Photoelectromagnetic triple-response manganese-based multifunctional color-changing material as well as preparation method and application thereof

Abstract

The invention provides a photo-electromagnetic triple response manganese-based multifunctional color-changing material as well as a preparation method and application thereof, and belongs to the technical field of manganese-based multifunctional color-changing materials. The structural formula is as shown in formula 1. The color-changing material Mn-1 shows reversible color change under the stimulation of visible light and an electric field, and has photochromic, electrochromic, light-operated fluorescent switch and chemical color changing behaviors at the same time. In addition, Mn-1 and an illumination product Mn-1P thereof show light-adjustable magnetic performance. On the basis of the dynamic color-changing characteristic of the Mn-1, the Mn-1 can be applied to inkless erasable printing, anti-fake two-dimensional codes and ammonia sensing systems, multiple encryption and trace ammonia detection (the detection limit LOD is equal to 5.076 mu M) are achieved, the Mn-1 is further compounded with polymethyl methacrylate, and the photochromic film with stable water resistance is prepared through a solution casting method.

Description

Technical Field

[0001] The present invention belongs to the technical field of manganese-based multifunctional color-changing materials, and in particular relates to a manganese-based multifunctional color-changing material with optical, electromagnetic and triple responses, and a preparation method and application thereof. Background Art

[0002] In recent years, multifunctional color-changing materials have shown great application prospects in the fields of optical storage, security systems, sensors and biomedical imaging. This type of material can respond to a variety of external stimuli such as light, heat, electricity, pressure, and change color. It can also combine other functions such as conductivity, fluorescence, magnetism, and self-repair. Existing studies have shown that inorganic metal oxides such as WO3 and NiO are classic electrochromic materials, but their photochromic properties are not outstanding. The electrochromic performance is limited by the kinetics of ion insertion / extraction, resulting in a slow response speed; organic molecules such as violaceous and spiropyran have fast photo / electrical response, but poor thermal and chemical stability; conductive polymers have excellent cyclic stability, but lack magnetic response and have a limited optical modulation range. It is worth noting that rare earth doped materials (such as Eu 3+ / Tb 3+ Doping system) can achieve magnetochromic change, but it relies on high-temperature synthesis and the mining of rare earth elements is limited.

[0003] To overcome the above limitations, researchers proposed to build a multifunctional hybrid material system based on the principle of molecular engineering by regulating the bonding mode and interaction of inorganic and organic molecules. Among them, transition metal-based materials have become the core research object of functional material design due to their unique electronic structure. Manganese-based materials have the characteristics of multivalent states (Mn 2+ / Mn 3+ / Mn 4+ ) and 3D 5 The electronic configuration can synergistically realize the photoelectromagnetic multi-response mechanism. However, the existing manganese-based material system still has three major technical bottlenecks: (1) Insufficient light / thermal stability. Under long-term light or high temperature, manganese-based materials are prone to ion migration or oxidation, resulting in performance degradation. (2) Poor environmental stability. Manganese-based materials are easily corroded by water and oxygen, causing manganese dissolution (Mn 2+ (3) The synthesis process is complicated. The preparation of manganese-based materials often requires high-temperature solid-phase reaction or strict inert atmosphere, which increases production cost and scale difficulty.

[0004] Through the above analysis, the problems and defects of the existing technology are: there are few methods for synthesizing manganese-based multifunctional materials with high stability, high selectivity and multi-response, and it is a major challenge to further expand them to practical applications. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a manganese-based multifunctional color-changing material with triple photoelectric and electromagnetic responses, as well as its preparation method and application. The method of preparing viologen-based multi-stimulus responsive color-changing materials with the technology of the present invention is relatively simple, and the solid product exhibits different color states under different stimuli.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention first provides a manganese-based multifunctional color-changing material with a photoelectric and electromagnetic triple response, the structural formula of which is shown in Formula 1:

[0008]

[0009] In Formula 1, n≥1.

[0010] The present invention also provides a method for preparing a manganese-based multifunctional color-changing material with optical, electromagnetic and triple responses, comprising:

[0011] The solvent thermal method was used to prepare 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridyl (Bpybc), 5-methylisophthalate ion (AIP 2- ) and water molecules as ligands, Mn 2+ Ions as the metal center to prepare photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material {[Mn2(Bpybc)(AIP)2·2H2O]·4H2O} n (Mn-1).

[0012] Preferably, the method comprises the following steps:

[0013] Step 1: 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridyl dichloride (H2Bpybc·2Cl), 5-methylisophthalic acid (H2AIP), MnAc·4H2O and a mixed solvent are sealed in a reaction vessel;

[0014] Step 2: Heat the reactor at high temperature and cool it to room temperature to obtain a photoelectromagnetic triple response manganese-based multifunctional color-changing material Mn-1.

[0015] Preferably, in step 1, the molar ratio of MnAc·4H2O, H2Bpybc·2Cl, and H2AIP is 0.078:0.038:0.089.

