Small molecule compound constructed based on 1, 10-phenanthroline and triphenylamine-4-boric acid as well as synthesis method and application of small molecule compound

Abstract

The invention discloses a small molecule compound constructed based on 1, 10-phenanthroline and triphenylamine-4-boric acid as well as a synthesis method and application of the small molecule compound. The preparation method is simple, one-step synthesis is performed through a Suzuki-Miyaura reaction, the reaction condition is mild, the reaction steps are simple, and the yield of a finished product is high. The novel multifunctional fluorescent molecule with the D-A-D structure takes an electron-deficient acceptor 1, 10-phenanthroline as a core and triphenylamine with a highly distorted structure as an electron donor, and has excellent luminescence property, the fluorescence emission of the novel multifunctional fluorescent molecule generates red shift along with the increase of the polarity of a solvent, and obvious solvation color development is shown; dFT (Discrete Fourier Transform) calculation proves that the fluorescent material has excellent photophysical characteristics, can specifically recognize residual Ag in a natural environment, can respond to temperature, has excellent reversible change in fluorescence and appearance color in mechanical grinding and acid environments, has multiple stimulation response performance, and has a good application prospect in the fields of fluorescent materials and the like.

Description

Technical Field

[0001] This invention belongs to the field of functional materials and organic synthetic chemistry, specifically relating to a small molecule compound based on 1,10-phenanthroline and triphenylamine-4-boronic acid, its synthesis method and application. Background Technology

[0002] Supramolecular chemistry, as an emerging interdisciplinary field, integrates organic chemistry, analytical chemistry, inorganic chemistry, and polymer chemistry. It primarily studies the functional aggregation of molecules formed between molecules through non-covalent interactions such as hydrogen bonding, metal coordination, host-guest interactions, and π-π stacking. With the development of materials science, scientists' deeper understanding of the relationship between molecular structure and properties, as well as the emergence of new synthetic methods and characterization techniques, has made it possible to design and prepare fluorescent materials with specific responsive properties. Stimulus-responsive fluorescent materials can hide information through changes in fluorescence signals, showing great potential in fields such as information encryption. Among them, monostimulus-responsive fluorescent materials have attracted widespread attention due to their relatively simple response mechanisms and ease of study and control. These materials have advantages such as high response specificity, high sensitivity, and real-time visualization, and are widely used in various fields such as chemical sensing, anti-counterfeiting inks, and optical data storage. In comparison, multistimulus-responsive fluorescent materials, with their "multiple signal output" capabilities, offer higher detection accuracy, higher efficiency, and higher functional integration, becoming an important direction in current fluorescent materials research. However, the development of fluorescent materials still faces many challenges, such as demanding preparation conditions, the need to improve luminescence performance, and insufficient stability.

[0003] In the existing technology, the preparation of multi-stimulus responsive fluorescent materials still faces the following bottlenecks: high synthesis complexity: most materials require multiple reaction steps to construct a conjugated system, which is cumbersome and has a low yield; poor performance stability: the reversibility of the stimulus response of some materials is insufficient, making it difficult to meet the needs of practical applications; weak response specificity: the recognition of target analytes is easily interfered with by other metal ions, and the quenching rate is low.

[0004] 1,10-phenanthroline (phen), a classic electron-deficient heterocyclic compound, possesses a rigid structure and strong coordination ability, making it an ideal core unit for constructing fluorescent materials. Triphenylamine (TPA), as an electron donor, has a trigonal pyramidal structure that can induce molecular distortion and enhance charge transfer (ICT) effects. This invention efficiently couples the two through the Suzuki-Miyaura reaction to construct a DAD-type conjugated system, solving the aforementioned problems of existing technologies. It achieves the construction of a simple-to-prepare, high-luminescence-performance, and highly stable organic fluorescent small molecule compound based on 1,10-phenanthroline and triphenylamine-4-boronic acid, which can be used in solvation color development, mechanical grinding, acid-induced color change, thermochromic reaction, and Ag... + It has significant research value in terms of specific identification. Summary of the Invention

[0005] The purpose of this invention is to provide a small molecule compound based on 1,10-phenanthroline and triphenylamine-4-boronic acid, and its application as a multi-stimulus responsive fluorescent material in solvation color development, mechanical grinding, acid-induced color change, thermochromic reaction, and Ag... + Applications in specific recognition. The fluorescence emission of the compound exhibits a red shift with increasing solvent polarity, showing a distinct solvation colorimetric effect. We investigated its photophysical properties using DFT and TD-DFT, discovering its excellent luminescence characteristics. Its fluorescence can specifically identify residual Ag in the natural environment. + It exhibits excellent fluorescence and color reversibility in mechanical grinding and acidic environments. Compared to traditional fluorescent materials, it boasts advantages such as simple preparation conditions, superior luminescent properties, and strong stability.

