Synthesis Method and Application of a p-tert-Butylcalix[4]arene-Protected Silver Cluster

Abstract

The present invention belongs to the technical field of nanomaterials, and provides a synthesis method and application of silver clusters protected by p-tert-butylthiacalix[4]arene, including the synthesis of p-methylphenylthio silver precursor, the preparation of a mixture, the synthesis of compound 1, the synthesis of compound 2, and the mixture control of compound 1-compound 2. The synthesis of p-methylphenylthio silver precursor includes AgNO3, acetonitrile, p-MePhSH, Et3N, and ethanol solution, and the mixture includes (p-MePhSAg) n , H4TC4A, K2Cr2O7, DMF, and PhCOOAg. The present invention regulates the aggregation of generated Ag(0) atoms by controlling the reduction kinetics of DMF to achieve the regulation of the silver core, synthesizes compound 1 and compound 2. Compound 1 exhibits good photothermal conversion performance as a photothermal conversion agent, and compound 2 exhibits good detoxification ability as a catalytic degradation agent for nitroaromatic chemicals.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and particularly relates to a synthesis method and application of silver clusters protected by p-tert-butylthiacalix[4]arene. Background Art

[0002] Due to the complex assembly process and the difficulty in obtaining high-quality crystals for single-crystal X-ray diffraction structure analysis, the controllable synthesis of metal nanoclusters with atomic precision is challenging. Although significant progress has been made in the crystallization of Ag 44 to Ag 374 and the determination of precise structures, the trial-and-error method is still the most commonly used means in the synthesis of silver clusters. Therefore, it is very important to master the method of regulating the growth of silver clusters, which is mainly related to the kinetic process affected by various factors such as temperature, reactant concentration, solvent, etc.

[0003] Some typical methods are known, such as thermally induced reversible isomerization and ligand-regulated synthesis of metal nanoclusters with different sizes and shapes. However, due to the fast growth rate of the metal core, it is difficult to express the importance of the metal core in cluster assembly in these regulation methods. The metal core represents the embryonic state during the cluster growth process, which not only provides some early structural models for understanding the cluster assembly mechanism but also has a decisive impact on the molecular and electronic structures of the clusters.

[0004] Compared with the rapid reduction process of NaBH 4 , N,N-dimethylformamide (DMF), as a mild reducing agent, has been widely used in the synthesis of metal nanoparticles and metal colloidal materials. During the process of obtaining silver clusters through the redox reaction involving DMF, the reaction mechanism is: Me 2 NCOH + 2Ag(I) + H 2 O → 2Ag(O) + Me 2 NCOOH + 2H + , and the reaction generates N,N-dimethylcarbamic acid and Ag(O), and the latter can aggregate to form silver nuclei.

[0005] For currently obtained silver clusters reduced by weak reducing agents such as TBA 8 [Ag 6 (γ-H 2 SiW 10 O 36 ) 2 , [Ag 6 @(CrO 4 ) 8 @Ag 52 , [Ag 10 @(Mo 7 O 26 )2 @Ag 70 and [Ag 6 @(MoO 4 ) 7 @Ag 56 , in these examples, there are significant differences in the reactants, solvents, temperatures, and experimental conditions used in the synthesis of silver clusters, and it can only prove that DMF has reducing ability during the silver cluster assembly process. However, through experiments, it is found that by regulating the reduction kinetics of DMF to adjust the silver cluster assembly process, different silver cluster compounds can be synthesized, and the produced compounds have their own advantages in terms of performance and practical applications. SUMMARY OF THE INVENTION

[0006] In view of the above technical problems existing in the method for synthesizing silver cluster nanomaterials, the present invention provides a method for synthesizing silver clusters protected by p-tert-butylthiacalix[4]arene. By regulating the reduction kinetics of DMF to adjust the aggregation of generated Ag(O) atoms, the regulation of the silver core is achieved, and compounds 1 with the chemical formula [(CrO 4 ) 4 @Ag 46 (C 4 OH 44 O 4 S 4 ) 5 (p-MePhS) 16 (C 3 H 7 NO) 5 ·6(C 3 H 7 NO) and compounds 2 with the chemical formula [(CrO 4 ) 2 @Ag 34 (C 4 OH 44 O 4 S 4 ) 4 (p-MePhS) 10 (PhCOO) 4 (C 3 H 7 NO) 7 (H 2 O)]·3(C 3 H 7 NO) are synthesized, and the application of compound 1 as a photothermal conversion agent and the application of compound 2 as a catalytic degradation agent are proposed.

