Hydrogen-bonded dimeric fluoran dye and method for preparing the same

Abstract

This invention discloses a hydrogen-bonded dimer fluorane dye and its preparation method, belonging to the fields of fine chemicals and materials science. This invention modifies fluoraneoxazolonic acid to a azelaspironamide skeleton, introduces hydrogen-bonded building groups, and synthesizes a single-component fluorane dye that can self-assemble into a hydrogen-bonded dimer. Relying on intermolecular hydrogen bonds to regulate the reversible opening and closing of the spirocyclic ring, thermochromic color change can be achieved without the addition of external electron acceptors and phase change solvents, exhibiting both color and fluorescence output properties. The dye is compounded with a thickener, an aqueous binder, and water to obtain a thermochromic color paste, which can be directly screen printed to produce thermochromic fabrics without encapsulation. This invention can prepare multi-color thermochromic dyes in purple, green, yellow, red, black, and orange, with no component leakage, compatible with various auxiliaries, and the fabric exhibits excellent wash resistance and abrasion resistance, making it suitable for military and civilian applications such as thermosensitive anti-counterfeiting, flexible temperature sensing, special camouflage fabrics, and smart wearables.

Description

Technical Field

[0001] This invention belongs to the fields of fine chemicals and materials science and technology, specifically relating to a hydrogen-bonded dimer fluorescent dye and its preparation method. Background Technology

[0002] Fluorescene dyes are the most widely used organic reversible thermochromic functional molecules. Their molecular skeleton, with an oxanthracene conjugated plane and spironolactone ring as its core structure, possesses outstanding advantages such as high chromatic density, a wide tunable color range, abundant molecular modification sites, and good reversible thermal response. By introducing different electron-donating / withdrawing substituents into the fluorane parent ring, the maximum absorption wavelength can be precisely controlled, achieving multi-color changing effects such as red, orange, blue, and black. Simultaneously, the thermal response threshold and molecular stability can be adjusted through side-chain structure modification. Based on these excellent properties, fluorane thermochromic materials have been widely used in dual-use fields such as thermosensitive anti-counterfeiting inks, temperature-indicating coatings, smart packaging, flexible temperature sensors, special camouflage fabrics, equipment thermal status early warning, aerospace thermal monitoring, and national defense security markings, demonstrating extremely high industrialization and special equipment application value.

[0003] Currently, industrialized and research-based thermochromic systems of fluorane dyes cannot achieve reversible thermochromic changes independently using a single fluorane dye molecule. They must be combined with an electron acceptor chromogenic agent and a long-chain alkane phase change solvent to construct a three-component composite thermochromic system. Some improved schemes simplify this to a two-component system through molecular modification, but still require the synergistic effect of the phase change solvent to achieve temperature-responsive color change. A single-molecule self-chromic fluorane dye system does not exist. Its color-changing mechanism is an intermolecular electron transfer mechanism: under low-temperature solid-state conditions, the phase change solvent crystallizes out, the fluorane leuco form binds to the chromogenic agent through hydrogen bonds and intermolecular forces, the spironolactone ring opens, and the central carbon atom undergoes sp... 3 Hybridization to sp 2 Hybridization occurs when molecules form a continuous large π-conjugated system, resulting in characteristic absorption in the visible light region and color development. Upon heating to the phase transition melting point, the phase transition solvent melts into a liquid state, the intermolecular forces are disrupted by the solvent, the spirocyclic ring of the fluorane molecule recloses, the conjugated system breaks down, and the system returns to a colorless state. The color change temperature is determined by the melting point of the phase transition solvent, the intensity of the color is controlled by the amount of colorant added, and the color is determined by the substitution structure of the fluorane parent compound.

[0004] Traditional three-component and existing modified two-component fluorane thermochromic systems have inherent fundamental defects that severely limit their application in high-precision sensing, durable textiles, long-lasting outdoor temperature indication, and special military equipment. Specifically: First, the fluorane dye, developer, and phase change solvent in the system are in a physically blended state, with multiple mutual interferences between molecules, including hydrogen bonding, dissolution, and electron competition. The phase change solvent competitively disrupts the electron donor-acceptor interaction between the dye and developer, resulting in insufficient color saturation at low temperatures and residual color difference due to fading at high temperatures. The proportions of each component can only be roughly controlled through physical weighing, making it impossible to achieve precise molecular-scale proportions, leading to large batch-to-batch deviations in color change temperature and color intensity. Furthermore, there is a significant color change lag during the heating and cooling process, and the temperature sensing accuracy is insufficient, making it difficult to meet the requirements for high-precision thermal monitoring.

[0005] Secondly, multi-component systems rely on weak intermolecular forces for coexistence. Under long-term high and low temperature alternating stimulation, the molecular chain order of the phase change solvent continuously decreases, making it easy for dyes and color developers to undergo phase separation and local enrichment. After repeated melt-crystallization cycles, the proportion of effective color-developing components continues to shift, and significant color differences appear after multiple hot and cold cycles, with a substantial decrease in color contrast, failing to meet the durability requirements for long-term repeated temperature indication and repeated use of wearable fabrics. For example, the two-component integrated fluorane thermochromic dye disclosed in the existing patent CN120623189A, although improving stability by covalently connecting the chromogenic matrix and the phase change side chain, still requires additional compounding of color developers to form a two-component system. It does not get rid of dependence on external electron acceptors, and there is still a risk of phase separation between the components in the system. There is still room for improvement in long-term cycling performance.

[0006] Finally, phase change solvents and small molecule color developers are highly mobile. When directly used in fiber dyeing, printing, and melt spinning, they easily migrate and seep into the fiber interior or surface, causing a sharp drop in color fastness and staining of the fabric. The industry-standard solution is microencapsulation, but this process significantly increases the complexity of the production process and manufacturing costs. The capsule shell can block heat transfer, reducing the dye's thermal response speed and weakening the color depth. During long-term washing, friction, and bending of fabrics, the microcapsules are prone to rupture and leakage. Once the phase change components are lost, the color-changing ability is permanently lost, failing to meet the washability and abrasion resistance standards for smart textiles and camouflage fabrics.

[0007] In addition, physical blending systems have poor solvent resistance, and small molecule organic solvents can penetrate and destroy the system's interactions, leading to permanent discoloration; most phase change solvents have a temperature resistance limit of less than 200°C, and the capsule and molecular structure are prone to decomposition and failure under high-temperature processing and high-temperature conditions; long-term ultraviolet light exposure will accelerate the oxidative degradation of multi-component systems, significantly shortening their service life in outdoor and aerial open-air monitoring scenarios.