[0016] Preferably, in step 2, the mixture is heated to 100° C. and kept at this temperature for 96 hours.

[0017] The present invention also provides the use of the above-mentioned optical, electromagnetic and triple-responsive manganese-based multifunctional color-changing material as a multi-stimulus responsive color-changing material in the field of inkless and erasable printing.

[0018] The present invention also provides the application of the above-mentioned optical, electromagnetic and triple-responsive manganese-based multifunctional color-changing material as a multi-stimulus responsive color-changing material in the field of two-dimensional code anti-counterfeiting.

[0019] The present invention also provides the application of the above-mentioned photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material as a multi-stimulus responsive color-changing material in the field of ammonia selective sensing.

[0020] The present invention also provides the use of the above-mentioned photochromic and electromagnetic triple-response manganese-based multifunctional color-changing material in the preparation of a photochromic waterproof organic film.

[0021] Preferably, the method for preparing the photochromic waterproof organic film comprises:

[0022] Step 1: Weigh PMMA into a small beaker containing DMF solution, heat and stir at 50°C for 2 h to form a viscous mixed liquid, and continue stirring to cool to room temperature;

[0023] Step 2: Weigh the photochromic and electromagnetic triple-responsive manganese-based multifunctional color-changing material Mn-1 and pour it into the above-mentioned viscous mixed liquid. Continue stirring until it is evenly dispersed, then drop it evenly on the surface of the quartz glass sheet and evaporate it for 1-2 days to obtain a photochromic waterproof organic film.

[0024] Beneficial effects of the present invention

[0025] First, under solvent thermal conditions, the present invention uses 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridine, 5-methylisophthalic acid ions and water molecules as ligands, Mn 2+ ions as the metal center to prepare the manganese-based material Mn-1. Single crystal X-ray analysis shows that AIP 2- Ions bridge the metal manganese ions to form a one-dimensional ribbon structure with infinite extension. The one-dimensional chain continues through AIP 2- The ions connect to form a two-dimensional layered structure. Adjacent layers are connected by Bpybc ligands to form a three-dimensional structure. A three-dimensional network structure of Mn-1 can be observed along the c-axis.

[0026] The manganese-based multifunctional color-changing material Mn-1 of the present invention exhibits reversible photochromic behavior under irradiation of a 300W xenon lamp, and its color changes from yellow to green (Mn-1P); when exposed to a 300W xenon lamp, Mn-1 exhibits light-adjustable magnetic properties; when an applied voltage of -1V to -0.5V is applied, Mn-1 exhibits reversible electrochromic behavior, and its color changes from colorless to light blue (Mn-1Q), and the color returns to its initial state after exposure to air or power failure for 2 minutes; when exposed to ammonia vapor, the color changes from yellow to dark brown after 3 minutes (Mn-1@NH3).

[0027] Second, the manganese-based multifunctional color-changing material prepared by the present invention is a functional color-changing material, and has been applied in the fields of inkless erasable printing, QR code anti-counterfeiting, and ammonia selective sensing.

[0028] Third, the manganese-based multifunctional color-changing material prepared by the present invention has an application CCDC number (2401340) and is a brand-new compound with an advanced, safe and environmentally friendly production process. The technical solution of the present invention is expected to fill the technical gaps in the industry at home and abroad and has good commercial value.

[0029] Fourthly, the photochromic organic film prepared by the present invention is a photochromic material with stable water resistance and can be applied in the field of inkless erasable printing. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart of a method for synthesizing a manganese-based multifunctional color-changing material with a photoelectric and electromagnetic triple response provided in Example 1 of the present invention;

[0031] Figure 2 This is an asymmetric unit diagram of a manganese-based multifunctional color-changing material with a photoelectric and electromagnetic triple response provided in Example 1 of the present invention;

[0032] Figure 3 1. The diagrams of the one-dimensional chain (a), two-dimensional layer (b), and three-dimensional (c) structures of a manganese-based multifunctional color-changing material with a photoelectromagnetic triple response provided in Example 1 of the present invention;

[0033] Figure 4 Schematic diagram of hydrogen bond diagram (a), DA distance and π…π distance (b) of a photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material provided in Example 1 of the present invention;

[0034] Figure 5 This is a diagram of the asymmetric unit of a manganese-based multifunctional color-changing material with a photoelectromagnetic triple response provided in Example 1 of the present invention after xenon lamp irradiation for 10 minutes (a) and a comparison diagram of the bond length between metals before and after irradiation (b);

[0035] Figure 6 The PXRD pattern (a), infrared spectrum (b) and TGA curve diagram (c) of a photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material before and after illumination provided in Example 1 of the present invention are shown;

[0036] Figure 7 The following are photos of a photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material before and after illumination, as well as a UV-visible spectrum (a), an EPR spectrum (b), and a color change cycle diagram (c) provided in Example 1 of the present invention;

