CN112645877B

CN112645877B - Fluorescent stress response material based on naphthalimide derivative and preparation and application thereof

Info

Publication number: CN112645877B
Application number: CN202011523265.1A
Authority: CN
Inventors: 瞿祎; 罗鑫; 王乐
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai University of Engineering Science
Priority date: 2020-12-22
Filing date: 2020-12-22
Publication date: 2022-08-26
Anticipated expiration: 2040-12-22
Also published as: CN112645877A

Abstract

The invention relates to a fluorescent stress response material based on a naphthalimide derivative, and preparation and application thereof, wherein the material has a structural formula shown in a formula (I):

wherein R is alkyl. The preparation method specifically comprises the following steps: (a) dissolving NI in acetic acid, heating for reaction, and carrying out primary post-treatment to obtain NIP; (b) dissolving NIP, triphenylamine-4-boric acid and tetrakis (triphenylphosphine) palladium obtained in the step (a) in N, N-dimethylformamide, adding potassium carbonate solution for heating reaction, and performing secondary post-treatment to obtain NITPA-Phenol; (c) and (c) dissolving the NITPA-Phenol, the 4-dimethylaminopyridine and the N, N' -dicyclohexylcarbodiimide obtained in the step (b) in tetrahydrofuran, adding fatty acid for reaction, and carrying out third post-treatment to obtain the NITPAC. Compared with the prior art, the stress response material provided by the invention has aggregation state luminescence properties with different quantum efficiencies, and different self-assembly structures can generate fluorescence difference, so that VOC gas detection and data storage are realized.

Description

Fluorescent stress response material based on naphthalimide derivative and preparation and application thereof

Technical Field

The invention belongs to the field of fine chemical engineering, and particularly relates to a fluorescent stress response material based on a naphthalimide derivative, and preparation and application thereof.

Background

The luminescent functional material has been widely used in many fields such as biological probes, chemical sensors, electroluminescent devices, etc. because of its property of exhibiting luminescent change under external stimulus. The fluorescence stress response material has the characteristic of generating obvious fluorescence signal change when being stimulated by external force, and the fluorescence emission change of the material is realized by the conversion between the ordered crystal structure and the disordered amorphous structure of the material when being stimulated by the external force.

Fluorescent stress response materials not only have important significance in basic research of material structures, but also attract people to pay attention in application fields of sensors, electroluminescent devices, optical data storage, safety ink and the like. Such materials can be broadly divided into: organic small molecules, complexes, organic macromolecules, coordination polymers, supramolecular materials and the like. The organic micromolecules have the advantages of easily modified structure, multiple types, complete functional strategies, mature synthesis technology, good structural repeatability and the like, and particularly, the organic micromolecules with aggregation-induced emission properties overcome the defect of fluorescence quenching in an aggregation state along with the discovery of aggregation-induced emission phenomena. In recent years, fluorescent stress responsive materials based on small organic molecules have been rapidly developed, and a series of fluorescent stress responsive materials constructed with tetraphenylethylene (Q.Qi, et al., adv.Funct.Mater.,2015,25, 4005-. In the materials, new aggregation-induced emission molecules are constructed by introducing tetraphenylethylene into other molecular structures, and relatively few single fluorophore small molecules with excellent performance are obtained.

Recently, some reports indicate that through appropriate modification, the naphthalimide derivative can realize aggregation-induced emission effect of a single molecule, and further prepare a corresponding stress response fluorescent functional material (Y.yin, et al., Acs.omega.,2019,4, 14324-14332). However, the development of the naphthalimide materials reported in the prior art still focuses on the yellow-green light region (500-550nm), and the materials emitting light in the yellow-green light region have the disadvantages of single signal channel, low signal resolution and the like. A few long-wave-band naphthalimide materials are difficult to reach a red light region, and the materials have the disadvantages of complex structure, high synthesis difficulty, low fluorescence quantum efficiency and low development value. Therefore, the development of the multichannel long-wave fluorescent stress response material with high quantum efficiency has important practical significance for further practical use of fluorescent sensors, optical information security and confidentiality and the like.

Disclosure of Invention

The invention aims to provide a fluorescent stress response material based on a naphthalimide derivative, and preparation and application thereof.

The purpose of the invention is realized by the following technical scheme:

a fluorescent stress response material based on naphthalimide derivatives can prepare a series of acicular or lamellar crystals with microscopic appearances by regulating and controlling the chain length, wherein the length of the crystals is within the range of 1-5 micrometers, the thickness of the lamellar crystals is within the range of 200-300 nanometers, and the crystals have pores with different diameters of 100-500 nanometers. The materials all have a structural formula shown in formula (I):

wherein R is alkyl.

Preferably, R is a C1-C7 alkyl group.

The fluorescence stress response material prepared by the invention is excited at 390nm, has an emission peak of 553-566 nm in a self-assembly state (namely an original state), has an emission peak of 568-610 nm in an amorphous state, has the quantum efficiency of 23.9-92.2% in the self-assembly state without external stimulation, and has the quantum efficiency of 43.7-59.2% in the amorphous state under the external stimulation. Specifically, NITPAC1 has 560nm emission peak under 390nm excitation and 92.2% of quantum efficiency in a self-assembly state, and has 610nm emission peak under an amorphous state and 59.2% of quantum efficiency; NITPAC3 has an emission peak of 566nm in a self-assembly state and a quantum efficiency of 23.9% when excited at 390nm, and has an emission peak of 602nm in an amorphous state and a quantum efficiency of 43.7%; NITPAC5 has emission peak of 557nm and quantum efficiency of 43.9% in self-assembly state and emission peak of 581nm in amorphous state under excitation of 390nm, and quantum efficiency of 58.0%; NITPAC7 excited at 390nm had an emission peak at 553nm in the self-assembled state with a quantum efficiency of 41.7% and an emission peak at 568nm in the amorphous state with a quantum efficiency of 46.1%.

The preparation method of the fluorescent stress response material based on the naphthalimide derivative is as shown in the following formula (II):

the preparation method specifically comprises the following steps:

(a) dissolving m-aminophenol and 4-bromo-1, 8-naphthalic anhydride (named NIP) in acetic acid, heating for reaction, and performing primary post-treatment to obtain N-m-phenol-4-bromo-1, 8-naphthalimide (named NIP);

(b) taking the N-m-phenol-4-bromine-1, 8-naphthalimide, triphenylamine-4-boric acid and tetrakis (triphenylphosphine) palladium (with the name of Pd (PPh) obtained in the step (a) ₃ ) ₄ ) Dissolving in N, N-dimethylformamide, adding potassium carbonate solution, heating for reaction, and performing secondary post-treatment to obtain 1, 8-naphthalimide-N-m-Phenol (named NITPA-Phenol) containing triphenylamine unit at 4-position;

(c) and (c) dissolving the 1, 8-naphthalimide-N-m-phenol, 4-dimethylaminopyridine and N, N' -dicyclohexylcarbodiimide which contain the triphenylamine unit at the 4-position obtained in the step (b) in tetrahydrofuran, adding fatty acid for reaction, and performing third post treatment to obtain 1, 8-naphthalimide-N-m-phenol alkyl ester (named NITPAC) which contains the triphenylamine unit at the 4-position.