[0008] In summary, existing thermochromic fluorane materials always rely on at least one external component, such as a phase change solvent or a color developer, for synergistic color change. The physical blending of multiple components leads to a series of bottlenecks, including poor compatibility, short cycle life, complex processing and packaging, and insufficient environmental stability. While existing two-component covalently modified fluorane dyes have optimized component compatibility, they still cannot be separated from the phase change medium, and the core issues for fabric applications and long-term sensing scenarios remain unresolved. Therefore, the industry urgently needs to develop a novel fluorane dye that requires no additional electron acceptors or phase change solvent compounding, and achieves reversible thermochromism based on its single-molecule structure, eliminating the problems of multi-component competition, phase separation, and migration leakage at the molecular level. Summary of the Invention

[0009] Technical issues Conventional fluorescein dyes require a three-component or two-component thermochromic system with electron-dependent acceptors and phase-change solvents to achieve thermochromic effects. Furthermore, these systems often require encapsulation before application to fabrics and other substrates, leading to issues such as low color / fluorescence intensity and leakage of the thermochromic system. Therefore, a solution is needed that achieves reversible thermochromism based on the single-molecule structure itself, without requiring additional electron acceptors or phase-change solvents.

[0010] Technical solution To address the aforementioned technical problems, this invention designs and synthesizes a series of color / fluorescence dual-output hydrogen-bonded dimer fluorane dyes. Based on the parent structure of fluorane dyes, this invention optimizes the isomerizable oxygen bridge into a nitrogen bridge and introduces hydrogen-bonding building groups, enabling the dye to autonomously form a molecular dimer structure. This enhances the dye's color rendering and fluorescence properties and allows for autonomous control of molecular isomerization via intermolecular hydrogen bonds, eliminating dependence on electron acceptors and phase-change solvents. This constructs a single-component dimer fluorane color-changing dye system capable of independently achieving thermochromic color changes. This dye can be directly compounded with thickeners, adhesives, and water to prepare thermochromic color pastes, which can then be processed into thermochromic smart fabrics, effectively avoiding the drawbacks of traditional thermochromic fabrics such as cumbersome packaging, material leakage, and poor durability.

[0011] The first objective of this invention is to provide a novel spironolactam-type dimer fluorane dye, the structure of which is shown in Formula I or Formula II: Formula I Formula II In Formula I, X1 is selected from -NH2 and -NH(CH2). n CH3, -N[(CH2)] n One of CH3]2, 0≤n≤10; X2 is selected from -NH2 and -NH(CH2). n CH3, -N[(CH2)] n CH3]2、-(CH2)n One of CH3, 0≤n≤10; X3 is selected from -H and -(CH2). n CH3, -NH2, One of the halogens; 0≤n≤5, halogens include chlorine, bromine and iodine atoms; X4 is selected from -H and -(CH2). n CH3, -NH2, One of the halogens; 0≤n≤5, halogens include chlorine, bromine and iodine atoms; R is either a nitrogen-hydrogen bond donor or an oxygen-hydrogen bond donor, specifically selected from... , , One of them; R1 is selected from one of the following: hydrogen, hydroxyl, C1~C6 straight / branched alkyl, C3~C6 cycloalkyl, C1~C3 alkylhydroxy, methyl-substituted phenyl, benzoyl, acyl C1~C3 alkyl (-C=O-alkyl), sulfonyl C1~C3 alkyl, methylbenzenesulfonyl, hydroxamic acid (-C=O-NH-OH), hydroxyphenyl, and carboxyphenyl. R2 is selected from one of hydrogen, hydroxyl, C1~C6 straight / branched alkyl, C3~C6 cycloalkyl, C1~C3 alkylhydroxy, methyl-substituted phenyl, aminoC1~C3 alkyl (-NH-C1~C3 alkyl), hydroxyphenyl, and carboxyphenyl; R3 is selected from one of phenolic hydroxyl, carboxyl, sulfonamide, formamide, hydroxamic acid (-C=O-NH-OH), C1~C6 alkyl hydroxyl, C3~C6 branched alkyl hydroxyl, C1~C6 alkyl carboxyl, and C3~C6 branched alkyl carboxyl; R4 is selected from one of hydrogen, phenolic hydroxyl, carboxyl, sulfonamide, formamide, hydroxamic acid, C1~C6 straight-chain alkyl, C3~C6 branched alkyl, and C3~C6 cycloalkyl. R4 may be present singly or in multiples on the benzene ring, and when multiple are present, the number shall not exceed four.

[0012] Furthermore, X1 is selected from one of -NH2, -NHCH3, -NHCH2CH3, -NHCH2CH2CH3, -NHCH2CH2CH2CH3, -N(CH3)2, -N(CH2CH3)2, -N[(CH2)2CH3]2, -N[(CH2)6CH3]2, -N[(CH2)7CH3]2, and -N[(CH2)8CH3]2.

[0013] Furthermore, X1 is selected from one of -N(CH2CH3)2, -NHCH2CH3, -NH2, and -N[(CH2)7CH3]2.

[0014] Furthermore, X2 is one of -N(CH3)2, -N(CH2CH3)2, -N[(CH2)2CH3]2, -NHCH3, -NHCH2CH3, -NHCH2CH2CH3, -NH2, -N[(CH2)6CH3]2, -N[(CH2)7CH3]2, -N[(CH2)8CH3]2, -CH3, and -CH2CH3.

[0015] Furthermore, X2 is one of -N(CH2CH3)2, -NHCH2CH3, -NH2, -N[(CH2)7CH3]2, and -CH3.

[0016] Furthermore, X3 is selected from one of -H, -CH3, -CH2CH3, and -Cl.

[0017] Furthermore, X3 is selected from -H or -CH3.

[0018] Furthermore, X4 is selected from one of -H, -CH3, -CH2CH3, and -Cl.

[0019] Furthermore, X4 is selected from -H or -CH3.

[0020] Furthermore, R is either a nitrogen-hydrogen bond donor or an oxygen-hydrogen bond donor, specifically selected from... , , One of them; R1 is selected from one of hydrogen, hydroxyl, C1~C3 straight / branched alkyl, C1~C3 alkylhydroxyl, methyl-substituted phenyl, benzoyl, acyl C1~C3 alkyl, sulfonyl C1~C3 alkyl, methylbenzenesulfonyl, hydroxamic acid, hydroxyphenyl, and carboxyphenyl; R2 is selected from one of hydrogen, hydroxyl, C1~C3 straight / branched alkyl, C3~C6 cycloalkyl, hydroxyC1~C3 alkyl, methyl-substituted phenyl, aminoC1~C3 alkyl, hydroxyphenyl, and carboxyphenyl. R3 is selected from one of phenolic hydroxyl, carboxyl, sulfonamide, formamide, hydroxamic acid, C1~C3 alkyl hydroxyl, C1~C3 alkyl carboxyl, and C3~C6 branched alkyl carboxyl; R4 is selected from one of hydrogen, C1~C3 straight-chain alkyl, and C3~C6 branched alkyl, and a maximum of 4 R4s can exist on the benzene ring at the same time.