[0007] To achieve the above object, the technical solution adopted by the present invention is that the present invention provides a method for synthesizing a silver cluster protected by p-tert-butylthiacalix[4]arene. The silver cluster includes Compound 1 and Compound 2, and their chemical formulas are respectively:

[0008] [(CrO 4 ) 4 @Ag 46 (C 4 OH 44 O 4 S 4 ) 5 (p-MePhS) 16 (C 3 H 7 NO) 5 ·6(C 3 H 7 NO);

[0009] [(CrO 4 ) 2 @Ag 34 (C 4 OH 44 O 4 S 4 ) 4 (p-MePhS) 10 (PhCOO) 4 (C 3 H 7 NO) 7 (H 2 O)]·3(C 3 H 7 NO);

[0010] The synthesis methods of the said Compound 1 and Compound 2 include the following steps:

[0011] S1. Synthesis of p-methylphenylthio silver precursor: Dissolve AgNO 3 in acetonitrile, then add an ethanol solution of p-MePhSH and Et 3 N, stir continuously in the dark for 5 hours, filter by suction, wash successively with ethanol and ether, and dry to synthesize (p-MePhSAg) n ;

[0012] S2. Preparation of the mixture: Take the (p-MePhSAg) n synthesized in Step S1 and mix it with H 4 TC4A, K 2 Cr 2 O 7 and disperse them in DMF. After stirring at 800 rpm at room temperature for 3 hours, add PhCOOAg and stir for another 3 hours at the same rotation speed;

[0013] S3. Prepare 3 portions of the mixture according to steps S1 and S2;

[0014] S4. Synthesis of Compound 1: Take one portion of the mixture from step S3, seal it in a stainless-steel autoclave with a polytetrafluoroethylene lining, and heat it at 65 °C for 33 hours; after cooling to room temperature, obtain Compound 1 in the form of black rod-shaped crystals;

[0015] S5. Synthesis of Compound 2: Take one portion of the mixture from step S3, centrifuge the red solution, and slowly volatilize it at room temperature in the dark for 1 - 2 weeks to obtain Compound 2 in the form of red block-shaped crystals;

[0016] S6. Control experiment of the mixture of Compound 1 - Compound 2: Take one portion of the mixture from step S3, perform a thermal reaction at 50 °C, filter the solution after the thermal reaction, and slowly volatilize it to obtain the mixture of Compound 1 - Compound 2.

[0017] Preferably, in step S1, the millimolar ratio of AgNO 3 , p-MePhSH, and Et 3 N is 5:5:6, the milligram mass ratio of the three is 125:93:125, the volume of acetonitrile is 75 ml, and the volume of ethanol is 100 ml.

[0018] Preferably, in step S2, the millimolar ratio of (p-MePhSAg) n , H 4 TC 4 , and K 2 Cr 2 O 7 is 1:3:5, the milligram mass ratio of the three is 114:108:73, the volume of DMF is 1.5 mL, and the mole number and mass of PhCOOAg are 0.1 mmol and 22.9 mg respectively.

[0019] Preferably, the Compound 1 is a 46-core two-electron non-superatomic cluster silver cluster.

[0020] Preferably, the Compound 2 is a 34-core silver cluster with two CrO 4 2- anion templates, and the two CrO 4 2- only serve as anion templates, both adopting μ 8 -κ 3 :κ 3 :κ 1 :κ 1The coordination mode plays a role in supporting the silver shell layer, and the Ag-O distance ranges from 2.302 to 2.561 Å; 5 DMF molecules and 1 H 2 O molecule cover the surface of the silver framework through Ag-O interactions.

[0021] An application of a p-tert-butylcalix[4]arene-protected silver cluster, and an application of the compound 1 as a photothermal conversion agent.

[0022] An application of a p-tert-butylcalix[4]arene-protected silver cluster, and an application of the compound 2 as a catalytic degradation agent for nitroaromatic chemicals.