In the step (a), the molar volume ratio of the 4-bromo-1, 8-naphthalic anhydride to the m-aminophenol to the acetic acid is (1.0-1.2) mmol, (1.95-2.3) mL, preferably 1.1mmol:2mmol:15 mL.

In the step (a), the heating reaction temperature is 110-130 ℃, preferably 120 ℃, and the heating reaction time is 4-6 h.

In the step (a), nitrogen bubbling is adopted to remove oxygen during reaction, the m-aminophenol is oxidized into quinone, and the removal of oxygen can prevent excessive byproducts.

In the step (a), the first post-treatment specifically comprises: after the reaction is finished, cooling to room temperature, adding water for suction filtration, drying the obtained filter cake in vacuum, and recrystallizing with absolute ethyl alcohol.

In the step (b), the molar volume ratio of the N-m-phenol-4-bromo-1, 8-naphthalimide, the triphenylamine-4-boric acid, the tetrakis (triphenylphosphine) palladium and the N, N-dimethylformamide (named as DMF) is (1.0-1.2) mmol, (0.026-0.028) mmol, (10-15) mL, preferably 1.1mmol:1.1mmol:0.026mmol:10mL, and the concentration of the potassium carbonate solution is (1.5-1.62) mol/L, preferably 1.62 mol/L.

In the step (b), the heating reaction temperature is 140-160 ℃, preferably 150 ℃, and the heating reaction time is 8-12 h.

In the step (b), nitrogen bubbling is used to remove oxygen during the reaction.

In the step (b), the second post-treatment specifically comprises: after the reaction is finished, cooling to room temperature, and sequentially adding dichloromethane, saturated saline water and anhydrous Na ₂ SO ₄ Respectively extracting, washing and drying, and finally purifying by using a 100-200-mesh silica gel chromatographic column.

The eluent for the silica gel column chromatography was dichloromethane.

In the step (c), the molar volume ratio of the N-m-phenol-4-triphenylamine-1, 8-naphthalimide, 4-dimethylaminopyridine (alias of DMAP), N' -dicyclohexylcarbodiimide (alias of DCC) and tetrahydrofuran (alias of THF) is (1.0-1.2) mmol, (1.25-1.40) mmol, (1.63-1.80) mmol, (10-12) mL.

In the step (c), the molar ratio of the N-m-phenol-4-triphenylamine-1, 8-naphthalimide to the fatty acid in the reaction is (1.0-1.2) to (2.5-4).

In the step (c), adding fatty acid under an ice bath condition, and then heating to room temperature for reaction for 2-4 h. Considering that fatty acids having unsaturated bonds or fatty acids having longer chains require lower temperatures and longer reaction times, the fatty acids are added under ice bath conditions and the reaction time is appropriately prolonged.

In the step (c), nitrogen bubbling is used to remove oxygen during the reaction.

In the step (c), the third post-treatment specifically comprises: after the reaction is finished, concentrating tetrahydrofuran under reduced pressure, adding saturated sodium bicarbonate solution for suction filtration, drying the obtained filter cake in vacuum, and purifying the filter cake by a 100-mesh 200-mesh silica gel chromatographic column.

The eluent of the silica gel chromatographic column is a mixed solution of dichloromethane and petroleum ether, and the volume ratio of the dichloromethane to the petroleum ether is 3: 1.

In both the step (a) and the step (c), stirring is performed during the reaction.

Use of a fluorescent stress-responsive material based on a naphthalimide derivative as described above, comprising detection of multiple VOC gases and optical information security.

The fluorescent stress response material based on the naphthalimide derivative is used for detecting VOC gas in a solid phase state. In the process of detecting VOC gas, the solid microstructure of the fluorescent stress response material based on the naphthalimide derivative is converted from a self-assembly structure into a blocky amorphous structure (which can be screened by a field emission scanning electron microscope). The fluorescent stress response material can react with VOC gas in powder, tabletting, soaking test paper, spin coating and polymer doped film, can realize the change of fluorescent light color and intensity after the action, can extract digital signals of green light and red light channels generated by the fluorescent stress response material through ImageJ software, and can be further processed into single-channel and double-channel detection signals, thereby qualitatively and quantitatively detecting VOC.

In the process of optical information security and confidentiality, a signal painted by the fluorescent stress response material based on the naphthalimide derivative is difficult to identify by naked eyes under the natural light condition, but can be clearly displayed under 365nm ultraviolet radiation.

The invention takes naphthalimide as a parent body and an electron acceptor, introduces triphenylamine as an electron donor, constructs strong intramolecular charge transfer to realize intramolecular charge distribution in different aggregation statesAnd (3) modulating, and introducing alkyl chains with different lengths as regulating units of the self-assembly structure. 1, 8-naphthalimide derivative (namely containing a compound with a structural formula of

The compound) has the advantages of high fluorescence quantum efficiency, strong solid state fluorescence, large Stokes displacement, good fluorescence aggregation performance, large molar extinction coefficient of an ultraviolet region, good light stability, good film forming property and the like, and can be used as a fluorescent probe, a laser dye, a dye-sensitized solar cell sensitizer, an electroluminescent material and the like. In electron donor arylamine (triphenylamine) and electron acceptor naphthalimide (structural formula is shown in the specification)

Naphthalimide units) are inserted into the polymer material, a rotatable rigid benzene ring is inserted between the naphthalimide units), conjugated molecules with certain dihedral angles are constructed, the amplitude of charge transfer in the molecules can be adjusted through the change of the dihedral angles in different aggregation states, and the change of fluorescence wavelength in different aggregation states is further realized. In the present invention, ordered packing of the self-assembled structures tends to planarize the molecules, thereby decreasing the dihedral angle within the molecules, resulting in a shorter fluorescence wavelength, while the amorphous state produced after milling will further increase the dihedral angle within the molecules, resulting in an increased intramolecular twist and a shift of the fluorescence wavelength towards red.

The stress response material provided by the invention has aggregation state luminescence properties with different quantum efficiencies, solves the technical problems of complex structure, high synthesis difficulty, high cost, scarcity of long-wave band stress response materials, lower quantum efficiency and the like of the stress response material in the prior art, and realizes VOC gas detection and optical information security by utilizing fluorescence difference under different self-assembly structures.

