Proton conductive cobalt-based single-molecular magnet bifunctional material and preparation method and application thereof

Abstract

The invention discloses a proton conductive cobalt-based monomolecular magnet bifunctional material as well as a preparation method and application thereof, and belongs to the technical field of organic magnetic materials. The method comprises the following steps: adding a chemical reaction amount of cobalt nitrate hexahydrate and 5-isoquinoline sulfonic acid into water, and mixing to obtain a reaction solution; and reacting the reaction liquid at a certain temperature, and cooling, recovering and purifying the product to obtain the proton conductive cobalt-based monomolecular magnet bifunctional material. According to the invention, organic sulfonic acid and coordinated water molecules are utilized to construct a new approach of an efficient proton conductor, and the method has the characteristics of simplicity and convenience in synthesis, low cost and suitability for large-scale production. The prepared proton conductive cobalt-based monomolecular magnet bifunctional material has a unique crystal structure, a proton conductive behavior and a monomolecular magnet behavior, realizes low-temperature and room-temperature bifunctionality, expands the application field of the proton conductive material, and has a good application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of organic magnetic materials, and in particular to a proton conductive cobalt-based single-molecule magnet dual-function material and a preparation method and application thereof. Background Art

[0002] Proton conductive materials are a type of electrolyte with hydrogen ions or proton carriers as carriers, also known as hydrogen ion conductors. Compared with other ions, protons have the characteristics of small radius, light weight and high mobility, which gives proton conductive materials high conductivity. In addition, proton conductors mainly refer to solid electrolyte materials with proton conductivity, which show unique conductive advantages and application characteristics in practical applications. The application of proton conductive materials is very wide and has great development potential. For example, they can be used in hydrogen and oxygen fuel cells, using proton conductive materials for efficient proton conduction and electrochemical reactions. In addition, due to the superior conductivity of proton conductors, this new conductive electrolyte can also be used in fields such as water electrolysis for hydrogen production, hydrogen sensors, and organic electrochemical hydrogenation.

[0003] A single-molecule magnet is a special metal compound whose characteristic is that a single molecule or atom can maintain the spin torque - the magnetization direction. Under specific low-temperature conditions, this material can switch between the two states of "0" (such as the molecule is oriented in the direction of the magnetic field) and "1" (the molecule is oriented in the direction of the antimagnetic field) like a tiny magnet, so it can be used as a quantum bit. However, a single-molecule magnet is not a magnet in the traditional sense, because its bistable behavior does not come from magnetic order. Each molecule behaves as a separate magnetic moment center, similar to the spin center in a paramagnet, and is a superparamagnet with highly uniform size. In addition, each molecule in a single-molecule magnet can be used as a memory unit, so it has the potential to be used in high-density magnetic storage.

[0004] In recent years, the design and development of new proton-conductive single-molecule magnets have attracted the attention of researchers. Some proton-conductive single-molecule magnets based on rare earths have been reported. For example, Shin-ichi Ohkoshi et al. from the University of Tokyo in Japan reported in the literature (Proton Conductive Luminescent Thermometer Based on Near Infrared Emissive {YbCo 2 A unique multifunctional molecular-based material with a three-dimensional structure (H 5 O 2 ) 2 (H)[Yb Ⅲ(hmpa) 4 ][Co Ⅲ (CN) 6 ] 2 0.2H 2 O (HMPA: hexamethylphosphoramide), composed of {YbCo 2} 3- Anions and acidic H 5 O 2+ and H + The ions are non-covalently bonded. Ⅲ The complex exhibits slow magnetic relaxation below 6 K and has a [Co(CN) 6 ] 3- Ion-sensitized NIR 4f centers emit light. The microporous framework built on these emitting magnetic molecules shows high proton conductivity, with the conductivity σ of the proton hopping mechanism reaching 1.7×10 -4 S cm -1 , which is classified as a superionic conductor at 97% relative humidity. This work demonstrates an unprecedented combination of magnetic, optical, and electronic functions in one stage as a proton-conducting near infrared (NIR) emission thermometer based on a single-molecule magnet. However, the material uses cyanide and rare earth ions. Cyanide is a highly toxic controlled compound that is difficult to purchase, rare earth metals are expensive, and the material preparation method is complicated, making it unsuitable for industrial production. Therefore, the reported material is difficult to synthesize and apply on a large scale.