[0037] Figure 8This is the XPS spectrum of the C1s (a), Mn 2p (b), N 1s (c), and O 1s (d) energy levels of a photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material before and after illumination provided in Example 1 of the present invention;

[0038] Figure 9 This is a color change photograph and CV curve of a photoelectric, electromagnetic, triple-responsive manganese-based multifunctional color-changing material provided in Example 1 of the present invention at a voltage of -1.2V to -0.4V;

[0039] Figure 10 The fluorescence spectrum of a manganese-based multifunctional color-changing material with a photoelectric and electromagnetic triple response as a function of illumination time provided in Example 1 of the present invention;

[0040] Figure 11 The present invention provides a photoelectromagnetic triple response manganese-based multifunctional color-changing material χ M T and 1 / χ M T spectrum (a), variable field magnetization intensity (MH) curve (b) and χ after blue light irradiation M T and 1 / χ M and T spectrum (c);

[0041] Figure 12 This is an inkless erasable printed pattern of a manganese-based multifunctional color-changing material with optical, electromagnetic and triple responses provided by Example 1 of the present invention;

[0042] Figure 13 This is an inkless and erasable printable image of a photochromic organic thin film of a manganese-based multifunctional color-changing material with a photoelectric and electromagnetic triple response provided by Example 1 of the present invention;

[0043] Figure 14 This is a QR code anti-counterfeiting pattern of a manganese-based multifunctional color-changing material with optical, electromagnetic and triple responses provided by Example 1 of the present invention;

[0044] Figure 15 IR spectrum (a) and PXRD spectrum (b) of a manganese-based multifunctional color-changing material with photoelectromagnetic triple response provided in Example 1 of the present invention before and after exposure to ammonia vapor;

[0045] Figure 16 These are photos before and after exposure to ammonia vapor, as well as UV-visible spectra (a), EPR spectra (b), and trace ammonia detection fitting curve diagram (c) of a photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] The present invention first provides a manganese-based multifunctional color-changing material with a photoelectromagnetic triple response, which is {[Mn2(Bpybc)(AIP)2·2H2O]·4H2O} n (Mn-1), the manganese-based multifunctional color-changing material is a compound with a three-dimensional structure, and the structural formula is shown in Formula 1:

[0048]

[0049] In Formula 1, n≥1.

[0050] The present invention also provides a method for preparing a manganese-based multifunctional color-changing material with optical, electromagnetic and triple responses, comprising:

[0051] With 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridine, 5-methylisophthalate ion and water molecule as ligand, Mn 2+ The ion is used as the metal center to prepare the manganese-based multifunctional color-changing material Mn-1.

[0052] The method preferably comprises the following steps:

[0053] Step 1: 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridinium chloride (H2Bpybc·2Cl), 5-methylisophthalic acid (H2AIP), MnAc·4H2O, and a solvent are sealed in a reaction kettle; the solvent is preferably a mixture of DMA, water, and ethanol in a volume ratio of 2:3:1, and the molar ratio of MnAc·4H2O, H2Bpybc·2Cl, and H2AIP is preferably 0.078:0.038:0.089.

[0054] Step 2: The reactor is heated to a high temperature, preferably to 100°C, kept at a constant temperature for 96 hours, and heated at 4°C / h -1 The material was cooled to room temperature at a rate of 100 nm to obtain a manganese-based multifunctional color-changing material Mn-1 with triple photo-electromagnetic responses.

[0055] The present invention also provides the use of the above-mentioned manganese-based multifunctional color-changing material Mn-1 as a multi-stimulus responsive color-changing material.

[0056] The manganese-based multifunctional color-changing material Mn-1 of the present invention exhibits reversible photochromic behavior from yellow to dark green in the solid state under irradiation of a 300W xenon lamp, and there is no obvious color reduction after 5 cycles.

[0057] The manganese-based multifunctional color-changing material Mn-1 described in the present invention was tested using cyclic voltammetry (CV) on a CHI 660E electrochemical workstation using a conventional three-electrode system: in a 0.05M tetrabutylammonium hexafluorophosphate (TBAPF6) / DMF solution, with an indium tin oxide glass (ITO) / glassy carbon (GC) electrode as the working electrode, a platinum sheet as the counter electrode, and a saturated Ag / AgCl electrode as the reference electrode. A redox peak appeared in the voltage range of -1.2V to -0.4V. As the voltage increased, the compound's color gradually deepened, eventually becoming visible to the naked eye (from colorless to light blue). Disconnecting the power supply or exposing the sample to air for a period of time restored the color to its original state. The compound exhibited reversible electrochromic behavior.

[0058] The manganese-based multifunctional color-changing material Mn-1 of the present invention exhibits reversible light-controlled fluorescence behavior in the solid state under irradiation of a 300W xenon lamp.

[0059] The present invention also provides the use of the above-mentioned optical, electromagnetic and triple-responsive manganese-based multifunctional color-changing material as a multi-stimulus responsive color-changing material in the field of inkless and erasable printing.