Drawings

FIG. 1 is a scanning electron micrograph of NITPAC1 prepared according to example 1, taken without external stimuli;

FIG. 2 is a SEM image of NITPAC1 prepared in example 1 under external force;

FIG. 3 is a SEM image of NITPAC3 prepared in example 3 without external stimulation;

FIG. 4 is a SEM image of NITPAC3 prepared in example 3 under external force;

FIG. 5 is a SEM image of NITPAC5 prepared in example 5 without external stimulation;

FIG. 6 is a SEM image of NITPAC5 prepared in example 5 under external force;

FIG. 7 is a SEM image of NITPAC7 prepared in example 7 without external stimulation;

FIG. 8 is a SEM image of NITPAC7 prepared in example 7 under external force;

FIG. 9 is a graph comparing the fluorescence emission spectra of NITPAC1 prepared in example 1 when unstimulated and stimulated by external force;

FIG. 10 is a graph comparing the fluorescence emission spectra of NITPAC3 prepared in example 3 when it was not stimulated by external force and when it was stimulated by external force;

FIG. 11 is a graph comparing the fluorescence emission spectra of NITPAC5 prepared in example 5 when it was not stimulated by external force and when it was stimulated by external force;

FIG. 12 is a graph comparing the fluorescence emission spectra of NITPAC7 prepared in example 7 when it was not stimulated by external force and when it was stimulated by external force;

FIG. 13 is a graph of the change in fluorescence of NITPAC1 prepared in example 1 for VOC detection at different response times;

FIG. 14 is a graph of a single channel digital signal of NITPAC1 for VOC detection prepared in example 1;

FIG. 15 is a two-channel ratio signal plot of NITPAC1 versus VOC detection prepared in example 1;

FIG. 16 is an illustration of the encryption and visualization of NITPAC1 prepared in example 1 when applied to the security of optical information;

FIG. 17 is a nuclear magnetic hydrogen spectrum of NITPAC1 prepared in example 1;

FIG. 18 is a nuclear magnetic carbon spectrum of NITPAC1 prepared in example 1;

FIG. 19 is a high resolution mass spectrum of NITPAC1 prepared in example 1;

FIG. 20 is a nuclear magnetic hydrogen spectrum of NITPAC3 prepared in example 3;

FIG. 21 is a nuclear magnetic carbon spectrum of NITPAC3 prepared in example 3;

FIG. 22 is a high resolution mass spectrum of NITPAC3 prepared in example 3;

FIG. 23 is a nuclear magnetic hydrogen spectrum of NITPAC5 prepared in example 5;

FIG. 24 is a nuclear magnetic carbon spectrum of NITPAC5 prepared in example 5;

FIG. 25 is a high resolution mass spectrum of NITPAC5 prepared in example 5;

FIG. 26 is a nuclear magnetic hydrogen spectrum of NITPAC7 prepared in example 7;

FIG. 27 is a nuclear magnetic carbon spectrum of NITPAC7 prepared in example 7;

FIG. 28 is a high resolution mass spectrum of NITPAC7 prepared in example 7;

FIG. 29 is a schematic view of a vapor smoked NITPAC1 ground to restore its original structural state;

FIG. 30 is a comparison of the solid state fluorescence emission spectra of NITPAC1 in FIG. 29 in three states;

FIG. 31 is a graph of the change in fluorescence before and after NITPAC1, NITPAC3, NITPAC5 and NITPAC7 milling;

figure 32 is a graph of the number of reversibility cycles of emission of NITPAC 1.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

A fluorescent stress response material based on naphthalimide derivatives has a structural formula shown as a formula (I):

wherein R is alkyl.

The preparation method of the fluorescent stress response material based on the naphthalimide derivative specifically comprises the following steps:

(a) dissolving m-aminophenol and 4-bromo-1, 8-naphthalic anhydride in acetic acid, heating and reacting for 4-6 hours at 110-130 ℃, removing oxygen by nitrogen bubbling during reaction, cooling to room temperature after the reaction is finished, adding water for suction filtration, drying the obtained filter cake in vacuum, and recrystallizing the dried filter cake with absolute ethyl alcohol to obtain N-m-phenol-4-bromo-1, 8-naphthalimide, wherein the molar volume ratio of the 4-bromo-1, 8-naphthalic anhydride to the m-aminophenol to the acetic acid is (1.0-1.2) mmol, (1.95-2.3) mmol, (15-30) mL;

(b) dissolving the N-m-phenol-4-bromine-1, 8-naphthalimide, the triphenylamine-4-boric acid and the tetrakis (triphenylphosphine) palladium obtained in the step (a) in N, N-dimethylformamide, adding a potassium carbonate solution, heating and reacting for 8-12 h at 140-160 ℃, removing oxygen by nitrogen bubbling during reaction, cooling to room temperature after the reaction is finished, and sequentially adding dichloromethane, saturated saline water and anhydrous Na ₂ SO ₄ Respectively extracting, washing and drying, and finally purifying by using a 100-200-mesh silica gel chromatographic column to obtain 4-position 1, 8-naphthalimide-N-m-phenol containing a triphenylamine unit, wherein the molar volume ratio of N-m-phenol-4-bromo-1, 8-naphthalimide, triphenylamine-4-boric acid, tetrakis (triphenylphosphine) palladium catalyst to N, N-dimethylformamide is (1.0-1.2) mmol, (1.1-1.2) mmol, (0.026-0.028) mmol, (10-15) mL, and the concentration of the potassium carbonate solution is (1.35-1.62) mol/L;

(c) dissolving the 4-position 1, 8-naphthalimide-N-m-phenol containing a triphenylamine unit, 4-dimethylaminopyridine and N, N' -dicyclohexylcarbodiimide obtained in the step (b) in tetrahydrofuran, adding fatty acid under an ice bath condition, heating to room temperature for reacting for 2-4 h, carrying out reaction, removing oxygen by bubbling nitrogen, after the reaction is finished, concentrating the tetrahydrofuran under reduced pressure, adding a saturated sodium bicarbonate solution for suction filtration, carrying out vacuum drying on the obtained filter cake, and purifying the filter cake by using a 100-mesh 200-mesh silica gel chromatographic column to obtain the 4-position 1, 8-naphthalimide-N-m-phenol alkyl ester containing the triphenylamine unit, wherein the N-m-phenol-4-triphenylamine-1, 8-naphthalimide, 4-dimethylaminopyridine, The molar volume ratio of N, N' -dicyclohexylcarbodiimide to tetrahydrofuran is (1.0-1.2) mmol, (1.25-1.40) mmol, (1.63-1.80) mmol, (10-12) mL, and the molar ratio of the reaction charge of the N-m-phenol-4-triphenylamine-1, 8-naphthalimide to fatty acid is (1.0-1.2) to (2.5-4). The 4-bromo-1, 8-naphthalic anhydride and triphenylamine-4-boric acid adopted by the invention are commercially available compounds, and can also be prepared by a conventional method in the literature, and the invention is not described in detail.

The application of the fluorescent stress response material based on the naphthalimide derivative comprises the detection of various VOC gases and the security of optical information.

The invention is further illustrated by the following examples, which are intended only for a better understanding of the contents of the invention and therefore do not limit the scope of protection of the invention.