[0006] This invention is based on a small molecule compound constructed from 1,10-phenanthroline and triphenylamine-4-boronic acid, with the following structural formula: The compound based on 1,10-phenanthroline and triphenylamine-4-boronic acid involved in this invention is obtained in one step via the Suzuki-Miyaura reaction. Specifically, it includes the following steps: 1,10-phenanthroline and triphenylamine-4-boronic acid were dissolved in a mixed solvent of 1,4-dioxane and water. Potassium carbonate and tetraphenylphosphine palladium catalyst were added, and the reaction was carried out at 80-100°C under nitrogen protection for 20-25 hours. After the reaction was completed, the product was obtained by extraction and column chromatography.

[0007] The molar ratio of 1,10-phenanthroline to triphenylamine-4-boronic acid is 1:2 to 1:2.5. The volume ratio of 1,4-dioxane to water is 4:1 to 6:1. The molar amount of potassium carbonate is 1 to 1.5 times that of 1,10-phenanthroline. The molar amount of tetratetraphenylphosphine palladium is 0.1 to 0.2 times that of 1,10-phenanthroline.

[0008] The synthesis route is as follows: The small molecule compound provided by this invention exhibits high stability in the Suzuki-Miyaura reaction system using a common haloalkane as the reaction solvent and tetraphenylphosphine palladium as the catalyst. This DAD-type small molecule fluorescent compound emits strong fluorescence even without any induction, and its fluorescence can respond to a variety of stimuli. It shows promising application prospects in the fields of fluorescent sensors and functional materials.

[0009] Compared with traditional fluorescent materials, the small molecule compound provided by this invention has simpler preparation conditions, fewer reaction steps, simpler operation, higher yield, excellent luminescence performance and strong stability. Due to its DAD type structure, the compound has excellent luminescence performance.

[0010] The small molecule compounds provided by this invention exhibit a significant Stokes shift in their photoluminescence (PL) spectra as the solvent polarity increases; for example, the emission maximum increases from λ in toluene. em = 436 nm redshifted to 494 nm in dimethylformamide, accompanied by a visible color transition from bright blue to green.

[0011] The present invention provides a solution of small molecule compounds with added Ag. + Subsequently, fluorescence exhibits quenching in over 95% of cases upon the addition of Ag. + When equal amounts of 11 other competing metal ions were added to the solution, the quenching efficiency remained consistent (with a variation of less than 5%), indicating that the compound possesses excellent binding affinity and structural robustness, enabling it to resist ion competition. Among the series of metal ions tested, this small molecule compound showed the best resistance to Ag. + It exhibits good inductive selectivity, and this is effective against Ag. + The inductive selectivity can be easily distinguished by observing fluorescence changes with the naked eye. These findings validate the molecular design principle based on the DAD structure of the 1,10-phenanthroline coordination center, a structure for Ag + A highly efficient geometrically complementary bonding pocket was created, making it an ideal tool for environmental monitoring and biosensing of harmful silver metals.

[0012] The small molecule compound provided by this invention exhibits excellent mechanochromic luminescence properties. Before grinding, its crystals have a dark brown, leaf-like structure; after mechanical grinding, its color changes to yellow. Furthermore, its fluorescence spectrum also changes before and after grinding; before grinding, its fluorescence peaks are complex, while after grinding, the peak positions shift blue and the peak shapes become simplified. This change can be reversibly achieved through recrystallization.

[0013] The small molecule compound provided by this invention can respond rapidly to acids. Upon dropwise addition of CH3COOH to the compound, the color instantly changes from yellow to red, and fluorescence quenching occurs. As CH3COOH evaporates, the color rapidly turns orange, and fluorescence gradually increases. Heating at 70°C for 1 hour causes the color to return to yellow, and the fluorescence intensity increases. This reversible color and emission spectrum transition between protonation and deprotonation can be sustained up to five times without significant fatigue.