[0060] The present invention also provides the application of the above-mentioned optical, electromagnetic and triple-responsive manganese-based multifunctional color-changing material as a multi-stimulus responsive color-changing material in the field of two-dimensional code anti-counterfeiting.

[0061] The present invention also provides the application of the above-mentioned photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material as a multi-stimulus responsive color-changing material in the field of ammonia selective sensing.

[0062] The present invention also provides the use of the above-mentioned manganese-based multifunctional color-changing material Mn-1 in the preparation of a photochromic waterproof organic film.

[0063] The method for preparing a photochromic waterproof organic film comprises:

[0064] Step 1: Weigh PMMA into a small beaker containing DMF solution, heat and stir at 50°C for 2 hours to form a viscous mixed liquid, and continue stirring to cool to room temperature; the PMMA mass g:DMF volume mL is 1.5:10;

[0065] Step 2: Weigh 0.15g of finely powdered manganese-based material Mn-1 into the viscous liquid mixture and continue stirring, preferably for 30 minutes, until the powder is evenly dispersed. The mixture is then evenly dropped onto the surface of a quartz glass sheet and allowed to evaporate for 1-2 days to form a durable, waterproof organic film. The mass ratio of PMMA to Mn-1 is preferably 1.5:0.15.

[0066] The present invention also provides application of the photochromic waterproof organic film in the field of inkless erasable printing.

[0067] The present invention is further described in detail below with reference to specific examples, in which the raw materials involved are all commercially available.

[0068] Example 1

[0069] like Figure 1 As shown, a method for synthesizing a manganese-based multifunctional color-changing material with a triple photo-electromagnetic response comprises the following steps:

[0070] S101, MnAc·4H2O (0.0190 g, 0.078 mmol), H2Bpybc·2Cl (0.0190 g, 0.038 mmol), H2AIP (0.0210 g, 0.089 mmol), 3 mL of distilled water, 2 mL of DMA, and 1 mL of ethanol were sealed in a polytetrafluoroethylene reactor;

[0071] S102, heat the reactor to 100℃ and keep the temperature constant for 96h; and -1 The material was cooled to room temperature at a rate of 100 nm to obtain a manganese-based multifunctional color-changing material (Mn-1) with triple photoelectromagnetic and electrical responses.

[0072] The performance of Mn-1 prepared in Example 1 was tested as follows:

[0073] 1. Experimental instruments

[0074] Elemental analysis (C, H, N) was performed on a PerkinElmer 2400 CHN elemental analyzer. Fourier transform infrared absorption spectroscopy was performed on a PerkinElmer Frontier TM Measured on an infrared spectrometer, ranging from 4000 to 450 cm -1 , using pure potassium bromide pellet method. Using Cu Kα radiation Powder X-ray diffraction (PXRD) patterns were recorded on a Rigaku Ultima IV-185 diffractometer within the 2θ range of 5° to 60°. PXRD models were simulated using single-crystal X-ray diffraction data in Mercury v1.4.2. UV-visible diffuse reflectance spectra of the solid powders at room temperature were measured using a Shimadzu UV-2600 UV-visible spectrophotometer. Electron spin resonance (ESR) spectra were recorded on a JeolJES FA200 paramagnetic resonance electron spectrometer. Thermogravimetric analysis was performed on a Tarsus TG 209F3 thermogravimetric analyzer at a heating rate of 20°C / min over a temperature range of 35°C to 800°C. A CHI 660E electrochemical workstation was used, available from Shanghai Chenhua Instrument Co., Ltd. Magnetic spectra were obtained using an MPMS (SQUID) XL-7 from Quantum Design, USA. All chemicals used in the experiments were of reagent grade.

[0075] C obtained in Example 1 44 H 44 Mn2N2O 18 Elemental analysis (%): C, 52.87; H, 4.41; N, 2.80%. Found: C, 52.79; H, 4.38; N, 2.75%.

[0076] 2. Crystal structure test

[0077] The single crystal X-ray diffraction data of compound Mn-1 were obtained at 296 K using Cu Kα radiation monochromatized on graphite. Diffractometer data were collected using a Bruker SMART APEX CCD diffractometer in ω-scan mode, with all data corrected for Lorentz polarization effects. The crystal structure was solved using a direct method using the SHELXS-2014 and OLEX2 structure-elucidation packages. Compound Mn-1 has the CCDC number 2401340 and crystallizes in the monoclinic P21 / c space group with the unit cell parameters: α=90°, β=93.3260(10)°, γ=90°, V=4280.19(9), Z=4, D=1.550g·cm -3 , μ=5.514mm -1 , F(000)=2064.0. The bond length, bond angle and hydrogen bond table of compound Mn-1 are shown in Table 1-3.