[0023] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0024] 1. A synthesis method of a p-tert-butylcalix[4]arene-protected silver cluster provided by the present invention utilizes temperature to regulate the reduction kinetics of DMF, and synthesizes two silver clusters protected by TC4A with different molecular and electronic structures, realizing the regulation of the growth of silver clusters from the embryonic state; a two-electron structure compound 1 with an Ag 4- core is obtained at high temperature, and a 34-nuclear Ag(I) cluster compound 2 is isolated at room temperature. The silver core in the early stage of nucleation has high activity and needs to be passivated by anions or ligands to prevent excessive aggregation; through the synergistic strategy of reduction and passivation, the silver core is captured to facilitate the understanding of the influence of silver species in the early stage of nucleation and their applications on the subsequent growth of silver clusters; anions play a dual role of internally passivating the silver core and externally shaping the silver shell layer, and CrO 10 8+ has multiple ligand sites and flexible coordination modes and is an ideal anion template; calixthiophenearene is a class of multidentate macrocyclic compounds, and its ligand sites are composed of phenolic hydroxyl groups and bridging sulfur atoms, and it is a good ligand and nuclear passivation group. 4 2- 2. An application of a p-tert-butylcalix[4]arene-protected silver cluster provided by the present invention, the compound 1 exhibits good photothermal conversion performance as a photothermal conversion agent, and the compound 2 exhibits good detoxification ability as a catalytic degradation agent for nitroaromatic chemicals. The Ag

[0025] core in the compound 1 represents a completely new embryonic state in the growth process of silver clusters; since the compound 2 has more exposed silver atoms and is easy for reactants to adsorb on the catalyst surface, it exhibits higher catalytic activity than the compound 1. 10 8+ 3. Description of the drawings Brief Description of the Drawings

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 It is the crystal structure diagram of Compound 1;

[0028] Figure 2 It is the crystal structure diagram of Compound 2;

[0029] Figure 3 It is the electrospray ionization mass spectrometry in the positive ion mode of Compound 2 dissolved in a mixed solvent of dichloromethane and methanol and the molecular formula schematic diagram of Species 1a - 1c;

[0030] Figure 4 It is the electrospray ionization mass spectrometry in the positive ion mode of Compound 2 dissolved in a mixed solvent of dichloromethane and methanol and the molecular formula schematic diagram of Species 2a - 2h;

[0031] Figure 5 It is the photothermal conversion diagram of chloroform solutions of Compound 1 with different concentrations under 660 nm 0.7 W / cm -2 laser irradiation;

[0032] Figure 6 It is the photothermal conversion diagram of chloroform solutions of Compound 2 with different concentrations under 660 nm 0.7 W / cm -2 laser irradiation;

[0033] Figure 7 It is the schematic diagram of the cyclic heating and cooling process of Compound 1;

[0034] Figure 8 It is the schematic diagram of the cyclic heating and cooling process of Compound 2;

[0035] Figure 9 It is the schematic diagram of the ultraviolet - visible absorption spectra of chloroform solutions of Compound 1 and Compound 2 with a concentration of 12.5 µM;

[0036] Figure 10 It is the schematic diagram of the heating and cooling curves of a chloroform solution of Compound 1 with a concentration of 100 µM under 660 nm laser irradiation;

[0037] Figure 11 It is the schematic diagram of the heating and cooling curves of a chloroform solution of Compound 2 with a concentration of 100 µM under 660 nm laser irradiation;

[0038] Figure 12Schematic diagram of the ultraviolet-visible spectrum of the reduction of p-NP by compounds 1 and 2 at 293.15 K in the presence of NaBH 4 ;

[0039] Figure 13 Reduction process of p-nitrophenol catalyzed by compound 1;

[0040] Figure 14 Reduction process of p-nitrophenol catalyzed by compound 2;

[0041] Figure 15 Time-dependent reduction process of p-NP with a concentration of 1.3×10 -3 M catalyzed by compound 2;

[0042] Figure 16 Time-dependent reduction process of p-NP with a concentration of 7.2×10 -3 M catalyzed by compound 2;

[0043] Figure 17 Schematic diagram of the time-dependent reduction process of p-NP catalyzed by compound 2 when the concentration of NaBH 4 is 0.176 M;

[0044] Figure 18 Schematic diagram of the time-dependent reduction process of p-NP catalyzed by compound 2 when the concentration of NaBH 4 is 0.264 M;

[0045] Figure 19 Schematic diagram of the effect of the concentration of p-NP on the reduction rate;

[0046] Figure 20 Schematic diagram of the effect of the concentration of NaBH 4 on the reduction rate of p-NP catalyzed by compound 2. Detailed implementation manners

[0047] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. For the convenience of narration, the words "upper", "lower", "left" and "right" as used below only indicate the same directions as the upper, lower, left and right directions of the accompanying drawings themselves, and do not limit the structure.

