阅读说明：本技术 一种对酸性环境具有双荧光检测信号的分子传感器及应用 (Molecular sensor with double fluorescence detection signals for acidic environment and application ) 是由 王芳 高艳艳 周连文 华晓莹 申青军 伍平 贾春晓 冯军 毛淑飞 于 2021-09-28 设计创作，主要内容包括：本发明提供了一种对酸性环境具有双荧光检测信号的分子传感器及应用,涉及有机功能材料检测技术领域。本发明公开的分子传感器,是以2-氨基芴和对-二苯胺基苯甲醛为反应原料,基于醛氨之间的亲核加成反应制备；该分子传感器同时含有二苯胺基及亚胺两类质子作用位点,其对酸性环境表现出灵敏的“关-开-关”双重荧光检测信号,灵敏度高、选择性好,具有显著的应用价值；且其制备方法具有产率高、合成工艺简单,易于实施等优点,适合工业化推广,为本分子传感器的推广应用创造了有利条件。(The invention provides a molecular sensor with double fluorescence detection signals for an acidic environment and application thereof, and relates to the technical field of organic functional material detection. The invention discloses a molecular sensor, which is prepared by taking 2-aminofluorene and p-diphenylamine benzaldehyde as reaction raw materials based on nucleophilic addition reaction between aldehyde and ammonia; the molecular sensor simultaneously contains two proton action sites of diphenylamine group and imine, shows sensitive 'off-on-off' dual fluorescence detection signals to an acid environment, has high sensitivity and good selectivity, and has obvious application value; the preparation method has the advantages of high yield, simple synthesis process, easy implementation and the like, is suitable for industrial popularization, and creates favorable conditions for the popularization and application of the molecular sensor.)

1. A molecular sensor with double fluorescence detection signals in an acidic environment has a molecular structure as follows:

。

2. the application of the molecular sensor with double fluorescence detection signals for acid environment as claimed in claim 1, characterized in that the acceptor unit contains two proton action sites of diphenylamino and imine, and can show sensitive 'off-on-off' double fluorescence detection signals for acid environment.

Technical Field

The invention relates to the technical field of organic material detection functions, in particular to a triphenylamine-fluorene single Schiff base molecular sensor with double fluorescence response signals in an acidic environment and application of the triphenylamine-fluorene single Schiff base molecular sensor in the detection field.

Background

With the development of society, the problem of environmental pollution is a hot spot of global common attention, and is also one of the main problems faced by the sustainable development of economy and society in China. For example, specific pH conditions have very important applications in current industrial and agricultural production processes. However, when the industrial wastewater with too high acidity or alkalinity is discharged into the nature, the pollution to the soil and the whole water system is serious, plants wither and animals die sometimes, and great harm is caused to the ecological system and the human living environment. In addition, the body fluid buffering system and the mutual regulation of organs are usually used to maintain a constant pH environment in the organism, so that the functions in the organism can be normally performed. Once the pH value in vivo deviates from the normal level, cell inactivation can be caused, normal dysfunction in human body can be caused, and further serious diseases such as inflammation, Alzheimer disease, malignant tumor and the like can be caused. Therefore, the development of an efficient and convenient pH value detection method has important significance on industrial and agricultural production, environmental science and the like.

Among many detection methods, fluorescent molecular sensors with high sensitivity, low cost and easy operation are receiving more and more attention. The fluorescent molecular sensor converts the identification process in the microscopic world into an optical signal easy to detect through ingenious design, and realizes the in-situ, real-time and sensitive detection process on the molecular level. Therefore, fluorescent molecular sensors are powerful tools for detecting pH changes in various fields. Based on different detection mechanisms, numerous and functionally diverse pH fluorescent molecular sensors have been invented. However, most of the detection signals of the currently prepared pH fluorescent molecular sensor change in a single direction, namely, the fluorescence signals only increase or decrease in intensity along with the increase/decrease of the acidic environment; ultrasensitive molecular sensors, in which the fluorescence signal intensity changes in an "off-on-off" two-way manner as the solution acidic environment changes, have been less studied. The demand for sensitive detection of dynamic pH change in work and life of people is higher and higher, and the development of a pH fluorescent molecular sensor which is fast, sensitive, easy to prepare and low in cost is an urgent demand in various monitoring fields at present.