[0005] The literature (A “Molecular Water Pipe”: A Giant Tubular Cluster {Dy72}Exhibits Fast Proton Transport and Slow Magnetic Relaxation. Adv. Mater.2016,28, 10772–10779.) provides a lanthanide cluster PCC-72, in which 72 Dy(III) ions are assembled into a tubular structure. PCC-72 exhibits superionic proton conductivity under both ambient (relative humidity RH<75%) and high temperature (T>90 ℃, RH=95%) conditions, and slow magnetic relaxation is observed. A two-dimensional octacyanoniobate manganese-based magnet Mn was prepared in the literature (Super-Ionic Conductive Magnet Based on aCyano-Bridged Mn−Nb Bimetal Assembly Cryst. Growth Des.2013, 13, 4673−4677.). Ⅱ3 [Nb Ⅳ (CN) 8 ] 2 (4-aminopyridine) 10 (4-aminopyridinium) 2 12H 2 O. The compound exhibits a spin-flip transition with a critical magnetic field value of about 200 Oe. In addition, impedance measurements show that the compound is a superionic conductor with a conductivity σ of 4.6×10 -4 S cm -1 However, existing proton conductive single-molecule magnets generally have complex preparation processes and are difficult to mass-produce. Their high cost (metal salts and organic ligands) has brought huge financial pressure to industrial production. During use, existing materials have single functionality and low proton conductivity at room temperature, which has brought difficulties to their practical application.

[0006] In summary, in order to solve the problem that the performance and preparation of existing materials are relatively complex and expensive, which is not conducive to the development of multifunctional molecular materials that can be applied in practice, the development of a proton-conducting single-molecule magnet that is low in cost, easy to synthesize, and has superior performance is of great significance for expanding the application of proton-conducting materials. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, in a first aspect of the present invention, a method for preparing a proton conductive cobalt-based single-molecule magnet dual-functional material with simple synthesis and low cost is provided, comprising the following steps: A chemical reaction amount of cobalt nitrate hexahydrate and 5-isoquinolinesulfonic acid (5-Isoquinolinesulfonicacid, IQS) is added to water and mixed to obtain a reaction solution; the reaction solution is reacted at a certain temperature, and after completion, it is cooled, and the product is recovered and purified to obtain a proton conductive cobalt-based single-molecule magnet dual-functional material.

[0008] Preferably, the molar ratio of the cobalt nitrate hexahydrate to 5-isoquinolinesulfonic acid is 1:1.9-2.1.

[0009] Theoretically, based on the target configuration of the proton conductive cobalt-based single-molecule magnet bifunctional material, cobalt nitrate hexahydrate and 5-isoquinolinesulfonic acid will react in a molar ratio of 1:2. In the actual synthesis process, due to the influence of factors such as reaction kinetics, the ratio parameter value fluctuates within a range of ±5%, and the purpose of synthesis can be achieved. Those skilled in the art can appropriately use a slightly excessive ratio to react so that it proceeds in the direction of generating the target product. Water is used as a solvent in the synthesis to promote the dispersion of the reactants and create a suitable reaction environment. Those skilled in the art can appropriately adjust the amount of water according to the actual amount of reactants added.

[0010] Preferably, the reaction temperature is 90-110° C. and the reaction time is 12-36 h.

[0011] Preferably, the cooling is performed at a cooling rate of 9-11°C / h to room temperature.

[0012] The appropriate reaction temperature range is conducive to the efficient reaction, and the target product can be prepared with a good yield under the temperature and time conditions specified in the present invention. The cooling rate is also preferably controlled within a preferred range. Due to the unique properties of the proton conductive cobalt-based single-molecule magnet bifunctional material, this helps to reduce lattice defects, improve the integrity and stability of the crystal, and significantly improve the comprehensive performance of the material.

[0013] In the second aspect of the present invention, a proton conductive cobalt-based single-molecule magnet dual-functional material with excellent comprehensive performance is provided, which is prepared by the preparation method of the first aspect of the present invention.

[0014] Preferably, the proton conductive cobalt-based single-molecule magnet bifunctional material is a neutral mononuclear complex; the mononuclear complex is composed of mononuclear cobalt units connected by O—H···O hydrogen bonds to form a three-dimensional hydrogen-bonded supramolecular network.

