CN107629008B

CN107629008B - Phenanthroimidazole micromolecule Fe3+Fluorescent probe and synthetic method thereof

Info

Publication number: CN107629008B
Application number: CN201710968079.0A
Authority: CN
Inventors: 阚伟; 刘婷; 阚宏泽; 王丽艳; 赵冰
Original assignee: Qiqihar University
Current assignee: Qiqihar University
Priority date: 2017-10-18
Filing date: 2017-10-18
Publication date: 2020-04-14
Anticipated expiration: 2037-10-18
Also published as: CN107629008A

Abstract

Phenanthroimidazole micromolecule Fe³⁺The invention relates to a fluorescent probe and a synthetic method thereof, which aims to solve the problem of the existing Fe³⁺The fluorescent probe is only suitable for acidic and neutral recognition environments, and has the technical problem that other metals interfere with the recognition of iron ions. The invention relates to phenanthroimidazole micromolecule Fe³⁺The structural formula of the fluorescent probe is as follows:

the synthesis method comprises the following steps: firstly, synthesizing an intermediate compound I by using phenanthrenequinone, m-nitrobenzaldehyde and ammonium acetate; secondly, synthesizing an intermediate compound II by reusing the intermediate compound I, Raney nickel and hydrazine hydrate solution; thirdly, synthesizing phenanthroimidazole micromolecule Fe by using intermediate compound II and 5-nitro salicylaldehyde³⁺A fluorescent probe. The probe can identify Fe in a water phase system with the pH value of 3-12³⁺Is free from interference of other ions and can be used for Fe in water³⁺Detection of contamination of (2).

Description

Phenanthroimidazole micromolecule Fe3+Fluorescent probe and synthetic method thereof

Technical Field

The invention relates to Fe³⁺Fluorescent probes and methods for their synthesis.

Background

Iron is one of the most important trace elements in the human body, and is the first element in importance or quantity. Iron deficiency in human bodies can cause various diseases, but excessive iron also has potential harm, so the method has great significance for detecting iron ions. In recent years, more and more researchers have started research on iron ion fluorescent probes. Libo et al report the recognition performance of rhodamine B derivatives on ferric ions in acidic environment [ organic chemistry, 2015, 35,2629-]Research shows that Fe³⁺The fluorescence of the rhodamine B derivatives can be selectively enhanced. In 2016, the recognition performance of rhodamine derivatives on ferric ions in neutral environments is reported in the article synthesis and spectral performance of iron ion fluorescent probes published by chemical reagents. In 2011 "sensor and actuator B: stage 160 of chemistry (Sensors and activators B: Chemical)1106 pages 1111 of the publication of' multifunctional identification Cu formed by dual-mode bonding²⁺And Fe³⁺The fluorescent probes of (Multi functional fluorescent Probe selective for Cu (II) and Fe (III) with a dual-mode of binding proproach) and 2015 published in European journal of inorganic chemistry (EurJIC) 311-317^II、Fe^IIAnd Fe^IIIApplications in biological cells and logic gates (A Simple Fluorescent detected from Naphtylamine for Selective Detection of Hg)^II,Fe^IIand Fe^IIIIonsin Mixed Aqueous Media, Applications in Living Cells and Logic Gates) are techniques for iron ion recognition, and in both articles, the host compound has recognition properties for divalent copper ions and divalent iron ions in addition to iron ions.

According to the research on iron ion fluorescent probes reported in the literature at present, the following two defects mainly exist:

1. the main compound has the recognition performance on iron ions only under the acidic or neutral environment, namely, the recognition under the alkaline environment has limitation;

2. the host compound has not only the ability to identify iron ions but also other metal ions, and therefore, the identification is not specific.

Disclosure of Invention

The invention aims to solve the problem of the existing Fe³⁺The fluorescent probe is only suitable for acidic and neutral recognition environments and the technical problem that other metals interfere with the recognition of iron ions, and provides the phenanthroimidazole small-molecule Fe³⁺Fluorescent probes and methods of synthesis and use thereof. Phenanthroimidazole small molecule Fe³⁺Fluorescent probes and methods for their synthesis.

