Phenothiazine illuminant and preparation method and application thereof

Abstract

The invention provides a phenothiazine illuminant as well as a preparation method and application thereof, and belongs to the field of mechanical force stimulation response materials. As an excellent photoelectric material, phenothiazine has an electron-rich characteristic and a unique'butterfly 'conformation and is expected to promote dynamic reversible molecular accumulation, so that a high-performance regrinding self-recovery characteristic is realized. The malononitrile derivative with strong electron withdrawing is an ideal element for constructing a high-efficiency aggregation-induced emission system. The phenothiazine illuminant emits orange light in a solid state, the phenothiazine illuminant can be converted into yellow light after being slightly ground (namely, mechanical force serves as an excitation source), and after further regrinding, the phenothiazine illuminant recovers to the color of the original state again through the yellow light triggered by slight grinding induction. The'blue shift-red shift 'bidirectional reversible color regulation triggered by the force can be repeatedly circulated. In addition, the high-contrast reversible force-induced discoloration phenomenon provides a beneficial reference value for developing a new generation of intelligent sensing luminescent materials.

Description

Technical Field

[0001] This invention relates to the field of mechanically responsive materials, specifically to a phenothiazine-based luminescent material, its preparation method, and its applications. Background Technology

[0002] Mechanochromic materials, a class of intelligent stimulus-responsive materials whose photophysical properties can be modulated through simple operations such as grinding and shearing, have attracted much attention due to their broad application prospects in fields such as visual stress sensing, high-security anti-counterfeiting, and information encryption. Although numerous mechanochromic materials have been reported, their performance still falls short of practical needs. The root cause lies in the fact that most mechanosensitive luminescent materials rely on irreversible physical or chemical changes induced by mechanical force to achieve color transitions; this irreversible nature severely limits their practical application value. Summary of the Invention

[0003] This invention provides a phenothiazine-based luminescent material, its preparation method, and its application. The phenothiazine-based luminescent material of this invention has the property of force-controlled high contrast and reversible color switching.

[0004] This invention provides a phenothiazine-based luminescent material having the structural formula shown in Figure 1: .

[0005] The present invention also provides a method for preparing the phenothiazine luminescent material described in the above technical solution, comprising the following steps: A substitution reaction was carried out by mixing phenothiazine, 4,4'-difluorobenzophenone, a catalyst and a first polar organic solvent to obtain compound 1-1; ; The compound 1-1, malononitrile, and a second polar organic solvent were mixed and subjected to a Knoevenagel condensation reaction to obtain the phenothiazine luminescent material.

[0006] Preferably, the molar ratio of the phenothiazine to 4,4'-difluorobenzophenone is 2 to 2.1:1.

[0007] Preferably, the molar ratio of the phenothiazine to the catalyst is 1:1 to 1.5; The catalyst includes potassium tert-butoxide.

[0008] Preferably, the first polar organic solvent includes N,N-dimethylformamide; The mass ratio of the phenothiazine to the volume of the first polar organic solvent is 1 g: 24~25 mL.

[0009] Preferably, the substitution reaction is carried out at a temperature of 115-120°C for 12-14 hours. The substitution reaction is carried out in a protective atmosphere.

[0010] Preferably, the molar ratio of compound 1-1 to malononitrile is 1:2.17~2.18.

[0011] Preferably, the mass ratio of compound 1-1 to the volume ratio of the second polar organic solvent is 1 g: 60~62 mL; The second polar organic solvent includes pyridine.

[0012] Preferably, the Knoevenagel condensation reaction is carried out at a temperature of 110~115℃ for 16~18h.

[0013] The present invention also provides the application of the phenothiazine luminescent material described in the above technical solution or the phenothiazine luminescent material prepared by the preferred preparation method in mechanical sensors.

