Organic framework material and preparation method thereof

Abstract

The invention provides an organic framework material and a preparation method thereof, and belongs to the technical field of metal-organic framework materials. The organic framework material is prepared from nitrate of lanthanide series metal and an organic ligand through a solvothermal method, and the organic ligand is 4, 4 '-[[2-[[3-(4-carboxyl phenoxy)-2, 2-bis [(4-carboxyl phenoxy) methyl] propoxy] methyl]-2-[(4-carboxyl phenoxy) methyl]-1, 3-propylene glycol] bis (oxy)] dibenzoic acid. The organic framework material prepared by the invention shows excellent second harmonic performance, and the highest strength can be 4 times or more than 4 times that of monopotassium phosphate crystals.

Description

Technical Field

[0001] The invention relates to the technical field of metal-organic framework materials, and in particular to an organic framework material and a preparation method thereof. Background Art

[0002] When laser acts on second-order nonlinear optical materials, in addition to light (linear part) with the same frequency as the incident frequency w, it also generates doubled frequency light with a frequency of 2w, which is called the second harmonic generation (SHG) effect. As a common characterization form of second-order nonlinear optical materials, SHG has been widely used in the field of harmonic imaging and sensing. The strong localization of nonlinear effects reduces the background interference caused by non-focused optics, improves the signal-to-noise ratio and three-dimensional spatial resolution; at the same time, it greatly reduces the photobleaching and phototoxicity on the non-focal plane, so that the sample can be imaged for a long time without affecting its activity. In addition, since the second harmonic microscope uses near-infrared light pumping, the absorption and scattering effects of the tissue on it are minimal, and the pump light can penetrate the tissue. Compared with traditional microscopes such as laser scanning confocal microscopes, it can perform deeper imaging. In addition, the emission wavelength and pump wavelength of the second harmonic imaging technology are far apart, which is easy to effectively separate. Despite these advantages, as a second-order nonlinear optical phenomenon, the intensity of SHG depends largely on the crystal structure. Only when the space group is restricted to non-centrosymmetric can it have SHG performance, which greatly limits the application of materials.

[0003] Metal-organic frameworks (MOFs) are composed of metal atoms / metal clusters and organic ligands bonded by coordination bonds. They have the advantages of diverse structures, adjustable pore sizes, multiple optical sites, and good thermal / hydrostability. Therefore, MOFs designed with asymmetric centers have good second harmonic performance. However, relevant theories are still scarce, and the relationship between the nonlinear optical properties of MOFs and pump wavelength, structural characteristics, metal atoms, and crystal size also needs to be systematically studied. Summary of the invention

[0004] Based on the above content, the present invention aims to provide an organic framework material and a preparation method thereof.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is a method for preparing an organic framework material, comprising the following steps:

[0007] Adding nitrate of lanthanide metal and organic ligand into a mixed solvent to obtain a mixed solution, adding 1-3 mL of acid solution, placing the obtained solution into a reactor liner, heating at 200° C. for 40-50 hours, centrifuging and washing, and obtaining a lanthanide metal-organic framework material with excellent second harmonic performance;

[0008] The organic ligand is 4,4'-[[2-[[3-(4-carboxyphenoxy)-2,2-bis[(4-carboxyphenoxy)methyl]propoxy]methyl]-2-[(4-carboxyphenoxy)methyl]-1,3-propanediol]bis(oxyl)]bisbenzoic acid; the molar ratio of the metal atom in the nitrate of the lanthanide metal to the organic ligand is 3:1.

[0009] The structural formula of the 4,4'-[[2-[[3-(4-carboxyphenoxy)-2,2-bis[(4-carboxyphenoxy)methyl]propoxy]methyl]-2-[(4-carboxyphenoxy)methyl]-1,3-propanediol]bis(oxy)]bisbenzoic acid is:

[0010]

[0011] In a preferred embodiment of the present invention, the nitrate of the lanthanide metal is lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate or terbium nitrate.

[0012] In a preferred embodiment of the present invention, the mixed solvent is a mixture of an organic solvent and water in a volume ratio of 8:1; the organic solvent is N,N-dimethylacetamide or N,N-diethylformamide.

[0013] In a preferred embodiment of the present invention, the acid solution is nitric acid, hydrochloric acid, sulfuric acid or acetic acid, the solvent is water and the concentration is 0.5-2M.

[0014] The second technical solution of the present invention is an organic framework material prepared by the above preparation method.

[0015] The present invention discloses the following technical effects:

[0016] 1. The lanthanide metal-organic framework material with excellent second harmonic performance of the present invention is a rare systematic study on the synthesis / structure and performance of lanthanide metal-organic frameworks. Under the premise of the lack of systematic research on related lanthanide MOFs, the present invention provides an important experimental reference for enriching the database of coordination chemistry and MOFs materials.

