Fe3 + specific recognition fluorescent probe based on phenanthroimidazole and application thereof

Abstract

The invention discloses a phenanthroimidazole-based Fe < 3 + > specific recognition fluorescent probe and application thereof. The fluorescent probe takes a phenanthroimidazole group as an electron donor unit and takes a benzene ring and a fluorine atom substituted benzene ring as an electron acceptor unit. An imidazole group and a fluorine atom are respectively introduced in the directions of a short axis and a long axis of a molecule, so that fine regulation and control of excited state properties are realized, vibration coupling in a first singlet excited state is effectively inhibited, high-purity blue light emission is obtained, and the photophysical properties of the material are remarkably improved. The fluorescent material is simple and convenient in synthesis method, easy to purify, excellent in thermal stability and remarkable in signal response, and has a wide application prospect in detection of Fe < 3 + > in a high-temperature industrial environment.

Description

Technical Field

[0001] This invention belongs to the field of organic light-emitting materials technology, specifically relating to a Fe based on phenanthreneimidazole. 3+ Specific recognition fluorescent probes and their applications. Background Technology

[0002] Fe 3+ As an important transition metal ion, Fe plays a crucial role in processes such as industrial catalysis, environmental monitoring, and biological metabolism. 3+ Identification materials face serious technical bottlenecks in complex industrial environments such as high temperature, strong corrosion, and high interference.

[0003] Existing probes mostly focus on single recognition functions, lacking multifunctional integrated designs that combine structural stability, high selectivity, and reversible detection at high temperatures. The phenanthreneimidazole (PI) framework, with its naturally rigid structure, possesses excellent thermal stability, perfectly matching the thermal stability requirements of materials in high-temperature environments. Furthermore, the conjugated structure of the imidazole ring N atom and phenanthrene ring in PI can be modulated through D-π-A configuration and substitution to control the frontier orbital energy levels, endowing the material with bipolar carrier transport capabilities. This balances charge injection and transport in the sensor, improving signal stability.

[0004] Odedara et al. (ChemPhotoChem, 2024, 8, e20240018.) publicly reported the synthesis and applications of three benzylidene imidazol derivatives, among which Pq-pF-OH showed the best performance and the lowest decomposition temperature T. d =348℃ meets the preset requirements, however, residual mass R W The 5% failure rate did not meet the standard, resulting in its long-term stability in high-temperature environments failing to meet practical application requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a Fe based on phenanthreneimidazole. 3+ The specific recognition fluorescent probe uses a phenanthreneimidazole group with a rigid structure to improve the molecular thermal stability, and introduces benzene rings and fluorinated benzene rings as electron-withdrawing groups to adjust the excited state properties and overcome the shortcomings of poor signal and low thermal stability of the fluorescent probe in high-temperature complex environments.

[0006] This invention provides Fe based on phenanthreneimidazole 3+ The structural formula of the specific recognition fluorescent probe is shown below:

[0007]

[0008] In the formula, Ar represents , , , , , Any one of them.

[0009] Furthermore, Ar is preferred as a representative. , , , Any one of them.

[0010] This invention is based on Fe from phenanthreneimidazole. 3+ The synthesis method of the specific recognition fluorescent probe is as follows:

[0011] Step 1: Add phenanthrenequinone, 1-(4-aminophenyl)imidazole, p-bromobenzaldehyde, and ammonium acetate to acetic acid in a molar ratio of 1:1–1.5:1–1.3:4–6, and react at 110–120°C for 1–3 hours under a nitrogen atmosphere. After the reaction is complete, pour the reaction solution into saturated brine, filter, wash with ethanol, and recrystallize from N,N-dimethylformamide to obtain compound MZPIBr. The reaction equation is as follows:

[0012]

[0013] MZPIBr

[0014] Step 2: Add MZPIBr, phenylboronic acid compounds, tetrabutylammonium bromide, and dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine palladium(II) in a molar ratio of 1:1.3–2:2–2.5:0.05–0.1 to DMF, then add an aqueous solution of K2CO3, wherein the molar ratio of K2CO3 to MZPIBr is 5–7:1. React at 70–80°C for 6–10 hours under a nitrogen atmosphere. After the reaction is complete, pour the reaction solution into saturated saline solution, filter, wash with ethanol, and perform column chromatography to obtain the fluorescent probe. The reaction equation is as follows:

[0015]

[0016] MZPIBr

[0017] This invention also provides the above-mentioned fluorescent probe for detecting Fe in high-temperature and complex industrial environments. 3+ Its uses.