[0014] The small molecule compounds provided by this invention undergo a redshift in their emission spectra as the temperature decreases between 345 and 130 K, and exhibit a fluorescence color change from pale blue to yellow-green in dichloromethane.

[0015] In summary, this invention synthesizes a DAD-type fluorescent small molecule compound based on 1,10-phenanthroline and triphenylamine-4-boronic acid in one step via the Suzuki-Miyaura reaction. This method has advantages such as mild reaction conditions, simple reaction steps (completed in one step), and high product yield. The prepared fluorescent small molecule compound, with the electron-deficient acceptor 1,10-phenanthroline as the core and the highly distorted triphenylamine as the electron donor, exhibits excellent luminescence properties. Its fluorescence emission red-shifts with increasing solvent polarity, showing obvious solvation color development. DFT calculations confirm its excellent photophysical properties, specifically recognizing residual Ag⁺ in the natural environment and responding to temperature. Furthermore, its fluorescence and appearance color undergo excellent reversible changes under mechanical grinding and acidic environments, demonstrating multi-stimulus response performance, and showing promising application prospects in the field of fluorescent materials. Attached Figure Description

[0016] Figure 1 The above is the 1H NMR spectrum of the compound constructed in this invention based on 1,10-phenanthroline and triphenylamine-4-boronic acid.

[0017] Figure 2 This is the carbon NMR spectrum of the compound constructed in this invention based on 1,10-phenanthroline and triphenylamine-4-boronic acid.

[0018] Figure 3 This is the mass spectrum of the compound constructed in this invention based on 1,10-phenanthroline and triphenylamine-4-boronic acid.

[0019] Figure 4 The diagram shows the single-crystal structure and crystal stacking diagram of the compound constructed based on 1,10-phenanthroline and triphenylamine-4-boronic acid in this invention.

[0020] Figure 5 This is a solvation colorimetric effect diagram of the compound constructed based on 1,10-phenanthroline and triphenylamine-4-boronic acid in five different polar solvents.

[0021] Figure 6 This is a DFT calculation of the photophysical properties of the compound constructed based on 1,10-phenanthroline and triphenylamine-4-boronic acid in this invention.

[0022] Figure 7 This invention relates to compounds constructed based on 1,10-phenanthroline and triphenylamine-4-boronic acid, which exhibit resistance to Ag in various metal cations. + Specific recognition map.

[0023] Figure 8 This is a mechanical color change diagram of the compound constructed in this invention based on 1,10-phenanthroline and triphenylamine-4-boronic acid.

[0024] Figure 9 This is an acid-induced color change diagram of the compound constructed in this invention based on 1,10-phenanthroline and triphenylamine-4-boronic acid.

[0025] Figure 10 The thermochromic diagram shows the compound constructed in this invention based on 1,10-phenanthroline and triphenylamine-4-boronic acid. Detailed Implementation

[0026] The following examples further illustrate the specific implementation methods of this product. Unless otherwise specified, all instruments and reagents used are commercially available conventional products.

[0027] Example 1: Method for constructing small molecule compounds based on 1,10-phenanthroline and 4-(9-carbazolyl)phenylboronic acid 1,10-Phenanthroline (338 mg, 1 mmol) and triphenylamine-4-boronic acid (723 mg, 2.5 mmol) were dissolved in 18 mL of a mixed solvent of 1,4-dioxane and water (1,4-dioxane:water = 5:1, v / v). Potassium carbonate (273 mg, 1.5 mmol) and tetrakis(triphenylphosphine)palladium (231 mg, 0.2 mmol) were added, and the reaction was carried out at 90 °C under nitrogen protection for 24 hours. After the reaction was completed, the product was extracted with CH2Cl2 / H2O and separated by column chromatography (petroleum ether:ethyl acetate = 40:1, v / v) to give a pale yellow solid product (compound 2, 1464 mg, 70%).

