CN111548368B

CN111548368B - Copper nanocluster with high stability and near-infrared phosphorescence and preparation method thereof

Info

Publication number: CN111548368B
Application number: CN202010465189.7A
Authority: CN
Inventors: 宋永波; 李�浩; 朱满洲; 周传君
Original assignee: Anhui University
Current assignee: Anhui University
Priority date: 2020-05-28
Filing date: 2020-05-28
Publication date: 2023-02-03
Anticipated expiration: 2040-05-28
Also published as: CN111548368A

Abstract

The invention discloses a copper nanocluster with high stability and near-infrared phosphorescence and a preparation method thereof, belonging to the cross field of coordination chemistry and nano materials. The copper nanocluster takes common p-tert-butylbenzene thiophenol and triphenylphosphine as protection ligands, and a copper nanocluster material with high yield and near-infrared luminescence is synthesized by a simple one-pot method at room temperature in an air atmosphere. The molecular formula of the copper nanocluster is [ Cu ] ₁₁ (SC ₁₀ H ₁₃ ) ₉ (PC ₁₈ H ₁₅ ) ₆ ](SbF ₆ ) ₂ Belongs to the monoclinic system, and the space group is P21/n. At room temperature, the solution and the solid of the copper nanocluster have strong red phosphorescence, and the absolute quantum yield of the solid is 22%. The solution of the copper nanocluster has strong stability at room temperature in an air atmosphere.

Description

Copper nanocluster with high stability and near-infrared phosphorescence and preparation method thereof

Technical Field

The invention belongs to the subject of nano materials, and relates to a copper nanocluster with high stability and near-infrared phosphorescence and a preparation method thereof.

Background

For having d ¹⁰ Photoluminescence is one of the most interesting properties for nanoclusters of electronic metals. Among them, the Cu (I) cluster has been widely studied because of its abundant raw material reserves, low price and ready availability, and particularly, it has unique optical properties, and it has been applied to highly efficient light-emitting inks, organic light-emitting materials, and the like.

Some Cu-X (X represents a halogen atom, e.g. Cu) ₄ I ₄ 、Cu ₃ I ₆ Etc.) clusters generally have strong phosphorescent and thermochromic behavior in the solid state. To is coming toIn pursuit of more copper nanoclusters having novel structural and optical properties, scientists used some organic ligands to synthesize copper nanoclusters, such as thiol/selenium ligands, phosphine ligands, alkyne ligands, etc. Shimada and his colleagues reported a series of Cu (I) clusters-Cu protected by thiol-phosphine bridging ligands ₂ 、Cu ₄ And Cu ₆ And found to have different light emission behaviors. Zhu Manzhou teaches a topic group to utilize the ligand effect and use the same synthetic method to obtain two copper nanoclusters, cu ₁₃ And Cu ₈ They are protected by phenylselenol and thiophenol, respectively. The results show that the difference of the ligands induces the structural difference, thereby leading to different thermochromic behaviors.

However, most of the atomically precise copper nanoclusters reported so far only have luminescence properties in a solid state, and few mention is made of optical properties of the copper nanoclusters in a solution state. This may be due to the lack of "gold-philic" interactions and instability of the copper nanoclusters in the solution state. This phenomenon has greatly hindered the use of copper nanoclusters in photosensitive materials, cell imaging, and biomarkers, among others. Therefore, the copper nanoclusters with good stability and strong fluorescence under the condition of preparing the solution still have the difficult problem to be solved urgently.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a copper nanocluster with high stability and near-infrared phosphorescence and a preparation method thereof. The copper nanocluster of the invention has good stability and photoluminescence performance, and particularly has high stability, near-infrared phosphorescence and larger Stokes shift in a solution state, so that the copper nanocluster has potential application value in the fields of biological markers and the like.

The copper nanocluster is protected by a mixed ligand and has the following molecular formula: [ Cu ] ₁₁ (SC ₁₀ H ₁₃ ) ₉ (PC ₁₈ H ₁₅ ) ₆ ](SbF ₆ ) ₂ Abbreviated as Cu ₁₁ Belongs to the monoclinic system, the space group is P21/n,

the preparation method of the copper nanocluster comprises the following steps:

the whole preparation process is carried out at room temperature under the condition of uniform stirring at 1200 rpm. First, 40 mg of cuprous chloride, 100 mg of tetraoctylammonium bromide, 15 ml of chloroform and 10 ml of methanol were added to a 100 ml pear-shaped flask. After 15 minutes of reaction, 100 mg of triphenylphosphine were added; after reacting for 30 minutes, adding 70 microliters of 4-tert-butyl thiophenol into the reaction system; after 30 minutes, weighing 50 mg of sodium borohydride solid, adding 5 ml of deionized water to prepare a solution, and directly and quickly adding the solution into the pear-shaped flask, wherein the solution immediately turns black; after the reaction is continuously stirred for 24 hours, stirring magnetons and aqueous solution in the reaction system are removed, and 5 ml of methanol solution dissolved with 100 mg of sodium hexafluoroantimonate is added; and then removing the organic solvent by a rotary evaporator, washing the organic solvent by methanol and toluene for several times respectively to remove redundant ligand and byproducts, finally dissolving the product in trichloromethane, diffusing normal hexane into the trichloromethane solution by using a gas phase diffusion method, and obtaining yellow needle-shaped crystals after one week, namely the target product.