The invention relates to phenanthroimidazole micromolecule Fe³⁺The structural formula of the fluorescent probe is as follows:

the above-mentioned phenanthroimidazole small molecule Fe³⁺The synthesis method of the fluorescent probe comprises the following steps:

firstly, synthesizing an intermediate compound I:

adding phenanthrenequinone, m-nitrobenzaldehyde and ammonium acetate into a reactor according to the molar ratio of 1 (1.4-1.6) to (1.8-2.1), adding glacial acetic acid as a solvent, heating to 80-110 ℃, stirring for 6-10 hours, stopping the reaction, cooling to room temperature, adding water into the reactor, adjusting the pH value to 8-10 by using a sodium hydroxide solution, performing suction filtration to obtain a yellow solid, drying, recrystallizing by using ethyl acetate, performing suction filtration and drying to obtain an intermediate compound I;

secondly, synthesizing an intermediate compound II:

weighing an intermediate compound I, Raney nickel and a hydrazine hydrate solution with the mass percentage concentration of 78-83%, wherein the mass ratio of the intermediate compound I to the Raney nickel is 1 mmol: (0.15-0.2) g, wherein the ratio of the substance amount of the intermediate compound I to the volume of the hydrazine hydrate solution with the mass percentage concentration of 78-83% is 1 mmol: (3-5) mL; adding an intermediate compound I and Raney nickel into a reactor, adding ethanol as a solvent, introducing nitrogen for protection, dropwise adding a hydrazine hydrate solution with the mass percentage concentration of 80% under the stirring condition, heating to 60-80 ℃ after dropwise adding, reacting for 6-9 h, cooling to room temperature, performing suction filtration, washing with ethyl acetate, and performing rotary evaporation to remove filtrate to obtain an intermediate compound II;

III, Fe³⁺Synthesis of fluorescent probe:

weighing the intermediate compound II and 5-nitrosalicylaldehyde according to the molar ratio of the intermediate compound II to the 5-nitrosalicylaldehyde of 1 (1-3), adding the intermediate compound II and the 5-nitrosalicylaldehyde into a reactor, adding an acidic medium serving as a solvent, stirring at normal temperature for reaction for 2-4 h, adding water into a reaction system after the reaction is finished to quench the reaction, adjusting the pH value to 8-10 by using a sodium hydroxide solution, precipitating a solid, performing suction filtration, washing a filter cake to be neutral, and drying to obtain the phenanthroimidazole micromolecule Fe³⁺A fluorescent probe.

The synthesis of the present invention can be represented by the following formula:

the invention provides phenanthroimidazole micromolecule Fe which has high selectivity, sensitive response and no interference of other metal ions in an aqueous phase system, has a pH value of 3-12³⁺A fluorescent probe. The fluorescent probe can selectively identify Fe³ ⁺Not subject to K⁺、Ba²⁺、Ca²⁺、Na²⁺、Mg²⁺、Zn²⁺、Cr³⁺、Cd²⁺、Ni²⁺、Co²⁺、Pb²⁺、Cu²⁺、 Ag+、Al³⁺And Hg²⁺Interference of other ions, and response time of only 10min for Fe³⁺The inspection is convenient and quick. The small molecular probe has simple synthesis steps, easy post-treatment and high yield.

Drawings

FIG. 1 shows the phenanthroimidazole small-molecule Fe prepared in experiment 1³⁺Ultraviolet absorption spectrograms of the fluorescent probe for different metal ions;

FIG. 2 shows the phenanthroimidazole small-molecule Fe prepared in experiment 1³⁺Fluorescence emission spectrograms of the fluorescence probes for different metal ions;

FIG. 3 shows the phenanthroimidazole small-molecule Fe prepared in experiment 1³⁺The fluorescent probe is Fe under the condition of the existence of other metal ions³⁺Fluorescence emission spectrum of fluorescent probe

FIG. 4 shows the phenanthroimidazole small-molecule Fe prepared in experiment 1³⁺Fluorescence emission spectrograms of the fluorescent probe at different concentrations of iron ions;

FIG. 5 shows the phenanthroimidazole small-molecule Fe prepared in experiment 1³⁺A fluorescence emission intensity map of the fluorescent probe under different pH conditions;

FIG. 6 shows the phenanthroimidazole small-molecule Fe prepared in experiment 1³⁺Fluorescence emission intensity profile of fluorescent probes at different complexation times.

