阅读说明：本技术 一种结构和光学性质可调的银簇聚集体的制备方法 (Preparation method of silver cluster aggregate with adjustable structure and optical properties ) 是由 孔令灿 吴林林 张琦 蒋瑜宏 周小新 于 2020-12-03 设计创作，主要内容包括：一种结构和光学性质可调的银簇聚集体的制备方法,属于纳米结构材料和光学性质的技术领域。本发明不同结构的银簇聚集体都是在室温下一步法定量制备的,而且可以通过简单地调节手性青霉胺和硝酸银的投料比实现；当银银相互作用作为主要驱动力时,形成的银簇聚集体表现出手性反转和发光行为,而氢键或偶极-偶极相互作用作为主要驱动力时,形成的银簇聚集体没有显示出这些光学性质。这种结构和光学性质可调的银簇聚集体有望发展成为生物成像、检测、纳米载药领域的实用技术。(A preparation method of silver cluster aggregates with adjustable structure and optical properties belongs to the technical field of nano-structure materials and optical properties. The silver cluster aggregates with different structures are quantitatively prepared at room temperature by a one-step method, and can be realized by simply adjusting the charge ratio of chiral penicillamine to silver nitrate; when silver-silver interaction is used as the main driving force, the formed silver cluster aggregates show chiral inversion and luminescence behavior, while when hydrogen bond or dipole-dipole interaction is used as the main driving force, the formed silver cluster aggregates do not show these optical properties. The silver cluster aggregate with adjustable structure and optical property is expected to be developed into a practical technology in the fields of biological imaging, detection and nano drug loading.)

1. A method for preparing silver cluster aggregates with adjustable structure and optical properties is characterized in that: the method is realized by adjusting the feed ratio of chiral penicillamine to silver nitrate, and comprises the following specific steps:

(1) dissolving chiral penicillamine: dissolving chiral penicillamine with different masses in double distilled water;

(2) preparation of silver cluster aggregates: and (2) adding a silver nitrate solution into the solution obtained in the step (1), and stirring at room temperature to obtain the silver cluster aggregation with different shapes, different optical properties and adjustable structures and optical properties.

2. The method of claim 1 for preparing silver cluster clusters with tunable structural and optical properties, wherein: the corresponding chiral penicillamine in step (1) and step (2): the molar ratio of silver nitrate is 1-4: 1.

3. the method of claim 1 for preparing silver cluster clusters with tunable structural and optical properties, wherein: the chiral penicillamine in the step (1) is specifically D-penicillamine or L-penicillamine.

4. The method of claim 2 for preparing silver cluster clusters with tunable structural and optical properties, wherein: when chiral penicillamine: the molar ratio of silver nitrate is 1:1, obtaining fibrous silver cluster aggregates; when chiral penicillamine: the molar ratio of silver nitrate is 4:1, obtaining a flaky silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is between 1:1 and 4:1, fibrous and plate-like doped silver cluster aggregates are obtained.

5. The method of claim 2 for preparing silver cluster clusters with tunable structural and optical properties, wherein: when chiral penicillamine: the molar ratio of silver nitrate is close to 2: 1, the formed silver cluster aggregate structure is mainly fibrous; when chiral penicillamine: the molar ratio of silver nitrate is close to 3: 1, the formed silver cluster aggregate structure is mainly flaky.

6. The method of claim 2 for preparing silver cluster clusters with tunable structural and optical properties, wherein: when chiral penicillamine: the molar ratio of silver nitrate is 1:1, obtaining a luminous silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is 4:1, obtaining a non-luminous silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is between 1:1 and 4:1, silver cluster aggregates with successively lower brightness are obtained.

7. The method of claim 1 for preparing silver cluster clusters with tunable structural and optical properties, wherein: the mass of the chiral penicillamine in the step (1) is 25 mg, 37.5 mg, 50 mg, 75 mg and 100 mg in sequence; dissolved in 5mL of double distilled water.

8. The method of claim 1 for preparing silver cluster clusters with tunable structural and optical properties, wherein: and (2) adding 3mL of silver nitrate solution containing 29mg of silver nitrate into the solution obtained in the step (1), and stirring at room temperature for 1-2 hours to obtain silver cluster aggregates with different shapes and different optical properties.

9. The method of claim 2 for preparing silver cluster clusters with tunable structural and optical properties, wherein: and (3) continuously stirring the silver cluster aggregates with different appearances and different optical properties obtained in the step (2) for 14d to obtain the fibrous silver cluster aggregates with adjustable structures and optical properties.

10. The method of claim 9 for preparing silver cluster clusters with tunable structural and optical properties, wherein: after the stirring is continued for 14d, fibrous silver cluster aggregates are obtained no matter the molar ratio;

when chiral penicillamine: the molar ratio of silver nitrate is 1:1, obtaining a luminous silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is 4:1, obtaining a non-luminous silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is between 1:1 and 4:1, silver cluster aggregates with successively lower brightness are obtained.