[0048] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the present invention is not limited by the specific embodiments disclosed in the following specification.

[0049] Embodiments, such asFigures 1 - 20 As shown, a synthesis method and application of a silver cluster protected by p-tert-butylthiacalix[4]arene provided by the present invention, the silver cluster includes Compound 1 and Compound 2 and their chemical formulas are respectively:

[0050] [(CrO 4 ) 4 @Ag 46 (C 4 OH 44 O 4 S 4 ) 5 (p-MePhS) 16 (C 3 H 7 NO) 5 ·6(C 3 H 7 NO);

[0051] [(CrO 4 ) 2 @Ag 34 (C 4 OH 44 O 4 S 4 ) 4 (p-MePhS) 10 (PhCOO) 4 (C 3 H 7 NO) 7 (H 2 O)]·3(C 3 H 7 NO);

[0052] The synthesis methods of the said Compound 1 and Compound 2 include the following steps:

[0053] S1. Synthesis of p-methylphenylthio silver precursor: Dissolve AgNO 3 in acetonitrile, then add an ethanol solution of p-MePhSH and Et 3 N, continuously stir in the dark for 5 hours, filter by suction, wash successively with ethanol and ether, and dry to synthesize (p-MePhSAg) n ; wherein, the millimolar ratio of AgNO 3 , p-MePhSH and Et 3 N is 5:5:6, and the milligram mass ratio of the three is 125:93:125; specifically, AgNO 3 , p-MePhSH and Et 3The molar amounts of the three are 30 mmol, 30 mmol, and 36 mmol respectively, and their masses are 5 g, 3.72 g, and 5 g respectively. The volume of acetonitrile is 75 ml, and the volume of ethanol is 100 ml;

[0054] S2. Preparation of the mixture: Take the (p-MePhSAg) synthesized in step S1 n Same as H 4 TC4A, K 2 Cr 2 O 7 , and their millimolar ratio is 1:3:5, and their milligram mass ratio is 114:108:73. Specifically, their molar amounts are 0.05 mmol, 0.015 mmol, and 0.025 mmol respectively, and their masses are 11.4 mg, 10.8 mg, and 7.3 mg respectively. Disperse the three in 1.5 mL of DMF, stir at 800 rpm at room temperature for 3 hours, then add 0.1 mmol, 22.9 mg of PhCOOAg, and stir for another 3 hours at the same rotation speed;

[0055] S3. Prepare 3 portions of the mixture according to steps S1 and S2;

[0056] S4. Synthesis of compound 1: Take one portion of the mixture from step S3, seal it in a stainless steel autoclave with a polytetrafluoroethylene liner, and heat it at 65 °C for 33 hours; after cooling to room temperature, obtain compound 1 in the form of black rod-shaped crystals;

[0057] S5. Synthesis of compound 2: Take one portion of the mixture from step S3, centrifuge the red solution, and slowly volatilize it at room temperature in the dark for 1 - 2 weeks to obtain compound 2 in the form of red block-shaped crystals;

[0058] S6. Control experiment of the mixture of compound 1 - compound 2: Take one portion of the mixture from step S3, carry out a thermal reaction at 50 °C, filter the solution after the thermal reaction, and slowly volatilize to obtain the mixture of compound 1 - compound 2.

[0059] It can be seen from the control in step S6 that the reduction kinetics of DMF is affected by temperature, and different temperatures can have an obvious impact on the final synthesis of the mixture in step S3.

[0060] A synthetic method of a tert-butylthiacalix[4]arene-protected silver cluster provided by the present invention regulates the aggregation of generated Ag(O) atoms to achieve the regulation of the silver core by controlling the reduction kinetic factors of DMF, including temperature, reactant concentration, solvent, and light conditions, and can synthesize Compound 1 and Compound 2. Specifically, the silver core in the early stage of nucleation has high activity and needs to be passivated by anions or ligands to prevent excessive aggregation; through the synergistic strategy of reduction and passivation, the silver core is captured to facilitate the understanding of the influence of silver species in the early stage of nucleation and their applications on the subsequent growth of the silver cluster; the anion plays a dual role of internally passivating the silver core and externally shaping the silver shell layer, and CrO4 2- Has multiple coordination sites and flexible coordination modes and is an ideal anion template; thiacalixarene is a class of multidentate macrocyclic compounds, and its coordination sites are composed of phenolic hydroxyl groups and bridging sulfur atoms, and it is a good ligand and nuclear passivation group.