[0021] Furthermore, R is selected from , , , , , , , , , One of them.

[0022] A second objective of this invention is to provide a method for preparing the novel spironolactam-type dimer fluorane dye, the method comprising the following steps: S1. Preparation of intermediates: Dissolve the corresponding color raw materials and oxalyl chloride in an organic solvent, stir and react. After the reaction is complete, remove the solvent to obtain intermediates corresponding to various colors.

[0023] S2. Amide condensation reaction: Dissolve the functional monomer containing hydrogen-bonded building groups in an organic solvent to obtain a functional monomer solution; dissolve the above intermediate in an organic solvent, add it dropwise to the monomer solution, and heat to react.

[0024] S3. Purification to obtain the target dye: After the reaction is completed, the mixture is cooled and the solvent is removed by rotary evaporation to obtain the crude product. The crude product is then purified to obtain the spironolactam type dimer fluorescent dye.

[0025] Furthermore, the color raw materials in step S1 include Rhodamine B, Rhodamine 110, Rhodamine 6G, Rhodamine 101, 2-[3,6-bis(dioctylamino)-9H-oxanthracene-9-yl]benzoic acid, and 2-[6-(diethylamino)-1,3-dimethyl-9H-oxanthracene-9-yl]benzoic acid.

[0026] Furthermore, in step S1, the molar ratio of the colorant and oxaloyl chloride is 1:1~2.

[0027] Furthermore, in step S1, the temperature of the stirring reaction is 20~30℃, and the time is 1~10 hours.

[0028] Furthermore, the hydrogen-bonded building groups in step S2 include acetylurea, 4-amino-N-hydroxybenzamide, urea, hydroxyurea, p-aminophenol, p-aminobenzyl alcohol, N-methylhydrazine carboxamide, o-aminophenol, 4-aminobenzoic acid, and o-aminobenzenesulfonamide.

[0029] Furthermore, in step S2, the molar ratio of the intermediate to the functional monomer is 1:1~2.

[0030] Furthermore, in step S2, the heating reaction temperature is 40~60℃, and the time is 5~20 hours.

[0031] Furthermore, the purification in step S3 can be performed using column chromatography, TLC, or HPLC.

[0032] Furthermore, the aforementioned organic solvents include one or more of chloroform, dichloromethane, anhydrous diethyl ether, and toluene.

[0033] A third objective of this invention is to provide a thermochromic color paste based on a single-component thermochromic system of spironolactam-type dimer fluorane dye, wherein the thermochromic color paste comprises spironolactam-type dimer fluorane dye, thickener, binder and water.

[0034] Furthermore, the thermochromic color paste is composed of spironolactone type dimer fluorane dye, thickener, binder and water.

[0035] Furthermore, the thickeners include one or more of the following: polyacrylic acid (PHT), sodium polyacrylate, guar gum, sodium alginate, sodium carboxymethyl cellulose, hydroxypropyl methyl cellulose, and polyvinyl alcohol.

[0036] Furthermore, the adhesive includes one or more of the following: polyacrylates (RSZ-301A), styrene-acrylate copolymers, waterborne polyurethanes, and ethylene-vinyl acetate copolymer emulsions.

[0037] Furthermore, based on mass percentage, spironolactam-type dimer fluorane dyes account for 0.01 to 5 wt% of the thermochromic color paste.

[0038] Furthermore, based on mass percentage, spironolactam-type dimer fluorane dyes account for 0.05~2wt% of the thermochromic color paste.

[0039] Furthermore, based on mass percentage, the thickener accounts for 0.01 to 10 wt% of the thermochromic pigment.

[0040] Furthermore, based on mass percentage, the thickener accounts for 0.05~5wt% of the thermochromic color paste.

[0041] Furthermore, based on mass percentage, the binder accounts for 1 to 25 wt% of the thermochromic pigment.

[0042] Furthermore, based on mass percentage, the binder accounts for 5 to 20 wt% of the thermochromic pigment.

[0043] The fourth objective of this invention is to provide applications of the above-mentioned thermochromic pigment in fields such as thermosensitive anti-counterfeiting, flexible temperature sensing, special camouflage fabrics, and smart wearables. The applications include preparing thermochromic fabrics using screen printing technology with the above-mentioned thermochromic pigment.

[0044] Beneficial effects (1) This invention modifies fluorane into a spironolactam hydrogen-bonded dimer structure, which can independently and reversibly change color at temperature without the need for color developer or phase change solvent. It relies on molecular hydrogen bonds to regulate the opening and closing of spiro rings, solving the problems of mutual interference between components, delayed color change, and large batch color difference in traditional systems. At the same time, it has both visible light color and fluorescence dual signal output, and the color system covers purple, green, yellow, red, black and orange, making it more applicable to a wider range of scenarios.

[0045] (2) The color-changing paste system of the present invention does not have a solid-liquid phase change process, has no risk of small molecule migration and leakage, and does not require microcapsule encapsulation; repeated hot and cold cycles do not cause significant color difference decay, the fabric has excellent water washing and abrasion resistance, and is resistant to light, solvents and high temperature, and is not prone to failure after long-term outdoor and high-temperature use.

[0046] (3) Dyes can be directly compounded with various water-based thickeners and water-based adhesives to form water-based color pastes. Thermochromic fabrics can be prepared by relying on conventional screen printing, eliminating the complex process of microcapsule preparation, simplifying the production process, reducing manufacturing costs, and adapting to large-scale intelligent textile processing. Attached Figure Description

[0047] Figure 1 This is a schematic diagram showing the structural changes of spironolactam-type dimer fluorane dyes.

[0048] Figure 2 The image shows the hydrogen NMR spectrum of PRB-AU1 (purple).

[0049] Figure 3 Here are the absorption spectra of the dye in different solvents; where Figure 3 (a) is PRB0, Figure 3 (b) is PRB-AU1.

[0050] Figure 4 The fluorescence spectra of the dye in different solvents are shown; where Figure 4 (a) is PRB0, Figure 4 (b) is PRB-AU1.

[0051] Figure 5 The color change process of fabrics using a thermochromic pigment containing PRB-AU1 (purple No. 1). Detailed Implementation

[0052] The following examples further illustrate the outstanding advantages and significant features of the present invention, but the present invention is by no means limited to the examples.

