe added with HCl of different concentrations in 95% DMF aqueous solution.

FIG. 5 shows fluorescence emission spectra of diphenol hydroxyfluorene Schiff base molecular probe added with NaOH of different concentrations in 95% DMF aqueous solution.

Detailed Description

The invention discloses a diphenol hydroxyl fluorene Schiff base molecular probe with sensitive 'off-on-off-on' four-conversion fluorescence detection signals to the change of acid and alkali environments, which has a molecular structure as follows:

；

the catalyst can be prepared by adopting 2, 3-dihydroxy benzaldehyde and 2, 7-diaminofluorene as reaction raw materials through one-step polymerization reaction, and the preparation reaction formula is as follows:

。

example 1

In N₂Under the protection condition, 2 mmol of 2, 3-dihydroxybenzaldehyde and 1 mmol of 2,7 diaminofluorene are sequentially put into a round-bottom flask, dissolved by 30 mL of anhydrous methanol, heated to 75 ℃ and reacted for 3 hours; the reaction mixture was filtered, washed with anhydrous methanol and dried to give a dark red schiff base compound a, 218 mg, in 50% yield.

To the embodiments1, the nuclear magnetic hydrogen spectrum data are as follows: in that¹H NMR (DMSO-d₆400 MHz), contains 4 OH proton signal peaks: 13.79 (s, 2H), 9.75 (s, 2H); 2 proton signal peaks on C = N-carbon: 8.90 (s, 2H); 12 aromatic ring proton signal peaks: 8.51 (s, 2H), 7.97 (d, 2H), 7.64 (s, 4H), 7.44 (d, 2H), 6.99 (d, 2H), 6.46 (d, 2H); CH on 2 fluorene groups₂-proton signal peak: 4.02 (s, 2H), which is basically consistent with the theoretical value of the molecular probe of the hydroxyl fluorene Schiff base of the diphenol. This confirmed that the molecular structure of compound a was:

namely a diphenol hydroxyl fluorene Schiff base molecular probe.

Example 2

The fluorescent detection function of the diphenol hydroxyfluorene Schiff base molecular probe in 95% DMSO aqueous solution on different acidic environments is as follows: at a concentration of 2X 10^-5HCl with different concentrations is respectively added into 95% DMSO aqueous solution of diphenol hydroxyl fluorene Schiff base molecules in mol/L, and the molar equivalent ratio of the two is respectively 1:0, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:6, 1:8, 1:10, 1:20, 1:40, 1:60, 1:80, 1:100 and 1: 500. Detailed fluorescence spectroscopic property studies show that: with the increasing of the amount of HCl substances in the solution, when the molar equivalent is increased from 0 to 3 times, the maximum fluorescence emission intensity of the diphenol hydroxyfluorene Schiff base molecular probe at 410 nm is remarkably increased; however, when the amount of the HCl substance is increased to 100 times, the strong fluorescence emission is quenched again, which shows that the diphenol hydroxyfluorene Schiff base molecular probe has sensitive 'off-on-off' fluorescence triple-conversion signal detection potential in an acidic environment in a 95% DMSO aqueous solution.

Example 3

The fluorescent detection function of the diphenol hydroxyfluorene Schiff base molecular probe in 95% DMSO aqueous solution on different alkaline environments is as follows: at a concentration of 2X 10^-5NaOH with different concentrations are respectively added into 95 percent DMSO aqueous solution of diphenol hydroxyfluorene Schiff base molecules in mol/L, and the molar equivalent ratio of the diphenol hydroxyfluorene Schiff base molecules to the DMSO aqueous solution is 1:0, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:6, 1:8, 1:10, 1:20, 1:40, 1:60, 1:80, or,1:100 and 1: 500. The series of fluorescence spectrum property researches show that: with the increasing of the amount of NaOH substances in the solution, when the molar equivalent is increased from 0 to 100 times, the maximum fluorescence emission intensity of the diphenol hydroxyfluorene Schiff base molecular probe at 410 nm is gradually increased; when the amount of NaOH substances is continuously increased even to 500 times, the strong fluorescence emission change is less, and the result shows that the diphenol hydroxyfluorene Schiff base molecular probe has sensitive off-on fluorescence signal detection potential in an alkaline environment in a 95% DMSO aqueous solution.

Example 4

The fluorescent detection function of the diphenol hydroxyfluorene Schiff base molecular probe on different acidic environments in 95% DMF aqueous solution is as follows: at a concentration of 2X 10^-5HCl with different concentrations is respectively added into 95% DMF aqueous solution of diphenol hydroxyl fluorene Schiff base molecules in mol/L, and the molar equivalent ratio of the two is respectively 1:0, 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1.0, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:6, 1:8, 1:10, 1:20, 1:40, 1:60, 1:80, 1:100 and 1: 500. With the increasing of the amount of HCl substances in the solution, when the molar equivalent is increased from 0 to 4 times, the maximum fluorescence emission intensity of the diphenol hydroxyfluorene Schiff base molecular probe at 410 nm is remarkably increased; however, when the amount of the HCl substance is increased to 100 times, the strong fluorescence emission is quenched again, which shows that the diphenol hydroxyfluorene Schiff base molecular probe has the fluorescent signal detection potential of 'on-off' in an acidic environment in 95% DMF aqueous solution.

Example 5

The fluorescent detection function of the diphenol hydroxyfluorene Schiff base molecular probe in 95% DMF aqueous solution to different alkaline environments is as follows: at a concentration of 2X 10^-5NaOH with different concentrations are respectively added into 95 percent DMF aqueous solution of diphenol hydroxyfluorene Schiff base molecules in mol/L, and the molar equivalent ratio of the two is respectively 1:0, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:4, 1:6, 1:8, 1:10, 1:20, 1:40, 1:60, 1:80, 1:100 and 1: 500. A series of studies show that: with the increasing of the amount of NaOH substances in the solution, when the molar equivalent is increased from 0 to 100 times, the maximum fluorescence emission intensity of the diphenol hydroxyfluorene Schiff base molecular probe at 410 nm is gradually increased; when the amount of NaOH substance is continuously increased even to 500 times, the strong fluorescence emission changes little, which indicates that the diphenol hydroxyfluorene schiffThe fujie molecular probe has sensitive 'off-on' fluorescence signal detection potential in an alkaline environment in a 95% DMF aqueous solution.