Example 1

wherein R is CH ₃ The preparation method comprises the following steps:

(1) synthesis of NIP

4-bromo-1, 8-naphthalic anhydride (NI) (340mg, 1.1mmol), m-aminophenol (218mg, 2mmol) and 15mL of acetic acid were added sequentially in a 100mL three-necked flask equipped with a magnetic stirrer, oxygen was removed by bubbling nitrogen, the temperature was raised to 120 ℃, and stirring was performed under reflux for 6 h. Naturally cooling to room temperature, then adding 20mL of water, standing, filtering, drying a filter cake in vacuum, and recrystallizing with absolute ethyl alcohol to obtain 292mg of gray yellow powder with the chemical name of N-m-phenol-4-bromo-1, 8-Naphthalimide (NIP) and the yield of 79%. ¹ H NMR(400MHz,DMSO-d ₆ )δppm:9.67(s,1H),8.58(s,1H),8.61(dd,2H),8.34-8.36(d,J＝7.48,1H),8.26(d,J＝8.23,1H),8.02-8.05(m,1H),7.29-7.32(m,1H)，6.85-6.87(m,1H),6.79(m,2H).

(2) Synthesis of NITPA-Phenol

NIP (405mg, 1.1mmol), triphenylamine 4-borate (318mg, 1.1mmol), tetrakis (triphenylphosphine) palladium (30mg, 0.026mmol) and 10mL of N, N-dimethylformamide were placed in a 100mL reaction tube at room temperature. Then 1.12g K was added ₂ CO ₃ /5mL H ₂ O solution (i.e. K) ₂ CO ₃ The concentration of the solution is 1.62mol/L) to completely dissolve the solid compound to obtain a clear and transparent solution, bubbling to remove oxygen, protecting with nitrogen, gradually heating to 150 ℃, and reacting for 8 hours. The reaction was monitored by TLC, and after completion of the reaction, heating was stopped, the reaction mixture was allowed to cool to room temperature, extracted with dichloromethane (20 mL. times.2), washed with saturated brine (20 mL. times.2), and washed with anhydrous Na ₂ SO ₄ Drying and purifying with 100-200 mesh silica gel chromatography column (eluent dichloromethane) to obtain 523mg of orange red pure product with chemical name of 1, 8-naphthalimide-N-m-Phenol (NITPA-Phenol) containing triphenylamine unit at 4-position and yield of 89%. ¹ H NMR(400MHz,DMSO-d ₆ )δppm:9.67(s,1H)，8.57-8.51(m，2H)，8.45(d,J＝8.5Hz,1H),7.95-7.88(m,1H),7.84(d,J＝7.6Hz,1H),7.52(d,J＝8.5Hz,2H),7.39(t,J＝7.9Hz,4H)，7.31(t,J＝8.0Hz,1H)，7.15(dd,J＝16.1,7.7Hz,8H),6.87(d,J＝7.5Hz,1H),6.80(d,J＝6.9Hz,2H). ¹³ C NMR(100MHz,DMSO-d ₆ )δppm:164.06,163.84,158.30,148.22,147.26,131.94,131.49,130.91,130.23,129.88,125.24,124.27，122.48.HRMS(ESI)calcd.for C ₃₆ H ₂₅ N ₂ O ₃ [M+H] ⁺ 533.1865，found 533.1864.

(3) Synthesis of Compound NITPAC1

NITPA-Phenol (532mg,1.0mmol), N' -dicyclohexylcarbodiimide (336mg, 1.63mmol) and 4-dimethylaminopyridine (153mg, 1.25mmol) were charged to a 50mL flask and dissolved in 10mL of tetrahydrofuran. Then slowly adding (150mg, 2.5mmol) acetic acid under ice bath condition, removing oxygen, transferringThe reaction was allowed to proceed at room temperature for 2 hours. After the reaction is finished, concentrating the solvent under reduced pressure, adding a saturated sodium bicarbonate solution, filtering to obtain a crude solid product, and finally purifying by a 100-mesh 200-mesh silica gel chromatography column (eluent volume ratio dichloromethane: petroleum ether is 3:1) to obtain 390mg of a yellow-green target product, wherein the chemical name of the yellow-green target product is 1, 8-naphthalimide-N-m-phenol alkyl ester containing a triphenylamine unit at the 4-position, the yellow-green target product is marked as NITPAC1, NITPAC1 is a needle-shaped crystal, the average length is about 2-3 micrometers, the thickness is about 200-300 nm, the pore size is about 200-300 nm, and the hydrogen spectrum of the material is as follows: 1H NMR (400MHz, CDCl) ₃ )δ8.69(d，J＝7.6Hz,2H),8.50(d,J＝9.4Hz,1H),7.81–7.75(m,2H),7.58(t,J＝8.1Hz,1H),7.43(d,J＝8.6Hz,2H),7.39–7.33(m，4H)，7.31(s,1H),7.25(dd,J＝8.0,2.5Hz,7H),7.20(t,J＝2.0Hz,1H),7.13(t,J＝7.3Hz,2H),2.32(s,3H).13C NMR(100MHz,CDCl ₃ )δ168.69,164.22,164.00,151.25，148.48，147.33,147.25,136.21，133.26,131.81，131.62,131.36,130.79,130.23，129.69,129.49,129.26,127.77,126.74,126.12,125.09，123.69，122.92,122.46,122.21,121.79，121.23，77.32，77.00,76.68,21.15.HR-MS(ESI)calcd.for C ₃₈ H ₂₆ N ₂ O ₄ [M+Na]+597.1790,found 597.1788.

80mg of the target product NITPAC1 was put in an agate mortar to emit yellow-green fluorescence (absolute quantum efficiency: 92.2%) under ultraviolet irradiation, the actual graph is shown in FIG. 31, the SEM graph of the material when not stimulated by external force is shown in FIG. 1, the fluorescence emission is red (absolute quantum efficiency: 59.2%) when the target product is ground with a pestle for 3 minutes, the actual graph is shown in FIG. 31, the SEM graph when stimulated by external force (external force stimulation is grinding in the present invention, and the same below) is shown in FIG. 2 (grinding is performed first and then scanning is performed, the same below), it can be seen from FIG. 1 that NITPAC1 undergoes significant self-assembly behavior (i.e. NITPAC1 is prepared and is self-assembled when not ground), comparing NITPAC1, NITPAC3, NITPAC5 and NITPAC7 initial state quantum efficiency and grinding state efficiency, the NITPAC1 is reduced after grinding, the other three quantum efficiencies are improved after being grinded, and the phenomenon can be explained from the following aspects: the quantum efficiency of the amorphous state is not greatly related to the length of the side chain, so the quantum efficiencies of the four products after grinding are the same, but the quantum efficiency of the self-assembly state is greatly influenced by the length of the side chain, the chain length of NITPAC1 is the shortest, the planarization degree is the greatest after self-assembly, and the formed structure similar to the crystalline state has strong fluorescence, so that only the quantum efficiency of NITPAC1 is reduced after grinding.

FIG. 9 is a graph showing a comparison of solid fluorescence emission spectra of NITPAC1 (in the figure, the abscissa is the emission wavelength in nanometers; the ordinate is the normalized fluorescence emission intensity, the same applies to the following), and it can be seen from FIG. 9 that NITPAC1 undergoes a spectral shift of about 50nm before and after being stimulated by an external force, and NITPAC1 has an emission peak of 560nm in the self-assembled state and an emission peak of 610nm in the amorphous state when being stimulated at 390 nm.