[0053] Raw material sources: The monomers used in the examples were Rhodamine B, p-aminophenol, 4-amino-N-hydroxybenzamide, and 4-aminobenzoic acid, with CAS numbers 81-88-9, 123-30-8, 26071-05-6, and 118-92-3, respectively, purchased from Sinopharm Chemical Reagent Co., Ltd.; Acetourea, urea, hydroxyurea, p-aminobenzyl alcohol, o-aminophenol, and o-aminobenzenesulfonamide, with CAS numbers 591-07-1, 57-13-6, 127-07-1, 623-04-1, 95-55-6, and 3306-62-5, respectively, purchased from Shanghai Titan Technology Co., Ltd.; N-methylhydrazine formamide, with CAS number 17696-95-6, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0054] The molecular structures of the fluorane dyes involved in the embodiments and comparative examples of this invention are as follows: Table 1. Structure of novel purple fluorane dyes

[0055] Table 2 Structure of novel green fluorane dyes

[0056] Table 3 Structure of novel yellow fluorane dyes

[0057] Table 4 Structure of novel red fluorane dyes

[0058] Table 5 Structure of novel black fluorane dyes

[0059] Table 6. Structure of novel orange fluorane dyes

[0060] Table 7 Structure of traditional fluorane dyes

[0061] Table 8. Structure of fluorane dyes

[0062] Example 1 This example describes the preparation of purple No. 1 to No. 11.

[0063] Preparation of the novel purple fluorane dye PRB-AU1: Rhodamine B (11 mmol) and oxaloyl chloride (20 mmol) were dissolved in 60 mL of dichloromethane (DCM) and reacted at room temperature for 2 h. After the reaction was completed, the mixture was cooled to room temperature, and the solvent was removed by rotary evaporation to obtain a purple-red intermediate (PRB-Cl). Acetourea (13.7 mmol) was dissolved in 150 mL of DCM and stirred in an ice-water bath for 10 min. The intermediate from the previous step was then dissolved in 20 mL of DCM and slowly added dropwise to the acetourea solution. The temperature was raised to 40 °C and the reaction was carried out for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and the solvent was removed by rotary evaporation to obtain a deep purple solid. Finally, the solid was purified by column chromatography (eluent volume ratio: CH2Cl2 / CH3OH = 30 / 1), and after drying, a pink powder was obtained, which is the novel purple fluorane dye PRB-AU1.

[0064] The intermediate PRB-Cl has the following molecular formula and a molecular weight of 413.26.

[0065]

[0066] Preparation of the novel purple fluorescent alkane dye PRB-AU2: The synthesis method of the novel purple fluorescent alkane dye PRB-AU1 was followed, except that acetourea was replaced with an equimolar amount of 4-amino-N-hydroxybenzamide to obtain the novel purple fluorescent alkane dye PRB-AU2.

[0067] Preparation of the novel purple fluorescent alkane dye No. 3 (PRB-AU3): The synthesis method of the novel purple fluorescent alkane dye No. 1 (PRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of urea to obtain the novel purple fluorescent alkane dye No. 3.

[0068] Preparation of the novel purple fluorescent alkane dye No. 4 (PRB-AU4): The synthesis method of the novel purple fluorescent alkane dye No. 1 (PRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of hydroxyurea to obtain the novel purple fluorescent alkane dye No. 4.

[0069] Preparation of the novel purple fluorescent alkane dye No. 5 (PRB-AU5): The synthesis method of the novel purple fluorescent alkane dye No. 1 (PRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of p-aminophenol to obtain the novel purple fluorescent alkane dye No. 5.

[0070] Preparation of the novel purple fluorescent alkane dye PRB-AU6: The synthesis method of the novel purple fluorescent alkane dye PRB-AU1 was followed, except that acetylurea was replaced with an equimolar amount of p-aminobenzyl alcohol to obtain the novel purple fluorescent alkane dye PRB-AU6.

[0071] Preparation of the novel purple fluorane dye No. 7 (PRB-AU7): The synthesis method of the novel purple fluorane dye No. 1 (PRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of N-methylhydrazine carboxamide to obtain the novel purple fluorane dye No. 7.

[0072] Preparation of the novel purple fluorane dye No. 8 (PRB-AU8): The synthesis method of the novel purple fluorane dye No. 1 (PRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of o-aminophenol to obtain the novel purple fluorane dye No. 8.

[0073] Preparation of the novel purple fluorescent alkane dye PRB-AU9: The synthesis method of the novel purple fluorescent alkane dye PRB-AU1 was followed, except that acetourea was replaced with an equimolar amount of 4-aminobenzoic acid to obtain the novel purple fluorescent alkane dye PRB-AU9.

[0074] Preparation of the novel purple fluorane dye No. 10 (PRB-AU10): The synthesis method of the novel purple fluorane dye No. 1 (PRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of o-aminobenzenesulfonamide to obtain the novel purple fluorane dye No. 10.

[0075] Preparation of Purple Fluorane Dye No. 11 (PRB-AU11): The synthesis method of Purple No. 1 novel fluorane dye (PRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of pentane to obtain Purple No. 11 fluorane dye.

[0076] Example 2 This example describes the preparation of green products No. 1 to No. 10.

[0077] Preparation of Green No. 1 Novel Fluorane Dye (GRB-AU1): Referring to the synthesis method of Purple No. 1 Novel Fluorane Dye (PRB-AU1) in Example 1, the reactant Rhodamine B in the preparation of intermediate (PRB-Cl) was adjusted to an equimolar amount of Rhodamine 110 to obtain a light green intermediate (GRB-Cl); then, according to the synthesis method of Purple No. 1 Novel Fluorane Dye (PRB-AU1) in Example 1, an equimolar amount of acetourea was added to obtain Green No. 1 Novel Fluorane Dye.

[0078] Preparation of Green No. 2 novel fluorane dye (GRB-AU2): The synthesis method of Green No. 1 novel fluorane dye (GRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of 4-amino-N-hydroxybenzamide to obtain Green No. 2 novel fluorane dye.

[0079] Preparation of Green No. 3 novel fluorescent alkane dye (GRB-AU3): The synthesis method of Green No. 1 novel fluorescent alkane dye (GRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of urea to obtain Green No. 3 novel fluorescent alkane dye.

[0080] Preparation of Green No. 4 novel fluorane dye (GRB-AU4): The synthesis method of Green No. 1 novel fluorane dye (GRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of hydroxyurea to obtain Green No. 4 novel fluorane dye.

[0081] Preparation of Green No. 5 novel fluorane dye (GRB-AU5): The synthesis method of Green No. 1 novel fluorane dye (GRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of p-aminophenol to obtain Green No. 5 novel fluorane dye.

[0082] Preparation of Green No. 6 novel fluorescent alkane dye (GRB-AU6): The synthesis method of Green No. 1 novel fluorescent alkane dye (GRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of p-aminobenzyl alcohol to obtain Green No. 6 novel fluorescent alkane dye.

[0083] Preparation of Green No. 7 novel fluorescent alkane dye (GRB-AU7): The synthesis method of Green No. 1 novel fluorescent alkane dye (GRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of N-methylhydrazine carboxamide to obtain Green No. 7 novel fluorescent alkane dye.