By means of an X-ray single crystal diffractometer, we obtained Cu ₁₁ The structure of the nanoclusters. The results showed that the copper nanoclusters contained 11 Cu atoms, 9 4-tert-butylphenol ligands, and 6 triphenylphosphine ligands (fig. 1), via Cu-P and μ ₃ The coordination of-S-Cu forms a cage structure (FIG. 2). In addition, two sbfs were found at the periphery of the copper nanocluster molecule ₆ ^- Counter ion (fig. 1). In conclusion, the molecular formula of the copper nanocluster is determined as [ Cu ] ₁₁ (SC ₁₀ H ₁₃ ) ₉ (PC ₁₈ H ₁₅ ) ₆ ](SbF ₆ ) ₂ 。

For Cu ₁₁ The uv-vis absorption spectra in the nanocluster solution were measured. C is to beu ₁₁ The crystal was dissolved in chloroform, and its UV-visible absorption spectrum showed a shoulder only at 400nm, as shown in FIG. 3.

Method for Cu in solution state by using ultraviolet-visible light absorption spectrum ₁₁ The stability of the nanoclusters was verified and the results are shown in fig. 4. Mixing Cu ₁₁ The nanoclusters are dissolved in trichloromethane, and after the sample is placed in the air atmosphere at room temperature for 2 months, the ultraviolet-visible light absorption spectrum of the sample has no obvious change, which proves that Cu ₁₁ The cluster has better stability in the solution.

Cu ₁₁ Nanoclusters exhibit near infrared photoluminescence in both solids and solutions. FIG. 5 shows Cu ₁₁ Photos of the solid of the nanocluster and the chloroform solution under the irradiation of a 365nm ultraviolet lamp have visible bright red light; FIG. 6 shows Cu ₁₁ Excitation and emission spectra of nanoclusters in solids and solutions. Cu ₁₁ Maximum emission wavelength (. Lamda.) in chloroform solution _em ) Is 685nm (excitation wavelength is lambda) _ex =430 nm), and the maximum emission wavelength of the solid body (λ) _em ) At 675nm (excitation wavelength. Lambda. _ex =450 nm). Compared with the ultraviolet absorption spectrum, the Stokes shift is 280nm. By using integrating sphere to Cu ₁₁ The quantum yield of the nanoclusters was measured, and the results showed Cu ₁₁ The absolute quantum yields of nanoclusters in chloroform solution and solid were 7% and 22%, respectively.

The invention uses direct synthesis method to obtain a copper nanocluster with novel and stable structure and photoluminescence property. The copper nanocluster shows good stability and photoluminescence performance in solid and solution, and has potential application value in the fields of biological labeling and the like. The synthesis method of the cluster is simple and convenient, and the precise structure of the cluster can be represented by an X-ray single crystal diffractometer.

Drawings

FIG. 1 shows the present invention [ Cu ₁₁ (SC ₁₀ H ₁₃ ) ₉ (PC ₁₈ H ₁₅ ) ₆ ](SbF ₆ ) ₂ Schematic diagram of the general structure of (1).

FIG. 2 is Cu ₁₁ The overall framework of cluster structure.

FIG. 3 is Cu ₁₁ Ultraviolet-visible absorption spectrum of the cluster.

FIG. 4 is Cu ₁₁ Stability test data for clusters.

FIG. 5 is Cu ₁₁ Photographs of the solid state and the solution state under a fluorescent lamp and a 365nm ultraviolet lamp.

FIG. 6 is Cu ₁₁ Excitation, emission spectra in solid and solution state.

Detailed Description

The invention is further illustrated by the following specific examples:

example 1: synthesis of copper nanoclusters

The whole preparation process is carried out at room temperature under the condition of uniform stirring at 1200 rpm. Firstly, 40 mg of cuprous chloride, 100 mg of tetraoctylammonium bromide, 15 ml of trichloromethane and 10 ml of methanol are added into a 100 ml pear-shaped flask, and after 15 minutes of reaction, 100 mg of triphenylphosphine is added; after reacting for 30 minutes, adding 70 microliter of 4-tert-butyl thiophenol into the reaction system; after continuing to react for 30 minutes, quickly adding 5 ml of deionized water solution in which 50 mg of sodium borohydride is dissolved into the pear-shaped flask, and immediately turning the color of the solution black; continuously stirring for 24 hours, then removing the stirring magneton and the aqueous solution in the reaction system, adding 5 ml of methanol solution dissolved with 100 mg of sodium hexafluoroantimonate, and removing the organic solvent through a rotary evaporator; and then, washing the product for multiple times by using methanol and toluene respectively to remove redundant ligand and byproducts, finally dissolving the product in chloroform, diffusing n-hexane into the chloroform solution by using a gas phase diffusion method, and obtaining yellow needle crystals after one week, namely the target product.