The nuclear magnetic hydrogen spectrum of NITPAC1 is shown in FIG. 17, the nuclear magnetic carbon spectrum of NITPAC1 is shown in FIG. 18, the high resolution mass spectrum of NITPAC1 is shown in FIG. 19, the three graphs are detected under the original state of NITPAC1, and the detection results of the material under the original state and the grinding state are the same, because the grinding only changes the macroscopic state and does not change the chemical structure.

The obtained NITPAC1 compound is adopted to carry out qualitative and quantitative detection on VOC, under the condition of natural environment, a clean round small filter paper sheet is soaked in a dichloromethane solution of NITPAC1 dye for 15s and then taken out, and the solvent is dried by an electric hair drier. The fluorescence image was taken under 365nm UV radiation. Then 5mL of each of the different VOC solvents (as exemplified by methylene chloride) were placed in a 10mL weighing bottle and allowed to reach the saturated vapor pressure. A small circular filter paper sheet carrying NITPAC1 dye is adhered to the inner side of a weighing bottle cap, then the weighing bottle cap is covered on the weighing bottle, after the weighing bottle is placed for the same time, under 365nm ultraviolet radiation, fluorescence shooting is carried out, red and green channel digital signals before film identification VOC and after film identification VOC made by NITPAC1 are respectively tested, ratio calculation is carried out, then a working curve is respectively drawn by taking response time as an abscissa and digital signal strength or digital signal ratio as an ordinate, specifically, as shown in figures 13, 14 and 15 (the abscissa in figure 13 is different VOC detection, the ordinate is different response time, the unit is second, the abscissa in figure 14 is response time, the ordinate is digital signal strength (the shaded part in figure 14 indicates signal conversion time, namely response time), the abscissa in figure 15 is response time, the unit is second, the ordinate is digital ratio signal (the shaded part in figure 15 also indicates signal conversion time, i.e., response time). Fig. 13 to 15 show that the fluorescent stress response material based on the naphthalimide derivative has a fast conversion speed (the response speed can reach 20 to 40s) and a high sensitivity (the digital ratio signal gain is as high as 400%) in the process of detecting VOC, and by comparing fig. 14 and fig. 15, the following results can be obtained: fluorescent stress responsive materials such as NITPAC1 have shorter response times when using the ratio of two channel signals as the response time of the detection signal (fig. 15) than when using one channel signal alone as the detection signal (fig. 14).

Further, the NITPAC1 compound obtained as described above was used in optical information security. The words "SUES" were written on filter paper sheets by using a dimethylsulfoxide solution (1mM) containing a low concentration of NITPAC1 dye, followed by natural air drying. Under the natural light condition, signals on the filter paper sheet are difficult to identify by naked eyes, but under 365nm ultraviolet radiation, words like SUES clearly appear, specifically as shown in FIG. 16, the left side in FIG. 16 is an encrypted regional natural light picture, and the right side in FIG. 16 is a visualized decrypted regional 365nm ultraviolet radiation picture, so that the fluorescent stress response material based on the naphthalimide derivative can encrypt and visualize signals in the same region to realize the security and confidentiality of optical information.

Fig. 29 is a schematic diagram of the restoration of the original structural state of the NITPAC1 by steam fumigation after grinding, the restoration can be ground again, fig. 30 is a comparison graph of the solid fluorescence emission spectra of the NITPAC1 under the original state, the ground state and the steam fumigation, and it can be seen that the coincidence ratio of the line representing the steam fumigation and the line representing the original state is very high, which shows that the NITPAC1 can be substantially restored to the original state by steam fumigation.

Example 2

A fluorescent stress response material based on naphthalimide derivatives, except thatNITPA-Phenol (639mg, 1.2mmol), N' -dicyclohexylcarbodiimide (371mg,1.8mmol) and 4-dimethylaminopyridine (171mg, 1.4mmol) were charged into a 50mL flask, and dissolved in 12mL of tetrahydrofuran. Then, under ice-bath conditions, the same procedure as in example 1 was followed, except that acetic acid (240mg, 4.0mmol) was slowly added, to finally obtain 440mg of a target product having a yellow-green color and the same structure as in example 1. The hydrogen spectrum of this material is as follows: 1H NMR (400MHz, CDCl) ₃ )δ8.69(d,J＝7.6Hz,2H),8.50(d,J＝9.4Hz,1H)，7.81–7.75(m，2H),7.58(t,J＝8.1Hz,1H),7.43(d,J＝8.6Hz,2H),7.39–7.33(m，4H)，7.31(s,1H),7.25(dd，J＝8.0,2.5Hz,7H),7.20(t，J＝2.0Hz,1H),7.13(t,J＝7.3Hz,2H)，2.32(s,3H).13C NMR(100MHz,CDCl ₃ )δ168.69,164.22，164.00,151.25,148.48,147.33,147.25,136.21,133.26，131.81,131.62,131.36,130.79,130.23,129.69，129.49,129.26,127.77,126.74，126.12,125.09，123.69,122.92,122.46，122.21,121.79，121.23,77.32，77.00,76.68,21.15.HR-MS(ESI)calcd.for C ₃₈ H ₂₆ N ₂ O ₄ [M+Na]+597.1790,found 597.1788.

Example 3

wherein R is C ₃ H ₇ Is prepared by the following steps

The preparation, in which the first two steps are identical to those of example 1, is carried out in the third step as follows:

(3) synthesis of Compound NITPAC3

NITPA-Phenol (532mg,1.0mmol), N' -dicyclohexylcarbodiimide (336mg, 1.63mmol) and 4-dimethylaminopyridine (153mg, 1.25mmol) were charged to a 50mL flask and dissolved in 10mL tetrahydrofuran. Then slowly add (220mg, 2.5mmol) under ice-bath conditions) Butyric acid, oxygen is removed, and the reaction solution is moved to room temperature for 2 hours. After the reaction is finished, concentrating the solvent under reduced pressure, adding a saturated sodium bicarbonate solution, filtering to obtain a crude solid product, and finally purifying by using a 100-200-mesh silica gel chromatographic column (eluent volume ratio dichloromethane: petroleum ether: 3:1) to obtain 443mg of a yellow target product, wherein the chemical name of the yellow-green target product is 1, 8-naphthalimide-N-m-phenol alkyl ester containing a triphenylamine unit at the 4-position, the yellow-green target product is marked as NITPAC3, NITPAC3 is a lamellar crystal, the average length is about 3-5 micrometers, the thickness is about 200-300 nm, the pore size is about 200-300 nm, and the hydrogen spectrum of the material is as follows: ¹ H NMR(400MHz,CDCl3)δ8.70(s,2H),8.50(s,1H),7.78(s,2H),7.59(s,1H),7.30(q，J＝46.2,35.9Hz,18H),2.57(s,2H),1.82(s,2H)，1.69(s,2H),1.07(s,3H). ¹³ C NMR(101MHz,CDCl ₃ )δ171.41,164.25,151.34,148.48,147.33，136.20，133.27,131.81,131.62,131.37,130.81,130.21,129.70,129.49,129.26，127.77,126.75,126.02,125.09,123.69,122.92,122.47,122.24,121.84，121.23，77.34,36.29,18.39，13.65.HR-MS(ESI)calcd.for C ₄₀ H ₃₀ N ₂ O ₄ [M+H] ⁺ 603.2284,found 603.2264.