[0018] The beneficial effects of this invention are as follows:

[0019] This invention's fluorescent probe uses a phenanthreneimidazole group as the electron donor unit and a benzene ring and a fluorine-substituted benzene ring as the electron acceptor unit. By introducing imidazole groups and fluorine substituents along the short and long axes of the molecule, and adjusting the electron-withdrawing ability by changing the number of fluorine atoms, the excited-state properties of the fluorescent probe are rationally controlled. This suppresses vibrational coupling occurring in the first singlet excited state, resulting in high-purity blue light emission and achieving significant signal response in complex environments, while ensuring excellent thermal stability of the fluorescent molecule. The preparation method of this invention's fluorescent probe is simple and easy to purify, achieving high luminescence efficiency. Its excellent thermal stability and significant signal response enable the recognition of Fe in high-temperature and complex environments. 3+ The field has enormous potential. Attached Figure Description

[0020] Figure 1 The fluorescent probes synthesized in Examples 1-4 specifically detect Fe. 3+ The fluorescence emission curve.

[0021] Figure 2 The fluorescent emission curves of 10 different metal ions detected by the fluorescent probes synthesized in Examples 1-4 are shown.

[0022] Figure 3 The fluorescent probes synthesized in Examples 1-4 are used to detect different concentrations of Fe in the presence of interfering ions. 3+ The fluorescence emission curve.

[0023] Figure 4 These are the thermogravimetric curves of the fluorescent probes synthesized in Examples 1-4. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0025] Example 1

[0026] Step 1: A mixture of phenanthrenequinone (12.10 g, 58.11 mmol), p-bromobenzaldehyde (10.75 g, 58.11 mmol), 1-(4-aminophenyl)imidazole (10.18 g, 63.92 mmol), ammonium acetate (22.40 g, 290.56 mmol), and acetic acid (120 mL) was added sequentially to a 150 mL three-necked flask equipped with a magnetic stirrer, a thermometer, and a spherical condenser. The mixture was placed in the three-necked flask with the thermometer inserted and reacted at 120 °C for 2 h under a nitrogen atmosphere. After the reaction was completed, the reaction solution was poured into saturated brine, and a yellow solid precipitated out. After filtration, washing with ethanol, and recrystallization from N,N-dimethylformamide, 19.00 g of white solid powder compound MZPIBr was obtained, with a yield of 70%. The reaction equation is shown below:

[0027]

[0028] MZPIBr

[0029] The structural characterization data of MZPIBr obtained are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.88 (d, J = 7.9Hz, 2H), 8.10 (s, 2H), 7.79 (t, J = 7.4 Hz, 2H), 7.67 (s, 2H), 7.49 (d, J =2.6 Hz, 8H), 7.35 (s, 1H), 7.29 (s, 2H).

[0030] Step 2: MZPIBr (0.80 g, 1.55 mmol), DMF (30 mL), phenylboronic acid (0.37 g, 2.33 mmol), tetrabutylammonium bromide (1.00 g, 3.10 mmol), dichlorodi-tert-butyl-(4-dimethylaminophenyl)phosphine(II) (60 mg, 97.01 µmol), and K₂CO₃ (1.29 g, 9.31 mmol) aqueous solution (10 mL) were added sequentially to a 150 mL three-necked flask equipped with a magnetic stirrer, a thermometer, and a spherical condenser. The reaction was carried out at a constant temperature of 75 °C for 8 h under a nitrogen atmosphere. After the reaction was complete, the reaction solution was poured into saturated brine, and a white solid precipitated. After filtration, washing with ethanol, and column chromatography, 0.40 g of a pale yellow solid powder, compound MZPT, was obtained, with a yield of 69%. The reaction equation is shown below:

[0031]

[0032] MZPT

[0033] The structural characterization data of the obtained compound MZPT are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.83 – 8.80(m, 2H), 8.71 (s, 2H), 7.98 (s, 2H), 7.59 (d, J = 1.1 Hz, 4H), 7.56 (s, 2H),7.50 (s, 4H), 7.38 (s, 4H), 7.24 (d, J = 2.8 Hz, 3H), 7.19 (s, 1H).