Technical Field

The invention relates to a preparation method of a silver cluster aggregate with adjustable structure and optical property, in particular to a method for preparing the silver cluster aggregate with adjustable structure and optical property in water at room temperature by one step under the drive of different non-covalent interactions, belonging to the technical field of nano-structure materials and optical property.

Background

Silver interaction is an oriented, non-covalent interaction and has attractive assembly characteristics and photophysical properties, and is therefore widely designed and used in silver-containing metalorganic and coordination compounds (Schmidbaur H, Schier a,Angew. Chem. Int. Ed. 2015, 54, 746-784). However, the assembly potential of silver-silver interaction in supramolecular self-assembly has not been fully exploited, mainly because its strength of force is much weaker than covalent bonds, so that stable assembly structures are difficult to form. To develop the assembly potential of silver-silver interactions, multiple silver-silver interactions have been proposed and applied to supramolecular self-assembly of silver nanocrystals and nanoclusters (Xie Y P, Jin J L, Duan G X, Lu X, Mak T C W,Coordin. Chem. Rev. 2017, 331, 54−72; Chakraborty I, Pradeep T, Chem. Rev. 2017, 117, 8208−8271; Kang X, Zhu M, Chem. Soc. Rev. 2019, 48, 2422-2457). Compared to mixed-valence Ag (0/1) nanoclusters, anisotropic polynuclear Ag-S nanoclusters are easier to assemble into 1D and 2D superstructures under silver-silver interaction and dipole-dipole interaction. It is conceivable that the interaction of polynuclear silver and the synergy of other various non-covalent interactions (such as hydrogen bonding and dipoles)Dipolar interaction) enables the adjustment of silver-silver interactions with concomitant changes in the assembly structure and optical properties.

In situ supramolecular self-assembly is a promising assembly strategy that allows to obtain highly ordered assemblies directly from the reactants, avoiding multiple separations and reaction processes (Wang H, Li Y, Yu H, Song B, Lu S, Hao X Q, Zhang Y, Wang M, Hla S W, Li X, J. Am. Chem. Soc. 2019, 141, 13187−13195; Lu W, Gao P, Jian W B, Wang Z L, Fang J, J. Am. Chem. Soc.2004, 126, 14816-14821). Such self-assembly processes are ubiquitous in nature, such as DNA replication and protein synthesis, and show promising application prospects (Tao Y, Li M, Ren J, Qu X,Chem. Soc. Rev. 2015, 44, 8636-8663). Wanlcon et al have recently successfully demonstrated in situ self-assembly of Ag-S nanocluster complexes and interesting morphological transformations by ultrasound methods, leading us to realize the full potential of Ag-S building blocks, which will open up a new area in material customization and biological applications (Sang Y, Han J, Zhao T, Duan P, Liu M,Adv. Mater.2019, 1900110). Although the mechanisms of formation, growth, assembly and morphological transformation of Ag-S superstructures are not well understood, their anisotropic assembly characteristics and strong luminescent properties have attracted much interest.

Anisotropic in situ supramolecular self-assembly can produce interesting optical properties such as chiral inversion and luminescent properties. However, there is still a lack of an ideal system for understanding such self-assembly processes and mechanisms of light emission.

Disclosure of Invention

The invention aims to overcome the defects and provide a preparation method of a silver cluster aggregate with adjustable structure and optical property, the prepared silver cluster aggregate is changed from a fiber structure to a sheet structure along with the adjustment of the reaction molar ratio of chiral penicillamine and silver nitrate, and the phenomena of chiral inversion and luminescence disappear.

The technical scheme of the invention is that the preparation method of the silver cluster aggregate with adjustable structure and optical property is realized by adjusting the charge ratio of chiral penicillamine and silver nitrate, and comprises the following specific steps:

(1) dissolving chiral penicillamine: dissolving chiral penicillamine with different masses in double distilled water;

(2) preparation of silver cluster aggregates: and (2) adding a silver nitrate solution into the solution obtained in the step (1), and stirring at room temperature to obtain the silver cluster aggregation with different shapes, different optical properties and adjustable structures and optical properties.

Further, the corresponding chiral penicillamine in step (1) and step (2): the molar ratio of silver nitrate is 1-4: 1.

further, the chiral penicillamine in the step (1) is specifically D-penicillamine or L-penicillamine.

Further, when chiral penicillamine: the molar ratio of silver nitrate is 1:1, obtaining fibrous silver cluster aggregates; when chiral penicillamine: the molar ratio of silver nitrate is 4:1, obtaining a flaky silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is between 1:1 and 4:1, fibrous and plate-like doped silver cluster aggregates are obtained.