[0028] 1 H NMR (400 MHz, Chloroform- d) δ 8.30 (d, J = 8.7 Hz, 1H),8.26 (d, J= 8.4 Hz, 1H), 8.07 (d, J = 8.4 Hz, 1H), 7.75 (s, 1H), 7.32 – 7.27 (m, 2H),7.24 (d, J = 8.7 Hz, 1H), 7.18 (d, J = 7.4 Hz, 1H), 7.06 (t, J = 7.3 Hz, 1H).;13C NMR (151MHz, cdcl3) δ 156.43, 149.09, 147.52, 146.04, 136.78,133.32, 129.32, 128.59, 127.56, 125.63, 124.82, 123.34, 123.22,119.53.;ESI-HRMS (m / z): calcd for C48H34N4 667.2783 (M+H+), found 667.2866 (M+H+).( 1 HNMR, 13 The C NMR and ESI-HRMS spectra are shown in Figures 1-3. Single crystal culture of small molecule compounds based on 1,10-phenanthroline and triphenylamine-4-boronic acid: Weigh 6 mg of the pure small molecule compound into a 10 mL glass vial, add 2.5 mL of analytical grade dichloromethane and heat to dissolve until the solution is clear and transparent. Then add 2.5 mL of analytical grade n-hexane into the glass vial, loosen the cap, and carry out single crystal culture by allowing the solvent to evaporate slowly. Place in a cool place and do not shake the glass vial during observation.

[0029] The single-crystal structure of the small molecule compound based on 1,10-phenanthroline and triphenylamine-4-boronic acid is shown below. Figure 4Compound 2 exhibits a V-shaped structure characterized by "offset π-π stacking-driven layered supramolecular self-assembly." Due to the tendency of π-π interactions to be coplanar or nearly coplanar, electron cloud overlap is maximized, but not completely coaxial; instead, it exhibits offset stacking, with horizontal misalignment between adjacent ring planes to avoid direct repulsion of π electron clouds, thus enhancing the stability of the stacked structure. Two molecules of compound 2 stack head-to-head along the planar direction through π-π interactions between phenanthroline groups to form a two-dimensional layered structure with a distance of 3.241 to 3.539 Å, and the molecules within the layers are tightly associated. The interlayer structure is maintained by multiple CH∙∙∙π interactions and π-π interactions of the triphenylamine groups, with a distance of 2.687 to 3.395 Å. The steric hindrance of the side chains determines the interlayer spacing and interlayer orientation. Furthermore, this DAD-type structure, with the electron-deficient acceptor 1,10-phenanthroline as the core and highly distorted triphenylamine as the electron donor, gives the compound excellent luminescent properties.

[0030] Example 2: Study on the luminescence properties of small molecule compounds Figure 5 To demonstrate the significant Stokes shift of small molecule compounds in five solvents of different polarities, the fluorescence emission spectrum of compound 2 exhibits a redshift as the solvent polarity increases. Figure 6 To obtain the HOMO-LUMO orbital diagram of compound 2 using Gaussian 09 at the B3LYP / 6-31G* level via DFT calculations, the triphenylamine electron-donating group exhibits a distorted conformation, while the electron acceptor phenanthroline maintains a planar conformation due to its rigid structure. The highest occupied molecular orbital (HOMO, 2 = -4.82 eV) shows the local electron density across the triphenylamine donor and phenanthroline donor, while the lowest unoccupied molecular orbital (LUMO, 2 = -2.16 eV) is predominantly located on the phenanthroline donor, except for the terminal unit of the triphenylamine group. This spatial overlap between the HOMO and LUMO regions facilitates an effective ICT effect, as evidenced by the narrow band gap of 3.23 eV.

[0031] Figure 7 For small molecule compounds to resist Ag in a variety of metal cations + Specific recognition. Ag was added to a THF-H2O solution of compound 2 (H2O volume fraction 10%). + Fe 3+ Pb 2+ Al 3+ Cr 3+ Co 2+ Ni 2+ Ba 2+Ca 2+ Cd 2 + Zn 2+ Mg 2+ Only by adding Ag + It will cause more than 95% fluorescence quenching, and the addition of other ions will not cause significant fluorescence changes. Figure 7 (a) indicates the effect of Ag + It exhibits excellent specific recognition properties. Adding Ag... + When equal amounts of several other competing metal ions were added to the solution, the quenching efficiency remained consistent (with a change of less than 5%), indicating that the compound has excellent binding affinity and structural robustness, can resist ion competition, and has good anti-interference properties. Figure 7 (b)).