[0034] Example 2

[0035]

[0036] 1F-MZPT

[0037] In step 2 of this embodiment, equimolar amounts of p-fluorophenylboronic acid were used to replace the phenylboronic acid in step 2 of Example 1. The other steps were the same as in Example 1, yielding 0.63 g of a white solid powder compound 1F-MZPT with a yield of 74%. Its structural characterization data are as follows: 1 HNMR (400 MHz, CDCl3) δ 8.88 (d, J = 7.0 Hz, 2H), 8.76 (s, 2H), 8.10 (s, 2H), 7.70 (s, 2H), 7.67 (s, 2H), 7.49 (s, 6H), 7.35 (s, 1H), 7.30 (s, 3H), 7.15 (t, J = 8.7 Hz, 3H).

[0038] Example 3

[0039]

[0040] 2F-MZPT

[0041] In step 2 of this embodiment, equimolar amounts of 3,5-difluorophenylboronic acid were used to replace the phenylboronic acid in step 2 of Example 1. The other steps were the same as in Example 1, yielding 0.33 g of a white solid powder compound 2F-MZPT with a yield of 51%. Its structural characterization data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.89 (d, J = 7.2 Hz, 2H), 8.74 (d, J = 8.3 Hz, 2H), 8.08 (s, 2H), 7.69 (s, 8H), 7.53 (s, 1H), 7.33 (s, 2H), 7.27 (s, 3H), 7.10 (s, 1H), 6.81 (s, 1H).

[0042] Example 4

[0043]

[0044] 3F-MZPT

[0045] In step 2 of this embodiment, equimolar amounts of 3,4,5-trifluorophenylboronic acid were used to replace the phenylboronic acid in step 2 of Example 1. The other steps were the same as in Example 1, yielding 0.40 g of the pale yellow solid powder compound 3F-MZPT with a yield of 69%. Its structural characterization data are as follows: 1H NMR (400 MHz, CDCl3) δ 8.71–8.66 (m, 2H), 8.54 (d, J=8.3 Hz, 2H), 7.88 (s, 2H), 7.47 (s, 8H), 7.45 (s, 1H), 7.27 (d, J=4.6 Hz, 5H), 7.13(s,1H).

[0046] The fluorescence properties of compounds MZPT, 1F-MZPT, 2F-MZPT, and 3F-MZPT synthesized in Examples 1-4 were tested using a steady-state-transient fluorescence spectrometer (Quanta Master 8000, manufactured by HORIBA, Canada). The testing method involved dissolving the test compounds in tetrahydrofuran to prepare a 1×10⁻⁶ solution. -5 mol L -1 The fluorescence intensity of the obtained compound solution was measured. Figure 1 (corresponding curve to 0 M); then the resulting compound solution was reacted with 10⁻ 4 mol L -1 Fe 3 The corresponding test samples were prepared by mixing the ⁺ aqueous solution at a volume ratio of 1:1, and their fluorescence intensity was measured. Figure 1 1×10 -4 (M corresponding curve). Simultaneously, its performance was compared with three fluorescent probes based on benzonaphthezide derivatives (Pq-tBu-OH, Pq-mF-OH, Pq-pF-OH) reported by Nisha Odedara et al. (ChemPhotoChem, 2024, 8, e20240018). Experimental results are shown in Table 1 and... Figure 1 .

[0047]

[0048] Pq-tBu-OH Pq-mF-OH Pq-pF-OH

[0049] Table 1. Photophysical parameters of compounds in Examples 1-4 and compounds in the literature.

[0050]

[0051] Note: In the table, F0 represents the fluorescence intensity of the compound; F represents the addition of Fe. 3+ The fluorescence intensity afterward.