[0017] 2. Compared with inorganic compounds, complexes or organic molecules, metal-organic framework materials are crystalline materials with ordered micropores, long-range ordered crystal structures and regular pores. Through single crystal analysis and PXRD, it was found that the crystals of this lanthanide metal-organic framework material are isomorphous. The microporous characteristics of MOFs were verified by nitrogen isotherm adsorption curves.

[0018] 3. The organic framework material prepared by the present invention exhibits excellent second harmonic performance, and the intensity can reach 4 times or more than that of potassium dihydrogen phosphate crystals. DETAILED DESCRIPTION

[0019] The contents of the present invention will be further explained below with reference to examples, but these examples do not limit the protection scope of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the protection scope of the present invention.

[0020] Embodiment 1:

[0021] The metal-organic framework material is synthesized by a solvothermal method using terbium nitrate and 4,4'-[[2-[[3-(4-carboxyphenoxy)-2,2-bis[(4-carboxyphenoxy)methyl]propoxy]methyl]-2-[(4-carboxyphenoxy)methyl]-1,3-propanediol]bis(oxy)]bisbenzoic acid. The specific synthesis route is as follows:

[0022] 0.3mmol of terbium nitrate and 0.1mmol of 4,4'-[[2-[[3-(4-carboxyphenoxy)-2,2-bis[(4-carboxyphenoxy)methyl]propoxy]methyl]-2-[(4-carboxyphenoxy)methyl]-1,3-propanediol]bis(oxy)]bisbenzoic acid were dissolved in 7mL of N,N-dimethylacetamide and 1mL of H2O mixed solvent, followed by adding 1mL of HNO3 aqueous solution (1M). The solution was encapsulated in a 20mL polytetrafluoroethylene reactor and placed in an oven at 200℃ for 45h. Cooled to room temperature, washed 3 times with N,N-dimethylacetamide to obtain a needle-shaped metal-organic framework material.

[0023] Embodiment 2:

[0024] Lanthanum nitrate and 4,4'-[[2-[[3-(4-carboxyphenoxy)-2,2-bis[(4-carboxyphenoxy)methyl]propoxy]methyl]-2-[(4-carboxyphenoxy)methyl]-1,3-propanediol]bis(oxy)]bisbenzoic acid were used to synthesize a metal-organic framework material by a solvothermal method. The specific synthesis route is as follows:

[0025] 0.3mmol of lanthanum nitrate and 0.1mmol of 4,4'-[[2-[[3-(4-carboxyphenoxy)-2,2-bis[(4-carboxyphenoxy)methyl]propoxy]methyl]-2-[(4-carboxyphenoxy)methyl]-1,3-propanediol]bis(oxy)]bisbenzoic acid were dissolved in 7mL of N,N-diethylformamide and 1mL of H2O mixed solvent, followed by adding 1mL of HNO3 aqueous solution (1M). The solution was encapsulated in a 20mL polytetrafluoroethylene reactor and placed in an oven at 200℃ for 50h. Cooled to room temperature, washed 3 times with N,N-diethylformamide to obtain a needle-shaped metal-organic framework material.

[0026] The metal-organic framework material prepared in the embodiment of the present invention exhibits excellent second harmonic performance, and the intensity can be up to 4 times or more than that of potassium dihydrogen phosphate crystals.

[0027] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an organic framework material, characterized in that: The following steps are involved: Adding nitrate of lanthanide metal and organic ligand into a mixed solvent to obtain a mixed solution, adding 1-3 mL of acid solution, placing the obtained solution into a reactor liner, heating at 200° C. for 40-50 hours, centrifuging and washing, and obtaining a lanthanide metal-organic framework material with excellent second harmonic performance; The organic ligand is 4,4'-[[2-[[3-(4-carboxyphenoxy)-2,2-bis[(4-carboxyphenoxy)methyl]propoxy]methyl]-2-[(4-carboxyphenoxy)methyl]-1,3-propanediol]bis(oxyl)]bisbenzoic acid; the molar ratio of the metal atom in the nitrate of the lanthanide metal to the organic ligand is 3:

1.

2. The method for preparing an organic framework material according to claim 1, characterized in that: The nitrate of the lanthanide metal is lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate or terbium nitrate.

3. The method for preparing an organic framework material according to claim 1, characterized in that: The mixed solvent is a mixture of an organic solvent and water in a volume ratio of 8:1; the organic solvent is N,N-dimethylacetamide or N,N-diethylformamide.

4. The method for preparing an organic framework material according to claim 1, characterized in that: The acid solution is nitric acid, hydrochloric acid, sulfuric acid or acetic acid, the solvent is water and the concentration is 0.5-2M.

5. An organic framework material prepared by the preparation method according to any one of claims 1 to 4.

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