Further, when chiral penicillamine: the molar ratio of silver nitrate is close to 2: 1, the formed silver cluster aggregate structure is mainly fibrous; when chiral penicillamine: the molar ratio of silver nitrate is close to 3: 1, the formed silver cluster aggregate structure is mainly flaky.

Further, when chiral penicillamine: the molar ratio of silver nitrate is 1:1, obtaining a luminous silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is 4:1, obtaining a non-luminous silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is between 1:1 and 4:1, silver cluster aggregates with successively lower brightness are obtained.

Further, the mass of the chiral penicillamine in the step (1) is 25 mg, 37.5 mg, 50 mg, 75 mg and 100 mg in sequence; dissolved in 5mL of double distilled water.

Further, 3mL of silver nitrate solution containing 29mg of silver nitrate is added into the solution obtained in the step (1) in the step (2), and the mixture is stirred for 1-2h at room temperature, so that silver cluster aggregates with different shapes and different optical properties are obtained.

Further, the silver cluster aggregates with different shapes and different optical properties obtained in the step (2) are continuously stirred for 14d, and the fibrous silver cluster aggregates with adjustable structure and optical properties are obtained.

Further, after continuing the stirring for 14d, fibrous silver cluster aggregates were obtained regardless of the molar ratio; when chiral penicillamine: the molar ratio of silver nitrate is 1:1, obtaining a luminous silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is 4:1, obtaining a non-luminous silver cluster aggregation; when chiral penicillamine: the molar ratio of silver nitrate is between 1:1 and 4:1, silver cluster aggregates with successively lower brightness are obtained.

According to the preparation method and the driving force of the silver cluster aggregate with adjustable structure and optical property, the silver cluster aggregate is converted into a sheet structure from a fiber structure by adjusting the molar charge ratio of the chiral penicillamine to the silver nitrate (from 1:1 to 4: 1), and the chiral inversion and luminescence phenomena disappear. After further stirring for a long period of 14 days, the silver cluster aggregates were transformed into a fibrous structure, but still without chiral inversion and luminescence. Various characterization means show that during the rapid stirring process, the fiber structure is formed by being driven by silver action, and the sheet structure is formed by being driven by hydrogen bond action; by stirring for a long time, the dipole-dipole effect plays a major role, which transforms both the fibrous and sheet-like structures into fibrous structures. Moreover, only the fiber structure formed by the action of silver as the main driving force shows chiral inversion and luminescence properties, and the sheet structure and the fiber structure formed by other hydrogen bonds and dipole-dipole interactions as the main driving forces do not show chiral inversion and luminescence behaviors. The silver cluster aggregate with adjustable structure and optical property is expected to be developed into a practical technology in the fields of biological imaging, detection and nano drug loading.

The invention has the beneficial effects that: the silver cluster aggregates with different structures prepared by the method are quantitatively prepared at room temperature by one step, and can be realized by simply adjusting the feed ratio of chiral penicillamine to silver nitrate; the formed silver cluster aggregates exhibit chiral inversion and luminescence behavior when silver-silver interaction is the main driving force, whereas the formed silver cluster aggregates do not show these interesting optical properties when hydrogen bonding or dipole-dipole interaction is the main driving force. The silver cluster aggregate with adjustable structure and optical property is expected to be developed into a practical technology in the fields of biological imaging, detection and nano drug loading.

The equipment and the preparation method used by the invention are simple and easy to popularize, and the structure and the luminescent property of the obtained silver cluster aggregate are easy to control, thereby having important guiding significance for further developing materials for preparing chiral reversal and luminescent intensity in water at room temperature.

Drawings

FIG. 1: the structure of single crystal of L-Ag.

FIG. 2: the double-spiral structure frame formed by sulfur and silver in the L-Ag single crystal.

FIG. 3-a: scanning electron micrograph of D-Ag.

FIG. 3-b: d₁Scanning electron micrograph (c).

FIG. 3-c: d₂Scanning electron micrograph (c).

FIG. 3-d: d₃Scanning electron micrograph (c).

FIG. 3-e: d₄Scanning electron micrograph (c).

FIG. 4-a: and (3) a transmission electron microscope image of D-Ag after adding D-penicillamine and silver nitrate and stirring for 2 minutes.

FIG. 4-b: transmission electron microscopy of D-Ag after 14 minutes stirring with D-penicillamine and silver nitrate.

FIG. 4-c: and (3) a transmission electron microscope image of D-Ag after adding D-penicillamine and silver nitrate and stirring for 60 minutes.

FIG. 4-d: and (3) a transmission electron microscope image of D-Ag after adding D-penicillamine and silver nitrate and stirring for 90 minutes.

FIG. 5-a: d-penicillamine and silver nitrate are added and stirred for 2 minutes, and then a high-resolution transmission electron microscope image of D-Ag is obtained.