[0078] The single crystal X-ray diffraction data of the illuminated compound Mn-1P were obtained at 298K using Cu Kα radiation monochromatized with graphite. Diffractometer data were collected using a Bruker SMART APEX CCD diffractometer in ω-scan mode, with all data corrected for Lorentz polarization effects. The crystal structure was solved using a direct method using the SHELXS-2014 and OLEX2 structure-solving software packages. The photoproduct of compound Mn-1, Mn-1P, has the CCDC number 2412336 and crystallizes in the monoclinic P21 / c space group with the unit cell parameters: α=90°, β=93.2330(10)°, γ=90°, V=4283.98(12), Z=4, D=1.548g·cm -3 , μ=5.509mm -1 , F(000)=2064.0. The bond lengths and bond angles of the compounds are shown in Table 4-5.

[0079] Table 1 Bond length of compound Mn-1

[0080]

[0081] Symmetric operation code: 1 -X,1 / 2+Y,1 / 2-Z; 2 1-X,-1 / 2+Y,1 / 2-Z.

[0082] Table 2 Bond angle table of compound Mn-1

[0083]

[0084]

[0085] Symmetric operation code: 1 -X,1 / 2+Y,1 / 2-Z; 2 1-X,-1 / 2+Y,1 / 2-Z.

[0086] Table 3 Hydrogen bond table of compound Mn-1

[0087]

[0088] Symmetric operation code: 1 +X,1 / 2-Y,1 / 2+Z; 2 +X,1 / 2-Y,-1 / 2+Z.

[0089] Table 4 Bond lengths of compounds Mn-1P

[0090]

[0091]

[0092] Symmetric operation code: 1-X,1 / 2+Y,1 / 2-Z; 2 1-X,-1 / 2+Y,1 / 2-Z.

[0093] Table 5 Bond angle table of compound Mn-1P

[0094]

[0095] Symmetric operation code: 1 -X,-1 / 2+Y,1 / 2-Z; 2 1-X,1 / 2+Y,1 / 2-Z.

[0096] Single crystal X-ray diffraction analysis showed that compound Mn-1 belongs to the monoclinic system P21 / c space group. The asymmetric unit of Mn-1 consists of two Mn 2+ ion, two halves of the deprotonated Bpybc ligand, and two AIP 2- Anion, two coordinated water molecules and four free water molecules. 2+ The ions all show a hexacoordinated octahedral geometry. The Mn1 ion is associated with the AIP from three symmetry related 2- The four oxygen atoms of the anion (O1 2 、O2 2 , O4, O6) and two oxygen atoms from two water molecules (O11 and O14), and the Mn2 ion is coordinated with two oxygen atoms from two Bpybc molecules (O9 and O12) and three symmetry-related AIP molecules. 2- The four oxygen atoms of the anion (O3, O5, O7 1 、O8 1 ) coordination( Figure 2 ). The range of Mn-O bonds is from arrive (See Table 1). The bond angle of O-Mn-O ranges from 56.56 (6)° to 175.55 (7)° (See Table 2). Among them, Mn1 and Mn2 are connected by two symmetry-related carboxyl oxygen atoms to form a dinuclear cluster. 2+ Ions by AIP 2- Anionic COO - The groups are connected to form a one-dimensional chain structure ( Figure 3 a). One-dimensional band continues through AIP 2- Anions bridge to form a two-dimensional layer ( Figure 3 b). Adjacent layers are connected by Bpybc ligands to form a three-dimensional structure, and the three-dimensional network structure of Mn-1 can be observed along the c-axis ( Figure 3 c). In addition, there is a hydrogen bond between the Bpybc ligand and the coordinated water molecules and lattice water molecules. The formation of OH…O further improves the stability of the crystal structure (Table 3, Figure 4 a).

[0097] It is worth noting that in compound Mn-1, the center-to-center distance between the pyridine ring of the Bpybc ligand and the adjacent aromatic ring is There is a weak π…π interaction, which provides a reasonable path for electron transfer. In addition, from the pyridinic N atom of the Bpybc ligand to AIP 2- The closest distance between the carboxyl O atoms of the anion is is a typical electron donor and acceptor group. This is consistent with the previously reported electron transfer distance range, which also provides a reasonable path for electron transfer ( Figure 4 b).

[0098] The structure of the compound Mn-1P after light irradiation ( Figure 5 a) Compared with the structure of compound Mn-1, metal Mn 2+ The distance between ions is determined by the Get bigger ( Figure 5 b).

[0099] 3. PXRD spectrum, IR spectrum and TGA analysis of compound Mn-1

[0100] The PXRD patterns of compound Mn-1 before and after irradiation were measured. The PXRD patterns simulated based on the single crystal structure are basically consistent with the experimental patterns, indicating that the synthesized sample has a high phase purity. The PXRD pattern after irradiation is basically the same as that before irradiation, indicating that the cause of photochromism is not light-induced isomerization or photolysis ( Figure 6 a). It is speculated that this behavior may be the result of the generation of viologen free radicals.