80mg of the target product NITPAC3 was placed in an agate mortar to emit yellow-green fluorescence (absolute quantum efficiency: 23.9%) under ultraviolet irradiation, the actual image is shown in FIG. 31, the SEM image of the material without external stimulation is shown in FIG. 3, the fluorescence emission is orange-yellow (absolute quantum efficiency: 43.7%) after the target product is ground with a pestle for 3 minutes, the actual image is shown in FIG. 31, the SEM image of the material with external stimulation is shown in FIG. 4, and the significant self-assembly behavior of NITPAC3 can be seen in FIG. 3. FIG. 10 is a comparison graph of solid fluorescence emission spectra of NITPAC3, from FIG. 10, it can be seen that NITPAC3 undergoes a spectral shift of about 36nm before and after being stimulated by external force, and NITPAC3 has an emission peak of 566nm in a self-assembled state and an emission peak of 602nm in an amorphous state when being excited at 390 nm. The nuclear magnetic hydrogen spectrum of NITPAC3 is shown in FIG. 20, the nuclear magnetic carbon spectrum of NITPAC3 is shown in FIG. 21, and the high resolution mass spectrum of NITPAC3 is shown in FIG. 22.

Example 4

A fluorescent stress responsive material based on a naphthalimide derivative except that NITPA-Phenol (639mg, 1.2mmol), N' -dicyclohexylcarbodiimide (371mg,1.8mmol) and 4-dimethylaminopyridine (171mg, 1.4mmol) were charged into a 50mL flask and dissolved by adding 12mL of tetrahydrofuran. Then under ice-bath conditions, the same as example 3 was followed except that (352mg, 4mmol) of butyric acid was slowly added, to finally obtain 460mg of a yellow-green objective product having the same structure as example 3. The hydrogen spectrum of this material is as follows: 1H NMR (400MHz, CDCl3) δ 8.70(s,2H),8.50(s,1H),7.78(s,2H),7.59(s,1H),7.30(q, J ═ 46.2,35.9Hz,18H),2.57(s,2H),1.82(s,2H),1.69(s,2H),1.07(s,3H). ¹³ C NMR(101MHz,CDCl ₃ )δ171.41,164.25,151.34，148.48,147.33,136.20,133.27,131.81,131.62,131.37,130.81,130.21，129.70，129.49,129.26，127.77，126.75,126.02,125.09,123.69,122.92，122.47,122.24,121.84,121.23,77.34,36.29,18.39,13.65.HR-MS(ESI)calcd.for C ₄₀ H ₃₀ N ₂ O ₄ [M+H]+603.2284,found 603.2264.

Example 5

wherein R is C ₅ H ₁₁ Is prepared by the following steps

The preparation, in which the first two steps are the same as in example 1, and the third step is as follows:

(3) synthesis of Compound NITPAC5

NITPA-Phenol (532mg,1.0mmol), N' -dicyclohexylcarbodiimide (336mg, 1.63mmol) and 4-dimethylaminopyridine (153mg, 1.25mmol) were added to a 50mL flask and dissolved in 10mL tetrahydrofuran. Hexanoic acid (290mg, 2.5mmol) was then added slowly under ice-bath conditions, oxygen was removed, and the reaction was allowed to warm to room temperature for 2 hours. After the reaction is finished, concentrating under reduced pressureAdding a saturated sodium bicarbonate solution into a solvent, filtering to obtain a solid crude product, and finally purifying by using a 100-200-mesh silica gel chromatographic column (eluent volume ratio dichloromethane: petroleum ether is 3:1) to obtain 363mg of a yellow target product, wherein the chemical name of the yellow-green target product is 1, 8-naphthalimide-N-m-phenol alkyl ester containing a triphenylamine unit at the 4-position, the yellow target product is marked as NITPAC5, NITPAC5 is a lamellar crystal, the average length is about 1-3 micrometers, the thickness is about 200-300 nm, the pore size is about 100-200 nm, and the hydrogen spectrum of the material is as follows: ¹ H NMR(400MHz，CDCl3)δ8.69(d，J＝7.6Hz,2H),8.50(d,J＝8.4Hz，1H),7.78(t,J＝8.2Hz,2H),7.58(t,J＝8.1Hz,1H),7.43(d,J＝8.4Hz,2H),7.36(t,J＝7.7Hz,4H),7.31(s,1H)，7.24(d，J＝7.8Hz,7H),7.19(s,1H),7.13(t,J＝7.2Hz,2H),2.58(t,J＝7.5Hz,2H),1.78(p,J＝7.3Hz,2H),1.47–1.34(m,4H),0.94(t，J＝6.8Hz,3H). ¹³ C NMR(101MHz,CDCl ₃ )δ171.57,164.25，164.03,151.36,148.48，147.33，147.24,136.19，133.26,131.82,131.61,131.36,130.22,129.69，129.48，129.26,127.77,126.74,125.99,125.09，123.68,122.93,122.47,122.22,121.82,121.24，77.31,34.41,31.25,24.56，22.30,13.86.HR-MS(ESI)calcd.for C ₄₂ H ₃₄ N ₂ O ₄ [M+H] ⁺ 631.2596,found 631.2597.

80mg of the target product NITPAC5 was placed in an agate mortar to emit yellow-green fluorescence (absolute quantum efficiency: 43.9%) under ultraviolet irradiation, the actual graph is shown in FIG. 31, the SEM image of the material when the material was not stimulated by external force is shown in FIG. 5, the fluorescence emission is yellow (absolute quantum efficiency: 58.0%) after the target product was ground with a pestle for 3 minutes, the actual graph is shown in FIG. 31, the SEM image when the material was stimulated by external force is shown in FIG. 6, and it can be seen from FIG. 5 that NITPAC5 has obvious self-assembly behavior. FIG. 11 is a comparison graph of solid fluorescence emission spectra of NITPAC5, from FIG. 11, it can be seen that NITPAC5 undergoes a spectral shift of about 24nm before and after being stimulated by external force, and NITPAC5 has an emission peak at 557nm in a self-assembled state and an emission peak at 581nm in an amorphous state when being excited at 390 nm. The nuclear magnetic hydrogen spectrum of NITPAC5 is shown in FIG. 23, the nuclear magnetic carbon spectrum of NITPAC5 is shown in FIG. 24, and the high resolution mass spectrum of NITPAC5 is shown in FIG. 25.