[0015] Further preferably, in the mononuclear cobalt unit, the average metal-ligand bond length is 2.216 Å.

[0016] Preferably, the crystal structure of the proton conductive cobalt-based single-molecule magnet dual-function material is a monoclinic system. P 2 1 / c space group; its unit cell parameters are as follows: a=8.5107(5) Å, b=15.0340(9) Å, c=7.7245(5) Å, α=90°, β=113.162(2)°, γ=90°, V=908.68(10) Å 3 , Z=2.

[0017] Preferably, at 40°C and 97% relative humidity, the proton conductivity of the proton conductive cobalt-based single-molecule magnet dual-functional material is 2.1×10-5 S cm -1 .

[0018] In the third aspect of the present invention, an application of the proton conductive cobalt-based single-molecule magnet bifunctional material of the second aspect of the present invention is provided, specifically, it is used as a proton conductive material for preparing solid-state batteries, energy storage materials, and quantum storage devices.

[0019] Based on the above technical solutions, the design concept and principle of the present invention are as follows: The present invention focuses on the design and development of proton conductive single-molecule magnets, and is committed to using low-cost cobalt ions as magnetic units and directly purchased organic sulfonic acid molecules as building ligands, designing and synthesizing new hydrogen bond bridged framework structures, and realizing the magnetic-electric dual functionality of the material.

[0020] The method of the present invention utilizes organic sulfonic acid and coordinated water molecules to construct a new approach for efficient proton conductors, and obtains cobalt complexes with proton conductive behavior and single-molecule magnetic behavior in a simple, inexpensive, and mass-preparable manner. The proton conductive cobalt-based single-molecule magnet dual-functional material is highly unique. Among them, cobalt salt and IQS form a mononuclear complex, and the complex has two coordinated waters in the axial coordination environment, and the sulfonic acid oxygens of the two organic sulfonic acids have one coordinated with the cobalt ion and two sulfonic acid oxygens that do not participate in the coordination. Organic sulfonic acid and coordinated water are very beneficial for constructing efficient proton conductors, and the present complex has these two favorable structural units at the same time and forms a hydrogen bond structure. A hydrogen-bonded network structure is constructed between adjacent mononuclear complexes through O—H···O, forming a clear one-dimensional hydrogen bond structure composed of one-dimensional sulfonic acid oxygen and coordinated water, which is particularly beneficial for proton transport. Proton-conductive cobalt-based single-molecule magnet bifunctional materials achieve dual functionality at low temperature and room temperature, increasing the practical application scenarios of the materials, such as solid-state batteries, energy storage materials, and quantum storage devices.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention provides a method for preparing a proton conductive cobalt-based single-molecule magnet bifunctional material, which utilizes organic sulfonic acid and coordinated water molecules to construct a new approach for constructing an efficient proton conductor. The method has the characteristics of simple synthesis, low cost, and suitability for large-scale production, and provides an important reference scheme for the development of high-performance proton conductive materials.

[0022] The present invention provides a proton conductive cobalt-based single-molecule magnet dual-functional material, which has a unique crystal structure, proton conductive behavior and single-molecule magnet behavior, and realizes dual functionality at low temperature and room temperature.

[0023] The present invention provides an application of a proton conductive cobalt-based single-molecule magnet dual-function material, expands the application field of the proton conductive material, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a single crystal photo of CoIQS; Figure 2 is the powder diffraction pattern of CoIQS; Figure 3 Schematic diagram of the asymmetric unit of the crystal structure of CoIQS; Figure 4 Schematic diagram of the stacking structure of the crystal structure of CoIQS; Figure 5 is the AC impedance spectrum of CoIQS; Figure 6 is the variable temperature DC susceptibility of CoIQS; Figure 7 is the temperature and frequency dependence of the AC magnetic susceptibility of CoIQS. DETAILED DESCRIPTION

[0025] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0026] Example 1 The preparation method of the proton conductive cobalt-based single-molecule magnet dual-function material comprises the following steps: Cobalt nitrate hexahydrate and 5-isoquinolinesulfonic acid were added to deionized water in a molar ratio of 1:2, and stirred at room temperature for 30 minutes to obtain a reaction solution; the reaction solution was placed in a Teflon-coated stainless steel container, heated to 100°C and maintained for 24 hours. After the reaction, the container was cooled to room temperature at a rate of 10°C / h, and the product was recovered and purified to obtain a proton conductive cobalt-based single-molecule magnet bifunctional material, recorded as CoIQS.