FIG. 5-b: d-penicillamine and silver nitrate are added and stirred for 90 minutes, and then a high-resolution transmission electron microscope image of D-Ag is obtained.

FIG. 6-a: adding D-penicillamine and silver nitrate, stirring for 1 minute, and then D₄Transmission electron micrograph (D).

FIG. 6-b: adding D-penicillamineAfter 3 minutes of stirring with silver nitrate D₄Transmission electron micrograph (D).

FIG. 6-c: adding D-penicillamine and silver nitrate, stirring for 15 minutes, and then adding D₄Transmission electron micrograph (D).

FIG. 6-d: adding D-penicillamine and silver nitrate, stirring for 15 minutes, and then adding D₄High resolution transmission electron microscopy.

FIG. 7-a: adding D-penicillamine and silver nitrate, stirring for 1 minute, and then D₄High resolution transmission electron microscopy.

FIG. 7-b: adding D-penicillamine and silver nitrate, stirring for 1 hour, and then D₄High resolution transmission electron microscopy.

FIG. 8-a: atomic force microscopy of D-Ag.

FIG. 8-b: d₄Atomic force microscopy of (2).

FIG. 9-a: D-Ag-D₄X-ray diffraction pattern of (a).

FIG. 9-b: amplified D-Ag-D₄X-ray diffraction pattern of (a).

FIG. 10-a: D-Ag-D₄Ultraviolet and visible absorption spectrum of (1).

FIG. 10-b: d-penicillamine, L-penicillamine, D₁、L₁、D₄、L₄Circular dichroism spectrum of (a).

FIG. 10-c: D-Ag-D₄Circular dichroism spectrum of (a).

FIG. 10-d: D-Ag-D₄The light emission spectrum of (1).

FIG. 10-e: luminescence lifetime of D-Ag at different wavelengths.

FIG. 10-f: the luminescence spectrum of D-Ag changes with increasing temperature.

FIG. 10-g: and calculating the band structure of the obtained D-Ag by DFT.

FIG. 10-h: calculating (a) VBM and (b) CBM of the obtained D-Ag by DFT theory.

FIG. 10-i: the energy level difference of the D-Ag is obtained through the solid ultraviolet spectrum of the D-Ag.

FIG. 10-j: proposed charge transfer model within a cluster.

FIG. 10-k: the proposed D-Ag luminescence principle diagram.

FIG. 11-a: D-Ag, D₄, L₄UV-VIS absorption spectrum after 14 days of stirring.

FIG. 11-b: d-penicillamine, D-Ag, D₄, L₄Round dichroism after 14 days of stirring.

FIG. 11-c: D-Ag, D₄, L₄X-ray diffraction pattern after 14 days of stirring.

FIG. 11-d: D-Ag, D₄, L₄Luminescence spectrum after stirring for 14 days.

FIG. 12: the experimental mechanism and the result of the invention are summarized schematically.

Detailed Description

The whole experimental mechanism and results of the invention are shown in fig. 12, and it can be seen from the figure that the chiral D-penicillamine (DPA) (or L-penicillamine (LPA)) and silver nitrate solution are stirred at room temperature for 1-2 hours to generate a white silver cluster aggregate turbid solution, and the silver cluster aggregate emits orange-red light under the irradiation of an ultraviolet lamp. This phenomenon of luminescence only occurs when the molar ratio of the DPA and silver nitrate charges is 1:1, when they form a fibrous structure; when the molar ratio of the silver clusters to the silver clusters is 4:1, only white silver clusters are formed, no luminescence phenomenon is generated under the irradiation of an ultraviolet lamp, and a scanning electron microscope shows that the silver clusters form a sheet structure. In addition, the single crystal structure of the silver cluster aggregate is shown, and only sulfur atoms and silver atoms are shown in the figure, and other carbon atoms, oxygen atoms, nitrogen atoms, and hydrogen atoms are not shown in order to clarify the single crystal structure skeleton of the silver cluster aggregate.

The present invention is described in more detail by the following examples, which are not intended to limit the present invention.

EXAMPLE 1 preparation of D-Penicilliamine stabilized silver Cluster D-Ag

Adding 25 mg of D-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing to stir for half an hour after the solution is turbid, and stirring for about 1.5 hours to obtain the fibrous silver cluster aggregate with adjustable chiral inversion and luminescence. The silver cluster aggregates in this case are driven primarily by the silver action. The solution is stirred for 14 days to obtain fibrous silver cluster aggregates, the main driving force is silver action, dipole-dipole action and hydrogen bond synergistic action, and chiral inversion and luminescence behaviors are shown.