Example 6

A fluorescent stress responsive material based on a naphthalimide derivative except that NITPA-Phenol (639mg, 1.2mmol), N' -dicyclohexylcarbodiimide (371mg,1.8mmol) and 4-dimethylaminopyridine (171mg, 1.4mmol) were charged into a 50mL flask and dissolved by adding 12mL of tetrahydrofuran. Then under ice-bath conditions, the same as example 5 was followed except that (464mg, 4mmol) of hexanoic acid was slowly added, to finally obtain 460mg of a yellow-green target product having the same structure as example 5. The hydrogen spectrum of this material is as follows: ¹ H NMR(400MHz,CDCl3)δ8.69(d,J＝7.6Hz,2H)，8.50(d,J＝8.4Hz,1H),7.78(t,J＝8.2Hz，2H),7.58(t,J＝8.1Hz,1H)，7.43(d,J＝8.4Hz,2H),7.36(t，J＝7.7Hz,4H),7.31(s，1H)，7.24(d，J＝7.8Hz，7H),7.19(s,1H),7.13(t,J＝7.2Hz，2H),2.58(t,J＝7.5Hz,2H),1.78(p,J＝7.3Hz,2H),1.47–1.34(m,4H),0.94(t,J＝6.8Hz,3H). ¹³ C NMR(101MHz，CDCl ₃ )δ171.57，164.25，164.03，151.36，148.48，147.33,147.24，136.19，133.26，131.82,131.61,131.36,130.22,129.69,129.48,129.26,127.77,126.74,125.99,125.09,123.68,122.93,122.47,122.22,121.82,121.24，77.31,34.41,31.25,24.56,22.30，13.86.HR-MS(ESI)calcd.for C ₄₂ H ₃₄ N ₂ O ₄ [M+H] ⁺ 631.2596,found 631.2597.

example 7

wherein R is C ₇ H ₁₅ The preparation method comprises the following steps, wherein the first two steps are the same as those in example 1, and the third step is as follows:

(3) synthesis of Compound NITPAC7

NITPA-Phenol (532mg,1.0mmol), N' -dicyclohexylcarbodiimide (336mg, 1.63mmol) and 4-dimethylaminopyridine (153mg, 1.25mmol) were added to a 50mL flask and dissolved in 10mL tetrahydrofuran. Then octanoic acid (360mg, 2.5mmol) was slowly added under ice-bath conditions, oxygen was removed, and the reaction was allowed to proceed at room temperature for 2 hours. After the reaction is finished, concentrating the solvent under reduced pressure, adding a saturated sodium bicarbonate solution, filtering to obtain a solid crude product, and finally purifying by a 100-mesh 200-mesh silica gel chromatographic column (eluent volume ratio dichloromethane: petroleum ether is 3:1) to obtain a yellow-green target product of 430mg, wherein the chemical name of the yellow-green target product is 1, 8-naphthalimide-N-m-phenol alkyl ester containing a triphenylamine unit at the 4-position, the yellow-green target product is marked as NITPAC7, NITPAC7 is a lamellar crystal, the average length is about 1-3 micrometers, the thickness is about 200-300 nm, the pore size is about 200-500 nm, and the hydrogen spectrum of the material is as follows: 1H NMR (400MHz, CDCl3) δ 8.70(dd, J ═ 7.4,1.9Hz,2H), 8.50(d, J ═ 8.4Hz, 1H),7.78 (t, J ═ 8.1Hz,2H),7.58(t, J ═ 8.1Hz, 1H), 7.43(d, J ═ 8.5Hz,2H),7.36(t, J ═ 7.9Hz, 4H),7.31(s,1H),7.25(dd, J ═ 8.1,2.5Hz,7H),7.19(s,1H),7.13(t, J ═ 7.3Hz,2H),2.58(t, J ═ 7.5, 2H),1.77(p, J ═ 7.4, 2H), 1.91.48H, 8.8, 6H, 8H, 6H). ¹³ CNMR(101MHz，CDCl3)δ171.55，164.23,164.01，151.37,148.49,147.34,147.23,136.19,133.24,131.83,131.60,131.35,130.79,130.23,129.66，129.48，129.26,127.76,126.73,125.99,125.09,123.68,122.94,122.47,122.22，121.80,121.26，77.31,76.99,76.68，34.45,31.62,29.05,28.89,24.88,22.57,14.01.HR-MS(ESI)calcd.For C ₄₄ H ₃₈ N ₂ O ₄ [M+H] ⁺ 659.2910，found 659.2955.

80mg of the target product NITPAC7 was placed in an agate mortar to emit yellow-green fluorescence (absolute quantum efficiency: 41.7%) under ultraviolet irradiation, the actual figure is shown in FIG. 31, the SEM image of the material when the material was not stimulated by external force is shown in FIG. 7, the fluorescence emission is yellow (absolute quantum efficiency: 46.1%) after the target product was ground with a pestle for 3 minutes, the actual figure is shown in FIG. 31, the SEM image of the material when the material was stimulated by external force is shown in FIG. 8, and the significant self-assembly behavior of NITPAC7 can be seen from FIG. 7. FIG. 12 is a comparison graph of solid fluorescence emission spectra of NITPAC7, from which it can be seen that NITPAC7 undergoes a spectral shift of about 15nm before and after external force stimulation, and NITPAC7 has an emission peak at 390nm when excited, 553nm in the self-assembled state, and 568nm in the amorphous state. The nuclear magnetic hydrogen spectrum of NITPAC7 is shown in FIG. 26, the nuclear magnetic carbon spectrum of NITPAC7 is shown in FIG. 27, and the high resolution mass spectrum of NITPAC7 is shown in FIG. 28.

Example 8

A fluorescent stress responsive material based on a naphthalimide derivative except that NITPA-Phenol (639mg, 1.2mmol), N' -dicyclohexylcarbodiimide (371mg,1.8mmol) and (171mg, 1.4mmol) 4-dimethylaminopyridine were charged into a 50mL flask and dissolved by adding 12mL tetrahydrofuran. Then, 485mg of a yellow-green target product having the same structure as in example 7 was obtained in the same manner as in example 7 except that octanoic acid (576mg, 4.0mmol) was slowly added under ice-bath conditions. The hydrogen spectrum of this material is as follows: ¹ H NMR(400MHz，CDCl3)δ8.70(dd,J＝7.4，1.9Hz,2H)，8.50(d,J＝8.4Hz，1H)，7.78(t，J＝8.1Hz，2H)，7.58(t，J＝8.1Hz,1H),7.43(d,J＝8.5Hz,2H),7.36(t,J＝7.9Hz，4H)，7.31(s,1H)，7.25(dd,J＝8.1,2.5Hz,7H),7.19(s，1H),7.13(t,J＝7.3Hz,2H),2.58(t，J＝7.5Hz，2H)，1.77(p,J＝7.4Hz,2H),1.48–1.28(m,8H),0.91(t,J＝6.8Hz，3H). ¹³ CNMR(101MHz,CDCl3)δ171.55，164.23,164.01,151.37,148.49,147.34,147.23,136.19,133.24,131.83,131.60,131.35,130.79,130.23,129.66,129.48，129.26，127.76，126.73,125.99,125.09,123.68，122.94,122.47，122.22，121.80,121.26，77.31，76.99，76.68,34.45,31.62，29.05,28.89，24.88,22.57，14.01.HR-MS(ESI)calcd.For C ₄₄ H ₃₈ N ₂ O ₄ [M+H] ⁺ 659.2910，found 659.2955.

the above results demonstrate that NITPAC1, NITPAC3, NITPAC5, and NITPAC7 all exhibit fluorescent stress responses. The NITPAC1 with the shortest carbon chain shows a stress response fluorescent color change effect with high contrast, which can emit yellow green fluorescence in the original state but shows red fluorescence after being grinded by mechanical force, the emission state with high contrast can be reversibly switched by volatile solvent steam fumigation and grinding (namely, the emission peak can be switched back and forth between 566nm and 610nm through two operations of steam fumigation and grinding), and the material can be repeatedly used (the repeated use refers to that the fluorescent stress response material can be selected to be grinded or steam fumigation to change the macroscopic state of the material according to the application scene and requirements, and the performance is unchanged). The self-assembly behavior of the molecules in the aggregated state is different due to the different lengths of the carbon chains. The fluorescent stress response material based on the naphthalimide derivative has obvious response to stress and volatile organic solvents, and response signals are positioned in red and green areas sensitive to human eyes, so that the fluorescent stress response material has potential application prospects in the fields of optical data recording, data safety, data protection and the like.