[0061] As Figure 1 Shown, regarding Compound 1: Compound 1 crystallizes in the triclinic system, space group P-1, and consists of 46 silver atoms, 4 CrO 4 2- Anions, 5 TC4A 4- 、16 p-MePhS − And 5 DMF. Specifically, the silver skeleton of Compound 1 consists of a pyramidal Ag 10 Core and an Ag 36 Shell layer. The pyramidal Ag 10 The core is composed of an Ag 6 Octahedron and silver atoms covering four adjacent triangular faces, while the other four adjacent triangular faces are covered with four CrO 4 2- Anions, supporting the silver shell layer through Ag-O bonds. 4 CrO 4 2- Anions in μ 7 -κ 3 :κ 2 :κ 1 :κ 1 , μ 8 -κ 3 :κ 2 :κ 2 :κ 1 :κ 1 And μ 6 -κ 2 :κ 2 :κ 1 :κ 1 Three different coordination modes connect the Ag 36 Outer shell and Ag 10The cores are connected by Ag-O bonds, and the Ag-O bond lengths range from 2.201 to 2.684 Å. CrO 4 2- The anions play a triple role in the construction of Compound 1: 1. Passivate the Ag 10 cores; 2. Support the Ag 36 shells; 3. Connect the core and the shell layers. In the Ag 10 cores, the range of Ag···Ag interactions is 2.729 - 3.091 Å, with an average value of 2.915 Å, indicating the existence of strong argentophilic interactions. For the entire Ag 46 skeleton, the Ag···Ag interactions are in the range of 2.729 Å - 3.375 Å. Five TC4A 4- ligands are all coordinated with silver atoms in the mode of Ag 5 @TC4A, forming a μ 5 -κ o 3 :κ o 3 :κ o 3 :κ o 3 :κ s 1 :κ s 1 :κ s 1 :κ s 1 :κ s 1 coordination mode. The distances of Ag-O and Ag-S are in the ranges of 2.230 - 2.672 Å and 2.437 - 2.621 Å respectively. This multi-dentate and multi-site coordination mode enhances the overall stability of Compound 1. Each TC4A 4- cavity encapsulates a DMF molecule, with its methyl group pointing into the cavity. The distances and angles of the C-H···π interactions formed by DMF and TC4A 4- are in the ranges of 2.532 - 3.113 Å and 135.08 - 175.03° respectively. Among the Ag 88 and Ag 18 disclosed in the current technology, solvent molecules CH 3 CN and CHCl 3 can also be encapsulated in the cavity of calixarene through C-H···π interactions, indicating that calixarene is a powerful platform demonstrating rich host-guest chemistry. Host-guest chemistry has also been widely applied in many aspects, such as detecting different types of toxic molecules, serving as a carrier for drugs and dye adsorption, etc. Sixteen p-MePhS− ligands adopt two coordination modes: among them, 12 p-MePhS− Adopt the μ 4 coordination mode, and the other four adopt the μ 3 coordination mode. Among them, the 4 p-MePhS 10 connected to the Ag − core all adopt the μ 4 coordination mode, and the other 12 p-MePhS − alternately arrange on the silver shell layer in the μ 4 and μ 3 coordination modes. In addition, 5 DMF molecules coordinate with silver atoms through Ag-O interactions, with an average distance of 2.366 Å. The steric hindrance, electronic properties, and coordination mode differences of p-MePhS − , TC4A 4- , PhCOO − and DMF enable them to cover different regions of the silver shell layer.

[0062] As Figure 3 and Figure 4 shown, electrospray ionization mass spectrometry has been widely used in the determination of the chemical composition and charge state of metal nanoclusters. The solution behavior of Compound 1 and Compound 2 in a mixed solvent of dichloromethane and methanol was determined using electrospray ionization mass spectrometry.