Example 2D-Penicilliamine stabilized silver Cluster D₁Preparation of

Adding 37.5 mg of D-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing to stir for half an hour after the solution is turbid, and stirring for about 1.5 hours to obtain the fibrous silver cluster aggregate with adjustable chiral inversion and luminescence. The silver cluster aggregates in this case are driven primarily by the silver action. The solution is stirred for 14 days to obtain fibrous silver cluster aggregates, the main driving force is silver action, dipole-dipole action and hydrogen bond synergistic action, and chiral inversion and luminescence behaviors are shown.

Example 3D-Penicilliamine stabilized silver Cluster D₂Preparation of

Adding 50 mg of D-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing stirring after the solution is turbid, and stirring for about 1.2 hours to obtain a silver cluster aggregate which does not show obvious chiral inversion and luminescence behaviors. The silver clusters in this case are a mixture of fibrous and platelet structures, most of which are platelet structures, driven primarily by hydrogen bonds. The solution is stirred for 14 days, fibrous silver cluster aggregates can be obtained, the main driving force is the synergy of dipole-dipole effect and hydrogen bonds, and chiral reversal and luminescence behavior are not shown.

Example 4D-Penicilliamine stabilized silver Cluster D₃Preparation of

Adding 75 mg of D-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing stirring after the solution is turbid, and stirring for about 1 hour to obtain the silver cluster aggregate which does not show chiral inversion and luminescence behaviors. The silver clusters in this case are a mixture of fibrous and platelet structures, most of which are platelet structures, driven primarily by hydrogen bonds. The solution is stirred for 14 days, fibrous silver cluster aggregates can be obtained, the main driving force is the synergy of dipole-dipole effect and hydrogen bonds, and chiral reversal and luminescence behavior are not shown.

Example 5D-Penicilliamine stabilized silver Cluster D₄Preparation of

Adding 100 mg of D-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing to stir for half an hour after the solution is turbid, and stirring for about 1 hour to obtain the silver cluster aggregate which does not show chiral inversion and luminescence behaviors. The silver clusters are now completely sheet-like structures, driven primarily by hydrogen bonds. The solution is stirred for 14 days, fibrous silver cluster aggregates can be obtained, the main driving force is the synergy of dipole-dipole effect and hydrogen bonds, and chiral reversal and luminescence behavior are not shown.

EXAMPLE 6 preparation of L-Penicillium amine stabilized silver Cluster L-Ag

Adding 25 mg of L-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing to stir for half an hour after the solution is turbid, and stirring for about 1.5 hours to obtain the fibrous silver cluster aggregate with adjustable chiral inversion and luminescence. The silver cluster aggregates in this case are driven primarily by the silver action. The solution is continuously stirred for 14 days, fibrous silver cluster aggregates can be obtained, the main driving force is silver action, dipole-dipole action and hydrogen bond synergistic action, and chiral inversion and luminescence behaviors are displayed.

Example 7L-Penicilliamine stabilized silver Cluster L₁Preparation of

Adding 37.5 mg of L-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing to stir for half an hour after the solution is turbid, and stirring for about 1.5 hours to obtain the fibrous silver cluster aggregate with adjustable chiral inversion and luminescence. The silver cluster aggregates in this case are driven primarily by the silver action. The solution is continuously stirred for 14 days, fibrous silver cluster aggregates can be obtained, the main driving force is silver action, dipole-dipole action and hydrogen bond synergistic action, and chiral inversion and luminescence behaviors are displayed.

Example 8L-Penicilliamine stabilized silver Cluster L₂Preparation of

Adding 50 mg of L-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing stirring after the solution is turbid, and stirring for about 1.2 hours to obtain a silver cluster aggregate which does not show obvious chiral inversion and luminescence behaviors. The silver clusters in this case are a mixture of fibrous and platelet structures, most of which are platelet structures, driven primarily by hydrogen bonds. The solution is stirred for 14 days, fibrous silver cluster aggregates can be obtained, the main driving force is the synergy of dipole-dipole effect and hydrogen bonds, and chiral reversal and luminescence behavior are not shown.

Example 9L-Penicilliamine stabilized silver Cluster L₃Preparation of

Adding 75 mg of L-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing stirring after the solution is turbid, and stirring for about 1 hour to obtain the silver cluster aggregate which does not show chiral inversion and luminescence behaviors. The silver clusters in this case are a mixture of fibrous and platelet structures, most of which are platelet structures, driven primarily by hydrogen bonds. The solution is stirred for 14 days, fibrous silver cluster aggregates can be obtained, the main driving force is the synergy of dipole-dipole effect and hydrogen bonds, and chiral reversal and luminescence behavior are not shown.