[0014] Phenothiazines, as excellent optoelectronic materials, possess electron-rich properties and a unique "butterfly" conformation, which promises to promote dynamically reversible molecular stacking, thereby achieving high-performance re-grinding self-recovery properties. Meanwhile, strongly electron-withdrawing malononitrile derivatives are ideal building blocks for constructing highly efficient AIE (aggregation-induced emission) systems. Compound 1-1 of this invention (where the carbonyl group is also a common electron-withdrawing group) exhibits a bright yellow light in the solid state. After slight grinding (i.e., using mechanical force as the excitation source), the emission shifts to red, and the color changes to a deep yellow. After further grinding, it remains deep yellow and cannot return to its initial state. In contrast, the phenothiazine luminescent material of this invention emits orange light in the solid state. After slight grinding, the phenothiazine luminescent material can change to yellow light. After further grinding, the yellow light induced by slight grinding returns to the original color. This force-triggered bidirectional reversible color modulation of "blue-red shift" can be repeated cyclically. Furthermore, this high-contrast reversible mechanochromatic phenomenon provides valuable reference for the development of next-generation intelligent sensing luminescent materials. Attached Figure Description

[0015] Figure 1 Solid UV-Vis absorption spectra of phenothiazine luminescent powder in its original state, after slight mechanical grinding, and after more vigorous grinding (excitation wavelength 365 nm). Figure 2 This is a schematic diagram illustrating how compound 1-1 modulates the color change of a solid sample using different degrees of force. Figure 3 This is a schematic diagram illustrating the application of phenothiazine luminescent materials to the reversible control of color changes in solid samples using varying degrees of force. Detailed Implementation

[0016] This invention provides a phenothiazine-based luminescent material having the structural formula shown in Figure 1: .

[0017] The present invention also provides a method for preparing the phenothiazine luminescent material described in the above technical solution, comprising the following steps: A substitution reaction was carried out by mixing phenothiazine, 4,4'-difluorobenzophenone, a catalyst and a first polar organic solvent to obtain compound 1-1; ; The compound 1-1, malononitrile, and a second polar organic solvent were mixed and subjected to a Knoevenagel condensation reaction to obtain the phenothiazine luminescent material.

[0018] In this invention, phenothiazine, 4,4'-difluorobenzophenone, a catalyst, and a first polar organic solvent are mixed to carry out a substitution reaction to obtain compound 1-1.

[0019] In this invention, the mixing is preferably carried out in a protective atmosphere.

[0020] In this invention, the mixing preferably includes mixing phenothiazine and the catalyst, then mixing with a first polar organic solvent and stirring, and then mixing with 4,4'-difluorobenzophenone; the stirring temperature is preferably 60°C and the stirring time is preferably 1 hour.

[0021] In this invention, the molar ratio of the phenothiazine and 4,4'-difluorobenzophenone is preferably 2 to 2.1:1.

[0022] In this invention, the molar ratio of the phenothiazine to the catalyst is 1:1 to 1.5; the catalyst preferably includes potassium tert-butoxide.

[0023] In this invention, the mass ratio of the phenothiazine to the volume of the first polar organic solvent is preferably 1 g: 24~25 mL; the first polar organic solvent preferably includes N,N-dimethylformamide.

[0024] In this invention, the temperature of the substitution reaction is preferably 115~120℃, and the time is preferably 12~14h. In specific embodiments of this invention, the temperature of the substitution reaction can be 116℃, 117℃, 118℃ or 119℃, and the time can be 12.5h, 13h or 13.5h. The substitution reaction is carried out in a protective atmosphere.

[0025] Following the substitution reaction, the present invention preferably further includes: cooling the system obtained from the substitution reaction to room temperature, mixing it with ice water for precipitation, filtering, and then washing and drying the obtained solid to obtain compound 1-1.

[0026] After obtaining compound 1-1, the present invention mixes compound 1-1, malononitrile, and a second polar organic solvent to carry out a Knoevenagel condensation reaction to obtain the phenothiazine luminescent material.

[0027] In this invention, the molar ratio of compound 1-1 to malononitrile is preferably 1:2.17~2.18, and in a specific embodiment of this invention it can be 2.176.