[0084] Preparation of Green No. 8 novel fluorescent alkane dye (GRB-AU8): The synthesis method of Green No. 1 novel fluorescent alkane dye (GRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of o-aminophenol to obtain Green No. 8 novel fluorescent alkane dye.

[0085] Preparation of Green No. 9 novel fluorane dye (GRB-AU9): The synthesis method of Green No. 1 novel fluorane dye (GRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of 4-aminobenzoic acid to obtain Green No. 9 novel fluorane dye.

[0086] Preparation of Green No. 10 novel fluorescent alkane dye (GRB-AU10): The synthesis method of Green No. 1 novel fluorescent alkane dye (GRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of o-aminobenzenesulfonamide to obtain Green No. 10 novel fluorescent alkane dye.

[0087] Example 3 This example describes the preparation of yellow No. 1 to No. 10.

[0088] Preparation of the novel yellow fluorane dye (YRB-AU1): Following the synthesis method of the novel purple fluorane dye (PRB-AU1) in Example 1, the reactant Rhodamine B in the preparation of the intermediate (PRB-Cl) was adjusted to an equimolar amount of Rhodamine 6G to obtain the light yellow intermediate (YRB-Cl); then, according to the synthesis method of the novel purple fluorane dye (PRB-AU1) in Example 1, an equimolar amount of acetylurea was added to obtain the novel yellow fluorane dye.

[0089] Preparation of novel yellow fluorescent alkane dye No. 2 (YRB-AU2): The synthesis method of novel yellow fluorescent alkane dye No. 1 (YRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of 4-amino-N-hydroxybenzamide to obtain novel yellow fluorescent alkane dye No. 2.

[0090] Preparation of novel yellow fluorescent alkane dye No. 3 (YRB-AU3): The synthesis method of novel yellow fluorescent alkane dye No. 1 (YRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of urea to obtain novel yellow fluorescent alkane dye No. 3.

[0091] Preparation of novel yellow fluorane dye No. 4 (YRB-AU4): The synthesis method of novel yellow fluorane dye No. 1 (YRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of hydroxyurea to obtain novel yellow fluorane dye No. 4.

[0092] Preparation of novel yellow fluorane dye No. 5 (YRB-AU5): The synthesis method of novel yellow fluorane dye No. 1 (YRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of p-aminophenol to obtain novel yellow fluorane dye No. 5.

[0093] Preparation of novel yellow fluorane dye No. 6 (YRB-AU6): The synthesis method of novel yellow fluorane dye No. 1 (YRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of p-aminobenzyl alcohol to obtain novel yellow fluorane dye No. 6.

[0094] Preparation of novel yellow fluorane dye No. 7 (YRB-AU7): The synthesis method of novel yellow fluorane dye No. 1 (YRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of N-methylhydrazine carboxamide to obtain novel yellow fluorane dye No. 7.

[0095] Preparation of novel yellow fluorane dye No. 8 (YRB-AU8): The synthesis method of novel yellow fluorane dye No. 1 (YRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of o-aminophenol to obtain novel yellow fluorane dye No. 8.

[0096] Preparation of novel yellow fluorane dye No. 9 (YRB-AU9): The synthesis method of novel yellow fluorane dye No. 1 (YRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of 4-aminobenzoic acid to obtain novel yellow fluorane dye No. 9.

[0097] Preparation of novel yellow fluorane dye No. 10 (YRB-AU10): The synthesis method of novel yellow fluorane dye No. 1 (YRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of o-aminobenzenesulfonamide to obtain novel yellow fluorane dye No. 10.

[0098] Example 4 This example describes the preparation of red No. 1 to No. 10.

[0099] Preparation of the novel red fluorescent alkane dye (RRB-AU1): Following the synthesis method of the novel purple fluorescent alkane dye (PRB-AU1) in Example 1, the reactant Rhodamine B in the preparation of the intermediate (PRB-Cl) was adjusted to an equimolar amount of Rhodamine 101 to obtain the light red intermediate (RRB-Cl); then, according to the synthesis method of the novel purple fluorescent alkane dye (PRB-AU1) in Example 1, an equimolar amount of acetourea was added to obtain the novel red fluorescent alkane dye.

[0100] Preparation of Red No. 2 novel fluorane dye (RRB-AU2): The synthesis method of Red No. 1 novel fluorane dye (RRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of 4-amino-N-hydroxybenzamide to obtain Red No. 2 novel fluorane dye.

[0101] Preparation of Red No. 3 novel fluorescent alkane dye (RRB-AU3): The synthesis method of Red No. 1 novel fluorescent alkane dye (RRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of urea to obtain Red No. 3 novel fluorescent alkane dye.

[0102] Preparation of Red No. 4 novel fluorane dye (RRB-AU4): The synthesis method of Red No. 1 novel fluorane dye (RRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of hydroxyurea to obtain Red No. 4 novel fluorane dye.

[0103] Preparation of Red No. 5 novel fluorane dye (RRB-AU5): The synthesis method of Red No. 1 novel fluorane dye (RRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of p-aminophenol to obtain Red No. 5 novel fluorane dye.

[0104] Preparation of Red No. 6 novel fluorescent alkane dye (RRB-AU6): The synthesis method of Red No. 1 novel fluorescent alkane dye (RRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of p-aminobenzyl alcohol to obtain Red No. 6 novel fluorescent alkane dye.

[0105] Preparation of Red No. 7 novel fluorane dye (RRB-AU7): The synthesis method of Red No. 1 novel fluorane dye (RRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of N-methylhydrazine carboxamide to obtain Red No. 7 novel fluorane dye.

[0106] Preparation of Red No. 8 novel fluorane dye (RRB-AU8): The synthesis method of Red No. 1 novel fluorane dye (RRB-AU1) was followed, except that acetylurea was replaced with an equimolar amount of o-aminophenol to obtain Red No. 8 novel fluorane dye.

[0107] Preparation of Red No. 9 novel fluorane dye (RRB-AU9): The synthesis method of Red No. 1 novel fluorane dye (RRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of 4-aminobenzoic acid to obtain Red No. 9 novel fluorane dye.

[0108] Preparation of Red No. 10 novel fluorane dye (RRB-AU10): The synthesis method of Red No. 1 novel fluorane dye (RRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of o-aminobenzenesulfonamide to obtain Red No. 10 novel fluorane dye.

[0109] Example 5 This example describes the preparation of black grades 1 through 10.

[0110] Preparation of the novel black fluorescent alkane dye BRB-AU1: Following the synthesis method of the novel purple fluorescent alkane dye PRB-AU1 in Example 1, the reactant Rhodamine B in the preparation of the intermediate (PRB-Cl) was adjusted to an equimolar amount of 2-[3,6-bis(dioctylamino)-9H-oxanthracene-9-yl]benzoic acid to obtain the light black intermediate (BRB-Cl); then, according to the synthesis method of the novel purple fluorescent alkane dye PRB-AU1 in Example 1, an equimolar amount of acetourea was added to obtain the novel black fluorescent alkane dye BRB-AU1.