Example 10L-Penicilliamine stabilized silver Cluster L₄Preparation of

Adding 100 mg of L-penicillamine into 5mL of double distilled water, adding a silver nitrate solution (29 mg of silver nitrate is dissolved in 3mL of double distilled water), stirring, continuing stirring after the solution is turbid, and stirring for about 1 hour to obtain a silver cluster aggregate which does not show chiral inversion and luminescence behaviors. The silver clusters are now completely sheet-like structures, driven primarily by hydrogen bonds. The solution is stirred for 14 days, fibrous silver cluster aggregates can be obtained, the main driving force is the synergy of dipole-dipole effect and hydrogen bonds, and chiral reversal and luminescence behavior are not shown.

The silver cluster aggregates obtained in examples 1 to 10 were subjected to studies on single crystals, scanning electron microscopes, transmission electron microscopes, atomic force microscopes, circular dichroism spectra, luminescence spectra, theoretical calculations, and the like, and the specific results were as follows:

FIG. 1: a single crystal structure of L-Ag; figure 1 shows that L-Ag contains many hydrogen bonds and silver-silver interactions, indicating that hydrogen bonds and silver-silver interactions are important driving forces for crystal formation.

FIG. 2: a double-spiral structure frame formed by sulfur and silver in the L-Ag single crystal; FIG. 2 shows that in the L-Ag single crystal structure, Ag and S are alternately arranged and the whole single crystal is uncharged. The single crystal can be regarded as Ag₂And Ag₆And Ag₂The distance of Ag.cndot.Ag in (C) is 2.953A₆The minimum Ag.cndot.Ag distance is 3.086A; in addition, the unit cell contains one secondary Ag-S bond, is 3.037A in length, and the shortest S.cndot.S distance is 3.418A.

FIG. 3-a: scanning electron microscope images of D-Ag; fig. 3-a shows that D-Ag is a fiber structure, with a length of several tens of micrometers and a width of several tens of nanometers.

FIG. 3-b: d₁Scanning electron microscope images of; FIG. 3-b shows D₁Is a fiber structure, with a length of tens of microns and a width of tens of nanometers.

FIG. 3-c: d₂Scanning electron microscope images of; FIG. 3-c shows D₂The composite material is a mixture of a fiber structure and a sheet structure, wherein the length of the fiber structure is more than ten microns, and the length and the width of the sheet structure are 1-5 microns.

FIG. 3-d: d₃Scanning electron microscope images of; FIG. 3-D shows D₃Is a mixture of fibrous structures and sheet-like structures, the majority of which are sheet-like structures.

FIG. 3-e: d₄Scanning electron microscope images of; FIG. 3-e shows D₄The composite material is completely composed of a sheet structure, and the length and the width of the composite material are between 1 and 5 micrometers.

FIG. 4-a: a transmission electron microscope image of D-Ag after adding D-penicillamine and silver nitrate and stirring for 2 minutes; figure 4-a shows that silver nanoclusters are rapidly formed after addition of D-penicillamine and silver nitrate, and in combination with the single crystal results, we believe that hydrogen bonding and silver-silver interaction are the main driving forces for silver nanocluster formation. The scale in the figure is 50 nm.

FIG. 4-b: a transmission electron microscope image of D-Ag after adding D-penicillamine and silver nitrate and stirring for 14 minutes; figure 4-b shows that after 14 minutes of stirring, the silver nanoclusters are gradually aligned along a linear structure, indicating the driving effect of the silver action. The scale in the figure is 50 nm.

FIG. 4-c: a transmission electron microscope image of D-Ag is obtained after D-penicillamine and silver nitrate are added and stirred for 60 minutes; figure 4-c shows that after stirring for 60 minutes, the solution was cloudy and the linear arrangement of silver nanoclusters was cleaner, further illustrating the important driving role of the silver action. The scale in the figure is 50 nm.

FIG. 4-d: a transmission electron microscope image of D-Ag is obtained after D-penicillamine and silver nitrate are added and stirred for 90 minutes; fig. 4-d shows that after stirring for 90 minutes, the solution has become very cloudy and the linear arrangement of silver nanoclusters is more mature, indicating that silver-silver action driven silver cluster aggregates have formed. The scale in the figure is 50 nm.

FIG. 5-a: d-penicillamine and silver nitrate are added and stirred for 2 minutes, and then a high-resolution transmission electron microscope image of D-Ag is obtained; figure 5-a shows that silver nanoclusters have been formed after stirring D-penicillamine and silver nitrate for 2 minutes.

FIG. 5-b: d-penicillamine and silver nitrate are added and stirred for 90 minutes, and then a high-resolution transmission electron microscope image of D-Ag is obtained; figure 5-b shows that after stirring for 90 minutes a well-matured fiber structure was formed, but still assembled from silver nanoclusters.

FIG. 6-a: adding D-penicillamine and silver nitrate, stirring for 1 minute, and then D₄Transmission electron microscopy images of; FIG. 6-a shows that silver clusters formed rapidly after 1 minute of stirring with D-penicillamine and silver nitrate. The scale in the figure is 500 nm.