[0028] In this invention, the mass ratio of compound 1-1 to the volume ratio of the second polar organic solvent is preferably 1 g: 60~62 mL; the second polar organic solvent preferably includes pyridine.

[0029] In this invention, the preferred temperature for the Knoevenagel condensation reaction is 110-115°C, and the preferred time is 16-18 hours. In specific embodiments of this invention, the preferred temperature for the Knoevenagel condensation reaction is 111°C, 112°C, 113°C, or 114°C, and the preferred time is 16.5 hours, 17 hours, or 17.5 hours. The Knoevenagel condensation reaction is preferably carried out in a protective atmosphere.

[0030] Following the Knoevenagel condensation reaction, the present invention preferably further includes: removing the polar organic solvent from the system obtained by the Knoevenagel condensation reaction and mixing it with an extractant for extraction; then washing, drying, and performing column chromatography on the obtained organic phase to obtain the phenothiazine luminescent material.

[0031] The present invention also provides the application of the phenothiazine luminescent material described in the above technical solution or the phenothiazine luminescent material prepared by the preparation method described in the above technical solution in mechanical sensors.

[0032] The following detailed description, in conjunction with embodiments, illustrates the phenothiazine-based luminescent material, its preparation method, and its applications provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0033] Example 1 Synthesis of Complex 1 The synthesis route is as follows: In the reaction formula, t-BuOK-potassium tert-butoxide; Pyridine; DMF-N,N-dimethylformamide The specific synthesis steps are as follows: 1. Under a nitrogen atmosphere, 5 g of phenothiazine and 2.92 g of potassium tert-butoxide were added sequentially to a 250 mL dry, nitrogen-filled three-necked flask. Then, 120 mL of ultra-dry N,N-dimethylformamide was added, and the mixture was heated to 60 °C and stirred for 1 h. Next, 2.62 g of 4,4'-difluorobenzophenone was added. After the addition was complete, the solution was heated to 120 °C and stirred for another 12 h. After the reaction was complete, the solution was cooled to room temperature, and a large amount of ice water was added to precipitate the solid. The precipitate was then filtered to obtain a yellow solid, which was washed with dichloromethane and dried to obtain a bright yellow solid 1-1. Yield: 76%. 1 H NMR (500 MHz, CDCl3): δ (ppm) = 7.86 (s, 2H), 7.84 (s, 2H), 7.30 (d, J = 1.5 Hz, 2H), 7.28 (d, J = 1.5 Hz, 2H), 7.26 (s, 2H), 7.25 (s, 2H), 7.16 (d, J = 1.5 Hz, 1H), 7.15 (d, J = 1.5Hz, 2H), 7.13 (d, J = 1.5 Hz, 1H), 7.08 (d, J = 1.5 Hz, 1H), 7.06 (d, J = 1.5Hz, 2H), 7.05 (d, J = 1.5 Hz, 1H), 6.94 (d, J = 1.5 Hz, 2H), 6.93 (d, J = 1.5Hz, 2H). ESI-MS (m / z): Found: [M + H] + 574.1400; 'molecular formulaC 37 H 24 N2OS2' requires [M + H] + 577.1403. 2. Under a nitrogen atmosphere, 1 g (1.7 mmol) of compound 1-1 was added to a 250 mL three-necked flask, followed by 60 mL of pyridine, and then 244.42 mg (3.7 mmol) of malononitrile. The Schlenk technique was used to ensure the reaction remained anhydrous and oxygen-free throughout, under an argon atmosphere. The mixture was heated to 110 °C and reacted for 16 h. After the reaction was complete, residual pyridine was removed by rotary evaporation. The mixture was extracted with dichloromethane and water, washed three times with saturated brine, dehydrated with anhydrous sodium sulfate, and finally purified by column chromatography to obtain the orange target product 1. Yield: 71%. 1HNMR (500 MHz, CDCl3): δ (ppm) = 7.43 (d, J = 10.0 Hz, 4H), 7.34 (s, 2H), 7.31(t, J = 2.5 Hz, 7H), 7.30 (d, J = 10.0 Hz, 3H), 7.21-7.17 (m, 4H), 7.09 (d, J= 10.0 Hz, 4H). ESI-MS (m / z): Found: [M + H] + 626.1517; 'molecular formulaC 40 H 25 N4S2' requires [M + H] + 625.1515. Solid UV-absorbing spectra of phenothiazine luminescent powder, lightly ground solid powder, and heavily ground solid powder are shown below. Figure 1 As shown.