[0052] Depend on Figure 1As shown in Table 1, the fluorescence intensity changes of compounds MZPT, 1F-MZPT, 2F-MZPT, and 3F-MZPT under the same test conditions are superior to those of compounds Pq-tBu-OH, Pq-mF-OH, and Pq-pF-OH. The fluorescence intensity change factor of the fluorescent probes of the present invention is significantly improved when imidazole groups and single fluorine atoms are introduced, giving the probes excellent characteristics of achieving significant signal response. This indicates that the introduction of imidazole groups and single fluorine atoms is beneficial to improving the response signal of the material.

[0053] Figure 2 In the above 1×10 -5 mol L -1 Ten different metal ions (1×10⁻⁶) were added to the compound solution respectively. -3 mol・L -1 The fluorescence emission curve of the system at that time shows that the fluorescent probe of the present invention can significantly identify Fe. 3+ However, Cr is present. 3+ Cu 2+ Al 3+ Mg 2+ Significantly responsive ions. Therefore, to assess coexisting ion interference and specific recognition, ions containing a fixed concentration of Cr were introduced. 3+ Cu 2+ Al 3+ Mg 2+ (6×10) -5 mol・L -1 ) of 1×10 -5 mol L -1 Different concentrations of Fe were added to the compound solution 3+ (0~5×10) -5 mol・L -1 And detect fluorescence changes. Figure 3 As shown, with Fe 3+ With increasing concentration, the fluorescence intensity of the system was significantly quenched; the fluorescence intensities of MZPT, 1F-MZPT, 2F-MZPT, and 3F-MZPT decreased, respectively. Furthermore, in the presence of competing metal ions, Fe... 3+ It can still effectively induce fluorescence quenching, confirming that this series of compounds are effective against Fe. 3+ It has high selectivity and specificity recognition capabilities.

[0054] To highlight the promoting effect of introducing fluorine atoms and imidazole groups on the thermal stability of fluorescent probes, the thermal properties of compounds MZPT, 1F-MZPT, 2F-MZPT, 3F-MZPT, Pq-tBu-OH, Pq-mF-OH, and Pq-pF-OH synthesized in Examples 1–4 were tested using a professional simultaneous thermal analyzer (model TGA / DSC1_*, manufactured by Mettler AG, Switzerland). The results are shown in Table 2 and [Table data would be inserted here]. Figure 4 .

[0055] Table 2 Comparison of thermal performance parameters of compounds in Examples 1-4 and compounds in the literature

[0056]

[0057] Depend on Figure 4 As shown in Table 2, the thermal decomposition temperatures (T) of compounds MZPT, 1F-MZPT, 2F-MZPT, and 3F-MZPT are... d The thermal decomposition temperatures (corresponding to a 5% weight loss) were 456℃, 409℃, 409℃, and 354℃, respectively. Among these, MZPT, 1F-MZPT, and 2F-MZPT all exhibited thermal stability exceeding 400℃, while the thermal decomposition temperatures of compounds Pq-tBu-OH, Pq-mF-OH, and Pq-pF-OH were 322℃, 342℃, and 348℃, respectively. This comparison shows that the introduction of the imidazole structure significantly improves molecular thermal stability, with compound MZPT reaching a high thermal decomposition temperature of 456℃, fully demonstrating the enhancing effect of the imidazole substituent on molecular thermal stability. Regarding the performance changes after the introduction of the fluorinated benzene ring, although the thermal decomposition temperature of the target compound decreased slightly, it still met the requirements for thermal stability of luminescent materials under high-temperature conditions. Furthermore, all compounds synthesized in Examples 1-4 showed good performance under high-temperature conditions. W The residual mass of the compound was not less than 62%, showing good long-term thermal stability. Furthermore, the residual mass of the compound gradually increased with the increase of the number of fluorine atoms introduced, indicating that the introduction of fluorine atoms can effectively enhance the structural stability of the compound under long-term high-temperature conditions.

Claims

1. A Fe based on phenanthreneimidazole 3+ A fluorescent probe for specific recognition, characterized in that, The structural formula of the fluorescent probe is shown below: In the formula, Ar represents , , , , , Any one of them.

2. The Fe based on phenanthreneimidazole according to claim 1 3+ A fluorescent probe for specific recognition, characterized in that, Ar represents , , , Any one of them.

3. The fluorescent probe of claim 1 for detecting Fe in a high-temperature, complex industrial environment. 3+ Its uses.

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