Example 9

The embodiment provides a reversible switching experiment of a fluorescent stress response material, which specifically comprises the following steps: (1) 80mg of NITPAC1 in a self-assembly state is taken to carry out fluorescence spectrum test, the excitation wavelength is 390nm, and the emission wavelength at the peak value of the fluorescence emission peak is 566 nm. (2) The sample was placed in an agate mortar and ground manually for two minutes, the sample (this is an amorphous state sample) was scraped off and its fluorescence emission was measured at an excitation wavelength of: 390nm, the emission wavelength at the peak of the obtained fluorescence emission peak is: 610 nm. (3) The sample of (2) was placed in a small petri dish, 10ml of dichloromethane (steam-applied as a volatile solvent) was placed in a large petri dish, the two dishes were covered with a beaker, and heated at 40 ℃ for one minute at the bottom of the large petri dish. Then, samples in small culture dishes are collected, and fluorescence spectra of the samples are tested, wherein excitation wavelengths are as follows: 390nm, the obtained fluorescence emission peak value is: and 610 nm. And then, the experiment is repeated for a plurality of times according to the sequence from (1) to (2) to (3), and the fluorescence emission peak-to-peak reversible switching times of the sample are tested to evaluate the reusability of the fluorescence signal, and the specific result is shown in FIG. 32. As can be seen from FIG. 32, the signal switching of the emission wavelength can still keep the fluorescence emission peak-to-peak signal within 10nm when the cycle is 30 times, which shows that the fluorescence stress response material of the present invention has superior reversible switching performance.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims

1. A fluorescent stress-responsive material based on a naphthalimide derivative, wherein the material has a structural formula shown in formula (i):

wherein R is alkyl;

r is C1-C7 alkyl.

2. The preparation method of the fluorescent stress response material based on the naphthalimide derivative as claimed in claim 1, characterized in that the preparation method specifically comprises the following steps:

(a) dissolving m-aminophenol and 4-bromo-1, 8-naphthalic anhydride in acetic acid, carrying out heating reaction, and carrying out primary post-treatment to obtain N-m-phenol-4-bromo-1, 8-naphthalimide;

(b) dissolving the N-m-phenol-4-bromine-1, 8-naphthalimide, the triphenylamine-4-boric acid and the tetrakis (triphenylphosphine) palladium obtained in the step (a) in N, N-dimethylformamide, adding a potassium carbonate solution for heating reaction, and performing secondary post-treatment to obtain 1, 8-naphthalimide-N-m-phenol containing a triphenylamine unit at the 4-position;

(c) and (c) dissolving the 1, 8-naphthalimide-N-m-phenol, 4-dimethylaminopyridine and N, N' -dicyclohexylcarbodiimide which contain the triphenylamine unit at the 4-position obtained in the step (b) in tetrahydrofuran, adding fatty acid for reaction, and performing third post-treatment to obtain the 1, 8-naphthalimide-N-m-phenol alkyl ester which contains the triphenylamine unit at the 4-position.

3. The preparation method of the fluorescent stress response material based on the naphthalimide derivative as claimed in claim 2, wherein in the step (a), the molar volume ratio of the 4-bromo-1, 8-naphthalic anhydride, the m-aminophenol and the acetic acid is (1.0-1.2) mmol, (1.95-2.3) mmol, (15-30) mL.

4. The preparation method of the fluorescent stress response material based on the naphthalimide derivative according to claim 2, wherein in the step (a), the heating reaction temperature is 110-130 ℃, the heating reaction time is 4-6 h, nitrogen bubbling is adopted to remove oxygen during the reaction, and the first post-treatment specifically comprises the following steps: after the reaction is finished, cooling to room temperature, adding water for suction filtration, drying the obtained filter cake in vacuum, and recrystallizing with absolute ethyl alcohol.

5. The preparation method of the fluorescent stress response material based on the naphthalimide derivative as claimed in claim 2, wherein in the step (b), the molar volume ratio of the N-m-phenol-4-bromo-1, 8-naphthalimide, the triphenylamine-4-boronic acid, the tetrakis (triphenylphosphine) palladium and the N, N-dimethylformamide is (1.0-1.2) mmol, (1.1-1.2) mmol, (0.026-0.028) mmol, (10-15) mL, and the concentration of the potassium carbonate solution is (1.5-1.62) mol/L.

6. The preparation method of the fluorescent stress response material based on the naphthalimide derivative as claimed in claim 2, wherein in the step (b), the temperature of the heating reaction is 140-160 ℃, the time of the heating reaction is 8-12 h, nitrogen bubbling is adopted to remove oxygen during the reaction, and the second post-treatment specifically comprises the following steps: after the reaction is finished, cooling to room temperature, and sequentially adding dichloromethane, saturated saline water and anhydrous Na ₂ SO ₄ Respectively extracting, washing and drying, and finally purifying by using a 100-200-mesh silica gel chromatographic column.

7. The method for preparing a fluorescent stress response material based on a naphthalimide derivative as claimed in claim 2, wherein in the step (c), the molar volume ratio of N-m-phenol-4-triphenylamine-1, 8-naphthalimide, 4-dimethylaminopyridine, N' -dicyclohexylcarbodiimide to tetrahydrofuran is (1.0-1.2) mmol, (1.25-1.40) mmol, (1.63-1.80) mmol, (10-12) mL, and the molar ratio of the N-m-phenol-4-triphenylamine-1, 8-naphthalimide to the fatty acid is (1.0-1.2) to (2.5-4).

8. The preparation method of the fluorescent stress response material based on the naphthalimide derivative according to claim 2, wherein in the step (c), the fatty acid is added under an ice bath condition, then the temperature is raised to room temperature for reaction, the reaction time is 2-4 h, nitrogen bubbling is adopted for removing oxygen during the reaction, and the third post-treatment specifically comprises the following steps: after the reaction is finished, concentrating tetrahydrofuran under reduced pressure, adding a saturated sodium bicarbonate solution for suction filtration, drying the obtained filter cake in vacuum, and purifying the filter cake by using a 100-mesh and 200-mesh silica gel chromatographic column.