FIG. 6-b: adding D-penicillamine and silver nitrate, stirring for 3 minutes, and then adding D₄Transmission electron microscopy images of; FIG. 6-b shows that after 3 minutes of stirring, the solution is already cloudy and the silver clusters are more regular. The scale in the figure is 500 nm.

FIG. 6-c: adding D-penicillamine and silver nitrate, stirring for 15 minutes, and then adding D₄Transmission electron microscopy images of; FIG. 6-c shows that after 15 minutes of stirring, the silver clusters are well organized. The scale in the figure is 500 nm.

FIG. 6-d: adding intoD-Penicillin and silver nitrate after 15 minutes stirring₄High resolution transmission electron microscopy images; FIG. 6-d shows that after stirring for 15 minutes, the regular silver cluster aggregates are also composed of silver nanoclusters. The scale in the figure is 20 nm.

FIG. 7-a: adding D-penicillamine and silver nitrate, stirring for 1 minute, and then D₄High resolution transmission electron microscopy images; FIG. 7-a shows that after 1 minute of stirring, silver nanoclusters are formed, similar to D-Ag, indicating D₄The initial silver clusters formed are also driven by hydrogen bonding and silver-silver interaction.

FIG. 7-b: adding D-penicillamine and silver nitrate, stirring for 1 hour, and then D₄High resolution transmission electron microscopy images; figure 7-b shows that after 1 hour of stirring with D-penicillamine and silver nitrate, the silver nanoclusters are further assembled, but the formation is a sheet structure, indicating that the silver-silver effect is not its primary driving force, and the hydrogen bonds further drive the silver nanoclusters to form a sheet structure.

FIG. 8-a: atomic force microscopy of D-Ag; fig. 8-a shows that the thickness of the D-Ag fiber is several tens of nanometers. The scale in the figure is 1 micron.

FIG. 8-b: d₄An atomic force microscope image of (a); FIG. 8-b shows D₄The thickness of the sheet structure is tens of nanometers, and the thickness of the step is 1.2 nm, which is consistent with the unit cell parameter b. The scale in the figure is 1 micron.

FIG. 9-a: D-Ag-D₄X-ray diffraction pattern of (a); FIG. 9-a shows D-Ag-D₄There are many diffraction peaks indicating that their structure is very ordered. Wherein a-g represent diffraction peaks of (001), (010), (01 ī), (10 ī), (1 ī ī), (011) and (1 ī 1), respectively.

FIG. 9-b: amplified D-Ag-D₄X-ray diffraction pattern of (a); D-Ag and D in FIG. 9-b₁The distances corresponding to the diffraction peaks are 0.309 nm, 0.302 nm and 0.294 nm respectively, and the distances are respectively equal to Ag₆The shortest silver-silver distance, the secondary Ag-S bond length and Ag₂The silver distances in (FIG. 2) are similar, and their presence indicates Ag₆Has strong silver-silver function, and secondary Ag-S bond is stronger, or Ag₂Has strong silver and silver effects.

FIG. 10-a: D-Ag-D₄Ultraviolet ray of (2)A visible absorption spectrum; FIG. 10-a shows D-Ag-D₄Has a strong absorption near 280 nm, and is referred to as a charge transfer transition from ligand to metal: (¹LMCT), and D-Ag and D₁Shows strong absorption at 350-600 nm, which is referred to as the charge transfer transition from ligand to metal: (¹LMMCT). In addition, D-Ag-D₄All show the turbid solution shown in the figure.

FIG. 10-b: d-penicillamine, L-penicillamine, D₁、L₁、D₄、L₄Circular dichroism chromatogram of (1); as can be seen from FIG. 10-b, D-penicillamine (DPA), L-penicillamine (LPA), D₁、L₁、D₄、L₄Coexisting in three chiral absorptions, the first peak at 224 nm is identified as the absorption peak of chiral penicillamine; the second absorption peak at 270-300 nm is designated as the charge transfer transition from ligand to metal (C:)¹LMCT); the third peak appears at 360 nm (D-Ag) and 322 nm (D)₄) Is referred to as¹Absorption peaks of LMMCT, which are respectively derived from Ag₆And Ag₂. From D-Ag to D₄In the transformation of (2), it can be seen that the source is Ag₆Is/are as follows¹The LMMCT gradually decreased with a concomitant Ag-derived source₂Is/are as follows¹LMMCT is relatively enhanced, which is consistent with X-ray diffraction results. In addition, D is comparable to the starting materials DPA and LPA₁And L₁All show inverted chiral signals, and D₄And L₄The chiral signals of (A) are respectively consistent with the DPA and LPA of the raw materials, and the chiral inversion phenomenon does not occur.