Detailed Description

The first embodiment is as follows: phenanthroimidazole small-molecule Fe according to this embodiment³⁺The structural formula of the fluorescent probe is as follows:

the second embodiment is as follows: the phenanthroimidazole micromolecule Fe³⁺The synthesis method of the fluorescent probe comprises the following steps:

firstly, synthesizing an intermediate compound I:

secondly, synthesizing an intermediate compound II:

III, Fe³⁺Synthesis of fluorescent probe:

according to the intermediate compound II with 5-nitroWeighing an intermediate compound II and 5-nitro salicylaldehyde according to the molar ratio of 1 (1-3), adding the intermediate compound II and the 5-nitro salicylaldehyde into a reactor, adding an acidic medium serving as a solvent, stirring at normal temperature for reaction for 2-4 hours, adding water into a reaction system after the reaction is finished to quench the reaction, adjusting the pH value to 8-10 by using a sodium hydroxide solution, separating out a solid, performing suction filtration, washing a filter cake to be neutral, and drying to obtain the phenanthroimidazole micromolecule Fe³⁺A fluorescent probe.

The third concrete implementation mode: the difference between the present embodiment and the second embodiment is that the reaction temperature in the first step is 100 ℃, and the reaction time is 10 hours. The rest is the same as the second embodiment.

The fourth concrete implementation mode: this embodiment differs from the second or third embodiment in that the pH in step one is 9. The other is the same as the second or third embodiment.

The fifth concrete implementation mode: the difference between the second embodiment and the fourth embodiment is that the mass percentage concentration of the sodium hydroxide solution in the first step is 8-12%. The other is the same as one of the second to fourth embodiments.

The sixth specific implementation mode: the difference between this embodiment and one of the second to fifth embodiments is that the reaction temperature in the second step is 95 ℃ and the reaction time is 8 hours. The other is the same as one of the second to fifth embodiments.

The seventh embodiment: this embodiment differs from one of the second to sixth embodiments in that the molar ratio of intermediate compound II to 5-nitrosalicylaldehyde in step three is 1: 2. The other is the same as one of the second to sixth embodiments.

The specific implementation mode is eight: the difference between the second embodiment and the seventh embodiment is that the acidic medium in the third step is glacial acetic acid, concentrated nitric acid with a mass percentage concentration of 65% -68%, and concentrated hydrochloric acid or benzoic acid with a mass percentage concentration of 36% -37%. The rest is the same as one of the second to seventh embodiments.

The specific implementation method nine: the difference between this embodiment and the second to eighth embodiments is that the reaction is performed for 3 hours under normal temperature stirring in the third step. The rest is the same as the second to eighth embodiments.

The detailed implementation mode is ten: the difference between the present embodiment and one of the second to ninth embodiments is that the mass percentage concentration of the sodium hydroxide solution in the third step is 8% -12%. The other is the same as in one of the second to ninth embodiments.

The concrete implementation mode eleven: this embodiment is different from the second to tenth embodiments in that the pH value in the third step is 9; the rest is the same as in one of the second to tenth embodiments.

The following examples were used to demonstrate the beneficial effects of the present invention:

test 1: phenanthroimidazole small-molecule Fe for this experiment³⁺The synthesis method of the fluorescent probe comprises the following steps:

firstly, synthesizing an intermediate compound I:

weighing 5.0mmol of phenanthrenequinone, 7.5mmol of m-nitrobenzaldehyde and 10.0mmol of ammonium acetate, adding the phenanthrenequinone, 40mL of glacial acetic acid serving as a solvent, heating to 110 ℃, continuously stirring, performing TLC tracking detection (developing agents are ethyl acetate and petroleum ether, V (ethyl acetate): V (petroleum ether): 3:7) in the reaction process, after the reaction is performed for 8 hours, basically completing the reaction, stopping the reaction, cooling to room temperature, adding 50mL of water into the three-necked bottle, placing the three-necked bottle into a 200mL beaker, adjusting the pH value to 9 by using 10% by mass of sodium hydroxide solution, performing suction filtration to obtain a yellow solid, and drying in an oven at 100 ℃ for 5 hours; after drying, dissolving in 30mL ethyl acetate, heating to boiling, refluxing, stirring for 2h, cooling to room temperature, separating out a large amount of solids, performing suction filtration, and drying to obtain an intermediate compound I;