The fluorene fluorophore has the advantages of higher molar extinction coefficient, good light stability, easy modification of structure and the like, and is an excellent fluorescent signal group. imine-C = N-group easy to synthesize has stronger proton complexing ability; when the nitrogen atom in the-C = N-group is complexed with a proton, a sensitive fluorescence intensity or two-channel spectral change can be induced. People synthesize a series of fluorescent molecular sensors [ X.Ma, J.Cheng, J.Liu, X.Zhou, H.Xiang ] with different recognition performances and optical transformation mechanisms by replacing and modifying the periphery of a-C = N-group,New J. Chem., 2015, 39, 492; F. Wang, C. Li,X. Zhang,A. Wang,L. Zhou,C. Jia,J. Xu, Y. Chen, Dyes and Pigments, 2019, 171, 107667]. However, the research on the molecular sensor which is constructed by the fluorene fluorophore, is easy to prepare and has sensitive 'off-on-off' dual fluorescence response to the acid environment is less.

Disclosure of Invention

The technical purpose of the invention is to provide a triphenylamine-fluorene single Schiff base molecular sensor which has double fluorescence response signals in an acidic environment and is easy to prepare.

The invention also aims to provide a method for dynamically detecting the acidic pH value in the working and domestic wastewater of people, which has the advantages of high efficiency, rapidness, simplicity, convenience, sensitivity, easy operation and the like.

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

a triphenylamine-fluorene single Schiff base molecular sensor with double fluorescence detection signals in an acidic environment has a molecular structure as follows:

a triphenylamine-fluorene single Schiff base molecular sensor with double fluorescence detection signals in an acidic environment is prepared by the following steps:

in N₂Under the protection condition, placing alpha mmol of p-diphenylamine benzaldehyde and beta mmol of 2-aminofluorene into a round-bottomed flask containing gamma mL of absolute ethyl alcohol, heating to reflux, and continuing to carry out reflux reaction for 6-10 hours; filtering a mixture obtained by the reaction, washing with absolute ethyl alcohol, and drying to obtain an orange triphenylamine-imine fluorene molecular sensor; the ratio of alpha, beta and gamma is 1:1: 20.

The preparation reaction formula of the triphenylamine-fluorene single Schiff base molecular sensor is as follows:

the invention has the following technical effects: the receptor unit of the triphenylamine-fluorene single Schiff base molecular sensor simultaneously contains two proton action sites of diphenylamino and imine, and the maximum fluorescence emission intensity of the molecule at the 384 nm position is firstly obviously increased and then reduced along with the continuous enhancement of the acid environment of the solution, so that a sensitive off-on-off dual fluorescence detection signal is presented to the acid environment, and the receptor unit has higher application value; the preparation process of the triphenylamine-fluorene single Schiff base molecular sensor provided by the invention has the advantages of high yield, mild synthesis conditions, simple preparation process and the like, is suitable for industrial implementation, and creates favorable conditions for popularization and application of the triphenylamine-fluorene single Schiff base molecular sensor.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of the compound obtained in example 1-2.

FIG. 2 shows fluorescence emission spectra of triphenylamine-fluorene bis-Schiff base molecular sensor prepared by adding HCl with different concentrations into 95% acetonitrile water solution.

FIG. 3 shows fluorescence emission spectra of triphenylamine-fluorene single Schiff base molecular sensor added with HAc of different concentrations in 95% acetonitrile water solution.

Fig. 4 shows fluorescence emission spectra of triphenylamine-fluorene single schiff base molecular sensor prepared by adding 10 times of HCl and 10 times of different metal ions into 95% acetonitrile water solution.

Detailed Description

The invention discloses a triphenylamine-fluorene single Schiff base molecular sensor with double sensitive detection signals in an acidic environment, which has the following molecular structure:

；

the compound can be prepared by adopting 2-aminofluorene and p-diphenylamine benzaldehyde as reaction raw materials through one-step polymerization reaction, and the synthesis reaction formula is as follows:

。

example 1

In N₂Under the protection condition, 1 mmol of p-diphenylamine benzaldehyde and 1 mmol of 2-aminofluorene are put into a round-bottom flask containing 20 mL of absolute ethyl alcohol, and then the temperature is raised to reflux; continuously carrying out reflux reaction for 6 hours; the reaction mixture was filtered, washed with anhydrous ethanol, and dried to obtain compound a as an orange powder, 226.7 mg, with a yield of 52%.