[0101] The infrared spectrum of compound Mn-1 was analyzed and the -1 The peak at 1634 cm corresponds to the stretching vibration of the hydroxyl group (-OH) in the water molecule, indicating the presence of lattice water molecules in the compound. -1 The absorption peak at 1156cm is the characteristic vibration peak of carboxyl group. -1 、1427cm -1 The vibration peaks of aromatic ring CN and CC are ( Figure 6 b) Infrared spectroscopy showed that the position of the infrared characteristic peak of compound Mn-1 did not change before and after xenon lamp irradiation, indicating that the color change did not cause a change in the functional groups in the compound, further proving that the color change of compound Mn-1 was not caused by photolysis and isomerization.

[0102] In order to study its thermal stability, compound Mn-1 was subjected to thermogravimetric tests at room temperature to 800 °C in a nitrogen atmosphere ( Figure 6 c) Compound Mn-1 loses 10.76% of its weight at 35-200°C, likely due to the loss of free and coordinated water molecules (calculated value: 10.81%). At 272°C, Compound Mn-1 begins to decompose and the skeleton collapses.

[0103] The color change performance of the compound Mn-1 prepared in Example 1 was tested as follows:

[0104] 1. Photochromic performance

[0105] Since compound Mn-1 contains a viologen ligand, it may exhibit photochromic properties. Therefore, Mn-1 was photostimulated. As expected, a color change occurred under 300W xenon lamp irradiation. Compound Mn-1 changed from yellow to dark green after 5 minutes of xenon lamp irradiation, and the color gradually deepened with the extension of irradiation time ( Figure 7 a). The photochromic behavior of compound Mn-1 was characterized using UV-Vis diffuse reflectance spectroscopy (UV-Vis) and electron spin resonance (EPR). Under UV irradiation, Mn-1 exhibited weak absorption bands centered at 403 nm and 612 nm, similar to those of reported viologen materials, and their intensities gradually increased with the duration of UV irradiation ( Figure 7 a). During the coloring process, the UV-Vis spectra of Mn-1 were significantly different, but neither IR nor PXRD showed significant changes, indicating no significant structural transformation or photolysis before and after irradiation. As confirmed by EPR measurements, this photoresponse phenomenon is caused by charge transfer. The EPR spectrum shows a strong singlet signal with g = 2.00345 after coloring, confirming that the light-induced color change is likely caused by the generation of viologen free radicals by the reduction of the photostimulated ligand ( Figure 7 b) At the same time, the photocycle stability of compound Mn-1 was studied and a photocycle test experiment was performed on it. Figure 7 As shown in Figure c, after five cycles of irradiation and fading, its photochromic properties remain stable. Therefore, this reversible photochromic behavior can be repeated at least five times. The Mn-1P after color change is very stable, and the charge separation state lasts for a long time. After being placed in the dark for a week, the EPR signal gradually disappears as the sample fades, indicating that the color change process is extremely reversible.

[0106] To further elucidate the mechanism of photoinduced electron transfer (ET), XPS experiments were performed. The detection of energy level spectra showed that the C 1s and Mn 2p spectra did not change significantly before and after irradiation ( Figure 8 a, 8b). However, the O 1s and N 1s spectra changed significantly. Specifically, the N 1s peak shifted to a lower binding energy position (402.27 eV → 402.17 eV), which indicates that the N atom has gained an electron ( Figure 8 c). In contrast, the O 1s peak shifts to a higher binding energy (531.22 eV → 531.32 eV), indicating that the O atom has lost an electron ( Figure 8 d). Therefore, it can be inferred that the photochromic behavior of compound Mn-1 is due to the electron transfer from AIP 2- The O atom of the carboxylic acid group is transferred to the N atom of the Bpybc ligand, leading to the formation of viologen radical.

[0107] 2. Electrochromic performance

[0108] The electrochromic properties of compound Mn-1 were studied by cyclic voltammetry (CV) with indium tin oxide (ITO) glass as the working electrode, Pt thin film as the counter electrode, and Ag / AgCl electrode as the reference electrode. A pair of redox peaks appeared in the CV curve in the voltage range of -1.2 to -0.4 V, indicating that it has single electron transfer behavior, confirming that Mn-1 has electrochemical activity. At the same time, Mn-1 has reversible electrochromic properties. In the above voltage range, the electrolyte solution of Mn-1 changes from colorless to light blue and returns to its initial state after power failure or exposure to air for 2 minutes ( Figure 9 ).

[0109] 3. Light-controlled fluorescence performance

[0110] Since Mn-1 changes color under the stimulation of visible light, its light-controlled fluorescence properties were further explored. A 300W xenon lamp was used to irradiate Mn-1 for different time periods at room temperature and then perform fluorescence tests. When the excitation wavelength was 329nm, a strong emission peak was observed at 671.6nm ( Figure 10 The results showed that compound Mn-1 exhibits light-controlled fluorescence, with the fluorescence intensity gradually quenching with increasing irradiation time. Notably, the photochromic behavior and light-modulated luminescence of Mn-1 can occur simultaneously. Therefore, this compound is classified as a fluorescent-photochromic binary system.