the yield of intermediate compound I obtained in this step was 94%, melting point: 271-273 ℃. The intermediate compound I was characterized by infrared, nuclear magnetic hydrogen and nuclear magnetic carbon spectra, with the following results:

IR(KBr,cm^–1)：3607,1676,1593,1531,1455,1347,754,740.¹H NMR(600MHz,DMSO):δ(ppm)13.826(s,1H),9.158(t,J＝7.20Hz,1H),8.879(d,J＝7.80Hz,2H), 8.763-8.745(m,1H),8.583(d,J＝7.20Hz,2H),8.338-8.319(m,1H),7.897(t,J＝7.80Hz, 1H),7.767(t,J＝7.20Hz,2H),7.687-7.660(m,2H),7.135(d,J＝7.80Hz,1H).¹³C NMR(150 MHz,DMSO):δ(ppm)148.36,146.71,135.34,132.06,131.79,131.16,130.58,129.24,129.03,127.23,127.09,126.69,125.71,125.39,124.35,124.10,123.71,123.45,121.98,121.83,120.16.

the structural formula of the intermediate compound I is shown as the characterization result

Secondly, synthesizing an intermediate compound II:

adding 2.0mmol of intermediate compound I, 0.35g of Raney nickel and 30mL of ethanol solvent into a 50mL three-neck flask, introducing nitrogen for 2 minutes, stirring, slowly dropwise adding 7.5mL of 80% hydrazine hydrate solution by using a constant-pressure dropping funnel, after dropwise adding, heating to 80 ℃, carrying out reflux reaction for 6 hours, tracking and detecting by using TLC (a developing agent is V ethyl acetate: V petroleum ether is 3:7), reacting basically completely, cooling to room temperature, carrying out suction filtration, washing with ethyl acetate for five times, and carrying out rotary evaporation on the filtrate to obtain a gray solid; drying, recrystallizing with ethyl acetate, heating to boil, refluxing, stirring for 2 hr, cooling to room temperature, separating out a large amount of solid, vacuum filtering, drying, and obtaining intermediate compound II. The yield of the intermediate compound II obtained in this step was 73%, melting point: 197 to 198 ℃;

the infrared spectrum, nuclear magnetic hydrogen spectrum and nuclear magnetic carbon spectrum are used for characterization, and the obtained results are as follows:

IR(KBr,cm^–1):3435,3362,1608,1595,1461,761,723.¹H NMR(600MHz,DMSO):δ(ppm)13.336(s,1H),8.854(d,J＝7.20Hz,2H),8.580(d,J＝7.80Hz,2H),7.732(t,J＝7.20Hz,2H),7.629(t,J＝7.80Hz,2H),7.570(s,1H),7.449(d,J＝7.20Hz,1H),7.240(t,J＝7.80 Hz,1H),6.705(d,J＝7.20Hz,1H),5.351(s,2H).¹³C NMR(150MHz,DMSO):δ(ppm)149.92,149.03,136.74,130.86,129.19,127.43,127.35,127.30,126.99,126.96,126.89,125.04, 124.88,123.93,123.61,122.39,121.88,121.68,114.94,113.74,111.52.

the structural formula of the intermediate compound II is shown as the characterization result

III, Fe³⁺Synthesis of fluorescent probe:

adding 0.46g (1.5mmol) of intermediate compound II and 0.25g (1.5mmol) of 5-nitro salicylaldehyde into a three-necked flask in sequence, adding 25mL of glacial acetic acid into the three-necked flask as a solvent, stirring at normal temperature for reaction for 2h, adding water into a reaction system after the reaction is finished, quenching the reaction, placing the reaction system into a 200mL beaker, adjusting the pH value to 9 by using a 10% sodium hydroxide solution in percentage by mass, carrying out suction filtration, washing a filter cake to be neutral, and drying. Drying to obtain the phenanthroimidazole micromolecule Fe³⁺A fluorescent probe. In this step, phenanthroimidazole small-molecule Fe³⁺The yield of fluorescent probe was 91%.