[0063] Compound 1 has a set of peaks in the range of mass-to-charge ratio of 3000 - 9000. By expanding each peak, the difference in the isotope distribution characteristics between adjacent two peaks was calculated to be 0.5, corresponding to the +2 valence species. 1a - 1c were respectively attributed to [Compound 1 - 2p-MePhS − + CH 2 Cl 2 + 3H 2 O] 2+ , [Compound 1 + Ag + - p-MePhS − + H 2 O] 2+ and [Compound 1 + Ag + - p-MePhS − +DMF + CH 3 OH + H 2 O] 2+ . Therefore, Compound 1 is a neutral cluster with a two-electron structure; at the same time, there are 2 free electrons in the core of Compound 1, belonging to the "magic numbers" (2, 8, 18, 20, etc.) of the spherical jellAum model. However, the orbital topological structure and DOS curve do not show the superatomic S orbital, probably due to the relatively low symmetry of the cluster. Therefore, it is inferred that Compound 1 is a two-electron non-superatomic cluster.

[0064] As Figure 2 shown, for Compound 2: it is a 34-nuclear silver cluster with two CrO 4 2- anion templates inside, and is protected outside by 10 p-MePhS − , 4 TC4A 4- , 4 PhCOO − , 7 DMF and 1 H 2 O together. The silver skeleton of Compound 2 after removing the peripheral ligands is dumbbell-shaped and can be regarded as composed of two CrO 4 @Ag 17 cages fused by Ag···Ag interactions. One of the two CrO 4 @Ag 17 cages can rotate 180 degrees around the axis and coincide with the other. The Ag···Ag interaction range of Compound 2 is 2.845 - 3.360 Å, with an average value of 3.130 Å, which is weaker than the Ag···Ag interaction of Compound 1 (3.020 Å). The four TC4A 4- ligands are all coordinated with six silver atoms to form Ag 6 @TC4A, forming a μ 6 -κ o 4 :κ o 3 :κ o 3 :κ o 3 :κ s 1 :κ s 1 :κ s 1 :κ s 1 :κ s 1 coordination mode. It is worth noting that the four TC4A 4- ligands are divided into two pairs and arranged on both sides of the silver skeleton. In addition to the TC4A 4- ligands, Compound 2 is also protected by p-MePhS − , PhCOO − , DMF and H 2 O, and they are almost symmetrically distributed on the surface of Compound 2. The 10 p-MePhS − ligands all adopt the μ 4 coordination mode and are located on an irregular Ag 4 quadrilateral, with the Ag-S distance range of 2.392 - 2.910 Å. The four PhCOO − ligands show two different coordination modes. Among them, two are in the μ4 -κ 2 :κ 2 The coordination mode plays a role in connecting two CrO 4 @Ag 17 , and the other two adopt the μ 2 -κ 1 :κ 1 coordination mode and are located on the surface of CrO 4 @Ag 17 . Obviously, the former coordination mode should be more stable than the latter, which is also confirmed by the following mass spectrometry studies. Different from Compound 1, the two CrO 4 2- in Compound 2 only act as anion templates and both adopt the μ 8 -κ 3 :κ 3 :κ 1 :κ 1 coordination mode to support the silver shell layer, and the Ag-O distance ranges from 2.302 to 2.561 Å. Five DMF molecules and one H 2 O molecule cover the surface of the silver skeleton through Ag-O interactions.

[0065] The present invention provides an application of a p-tert-butylthiacalix[4]arene-protected silver cluster, including the application of Compound 1 as a photothermal conversion agent. As a better photothermal conversion agent than Compound 2, Compound 1 can be used in application scenarios that require the participation of a photothermal conversion agent.