[0034] pass Figure 1 It can be seen that the solid-state luminescent material 1 underwent significant changes in its solid-state UV-Vis absorption spectrum after light grinding. Specifically, the high-energy absorption edge of the spectrum broadened significantly. After further grinding, the spectrum almost completely overlapped with the spectrum in its initial state. This once again verifies the reversibility of the mechanochromic behavior of the luminescent material.

[0035] Figure 2 This is a schematic diagram illustrating how compound 1-1 modulates the color change of a solid sample using forces of varying degrees.

[0036] Depend on Figure 2 It is known that compound 1-1 exhibits a bright yellow light in the solid state. After slight grinding (i.e., using mechanical force as the excitation source), the light emission shifts to red and the color changes to a deep yellow. After further grinding, it remains a deep yellow and cannot be restored to its initial state.

[0037] Figure 3 This diagram illustrates the application of phenothiazine luminescent materials to the reversible color change of solid samples controlled by varying degrees of force: A slightly ground solid sample 1 is laid flat in a mortar. The letter "M" is written on the mortar surface using a pestle, resulting in a distinct orange "M". Subsequently, writing pressure is repeatedly applied along the orange "M" writing path, causing the letter "M" to revert to the background yellow color. The subsequent writing of the letter "C" and the asterisk pattern are performed by repeating the above operation. This inkless writing application clearly demonstrates the excellent reversibility of the mechanochromic behavior of phenothiazine luminescent materials, indicating their broad application prospects in fields such as visual sensing, anti-counterfeiting, and information security.

[0038] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A phenothiazine-based luminescent material, characterized in that, It has the structural formula shown in Figure 1: 。 2. The method for preparing the phenothiazine-based luminescent material according to claim 1, characterized in that, Includes the following steps: A substitution reaction was carried out by mixing phenothiazine, 4,4'-difluorobenzophenone, a catalyst and a first polar organic solvent to obtain compound 1-1; ； The compound 1-1, malononitrile, and a second polar organic solvent were mixed and subjected to a Knoevenagel condensation reaction to obtain the phenothiazine luminescent material.

3. The preparation method according to claim 2, characterized in that, The molar ratio of the phenothiazine to 4,4'-difluorobenzophenone is 2 to 2.1:

1.

4. The preparation method according to claim 2, characterized in that, The molar ratio of phenothiazine to catalyst is 1:1 to 1.5; The catalyst includes potassium tert-butoxide.

5. The preparation method according to claim 2, characterized in that, The first polar organic solvent includes N,N-dimethylformamide; The mass ratio of the phenothiazine to the volume of the first polar organic solvent is 1 g: 24~25 mL.

6. The preparation method according to claim 2, characterized in that, The substitution reaction was carried out at a temperature of 115-120°C for 12-14 hours. The substitution reaction is carried out in a protective atmosphere.

7. The preparation method according to claim 2, characterized in that, The molar ratio of compound 1-1 to malononitrile is 1:2.17~2.

18.

8. The preparation method according to claim 2, characterized in that, The mass ratio of compound 1-1 to the volume ratio of the second polar organic solvent is 1 g: 60~62 mL; The second polar organic solvent includes pyridine.

9. The preparation method according to claim 1, characterized in that, The Knoevenagel condensation reaction was carried out at a temperature of 110-115°C for 16-18 hours.

10. The application of the phenothiazine luminescent material according to claim 1 or the phenothiazine luminescent material prepared by the preparation method according to any one of claims 2 to 9 in mechanical sensors.

Images