Phenanthroimidazole small molecule Fe³⁺The melting point of the fluorescent probe is>300℃。

The infrared spectrum and the nuclear magnetic resonance spectrum are used for characterization, and the obtained results are as follows:

IR(KBr,cm^–1)：3435,3060,1617,1595,1566,1493,1450,1277,759.¹H NMR(600MHz, DMSO):δ(ppm)14.229(s,1H),13.555(s,1H),9.328(s,1H),8.875(d,J＝9.6Hz,2H),8.792 (d,J＝7.20Hz,1H),8.617(d,J＝7.20Hz,1H),8.562(d,J＝7.80Hz,1H),8.371(s,1H), 8.324-8.301(m,2H),7.787-7.662(m,5H),7.617(dd,J₁＝6.40Hz,J₂＝6.20Hz,1H),7.197(d, J＝9Hz,1H).¹³C NMR(150MHz,DMSO):δ(ppm)170.81,166.96,162.31,148.82,148.13, 139.85,135.93,132.17,131.18,130.79,129.83,129.05,128.63,128.19,127.64,125.90,125.65, 124.93,124.33,122.45,121.99,119.94,119.43,118.76.

from the above characterization results, it is clear that the phenanthroimidazole small molecule Fe³⁺The structural formula of the fluorescent probe is as follows:

the phenanthroimidazole micromolecule Fe prepared by the test³⁺The fluorescent probe is used for carrying out spectrum performance test and comprises the following steps:

first, preparation of stock solution

Phenanthroimidazole small-molecule Fe³⁺The fluorescent probe is prepared by taking N, N-Dimethylformamide (DMF) as a solvent, and the concentration of the fluorescent probe is 1.0 multiplied by 10^–4A main stock solution of mol/L is reserved;

preparing metal nitrate and chloride into metal ion stock solution with the concentration of 0.1mol/L for later use;

HEPES buffer solution: adding 0.60g of N-2-hydroxyethyl piperazine-N' -2-ethanesulfonic acid into a volumetric flask with 250mL, fixing the volume with distilled water to prepare a 0.01mol/L solution, shaking up, standing for 3 hours, adjusting the pH value with a sodium hydroxide solution to prepare a buffer solution with the pH value of 7.4-12, and adjusting the pH value with a nitric acid solution to prepare a buffer solution with the pH value of 3-6. Shaking up for use.

Second, testing spectral performance

To a 10.0mL volumetric flask was added a 1.0X 10 concentration^–41mL of the main stock solution at mol/L, metal ions to be measured at a concentration of 0.1mol/L are added, and a constant volume is determined by using HEPES buffer solution at a concentration of 0.01mol/L, pH-7.4. At this time, the body and Fe³⁺The molar concentration ratio was 1: 50. After keeping the temperature for 1h, testing the ultraviolet absorption spectrum and the fluorescence emission spectrum respectively.

Firstly, selective identification of metal ions by a phenanthroimidazole micromolecule fluorescent probe is examined, and a mixed solution of DMF (dimethyl formamide)/HEPES (high efficiency particulate air) with the volume ratio of 1:1 is selected as a solvent (wherein the concentration of the HEPES buffer solution is 0.01mol/L, and the pH value is 7.4), and the mixed solution is prepared into a concentration of 1.0 multiplied by 10^-5Adding K with concentration of 0.10mol/L into the main body solution⁺、Ba²⁺、Ca²⁺、Na⁺、Mg²⁺、Zn²⁺、Cr³⁺、Fe³⁺、Cd²⁺、Ni²⁺、Co²⁺、Pb²⁺、Cu²⁺、Ag⁺、 Al³⁺And Hg²⁺Metal ions were measured and the ultraviolet absorption spectra were measured, respectively, as shown in FIG. 1, in which L represents a main compound, phenanthroimidazole small molecule Fe³⁺A fluorescent probe. As can be seen from FIG. 1, after adding different metal ions, K can be seen⁺、Ba²⁺、Ca²⁺、Na⁺、Mg²⁺、Zn²⁺、Cr³⁺、Cd²⁺、Cu²⁺、Ni²⁺、Co²⁺、Pb²⁺、Hg²⁺、Ag⁺And Al³⁺Similar to the shape of the ultraviolet absorption spectrum curve and the absorbance of the main body. Adding Fe³⁺Then, in the ultraviolet absorption spectrum, the absorbance at a wavelength of 425nm was significantly increased, and the intensity was about 2 times that of the host compound L. Therefore, it can be preliminarily presumed from the ultraviolet absorption spectrum that the host compound is responsible for Fe³⁺With selective recognition features.