[0066] As Figures 5 - 11 shown, among them, Figure 5 when viewed from top to bottom, line a, line b, line c, and line d are green lines, 100 µM; orange line, 50 µM; light purple, 25 µM; navy blue, chloroform. Regarding the photothermal response of Compound 1 and Compound 2: Under the irradiation of a 660 nm laser, no fluorescence was observed for Compound 1 and Compound 2, indicating that the radiative transition is very weak, so photothermal conversion becomes the main way of energy release. To evaluate the photothermal conversion ability of the chloroform solutions of Compound 1 and Compound 2, their photothermal conversion properties were studied under the irradiation of a 660 nm laser with a power density of 0.7 Wcm -2 . After continuous laser irradiation, the temperature of the Compound 1 solution increased rapidly and reached the highest temperature within 4 minutes. When the concentration was 100 µM, the highest temperature reached 56.12 °C (ΔT = 36.12 °C), which is 5.65 times that of Compound 2 (ΔT = 6.39 °C). The highest temperature of Compound 1 is significantly higher than that of Compound 2 because Compound 1 has a smaller HOMO-LUMO energy gap, resulting in stronger absorption at 660 nm than Compound 2. Under a power density of 0.7 Wcm -2Under the irradiation of 660 nm laser, the photothermal conversion efficiencies η of the chloroform solution of Compound 2 with a concentration of 100 μM were 48.68% and 10.7% respectively. Compared with silver nanocages (46.1%), silver nanoparticles (36.8%), SDBS-Ag 2 Se (22.9%) and CTAB-Ag 2 Se (20.1%) in the prior art, Compound 1 has a higher η and can be used as a good photothermal conversion agent. In addition, the maximum temperature increases with the increase of the sample concentration. At each concentration, Compound 1 shows a faster heating rate and a higher temperature than Compound 2 under laser irradiation. In addition, they both have good photothermal stability. After 6 rounds of heating and natural cooling processes, the maximum temperature hardly changes.

[0067] The present invention provides an application of a p-tert-butylthiacalix[4]arene-protected silver cluster, and an application of the Compound 2 as a catalytic degradation agent for nitroaromatic chemical substances. Since Compound 2 has more exposed silver atoms and is easy for reactants to adsorb on the catalyst surface, it shows higher catalytic activity than Compound 1 and has good application in detoxification.

[0068] Regarding the catalytic activities of Compound 1 and Compound 2 in reducing nitrophenol: Nitroaromatic chemical substances are highly toxic and biodegradeable with difficulty. They can enter the human body through the respiratory tract or skin, causing neurological diseases, anemia and liver damage. However, aminophenol is widely used as a fine organic chemical intermediate, a raw material for the pharmaceutical industry, dyes, imaging agents and antioxidants. The present invention uses the reduction of p-nitrophenol (p-NP) as a model reaction to test the catalytic activities of Compound 1 and Compound 2.

[0069] Specifically, as Figures 12 - 14 shown, the reagent conditions are [p-NP] = 3.6×10 -3 M; [NaBH 4 = 0.088 M. The p-NP solution has characteristic absorption peaks at 322 nm and 400 nm. With the addition of NaBH 4 , there is only one peak at 400 nm and the color changes from light yellow to bright yellow, which is due to the formation of deprotonated p-NP. After reacting for 4 hours without a catalyst, the position and absorption intensity of the peak do not change significantly, indicating that NaBH 4 cannot reduce p-NP without the action of a catalyst. Under the catalysis of Compound 1 and Compound 2, NaBH 4The UV-visible spectral evolution of the reduction of p-NP shows that the intensity of the characteristic absorption peak of p-nitrophenol ions at 400 nm decreases with the increase in the intensity of the absorption peak of p-aminophenol (p-AP) ions at 297 nm. In addition, the appearance of isosbestic points (281 nm and 313 nm) indicates that p-NP is completely converted to p-AP without the formation of by-products. Moreover, under the catalysis of Compound 2, p-NP can be completely reduced to p-AP within 30 minutes, while under the same reaction conditions, Compound 1 takes 3 hours to complete, indicating that the catalytic activity of Compound 2 is higher than that of Compound 1, and regulating the structure of metal nanoclusters is of great significance for regulating their catalytic performance.

[0070] Taking Compound 2 with higher catalytic activity as an example, a series of kinetic experiments were carried out by changing the concentrations of p-NP and NaBH 4 to investigate whether the reaction process has concentration dependence and further determine the reaction mechanism. Obviously, reducing the concentration of p-NP or increasing the concentration of NaBH 4 accelerated the completion of the reaction, indicating that the reaction mechanism involves the adsorption of p-NP ions and BH 4- on the catalyst surface, which conforms to the LangmuAr-HAnshelwood (L-H) model. The reduction rate of nitrophenol can be calculated by the pseudo-first-order kinetic equation: − = − = kapp; where Ct (At) and C0 (A0) are the concentration and initial concentration (absorbance) at time t during the p-NP reduction reaction. The kapp of Compound 2 was calculated to be 8.93 h −1 , which is 3.59 times that of Compound 1 (2.49 h −1 ).