[0111] 4. Magnetic properties

[0112] Normally, the paramagnetic Mn 2+ Compounds constructed by ions, carboxylic acid ligands and nitrogen-containing ligands often have magnetic coupling properties. 2+ The magnetic performance of ionic compounds was studied by measuring the magnetic susceptibility of compounds Mn-1 and Mn-1P at a temperature of 2-300K and an external magnetic field strength of 1000Oe. M T value is 8.90cm 3 ·K·mol -1, than two uncoupled high-spin Mn 2+ The theoretical value of ions is 8.75 cm 3 ·K·mol -1 Slightly higher (4.375cm 3 ·K·mol -1 , S = 5 / 2, g = 2.00). The x value of compound Mn-1 M The T value decreases gradually with decreasing temperature from 300 to 50 K, drops sharply after 50 K, and reaches the lowest value of 1.39 cm at 2 K. 3 ·K·mol -1 ( Figure 11 a). At the same time, the 1 / χ M The linear fit of T yields the Curie constant (C) = 9.12 cm 3 ·K·mol -1 , Weiss constant (θ) = -132.03K, and the negative θ value indicates the existence of antiferromagnetic interaction between metal ions. In addition, the magnetization intensity curve (MH) of compound Mn-1 was tested at a temperature of 2K. The magnetization curve did not reach saturation at a magnetic field of 70kOe ( Figure 11 b).

[0113] The χ value of the compound Mn-1P obtained after irradiation (300W xenon lamp, 5min) at 300K is M T value is 8.57cm 3 ·K·mol -1 , slightly lower than Mn-1's 8.90cm 3 ·K·mol -1 , than two uncoupled high-spin Mn 2+ The theoretical value of ions is 8.75 cm 3 ·K·mol -1 To be low (4.375cm 3 ·K·mol -1 , S = 5 / 2, g = 2.00). This difference may be due to the magnetic contribution of a small amount of free radicals generated under natural light. M The T value drops sharply at 40K and reaches the lowest value of 1.46cm at 2K. 3 ·K·mol -1 ( Figure 11 c) At the same time, the 1 / χ M The linear fit of T yields the Curie constant (C) = 8.81 cm 3 ·K·mol -1 , Weiss constant (θ) = -104.87K.

[0114] Before and after illumination, it was found that θ was negative, indicating that in compounds Mn-1 and Mn-1P, adjacent Mn 2+ There is an antiferromagnetic interaction between ions. Comparing the absolute values ​​of θ before and after illumination, it is found that Mn-1 (-132.03K) is larger than Mn-1P (-131.25K). This may be due to the fact that after the xenon lamp is irradiated, the distance between the metal (Mn) and the metal (Mn) becomes larger. This also further confirms that increasing the distance between the metals by adjusting the illumination can make Mn 2+ The antiferromagnetic interaction between ions is weakened.

[0115] Application Example 1

[0116] The optical, electromagnetic and triple-responsive manganese-based multifunctional color-changing material provided in Example 1 of the present invention is used as a multi-stimulus responsive color-changing material in the field of inkless erasable printing. The specific application method is as follows:

[0117] Finely ground compound Mn-1 crystal powder was soaked in an ethanol solution to form a suspension, which was then ultrasonicated for 30 minutes. The ethanol suspension containing Mn-1 was placed on filter paper with a dropper, then dried. The drop casting was repeated until the powder sample was evenly dispersed on the filter paper surface. A butterfly-shaped template was placed on the filter paper and a dark blue butterfly pattern ( Figure 12 The color difference between the butterfly and the background was sufficient for visual observation, and the printed pattern returned to its original state after a week in darkness. Furthermore, the printed pattern could be reprinted at least three times, sufficient for some daily needs. Therefore, Mn-1 is a viable inkless, erasable printing medium, offering an environmentally friendly and sustainable alternative to traditional printing methods.

[0118] Application Example 2

[0119] The photochromic organic film provided in Example 1 of the present invention is used as an inkless erasable printing medium, and the specific application method is as follows:

[0120] Weigh 1.5g of PMMA and dissolve it in 10mL of DMF solution by heating. Stir to form a viscous liquid mixture. Cool the mixture and add 0.15g of Mn-1 powder. Continue stirring until the mixture is evenly dispersed. Then, drop the mixture evenly onto the surface of a quartz glass sheet and allow it to evaporate for 1-2 days to obtain a transparent film.

[0121] Controlling the UV light exposure through the covering template can obtain clearly visible information. It is worth noting that it has a longer service life, good toughness, and is both waterproof and water-resistant. After it changes color, it will completely fade after being placed in a dark environment for 3 days, and there is no obvious color decay after 5 color change cycles. Not only that, even if it is placed in an environment with a humidity of up to 95% for 12 hours, its performance will not decay ( Figure 13 ).