Example 2: characterization of the Crystal Structure

The copper nanoclusters produced in example 1 were further characterized as follows:

(1) Determination of Crystal Structure

Selecting needle-like crystals under optical microscope, and selecting a particlePreparing Ga-Kalpha with crystals with good amount and larger size under the protection of nitrogen atmosphere (170K)

The data was collected by a Bruker D8 Venture diffractometer from a light source, after which the data was integrated and restored using APEX 3 software. The structure was then parsed and refined in Olex 2 software using ShelXT and ShelXL programs. All Au, ag and S atoms are directly found, and the remaining non-hydrogen atoms are generated by differential fourier synthesis. All non-hydrogen atoms are anisotropically refined. All hydrogen atoms are given positions by geometric calculations and are isotropically refined. The electron density generated by residual solvent molecules was filtered from the data using the SQUEEZE method in PLATON. Detailed crystal data are shown in table 1 below, and important bond length data are shown in table 2 below.

TABLE 1 Cu ₁₁ Cluster principal crystallographic data

TABLE 2 Cu ₁₁ Nanocluster dominant bond length statistics

Cu1-Cu2	2.783(4)	Cu9-S3	2.239(6)
				Cu1-Cu6	2.995(4)	Cu6-S4	2.238(5)
Cu2-Cu11	3.039(4)	Cu8-S4	2.277(5)
				Cu6-Cu11	3.045(4)	Cu11-S4	2.248(5)
Cu7-Cu11	2.894(4)	Cu1-S5	2.274(5)
				Cu5-P1	2.223(5)	Cu3-S5	2.260(5)
Cu10-P2	2.242(6)	Cu7-S5	2.234(5)
				Cu4-P3	2.203(5)	Cu3-S6	2.272(5)
Cu9-P4	2.199(5)	Cu6-S6	2.293(5)
				Cu8-P5	2.212(5)	Cu10-S6	2.259(5)
Cu3-P6	2.204(6)	Cu2-S7	2.283(5)
				Cu1-S1	2.220(5)	Cu5-S7	2.250(5)
Cu5-S1	2.284(5)	Cu8-S7	2.243(5)
				Cu6-S1	2.264(5)	Cu2-S8	2.226(5)
Cu1-S2	2.235(5)	Cu9-S8	2.249(5)
				Cu2-S2	2.288(5)	Cu11-S8	2.221(5)
Cu4-S2	2.296(4)	Cu7-S9	2.215(6)
				Cu4-S3	2.247(5)	Cu10-S9	2.304(5)
Cu7-S3	2.273(5)	Cu11-S9	2.239(6)

The above examples are merely illustrative of the present invention, and other embodiments of the present invention are possible. However, all the technical solutions formed by equivalent alternatives or equivalent modifications fall within the protection scope of the present invention.

Claims

1. A copper nanocluster having high stability and near-infrared phosphorescence, comprising:

the molecular formula of the copper nanocluster is [ Cu ] ₁₁ (SC ₁₀ H ₁₃ ) ₉ (PC ₁₈ H ₁₅ ) ₆ ](SbF ₆ ) ₂ Abbreviated as Cu ₁₁ Belonging to the monoclinic system, space group P21/n, a =26.564 (2) A, b =26.692 (2) A, c =33.045 (3) A,V=22448(3) Å ³ ；

the copper nanocluster consists of 11 Cu atoms, 9 4-tert-butyl thiophenol ligands and 6 triphenylphosphine ligands, and is prepared by mixing P-Cu with P-Cuµ ₃ -S-Cu coordination forming a cage structure and provided with two SbFs ₆ ^- A counter ion.

2. A method for producing the copper nanocluster of claim 1, comprising the steps of:

adding 40 mg of cuprous chloride, 100 mg of tetraoctylammonium bromide, 15 ml of trichloromethane and 10 ml of methanol into a reactor, reacting for 15 minutes, and adding 100 mg of triphenylphosphine; after reacting for 30 minutes, adding 70 microliter of 4-tert-butyl thiophenol into the reaction system; after 30 minutes, weighing 50 mg of sodium borohydride solid, adding the sodium borohydride solid into deionized water to prepare a solution, and directly adding the solution into the system, wherein the solution immediately turns black; after the reaction is continuously stirred for 24 hours, stirring magnetons and aqueous solution in the reaction system are removed, and 5 ml of methanol solution dissolved with 100 mg of sodium hexafluoroantimonate is added; and then, removing the solvent by rotary evaporation, washing by using methanol and toluene respectively, dissolving the product in chloroform, diffusing n-hexane into the chloroform solution by using a gas phase diffusion method, and obtaining yellow needle-shaped crystals after one week, namely the target product.

3. The method of claim 2, wherein:

the whole preparation process is carried out at room temperature under the condition of uniform stirring at 1200 rpm.