[0071] As shown in Figure 15 , 16 and 19, where NaBH 4 = 0.088 M; as shown in Figure 17 , 18 , 20, where p-NP = 3.6×10 -3 M. The kapp of different concentrations of p-NP or NaBH 4 further indicates that the catalytic reaction conforms to the L-H model.

[0072] To further investigate the catalytic activities of Compound 1 and Compound 2, we carried out the reduction of o-nitrophenol (o-NP) and m-nitrophenol (m-NP) under the same conditions as the p-NP reduction reaction. Experiments showed that Compound 2 had more exposed silver atoms than Compound 1, so it had higher activity in catalyzing the reduction of nitrophenol, and the reduction rates of the three nitrophenol isomers were in the order: p-NP > o-NP > m-NP. This work not only revealed the tunability of the DMF reduction kinetics but also provided new ideas for regulating the assembly process of silver clusters.

[0073] As described above, it is only the preferred embodiment of the present invention, and it is not intended to limit the present invention in other forms. Any person skilled in the art may use the disclosed technical content to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the technical solution content of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for synthesizing a silver cluster protected by tert-butylthiacalix[4]arene, characterized in that: The following steps are involved: S1. Synthesis of p-MePhSAg precursor: AgNO3 was dissolved in acetonitrile, followed by addition of p-MePhSH and Et3N ethanol solution, stirring for 5 hours in the dark, filtered, washed with ethanol and ether in turn, and dried to synthesize (p-MePhSAg). n ; S2. Preparation of the mixture: Take (p-MePhSAg) synthesized in step S1 n Dispersed in DMF together with H4TC4A and K2Cr2O7, stirred at 800 rpm for 3 hours at room temperature, PhCOOAg was added, and stirred at the same speed for another 3 hours; S3, prepare 3 parts of the mixture according to steps S1 and S2; S4. Take a portion of the mixture in step S3, heat react at 50° C., filter the solution after the heat reaction, and slowly evaporate to obtain a mixture of compound 1 and compound 2, wherein the chemical formulas of compound 1 and compound 2 are: [(CrO4)4@Ag 46 (C40H 44 O4S4)5(p-MePhS) 16 (C3H7NO)5]·6(C3H7NO); [(CrO4)2@Ag 34 (C40H 44 O4S4)4(p-MePhS) 10 (PhCOO)4(C3H7NO)7(H2O)]·3(C3H7NO); In step S1, the millimole ratio of AgNO3, p-MePhSH and Et3N is 5:5:6, the volume of acetonitrile is 75 ml, and the volume of ethanol is 100 ml; In step S2, (p-MePhSAg) n The millimole ratio of H4TC4A and K2Cr2O7 is 1:3:5, the milligram mass ratio of the three is 114:108:73, the volume of DMF is 1.5 mL, and the molar number and mass of PhCOOAg are 0.1 mmol and 22.9 mg respectively.

2. The method for synthesizing a p-tert-butylthiacalix[4]arene-protected silver cluster according to claim 1, characterized in that: Take a portion of the mixture in step S3, seal it in a stainless steel autoclave with a polytetrafluoroethylene liner, and heat it at 65° C. for 33 hours; after cooling to room temperature, a black rod-shaped crystal compound 1 is obtained, wherein the compound 1 is a 46-nuclear two-electron non-superatomic cluster silver cluster.

3. The method for synthesizing a p-tert-butylthiacalix[4]arene-protected silver cluster according to claim 1, characterized in that: Take a portion of the mixture in step S3, centrifuge the red solution, and slowly evaporate it at room temperature in the dark for 1-2 weeks to obtain compound 2 in the form of red block crystals.

4. The method for synthesizing a p-tert-butylthiacalix[4]arene-protected silver cluster according to claim 3, characterized in that: The compound 2 has two CrO4 2- Anion template of 34-core silver cluster, two of the CrO4 2- Only as anionic template, μ8-κ 3 :κ 3 :κ 1 :κ 1 The coordination mode plays a role in supporting the silver shell, and the Ag-O distance ranges from Five DMF molecules and one H2O molecule were covered on the surface of the silver skeleton through Ag-O interactions.

5. An application of a silver cluster protected by tert-butylthiacalix[4]arene, characterized in that: Use of the compound 1 described in claim 2 as a photothermal conversion agent.

6. An application of a silver cluster protected by tert-butylthiacalix[4]arene, characterized in that: The use of the compound 2 described in claim 4 as a catalytic degradation agent for nitroaromatic chemicals.

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