Example 2

In N₂Under the protection condition, 1 mmol of p-diphenylamine benzaldehyde and 1 mmol of 2-aminofluorene are put into a round-bottom flask containing 20 mL of absolute ethyl alcohol, and then the temperature is raised to reflux; continuously refluxing and reacting for 10 hours; the reaction mixture was filtered, washed with anhydrous ethanol, and dried to give compound B as an orange powder, 228.9 mg, in 52.5% yield.

The nuclear magnetic hydrogen spectra of the compounds A and B obtained in examples 1-2 were identical, and the data were as follows: in that¹H NMR (CDCl₃400 MHz), contains 1 proton signal peak on C = N-carbon: 8.63 (s, 1H); 21 aromatic ring proton signal peaks: 7.95 (t, 2H), 7.87 (d, 2H), 7.61 (d, 1H), 7.51 (s, 1H), 7.44 (t, 5H), 7.35 (s, 1H), 7.33 (t, 1H), 7, 22 (t, 4H), 7.18 (d, 2H), 7.02 (d, 2H); 2 CH₂-protonsSignal peak: 3.98 (s, 2H), which is basically consistent with the molecular theoretical value of triphenylamine-fluorene single Schiff base. From this, it was confirmed that the molecular structures of compounds a and B were:

namely triphenylamine-fluorene mono schiff base molecules.

Example 3

The fluorescent detection performance of the triphenylamine-fluorene single Schiff base molecular sensor on hydrochloric acid with different concentrations in 95% acetonitrile water solution is as follows: at a concentration of 2X 10^-5HCl with different concentrations is added into 95% acetonitrile water solution of a triphenylamine-fluorene single Schiff base molecular sensor in mol/L, and the molar equivalent ratio of HCl to acetonitrile is 1:0, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:90, 1:100 and 1: 500. The spectral properties of the system study showed that: with the increasing amount of HCl substance in the solution, from 0 → 10 → 100 times, the 384 nm weak fluorescence emission intensity is firstly increased remarkably and then quenched in the free state of the triphenylamine-fluorene single Schiff base molecular sensor. These studies indicate that the triphenylamine-fluorene single schiff base molecular sensor has sensitive off-on-off double-fluorescence signal detection potential in an acidic environment in 95% acetonitrile water solution.

Example 4

The fluorescent detection performance of the triphenylamine-fluorene single Schiff base molecular sensor on acetic acid with different concentrations in 95% acetonitrile water solution is as follows: at a concentration of 2X 10^-5HAc with different concentrations is added into 95% acetonitrile water solution of a triphenylamine-fluorene single Schiff base molecular sensor in mol/L, and the amount ratio of the two substances is 1:0, 1:2, 1:4, 1:6, 1:8, 1:10, 1:12, 1:16, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100 and 1:200 respectively. The fluorescence emission spectrum property study of the system shows that: with the increasing of the amount of acetic acid substances in the solution, from 0 → 20 → 200 times, the weak fluorescence emission intensity of the triphenylamine-fluorene single Schiff base molecular sensor is obviously increased and then reduced, even quenched, which shows that the triphenylamine-fluorene single Schiff base molecular sensor is in 95% acetonitrile waterThe solution has sensitive 'off-on-off' dual fluorescence signal detection potential to the acid environment caused by acetic acid.

Example 5

The triphenylamine-fluorene single Schiff base molecular sensor has the following fluorescence detection performance on different acidic environments in the presence of different metal ions: adding hydrochloric acid with 10 times of molar equivalent into 95% acetonitrile aqueous solution of a triphenylamine-fluorene single Schiff base molecular sensor, and respectively adding K with 10 times of molar weight⁺、Na⁺、Ba²⁺、Ca²⁺、Mg²⁺、Cd²⁺、Hg²⁺、Mn²⁺、Ni²⁺、Zn²⁺、Co²⁺、Cu²⁺Plasma metal ions, from the change of their fluorescence emission spectra, can be found: after 10 times of hydrochloric acid is added, the maximum fluorescence emission intensity of the fluorescent compound at the 384 nm position is obviously increased; k⁺、Na⁺、Ba²⁺、Ca²⁺、Mg²⁺、Cd²⁺、Hg²⁺、Mn²⁺、Ni²⁺、Zn²⁺、Co²⁺、Cu²⁺After the metal ions are added into a triphenylamine-fluorene single Schiff base molecular sensor-HCl mixed system, the strong fluorescence emission of the system is basically unchanged, which shows that the triphenylamine-fluorene single Schiff base molecular sensor has good detection potential to the acid environment even in the presence of the metal ions.