[0111] Preparation of novel black fluorescent alkane dye BRB-AU2: The synthesis method of novel black fluorescent alkane dye BRB-AU1 was followed, except that acetourea was replaced with an equimolar amount of 4-amino-N-hydroxybenzamide to obtain novel black fluorescent alkane dye BRB-AU2.

[0112] Preparation of Black No. 3 Fluorane Dye (BRB-AU3): The synthesis method of Black No. 1 Fluorane Dye (BRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of urea to obtain Black No. 3 Fluorane Dye.

[0113] Preparation of novel black fluorescent alkane dye BRB-AU4: The synthesis method of novel black fluorescent alkane dye BRB-AU1 was followed, except that acetourea was replaced with an equimolar amount of hydroxyurea to obtain novel black fluorescent alkane dye BRB-AU4.

[0114] Preparation of novel black fluorescent alkane dye BRB-AU5: The synthesis method of novel black fluorescent alkane dye BRB-AU1 was followed, except that acetylurea was replaced with an equimolar amount of p-aminophenol to obtain novel black fluorescent alkane dye BRB-AU5.

[0115] Preparation of novel black fluorescent alkane dye BRB-AU6: The synthesis method of novel black fluorescent alkane dye BRB-AU1 was followed, except that acetylurea was replaced with an equimolar amount of p-aminobenzyl alcohol to obtain novel black fluorescent alkane dye BRB-AU6.

[0116] Preparation of novel black fluorescent alkane dye BRB-AU7: The synthesis method of novel black fluorescent alkane dye BRB-AU1 was followed, except that acetourea was replaced with an equimolar amount of N-methylhydrazine carboxamide to obtain novel black fluorescent alkane dye BRB-AU7.

[0117] Preparation of novel black fluorane dye BRB-AU8: The synthesis method of novel black fluorane dye BRB-AU1 was followed, except that acetylurea was replaced with an equimolar amount of o-aminophenol to obtain novel black fluorane dye BRB-AU8.

[0118] Preparation of novel black fluorescent alkane dye BRB-AU9: The synthesis method of novel black fluorescent alkane dye BRB-AU1 was followed, except that acetourea was replaced with an equimolar amount of 4-aminobenzoic acid to obtain novel black fluorescent alkane dye BRB-AU9.

[0119] Preparation of Black No. 10 novel fluorescent alkane dye (BRB-AU10): The synthesis method of Black No. 1 novel fluorescent alkane dye (BRB-AU1) was followed, except that acetourea was replaced with an equimolar amount of o-aminobenzenesulfonamide to obtain Black No. 10 novel fluorescent alkane dye.

[0120] Example 6 This example describes the preparation of orange samples 1 through 10.

[0121] Preparation of the novel orange fluorescent alkane dye ORB-AU1: Following the synthesis method of the novel purple fluorescent alkane dye PRB-AU1 in Example 1, the reactant Rhodamine B in the preparation of the intermediate (PRB-Cl) was adjusted to an equimolar amount of 2-[6-(diethylamino)-1,3-dimethyl-9H-oxanthracene-9-yl]benzoic acid to obtain the light orange intermediate (ORB-Cl); then, according to the synthesis method of the novel purple fluorescent alkane dye PRB-AU1 in Example 1, an equimolar amount of acetourea was added to obtain the novel orange fluorescent alkane dye ORB-AU1.

[0122] Preparation of Orange No. 2 Fluorane Dye (ORB-AU2): The synthesis method of Orange No. 1 Fluorane Dye (ORB-AU1) was followed, except that acetourea was replaced with an equimolar amount of 4-amino-N-hydroxybenzamide to obtain Orange No. 2 Fluorane Dye.

[0123] Preparation of Orange No. 3 Fluorane Dye (ORB-AU3): The synthesis method of Orange No. 1 Fluorane Dye (ORB-AU1) was followed, except that acetourea was replaced with an equimolar amount of urea to obtain Orange No. 3 Fluorane Dye.

[0124] Preparation of the novel orange fluorane dye ORB-AU4: The synthesis method of the novel orange fluorane dye ORB-AU1 was followed, except that acetourea was replaced with an equimolar amount of hydroxyurea to obtain the novel orange fluorane dye ORB-AU4.

[0125] Preparation of the novel orange fluorane dye ORB-AU5: The synthesis method of the novel orange fluorane dye ORB-AU1 was followed, except that acetylurea was replaced with an equimolar amount of p-aminophenol to obtain the novel orange fluorane dye ORB-AU5.

[0126] Preparation of the novel orange fluorane dye ORB-AU6: The synthesis method of the novel orange fluorane dye ORB-AU1 was followed, except that acetylurea was replaced with an equimolar amount of p-aminobenzyl alcohol to obtain the novel orange fluorane dye ORB-AU6.

[0127] Preparation of the novel orange fluorane dye ORB-AU7: The synthesis method of the novel orange fluorane dye ORB-AU1 was followed, except that acetourea was replaced with an equimolar amount of N-methylhydrazine carboxamide to obtain the novel orange fluorane dye ORB-AU7.

[0128] Preparation of the novel orange fluorane dye ORB-AU8: The synthesis method of the novel orange fluorane dye ORB-AU1 was followed, except that acetylurea was replaced with an equimolar amount of o-aminophenol to obtain the novel orange fluorane dye ORB-AU8.

[0129] Preparation of the novel orange fluorane dye ORB-AU9: The synthesis method of the novel orange fluorane dye ORB-AU1 was followed, except that acetourea was replaced with an equimolar amount of 4-aminobenzoic acid to obtain the novel orange fluorane dye ORB-AU9.

[0130] Preparation of Orange No. 10 Fluorane Dye (ORB-AU10): The synthesis method of Orange No. 1 (ORB-AU1) was followed, except that acetourea was replaced with an equimolar amount of o-aminobenzenesulfonamide to obtain Orange No. 10 Fluorane Dye.

[0131] Example 7 Traditional purple fluorane dye (purple 0, PRB0): purchased from Haishan Technology Co., Ltd.

[0132] Preparation of traditional purple fluorane dye thermochromic paste (PTCP0): Take purple fluorane dye No. 0 and mix it with 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water. Stir magnetically for 45 min to obtain uniformly mixed PTCP0.

[0133] The PTCP0 is colorless at room temperature and remains colorless when heated to 90 °C; there is no color change during the cooling process.

[0134] Example 7-1 Preparation of a traditional purple fluorane dye three-component thermochromic system (tri-PTC0): Purple fluorane dye No. 0 was taken and mixed with fluorane dye, bisphenol A and tetradecyl alcohol in a mass ratio of 1:4:60. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed tri-PTC0.