Further verifying the phenanthroimidazole small-molecule fluorescent probe pair prepared by the test to Fe³⁺The fluorescence emission spectrum test has the characteristic of selective identification, and the fluorescence emission spectrum intensity is obtained by testing the fluorescence emission spectrum under the conditions that the excitation wavelength is 325nm and the excitation slit width is 10, and the result is shown in FIG. 2. As can be seen from fig. 2, the fluorescence emission wavelength of the host is 400 nm, and the fluorescence intensity is about 600a.u. After addition of different metal ions, K can be seen⁺、Ba²⁺、Ca²⁺、Na⁺、 Mg²⁺、Zn²⁺、Cd²⁺、Ni²⁺、Co²⁺、Cr³⁺、Pb²⁺、Hg²⁺、Ag⁺、Al³⁺And Cu²⁺The fluorescence intensity of the main body is not greatly influenced, and the intensity is about 600a.u. While adding Fe³⁺After that, the fluorescence intensity was remarkably quenched to about 150a.u., and quenched to 1/4 which is the original intensity. Thus, from the fluorescence emission spectra, it can be determined that the host compound is in the presence of Fe³⁺With selective recognition features.

To further verify the phenanthroimidazole small-molecule fluorescent probe pair prepared in the experiment against Fe³⁺Has the characteristic of selective identification. A mixed DMF/HEPES solution (wherein, the concentration of the HEPES buffer solution is 0.01mol/L, and the pH value is 7.4) in a volume ratio of 1:1 is used as a solvent to prepare a mixed solution with the concentration of 1.0X 10^-5Adding 5.0 × 10mol/L main solution into the main solution^–4mol/L of K⁺、Ba²⁺、Ca²⁺、Na⁺、Mg²⁺、Zn²⁺、Cr³⁺、Cd²⁺、Ni²⁺、Co²⁺、 Pb²⁺、Cu²⁺、Ag⁺、Al³⁺And Hg²⁺A metal ion solution. Mixing, standing for 5min, and adding 1.0 × 10^-5mol/L of Fe³⁺And then mixing uniformly. At this time, host compound/metal ion/Fe³⁺The molar concentration ratio of the three is 1:50: 50. After keeping the temperature for 1h, the fluorescence emission spectrum was measured at an excitation wavelength of 325nm and an excitation slit width of 10.0 nm. The obtained fluorescence emission spectrum intensity results are shown in fig. 3. In other metal ions (K)⁺、Ba²⁺、 Ca²⁺、Na⁺、Mg²⁺、Zn²⁺、Cr³⁺、Cd²⁺、Ni²⁺、Co² ⁺、Pb²⁺、Cu²⁺、Ag⁺、Al³⁺And Hg²⁺) In the presence of Fe³⁺When the host compound coexists with other metal ions, the fluorescence intensity recognized by the host compound and the iron ions is not affected by the other metal ions. That is, the presence of other metal ions does not interfere with the host compound's contribution to Fe³⁺And (5) identifying. Thus, FIG. 3 demonstrates that the host compound is specific for Fe³⁺With selective recognition features. And can also explain that other metal ions identify Fe to the main compound³⁺Has no influence.