[0027] The actual photo of CoIQS single crystal is as follows Figure 1 As shown, a large number of blocky light yellow single crystals can be obtained in this embodiment. The material was collected and the yield was calculated. The yield of this embodiment was about 62%. The target product can be synthesized by adjusting parameters such as ratio, temperature, time, etc. within the range defined by the present invention. The purity of CoIQS was characterized by powder diffraction pattern, and the results were as shown in Figure 2 shown. Figure 2 It shows that the bulk crystalline material is a pure single-phase material.

[0028] Example 2 In this example, the single crystal structure of CoIQS was measured at 150 K using single crystal X-ray diffraction analysis (measurement instrument: Bruker D8 Advancediffractometer), and the structural refinement data are shown in Table 1. The asymmetric unit and stacking structure schematic diagram of the crystal structure of CoIQS were constructed (measurement instrument: Bruker D8 quest), and the results are shown in order. Figure 3 , 4 shown.

[0029] Table 1: Crystal structure refinement parameters of CoIQS

[0030] Combined with the structural analysis data in Table 1 and the schematic diagram of the asymmetric unit and stacking structure, the results show that CoIQS is a neutral mononuclear complex with a distorted octahedral geometry ( Figure 3 The average metal-ligand bond length is 2.216 Å, revealing that the divalent cobalt ion in CoIQS is high spin. The continuous shape measurement software analysis calculated that it is 0.343 (ideal octahedron, CSM=0), indicating that relative to O h The symmetry is moderately distorted, which usually leads to large magnetic anisotropy for cobalt complexes. From the crystal structure stacking diagram, it can be seen that the mononuclear cobalt units are connected into a hydrogen bond framework structure ( Figure 4 ). Through these multiple hydrogen-bonding interactions, the molecular complex units are connected to form a three-dimensional hydrogen-bonded supramolecular network. The shortest intermolecular Co···Co distance in the structure is 8.493 Å.

[0031] Example 3 This example studies the proton conductive behavior of the proton conductive cobalt-based single-molecule magnet bifunctional material and measures the CoIQS at 1.0×10 5 The AC impedance spectrum at 97% relative humidity and 40 °C in the range of -1 Hz is shown in the following figure. Figure 5 In the test, about 100 mgCoIQS was compressed at 50 kg / cm 2Under a pressure of , a disc with a diameter of 10 mm and a thickness of about 0.5 mm was made. AC impedance measurements were performed using a multi-channel electrochemical workstation (measuring instrument: Donghua DH7007) in a temperature and humidity controlled room (measuring instrument: DHT-benchtop constant temperature and humidity test chamber DHTHM-27-0-P-SD) with a frequency range of 1 Hz to 1 MHz and an AC amplitude of 100 mV. Gold electrodes were attached to both sides of the disc. The bulk conductivity was estimated by semicircle fitting of the Nyquist plot. An equivalent circuit model, consisting of a series inductor (H) representing the external circuit effect and three parallel resistors (R) and a constant phase element (used to represent a non-ideal capacitor), representing the bulk phase, grain boundary and electrode interface, was used to fit the impedance spectrum. The Nyquist plot consists of a semicircle in the high-frequency part and a tilted tail in the low-frequency part, which is a typical AC impedance spectrum of a proton conductor. The proton conductivity of the CoIQS material can be calculated to be 2.1×10 based on the resistance read from the semicircle diameter. -5 S cm -1 (40°C, 97% RH).

[0032] Example 4 This example studies the magnetic properties of proton conductive cobalt-based single-molecule magnet bifunctional materials. The direct current (dc) magnetic susceptibility of the ground single crystal sample (15.2 mg) of CoIQS was measured in the range of 2-300 K under an applied 1000 Oe DC field (measurement instrument: Quantum Design SQUID VSM magnetometer). The alternating current (ac) magnetic susceptibility data were collected under zero DC field or an applied 1000 Oe DC field, with a temperature range of 2-10 K, an AC field of 2 Oe, and a frequency range of 1-1000 Hz. All magnetic data have been corrected for the contribution of sample diamagnetism and corrected using the Pascal constant. The results are shown in Figure 2. Figure 6 , 7 shown.