[0135] The tri-PTC0 is purple at room temperature, turns colorless when heated to 38 °C, and turns purple again when cooled to 35 °C.

[0136] Example 7-2 Preparation of traditional purple fluorane dye three-component thermochromic color paste (Tri-PTCP0): Purple fluorane dye No. 0 was taken and mixed in the following proportions: 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water. Then, based on the mass of purple fluorane dye No. 0 in the color paste, bisphenol A and tetradecyl alcohol were added to the base color paste in a mass ratio of purple fluorane dye No. 0, bisphenol A and tetradecyl alcohol of 1:4:60. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed Tri-PTCP0.

[0137] The Tri-PTCP0 is colorless at room temperature and remains colorless when heated to 90 °C; there is no color change during the cooling process.

[0138] Example 8 Preparation of Purple No. 1 thermochromic color paste (PTCP1): Purple No. 1 novel fluorane dye was taken and mixed in the proportion of 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0139] The PTCP1 is pink at room temperature, turns purple when heated to 90 ℃, and turns pink again when cooled to 88 ℃.

[0140] Example 8-1 Preparation of Purple No. 11 thermochromic color paste (PTCP11): Purple No. 11 fluorane dye was taken and mixed in the proportion of 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0141] The PTCP11 is white at room temperature and remains white when heated to 90 ℃; there is no color change during the cooling process.

[0142] Example 9 Preparation of Green No. 1 thermochromic color paste (GTCP1): Take Green No. 1 novel fluorane dye, mix it with 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water, and stir magnetically for 45 min to obtain uniformly mixed GTCP1.

[0143] The GTCP1 is yellow at room temperature, turns green when heated to 90 ℃, and turns yellow again when cooled to 88 ℃.

[0144] Example 10 Preparation of Yellow No. 1 thermochromic color paste (YTCP1): Take Yellow No. 1 novel fluorane dye, mix it with 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water, and stir magnetically for 45 min to obtain uniformly mixed YTCP1.

[0145] The YTCP1 is white at room temperature, turns yellow when heated to 90 ℃, and turns white again when cooled to 88 ℃.

[0146] Example 11 Preparation of Red No. 1 thermochromic color paste (RTCP1): Take Red No. 1 novel fluorane dye, mix it with 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water, and stir magnetically for 45 min to obtain uniformly mixed RTCP1.

[0147] The RTCP1 is pink at room temperature, turns red when heated to 90 ℃, and turns red again when cooled to 88 ℃.

[0148] Example 12 Preparation of Black No. 1 thermochromic color paste (BTCP1): Take Black No. 1 novel fluorane dye, mix it with 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water, and stir magnetically for 45 min to obtain a uniformly mixed BTCP1.

[0149] The BTCP1 is light gray at room temperature, turns black when heated to 90 ℃, and turns light gray again when cooled to 88 ℃.

[0150] Example 13 Preparation of Orange No. 1 thermochromic paste (OTCP1): Orange No. 1 novel fluorane dye was taken and mixed in the proportion of 0.05% fluorane dye, 3% PHT, 18% RSZ-301A and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed OTCP1.

[0151] The OTCP1 exhibits a light color at room temperature, turns orange when heated to 90 ℃, and becomes light pink when cooled to 88 ℃.

[0152] Table 9 Color-changing performance of Examples 7-13

[0153] Table 10 Color-changing performance of Examples 7, 7-1, 7-2 and 7-3

[0154] As shown in Tables 9-10, compared with traditional fluoroalkane dyes, the designed and synthesized spirolamide-type fluoroalkane dyes can achieve thermochromic changes independently in a single-component color-changing system by autonomously regulating molecular isomerization through intermolecular hydrogen bonds without the addition of electron acceptors, phase change solvents, or other components. However, when spirolamide-type fluoroalkane dyes lack intermolecular hydrogen bonds (such as the purple fluoroalkane dye No. 11), these dyes cannot change color independently.

[0155] Furthermore, in performance testing, it was found that the multi-component system of Example 7-1 had a dye leakage problem during the solid-to-liquid transition. In contrast, Examples 7-13 were all single-dye systems, and no solid-liquid conversion occurred during the temperature-induced color change process (except for Example 8-1), so there was no leakage defect and the durability was higher.

[0156] Example 14 Preparation of Purple No. 1 thermochromic color paste (PTCP1): Purple No. 1 novel fluorane dye was taken and mixed in the proportion of 0.05% fluorane dye, 3% sodium polyacrylate, 18% RSZ-301A and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0157] The PTCP1 is pink at room temperature, turns purple when heated to 90 ℃, and turns pink again when cooled to 88 ℃.

[0158] Example 15 Preparation of Purple No. 1 thermochromic color paste (PTCP1): Purple No. 1 novel fluorane dye was taken and mixed in the proportion of 0.05% fluorane dye, 3% guar gum, 18% RSZ-301A and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0159] The PTCP1 is pink at room temperature, turns purple when heated to 90 ℃, and turns pink again when cooled to 88 ℃.

[0160] Example 16 Preparation of Purple No. 1 thermochromic color paste (PTCP1): Purple No. 1 novel fluorane dye was taken and mixed in the proportion of 0.05% fluorane dye, 3% sodium alginate, 18% RSZ-301A and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0161] The PTCP1 is pink at room temperature, turns purple when heated to 90 ℃, and turns pink again when cooled to 88 ℃.

[0162] Example 17 Preparation of Purple No. 1 thermochromic color paste (PTCP1): Purple No. 1 novel fluorane dye was taken and mixed in the proportion of 0.05% fluorane dye, 3% polyvinyl alcohol, 18% RSZ-301A and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0163] The PTCP1 is pink at room temperature, turns purple when heated to 90 ℃, and turns pink again when cooled to 88 ℃.

[0164] Table 11 Color-changing performance of Examples 14-17

[0165] Example 18 Preparation of Purple No. 1 thermochromic color paste (PTCP1): Purple No. 1 novel fluorane dye was taken and mixed with 0.05% fluorane dye, 3% PHT, 18% styrene-acrylate copolymer and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0166] The PTCP1 is pink at room temperature, turns purple when heated to 90 ℃, and turns pink again when cooled to 88 ℃.

[0167] Example 19 Preparation of Purple No. 1 thermochromic color paste (PTCP1): Purple No. 1 novel fluorane dye was taken and mixed in the proportion of 0.05% fluorane dye, 3% PHT, 18% waterborne polyurethane and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0168] The PTCP1 is pink at room temperature, turns purple when heated to 90 ℃, and turns pink again when cooled to 88 ℃.

[0169] Example 20 Preparation of Purple No. 1 thermochromic color paste (PTCP1): Purple No. 1 novel fluorane dye was taken and mixed with 0.05% fluorane dye, 3% PHT, 18% ethylene-vinyl acetate copolymer emulsion and 78.95% water. The mixture was magnetically stirred for 45 min to obtain a uniformly mixed PTCP1.