To examine Fe³⁺Concentration to Fe³⁺Influence of fluorescence intensity of the fluorescent probe, a mixed solution of DMF and HEPES (where the concentration of the HEPES buffer solution is 0.01mol/L and the pH is 7.4) at a volume ratio of 1:1 was used as a solvent to prepare a host compound solution, the concentration of iron ions (the concentration of metal ions is 0 to 100 equivalents of the host concentration) was gradually increased in the host compound solution, and a fluorescence emission spectrum was measured. The results are shown in FIG. 4, and it can be seen from FIG. 4 that with Fe³⁺The fluorescence intensity gradually decreased with increasing concentration. When the equivalent weight is 80, the reaction is extinguished to the minimum value of about 50a.u. Further increase of Fe³⁺At a concentration of (a), the fluorescence intensity does not substantially change any more.

Under different pH (3-12) values of the solution, the pH value is considered to be the main bodyIdentification of Fe by Compounds³⁺Change in fluorescence emission spectra. The change of fluorescence intensity with pH is shown in FIG. 5. As can be seen from fig. 5: the fluorescence intensity of the host compound does not change much with the change of pH, and is about 600a.u. under acidic, neutral or alkaline conditions. When it is added to the bulk solution (1.0X 10)^-5mol/L) adding Fe³⁺(5.0×10^-4mol/L), and inspecting a main compound with pH of 3-12 to Fe³⁺The change in fluorescence identified. As a result, it was found that in this pH range, Fe³⁺The fluorescence of the host compound can be extinguished and the fluorescence intensity can be kept substantially unchanged. That is, the change in pH value shows the fluorescence intensity of the host and the recognition of Fe by the host³⁺The fluorescence intensity of (a) has almost no influence. The results of this study demonstrate that the host compound is associated with Fe³⁺The fluorescent recognition of (2) can be achieved at different pH values.

In addition, the host compound is p-Fe³⁺The time response of the identified fluorescence is short. At a pH of 7.4, the concentration was 1.0X 10^-5Adding the host compound with the concentration of 5.0 multiplied by 10 into mol/L^-4mol/L Fe³⁺And mixing uniformly. The fluorescence emission spectrum was measured after 10min and every 10min, and the results are shown in FIG. 6. As can be seen from fig. 6, the host compound has stable fluorescence intensity over the time of measurement, which indicates that the host compound in this patent has stable fluorescence emission in an aqueous solution. Measuring host compound and Fe at 10min³⁺The fluorescence intensity has been significantly extinguished. 20. The difference between the fluorescence intensity and 10min is not great at 30 min, 40 min and 50 min. This indicates that the host compound can achieve the effect on Fe in aqueous solution³⁺And maintaining the stability of the quenched fluorescence. This result is of great significance in the practical application of the host compound.

The test prepares the phenanthroimidazole micromolecule Fe³⁺Fluorescent probes, demonstrated by the above experiments in DMF/H at a volume ratio of 1:1₂In a system in which a mixed solution of O (HEPES buffer solution, concentration of 0.01mol/L, pH 7.4) is used as a solvent, the host compound is Fe³⁺The function of selective recognition is achieved, and the response sensitivity is outstanding. But has no identification characteristic to other metal ions and does not interfere the compound to identify Fe when coexisting with other metal ions³⁺. Even if the pH environment of the solution is changed, the Fe can be treated³⁺Fluorescent recognition of (2).

Test 2: this experiment differs from experiment 1 in that the procedure of experiment 1 is replaced by the following three procedures: adding 0.46g (1.5mmol) of intermediate compound II, 0.42g (2.5mmol) of 5-nitro salicylaldehyde and 20mL of concentrated nitric acid with the mass percentage concentration of 65-68% into a three-necked flask in sequence as a solvent, stirring at normal temperature for reaction for 2.5h, after the reaction is finished, adding water into a reaction system for quenching reaction, placing the reaction system into a 200mL beaker, adjusting the pH value to 9 by using 10% sodium hydroxide solution, then carrying out suction filtration, washing a filter cake to be neutral by using water, and drying. Drying to obtain the phenanthroimidazole micromolecule Fe³⁺A fluorescent probe. Phenanthroimidazole small-molecule Fe obtained in the test³⁺The structural formula of the fluorescent probe is as follows:

the yield was 47%.