[0122] Application Example 3

[0123] The optical, electromagnetic and triple-responsive manganese-based multifunctional color-changing material provided in Example 1 of the present invention is used as a multi-stimulus responsive color-changing material in the field of QR code anti-counterfeiting. The specific application method is as follows:

[0124] like Figure 14 As shown, the official website data of "Mudanjiang Normal University" was encoded and stored as a QR code. The black dots selected to store and display the QR code information were replaced with pale yellow sites containing compound Mn-1, thus completing the preparation of a new color-changing QR code. When initially scanned with a mobile phone, the QR code was in an encrypted state and no information could be read. When the selected colorless blank dots turned dark blue under light stimulation, the information in the QR code could be quickly read out by scanning it again with a mobile phone. In addition, for the QR code after light treatment, the colored state can be placed in a dark environment and gradually faded to hide the information.

[0125] Application Example 4

[0126] The application of the manganese-based multifunctional color-changing material with triple photo-electromagnetic responses provided in Example 1 of the present invention as a multi-stimulus responsive color-changing material in the field of ammonia selective sensing is as follows:

[0127] Mn-1 was placed on a fiber filter paper above a beaker containing ammonia water and left to stand for 3 minutes. It was found that the color of compound Mn-1 changed from yellow to dark brown under the action of NH3 ( Figure 16 a). It is worth noting that the IR and PXRD of the comparative compounds Mn-1 and Mn-1@NH3 confirm that there is no obvious structural transformation of the compounds before and after ammonia fumigation ( Figure 15 a, 15b). UV-Vis spectroscopy revealed a significant enhancement of the absorption peak at 516 nm, indicating that intermolecular electrons were transferred from ammonia to the Bpybc ligand ( Figure 16 a). The generation of free radicals was further confirmed by EPR (g = 2.00025) spectroscopy ( Figure 16 b). Using the Stern-Volmer (SV) equation, I0 / I=1+KSV[μM], we determined that the KSV value of ammonia is 7.65×10 2 μM-1 ( Figure 16 c). There is a strong linear relationship between I0 / I-1 and the concentration of 10μM to 100μM, and the correlation coefficient (R 2 ) was 0.9954. Using the formula LOD = 3σ / k (k, slope; σ, standard), the detection limit of ammonia was calculated to be 5.076 μM. Based on these results, it was shown that compound Mn-1 can be used as a medium for selective sensing of ammonia.

[0128] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A manganese-based multifunctional color-changing material with a triple photoelectric and electromagnetic response, characterized in that: The structural formula is shown in Formula 1: In Formula 1, n≥1.

2. The method for preparing a manganese-based multifunctional color-changing material with a photoelectric and electromagnetic triple response according to claim 1, characterized in that: include: By solvothermal method, Mn 2+ Ions as the metal center to prepare photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material {[Mn2(Bpybc)(AIP)2·2H2O]·4H2O} n .

3. The method for preparing a manganese-based multifunctional color-changing material with a photoelectric and electromagnetic triple response according to claim 2, characterized in that: The method comprises the following steps: Step 1: 1,1'-bis(4-carboxybenzyl)-4,4'-bipyridyl dichloride H2Bpybc·2Cl, 5-methylisophthalic acid H2AIP, MnAc·4H2O and a mixed solvent are sealed in a reaction vessel; Step 2: Heat the reactor at high temperature and cool it to room temperature to obtain a photoelectromagnetic triple response manganese-based multifunctional color-changing material Mn-1.

4. The method for preparing a manganese-based multifunctional color-changing material with optical, electromagnetic and triple responses according to claim 3, characterized in that: In the step 1, the molar ratio of MnAc·4H2O, H2Bpybc·2Cl, and H2AIP is 0.078:0.038:0.

089.

5. The method for preparing a manganese-based multifunctional color-changing material with optical, electromagnetic and triple responses according to claim 3, characterized in that: In the step 2, the mixture is heated to 100° C. and kept at this temperature for 96 hours.

6. Application of the photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material according to claim 1 as a multi-stimulus responsive color-changing material in the field of inkless erasable printing.

7. Application of the photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material according to claim 1 as a multi-stimulus responsive color-changing material in the field of two-dimensional code anti-counterfeiting.

8. Application of the photoelectromagnetic triple-responsive manganese-based multifunctional color-changing material according to claim 1 as a multi-stimulus responsive color-changing material in the field of ammonia selective sensing.

9. Use of the photochromic, electromagnetic triple-response manganese-based multifunctional color-changing material according to claim 1 in the preparation of a photochromic waterproof organic film.

10. The use according to claim 9, characterized in that The method for preparing a photochromic waterproof organic film comprises: Step 1: Weigh PMMA into a small beaker containing DMF solution, heat and stir at 50°C for 2 h to form a viscous mixed liquid, and continue stirring to cool to room temperature; Step 2: Weigh the photochromic and electromagnetic triple-responsive manganese-based multifunctional color-changing material Mn-1 and pour it into the above-mentioned viscous mixed liquid. Continue stirring until it is evenly dispersed, then drop it evenly on the surface of the quartz glass sheet and evaporate it for 1-2 days to obtain a photochromic waterproof organic film.

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