FIG. 10-c: D-Ag-D₄Circular dichroism chromatogram of (1); as can be seen from FIG. 10-c, D-Ag and D₁And D₂-D₄The chiral signals of (A) are opposite to each other, further illustrating that their driving forces are different, D-Ag and D₁Mainly silver-silver action driven, and D₂-D₄Is hydrogen bond driven.

FIG. 10-d: D-Ag-D₄The luminescence spectrum of (a); from FIG. 10-D, it can be seen that from D-Ag to D₄The light-emitting spectrum is gradually weakened, which shows that only the silver cluster formed by the driving of silver and silver action has strong light-emitting phenomenon, and hydrogen bondsThe silver clusters formed by driving do not exhibit such a light emission phenomenon.

FIG. 10-e: the luminescence lifetime of D-Ag at different wavelengths; as can be seen from FIG. 10-e, the luminescence lifetimes of D-Ag at 620 nm, 640 nm, and 660 nm are similar, all in the range of 4.6-4.8 μ s, indicating that D-Ag has the same luminescence center at different wavelengths.

FIG. 10-f: the light-emitting spectrum of the D-Ag changes along with the increase of the temperature; as can be seen from fig. 10-f, the luminescence of the silver cluster aggregates gradually decreased with increasing temperature, and the luminescence peak position gradually red-shifted, which is the result of vibrational relaxation and nonradiative transition, and this result excludes the possibility of thermally activated delayed phosphorescence and luminescence of metal defect state.

FIG. 10-g: calculating the band structure of the D-Ag by DFT; as can be seen from FIG. 10-g, D-Ag is a direct bandgap structure, and the energy difference between the Valence Band Maximum (VBM) and the Conduction Band Minimum (CBM) is 2.36 eV.

FIG. 10-h: calculating (a) VBM and (b) CBM of the D-Ag by DFT theory; as can be seen from FIG. 10-h, the Valence Band Maximum (VBM) is mainly distributed over Ag₂ + Ag₄Group, and Conduction Band Minimum (CBM) mainly distributed in Ag₆A group.

FIG. 10-i: the energy level difference of the D-Ag is obtained through the solid ultraviolet spectrum of the D-Ag; as can be seen from FIG. 10-i, the difference between the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) of solid D-Ag is 3.42 eV, which is greater than that of VBM and CBM, indicating that the luminescence of the silver clusters does not originate from the electron transitions of VBM and CBM.

FIG. 10-j: proposed intra-cluster charge transfer model; as can be seen from FIG. 10-j, we propose a charge transfer model within the clusters that is good at explaining the phenomenon of luminescence of silver clusters, namely from (Ag)₂ + Ag₄) To Ag₆The groups present charge transfer which inhibits charge transfer from Ag₆Of radicals³LMMCT luminescence transitions.

FIG. 10-k: the proposed D-Ag luminescence schematic diagram; as can be seen from FIG. 10-k, we propose a schematic diagram of the luminescence of D-Ag, only when Ag₆Silver phase of silverThe silver cluster aggregates exhibit strong luminescence when the interaction is very strong, i.e., the silver clusters are predominantly silver-silver interaction driven, otherwise the luminescence is quenched by charge transfer transitions within the clusters.

FIG. 11-a: D-Ag, D₄, L₄Ultraviolet-visible absorption spectrogram after stirring for 14 days; as can be seen in FIG. 11-a, and D₄And L₄In contrast, D-Ag has an ultraviolet-visible absorption spectrum¹The LMCT generates obvious red shift and has stronger¹LMMCT absorb, consistent with their light emission behavior.

FIG. 11-b: d-penicillamine, D-Ag, D₄, L₄Round dichroism after 14 days of stirring; as can be seen from FIG. 11-b, D was around 225 nm after stirring for 14 days₄And L₄Both chiral absorptions appeared, indicating that they appeared to be different structures, while D-Ag agreed with the chiral absorption signal upon its rapid formation.

FIG. 11-c: D-Ag, D₄, L₄X-ray diffraction pattern after 14 days of stirring; as can be seen from FIG. 11-c, after stirring for 14 days, D₄And L₄Both sets of hexagonal packing structures appeared and the respective unit cell parameters a = b = 1.15 nm and a = b = 1.21 nm were substantially identical to the unit cell parameters a = 1.16 nm, b = 1.27 nm of their single crystals, indicating that D is a more stable structure to maintain₄And L₄The two sets of hexagonal structures are alternately arranged along the c-axis.

FIG. 11-d: D-Ag, D₄, L₄Luminescence spectrum after stirring for 14 days; as can be seen from FIG. 11-D, D-Ag exhibited strong luminescence properties, indicating that the silver-silver interaction between them was not weakened by long-term stirring, with the driving force being silver-silver interaction, synergy of hydrogen bonding and dipole-dipole interaction, while D₄And L₄There is no luminescent property although it becomes a fibrous structure, the driving forces among which are hydrogen bonding and dipole-dipole interactions.