Test 3: this experiment differs from experiment 1 in that the procedure of experiment 1 is replaced by the following three procedures: adding 0.46g (1.5mmol) of intermediate compound II, 0.50g (3.0mmol) of 5-nitro salicylaldehyde and 20mL of benzoic acid serving as solvents into a three-necked flask in sequence, stirring at normal temperature for reaction for 3 hours, adding water into a reaction system after the reaction is finished to quench the reaction, placing the reaction system into a 200mL beaker, adjusting the pH value to 9 by using 10% sodium hydroxide solution, then carrying out suction filtration, washing a filter cake to be neutral, and drying. Drying to obtain the phenanthroimidazole micromolecule Fe³⁺A fluorescent probe. Phenanthroimidazole small-molecule Fe obtained in the test³⁺The structural formula of the fluorescent probe is as follows:

the yield was 61%.

Test 4: this experiment differs from experiment 1 in that the procedure of experiment 1 is replaced by the following three procedures: sequentially adding into three-mouth bottleAdding 0.46g (1.5mmol) of intermediate compound II, 0.75g (4.5mmol) of 5-nitro salicylaldehyde and 15mL of 37% concentrated hydrochloric acid as solvents, stirring at normal temperature for reaction for 4 hours, adding water into a reaction system after the reaction is finished to quench the reaction, placing the reaction system in a 200mL beaker, adjusting the pH value to 9 by using 10% sodium hydroxide solution, then carrying out suction filtration, washing a filter cake to be neutral, drying, and drying to obtain the phenanthroimidazole micromolecule Fe³⁺A fluorescent probe. Phenanthroimidazole small-molecule Fe obtained in the test³⁺The structural formula of the fluorescent probe is as follows:

the yield was 52%.

Claims

1. Phenanthroimidazole micromolecule Fe³⁺The fluorescent probe is characterized in that the structural formula of the fluorescent probe is as follows:

2. synthesis of a Phenanthroimidazole Small molecule Fe according to claim 1³⁺The method for preparing the fluorescent probe is characterized by comprising the following steps of:

firstly, synthesizing an intermediate compound I:

secondly, synthesizing an intermediate compound II:

III, Fe³⁺Synthesis of fluorescent probe:

3. The phenanthroimidazole small molecule Fe as claimed in claim 2³⁺The synthesis method of the fluorescent probe is characterized in that the reaction temperature in the step one is 100 ℃, and the reaction time is 10 hours.

4. Phenanthroimidazole small-molecule Fe according to claim 2 or 3³⁺The synthesis method of the fluorescent probe is characterized in that the pH value in the step one is 9.

5. Phenanthroimidazole small-molecule Fe according to claim 2 or 3³⁺The synthesis method of the fluorescent probe is characterized in that the mass percentage concentration of the sodium hydroxide solution in the step one is 8-12%.

6. Phenanthroimidazole small-molecule Fe according to claim 2 or 3³⁺The method for synthesizing the fluorescent probe is characterized by comprising the following stepsThe reaction temperature in the second step is 95 ℃, and the reaction time is 8 h.

7. Phenanthroimidazole small-molecule Fe according to claim 2 or 3³⁺The synthesis method of the fluorescent probe is characterized in that the molar ratio of the intermediate compound II to the 5-nitro salicylaldehyde in the step III is 1: 2.

8. Phenanthroimidazole small-molecule Fe according to claim 2 or 3³⁺The method for synthesizing the fluorescent probe is characterized in that the acidic medium in the third step is glacial acetic acid, concentrated nitric acid with the mass percentage concentration of 65-68% and concentrated hydrochloric acid or benzoic acid with the mass percentage concentration of 36-37%.

9. Phenanthroimidazole small-molecule Fe according to claim 2 or 3³⁺The synthesis method of the fluorescent probe is characterized in that the mass percentage concentration of the sodium hydroxide solution in the step three is 8-12%.

10. Phenanthroimidazole small-molecule Fe according to claim 2 or 3³⁺The synthesis method of the fluorescent probe is characterized in that the pH value in the step three is 9.