[0170] The PTCP1 is pink at room temperature, turns purple when heated to 90 ℃, and turns pink again when cooled to 88 ℃.

[0171] Table 12 Color-changing performance of Examples 18-20

[0172] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A spironolactam-type dimer fluorane dye, characterized in that, The structure of the spironolactam type dimer fluorane dye is shown in Formula I or Formula II below: Formula I Formula II In Formula I, X1 is selected from -NH2 and -NH(CH2). n CH3, -N[(CH2)] n One of CH3]2, 0≤n≤10; X2 is selected from -NH2 and -NH(CH2). n CH3, -N[(CH2)] n CH3]2、-(CH2) n One of CH3, 0≤n≤10; X3 is selected from -H and -(CH2). n CH3, -NH2, One of the halogens; 0≤n≤5, the halogen is a chlorine atom, a bromine atom, or an iodine atom; X4 is selected from -H and -(CH2). n CH3, -NH2, One of the halogens; 0≤n≤5, the halogen is a chlorine atom, a bromine atom, or an iodine atom; In formula I or formula II, R is selected from... , , One of them; R1 is selected from one of hydrogen, hydroxyl, C1~C6 straight / branched alkyl, C3~C6 cycloalkyl, C1~C3 alkylhydroxy, methyl-substituted phenyl, benzoyl, acyl C1~C3 alkyl, sulfonyl C1~C3 alkyl, methylbenzenesulfonyl, hydroxamic acid (-C=O-NH-OH), hydroxyphenyl, and carboxyphenyl; R2 is selected from one of hydrogen, hydroxyl, C1~C6 straight / branched alkyl, C3~C6 cycloalkyl, C1~C3 alkylhydroxy, methyl-substituted phenyl, aminoC1~C3 alkyl, hydroxyphenyl, and carboxyphenyl. R3 is selected from one of phenolic hydroxyl, carboxyl, sulfonamide, formamide, hydroxamic acid, C1~C6 alkyl hydroxyl, C3~C6 branched alkyl hydroxyl, C1~C6 alkyl carboxyl, and C3~C6 branched alkyl carboxyl; R4 is selected from one of hydrogen, phenolic hydroxyl, carboxyl, sulfonamide, formamide, hydroxamic acid, C1~C6 straight-chain alkyl, C3~C6 branched alkyl, and C3~C6 cycloalkyl. R4 may be present singly or in multiples on the benzene ring, and when multiple are present, the number shall not exceed four.

2. The spironolactam-type dimer fluorane dye according to claim 1, characterized in that, X1 is selected from one of -NH2, -NHCH3, -NHCH2CH3, -NHCH2CH2CH3, -NHCH2CH2CH2CH3, -N(CH3)2, -N(CH2CH3)2, -N[(CH2)2CH3]2, -N[(CH2)6CH3]2, -N[(CH2)7CH3]2, -N[(CH2)8CH3]2.

3. The spironolactam-type dimer fluorane dye according to claim 1, characterized in that, X1 is selected from one of -N(CH2CH3)2, -NHCH2CH3, -NH2, and -N[(CH2)7CH3]2.

4. The spironolactam-type dimer fluorane dye according to claim 1, characterized in that, X2 is one of -N(CH3)2, -N(CH2CH3)2, -N[(CH2)2CH3]2, -NHCH3, -NHCH2CH3, -NHCH2CH2CH3, -NH2, -N[(CH2)6CH3]2, -N[(CH2)7CH3]2, -N[(CH2)8CH3]2, -CH3, and -CH2CH3.

5. The spironolactam-type dimer fluorane dye according to claim 1, characterized in that, X2 is one of -N(CH2CH3)2, -NHCH2CH3, -NH2, -N[(CH2)7CH3]2, or -CH3.

6. The spironolactam-type dimer fluorane dye according to claim 1, characterized in that, X3 is selected from one of -H, -CH3, -CH2CH3, and -Cl; X4 is selected from one of -H, -CH3, -CH2CH3, and -Cl.

7. The spironolactam-type dimer fluorane dye according to claim 1, characterized in that, R is selected from , , One of them; R1 is selected from one of hydrogen, hydroxyl, C1~C3 straight / branched alkyl, C1~C3 alkylhydroxyl, methyl-substituted phenyl, benzoyl, acyl C1~C3 alkyl, sulfonyl C1~C3 alkyl, methylbenzenesulfonyl, hydroxamic acid, hydroxyphenyl, and carboxyphenyl; R2 is selected from one of hydrogen, hydroxyl, C1~C3 straight / branched alkyl, C3~C6 cycloalkyl, hydroxyC1~C3 alkyl, methyl-substituted phenyl, aminoC1~C3 alkyl, hydroxyphenyl, and carboxyphenyl. R3 is selected from one of phenolic hydroxyl, carboxyl, sulfonamide, formamide, hydroxamic acid, C1~C3 alkyl hydroxyl, C1~C3 alkyl carboxyl, and C3~C6 branched alkyl carboxyl; R4 is selected from one of hydrogen, C1~C3 straight-chain alkyl, and C3~C6 branched alkyl, and a maximum of 4 R4s can exist on the benzene ring at the same time.

8. The spironolactam-type dimer fluorane dye according to claim 1, characterized in that, R is selected from , , , , , , , , , One of them.

9. The method for preparing the spironolactam-type dimer fluorane dye according to any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: S1. Preparation of intermediates: Take the corresponding color raw material and oxalyl chloride and dissolve them in an organic solvent. Stir and react. After the reaction is complete, remove the solvent to obtain intermediates corresponding to various colors. S2. Amide condensation reaction: Dissolve the functional monomer containing hydrogen-bonded building groups in an organic solvent to obtain a functional monomer solution; dissolve the above intermediate in an organic solvent, add it dropwise to the monomer solution, and heat to react; S3. Purification to obtain the target dye: After the reaction is completed, the mixture is cooled and the solvent is removed by rotary evaporation to obtain the crude product. The crude product is then purified to obtain the spironolactam type dimer fluorescent dye.

10. The preparation method according to claim 9, characterized in that, The color raw materials in step S1 include Rhodamine B, Rhodamine 110, Rhodamine 6G, Rhodamine 101, 2-[3,6-bis(dioctylamino)-9H-oxanthracene-9-yl]benzoic acid, and 2-[6-(diethylamino)-1,3-dimethyl-9H-oxanthracene-9-yl]benzoic acid; the hydrogen-bonded building groups in step S2 include acetylurea, 4-amino-N-hydroxybenzamide, urea, hydroxyurea, p-aminophenol, p-aminobenzyl alcohol, N-methylhydrazine carboxamide, o-aminophenol, 4-aminobenzoic acid, and o-aminobenzenesulfonamide.

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