[0032] Figure 8 The images show the mechanical chromatogram (a) and photograph (b) of a small molecule compound. Before grinding, its crystals have a dark brown, leaf-like structure; after mechanical grinding, its color changes to yellow. Furthermore, its fluorescence spectrum also changes before and after grinding; before grinding, the peak shapes are complex, while after grinding, the peaks shift blue and the shapes become simpler. This change can be reversibly achieved through recrystallization.

[0033] Figure 9 The images (a) and (b) show the acid-induced color change chromatograms of the small molecule compound 2. Upon addition of CH3COOH, the color of compound 2 instantly changes from yellow to red, accompanied by fluorescence quenching. As the CH3COOH evaporates, the color rapidly turns orange, and the fluorescence gradually increases. Heating at 70°C for 1 hour reverts the color back to yellow, with an increase in fluorescence intensity. This reversible color and emission spectrum between protonation and deprotonation persists for up to five cycles without significant fatigue.

[0034] Figure 10 The thermochromatograms (a) and photographs (b) show the thermochromatograms of small molecule compounds. Compound 2 undergoes a redshift in its emission spectrum as the temperature decreases between 345 K and 130 K, and exhibits a fluorescence color change from pale blue to yellow-green in dichloromethane.

Claims

1. A small molecule compound constructed based on 1,10-phenanthroline and triphenylamine-4-boronic acid, characterized in that, Its structural formula is as follows: 。 2. The method for synthesizing the small molecule compound as described in claim 1, characterized in that, Includes the following steps: 1,10-phenanthroline and triphenylamine-4-boronic acid were dissolved in a mixed solvent of 1,4-dioxane and water. Potassium carbonate and tetraphenylphosphine palladium catalyst were added, and the reaction was carried out at 80-100°C under nitrogen protection for 20-25 hours. After the reaction was completed, the product was obtained by extraction and column chromatography.

3. The synthesis method as described in claim 2, characterized in that, The molar ratio of 1,10-phenanthroline to triphenylamine-4-boronic acid is 1:2 to 1:2.

5.

4. The synthesis method according to claim 2, characterized in that, The volume ratio of 1,4-dioxane to water is 4:1 to 6:

1.

5. The synthesis method as described in claim 2, characterized in that, The molar amount of potassium carbonate is 1 to 1.5 times the molar amount of 1,10-phenanthroline.

6. The synthesis method according to claim 2, characterized in that, The molar amount of the tetra-triphenylphosphine palladium is 0.1 to 0.2 times the molar amount of 1,10-phenanthroline.

7. An application of the small molecule compound as described in claim 1, characterized in that, It can be used as a multi-stimulus responsive fluorescent material in at least one of the following scenarios: (a) Solvation color development: The fluorescence emission wavelength red-shifts with increasing solvent polarity; (b) Ag + Specific recognition: It can selectively react with Ag in a variety of metal ions. + (c) Mechanical color change: After grinding, the crystal color changes from dark brown to yellow, the fluorescence peak position is blue shifted and the peak shape is simplified; (d) Acid-induced color change: In an acidic environment, the color changes from yellow to red and the fluorescence is quenched, which can be reversibly restored by heating; (e) Thermochromic color change: The fluorescence emission is reduced by red shift in the temperature range of 345 ~ 130 K, and the fluorescence color changes from pale blue to yellow-green in dichloromethane.

8. The application according to claim 7, characterized in that: Ag + Specific recognition involves adding Ag to a solution of small molecule compounds in THF-H2O. + Fe 3+ Pb 2+ Al 3+ Cr 3+ Co 2+ Ni 2+ Ba 2+ Ca 2+ Cd 2+ Zn 2+ Mg 2+ Only Ag + The addition of the compound can significantly quench the fluorescence of the small molecule compound solution, while the addition of other metal ions cannot cause significant fluorescence changes. Furthermore, when the other metal ions mentioned above are present as competing ions, the fluorescence quenching efficiency of Ag+ fluctuates by ≤5%; the volume fraction of H2O in the THF-H2O solution is 10%.

9. The application according to claim 7, characterized in that: The acid-induced discoloration process can be reversibly cycled ≥5 times through acid volatilization or heating; the mechanochromic discoloration can be reversibly restored through recrystallization.

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