[0033] Depend on Figure 6 It can be seen that the DC magnetic susceptibility test confirms that the room temperature magnetic susceptibility of cobalt ions is 3.03 cm 3 mol -1 K, so the cobalt ion is in a high spin state and has a high magnetic anisotropy. Figure 7 This indicates that the AC magnetic susceptibility test observed obvious frequency and temperature dependent magnetic susceptibility variation behavior, and the magnetic relaxation energy barrier of the compound was determined to be 32.4 cm -2 .

[0034] Based on the unique structure, proton conductive behavior and magnetic properties of the proton conductive cobalt-based single-molecule magnet bifunctional material, this material has broad application prospects. For example, with each cobalt ion in the molecule as a magnetic storage node, the information storage capacity per mole of this compound will reach 2 50 At the byte level, it can solve the current storage anxiety problem; the material has good water stability and electrochemical stability, and it can be prepared into a proton exchange membrane for use in fuel cells, which can reduce the cost of fuel cells, solve the current high cost and stability problems of proton exchange membranes, and promote the development of clean energy.

[0035] In summary, the present invention provides a new way to construct an efficient proton conductor using organic sulfonic acid and coordinated water molecules, and provides an important reference scheme for the development of high-performance proton conductive materials. The present invention uses a simple, inexpensive, and large-scale cobalt complex that has proton conductive behavior and single-molecule magnetic behavior, namely a proton conductive cobalt-based single-molecule magnet dual-functional material. The material can achieve dual functionality at low temperature and room temperature, which increases the practical application scenarios of the material, such as solid-state batteries, energy storage materials, and quantum storage devices, and has broad application prospects.

[0036] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for preparing a proton conductive cobalt-based single-molecule magnet dual-functional material, characterized in that: The method comprises the following steps: adding a chemical reaction amount of cobalt nitrate hexahydrate and 5-isoquinoline sulfonic acid into water and mixing to obtain a reaction solution; reacting the reaction solution at a certain temperature, cooling the reaction solution after completion, recovering and purifying the product to obtain a proton conductive cobalt-based single-molecule magnet dual-functional material.

2. The method for preparing the proton conductive cobalt-based single-molecule magnet dual-function material according to claim 1, characterized in that: The molar ratio of the cobalt nitrate hexahydrate to 5-isoquinolinesulfonic acid is 1:1.9-2.

1.

3. The method for preparing the proton conductive cobalt-based single-molecule magnet dual-function material according to claim 1, characterized in that: The reaction temperature is 90-110° C. and the reaction time is 12-36 h.

4. The method for preparing the proton conductive cobalt-based single-molecule magnet dual-function material according to claim 1, characterized in that: The cooling is performed at a cooling rate of 9-11°C / h to room temperature.

5. A proton conductive cobalt-based single-molecule magnet dual-function material, characterized in that: The method is prepared according to any one of claims 1 to 4.

6. The proton conductive cobalt-based single-molecule magnet dual-function material according to claim 5, characterized in that: The proton conductive cobalt-based single-molecule magnet bifunctional material is a neutral mononuclear complex; the mononuclear complex is composed of mononuclear cobalt units connected by O—H···O hydrogen bonds to form a three-dimensional hydrogen bond supramolecular network.

7. The proton conductive cobalt-based single-molecule magnet dual-function material according to claim 6, characterized in that: In the mononuclear cobalt unit, the average metal-ligand bond length is 2.216 Å.

8. The proton conductive cobalt-based single-molecule magnet dual-function material according to claim 5, characterized in that: The crystal structure of the proton conductive cobalt-based single-molecule magnet dual-function material is a monoclinic system. P 21 / c space group; its unit cell parameters are as follows: a=8.5107(5) Å, b=15.0340(9) Å, c=7.7245(5) Å, α=90°, β=113.162(2)°, γ=90°, V=908.68(10) Å 3 , Z=2.

9. The proton conductive cobalt-based single-molecule magnet dual-function material according to claim 5, characterized in that: At 40°C and 97% relative humidity, the proton conductivity of the proton conductive cobalt-based single-molecule magnet dual-functional material is 2.1×10 -5 S cm -1 .

10. An application of the proton conductive cobalt-based single-molecule magnet dual-function material according to any one of claims 5 to 9, characterized in that: As a proton conductive material, it is used to prepare solid-state batteries, energy storage materials, and quantum storage devices.

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