CN105732671A - Spiral-containing cadmium metal organic framework fluorescent material and preparation method thereof - Google Patents

Abstract

A helix-containing cadmium metal-organic framework fluorescent material and a preparation method thereof, the material is a self-entangled helix-containing 1,4 dibenzyl (2-methylbenzimidazole) cadmium metal-organic framework, and the chemical formula is {[Zn( bmb)(mada)]·1.5H ₂ O} _<i>n</i> , bmb is 1,4 dibenzyl (2-methylbenzimidazole), mada is 1,3 adamantanediacetate anion; its preparation The method is to mix cadmium nitrate tetrahydrate, 1,4 dibenzyl (2-methylbenzimidazole), 1,3 adamantanediacetic acid, sodium hydroxide and distilled water to obtain the mixed solution A, and then move it to a In a polytetrafluoroethylene-lined stainless steel reaction kettle, keep the temperature at 170°C for three days, and then slowly lower it to room temperature at a rate of 5°C per hour to obtain colorless prismatic crystals, which are washed, filtered, and dried to obtain helical Cadmium metal organic framework fluorescent materials. The method of the invention is simple, and the prepared helical cadmium metal organic framework fluorescent material has stable fluorescent performance and can be applied to the field of luminescent material science.

Description

A kind of helical cadmium metal organic framework fluorescent material and preparation method thereof

technical field

The invention relates to a fluorescent material, in particular to a helical cadmium metal organic frame fluorescent material and a preparation method thereof.

Background technique

Helices are ubiquitous in nature, and metal-organic frameworks with helical structures often show some special properties due to their own structure, such as in luminescent materials, nonlinear optical materials, magnetic materials, superconducting materials and catalytic materials, etc. There are broad application prospects in all aspects.

Contents of the invention

The purpose of the present invention is to solve the deficiencies of the above technical problems, to provide a helical cadmium metal organic framework fluorescent material and its preparation method, the method is simple, the prepared material contains a helical structure, has excellent luminescence performance, and its synthesis method is simple , easy operation, high yield and good reproducibility.

The technical solution adopted by the present invention to solve the above technical problems is: a helical cadmium metal organic framework fluorescent material, which is self-entangled helical 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal Organic framework, the chemical formula is {[Zn(bmb)(m-ada)]·1.5H ₂ O} _n , where n is greater than one, bmb is 1,4-dibenzyl(2-methylbenzimidazole), m- ada is 1,3-adamantanediacetate anion; the simplified structure of bmb and mH ₂ ada is as follows:

bmb mH ₂ ada

The 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal organic framework belongs to the monoclinic crystal system, the space group is P2/c, and the unit cell parameter is a = 9.3237 (19) , b = 10.479(2) , c = 17.961(5) , α = 90°, β = 108.80(3)°, γ = 90°, V = 1661.2(7) ³ .

The basic structure of the 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal organic framework is that the central metal Cd(II) ion of the target metal organic framework is in an octahedral coordination environment, with two symmetrical The carboxyl oxygen atom on the sex-related m-ada ^2- anion is coordinated with the two nitrogen atoms of the two symmetry-related bmb ligands. Cd–O bond lengths are 2.319(2) and 2.377(2) , the Cd–N bond length is 2.293(3) ; Ligand bmb adopts a symmetrical trans conformation, N _donor ··· N–C _sp3 ···C _sp3 torsion angle is 110.977°; Cd(II) ion coordinates with bmb to form a meso-helix with a pitch of 17.961 , corresponding to the length of the c-axis; the two free acetate groups of the flexible m-ada ^2- anion adopt a bidentate chelating coordination mode, and the Cd/bmb meso _- helical The chains form a 2D structure whose sides reveal elliptical channels; adjacent 2D layers are stacked in an overlapping manner.

The preparation method of the helical cadmium metal organic framework fluorescent material comprises the following steps: cadmium nitrate tetrahydrate, 1,4-dibenzyl (2-methylbenzimidazole), 1,3-adamantane diacetic acid , sodium hydroxide and distilled water are mixed to obtain a mixed solution A, so that the molar concentration of cadmium nitrate tetrahydrate in the gained mixed solution A is 0.1-0.8 mmol/L, 1,4-dibenzyl (2-methylbenzimidazole) The molar concentration is 0.1-0.8 mmol/L, the molar concentration of 1,3-adamantane diacetic acid is 0.1-0.8 mmol/L, and the molar concentration of sodium hydroxide is 0.4-1.6 mmol/L; then the mixed solution A is moved to In a stainless steel reaction kettle with polytetrafluoroethylene lining, keep the temperature at 170°C for three days, and then slowly lower it to room temperature at a rate of 5°C per hour to obtain colorless prism crystals, which are separated, After washing, filtering and drying, the helical cadmium metal organic framework fluorescent material is obtained.

The molar concentration of sodium hydroxide in the mixed solution A is preferably twice the molar concentration of 1,3-adamantanediacetic acid.

The drying method is vacuum drying or blast drying.

The beneficial effect is that the synthesis method of the invention is simple, convenient to operate, high in yield, good in reproducibility and the like. The raw material 1,4-dibenzyl (2-methylbenzimidazole) in the present invention is an important semi-rigid bridging ligand, and the methyl substituent on the benzimidazole ring makes it easier to coordinate with the metal and Metal-organic frameworks containing helical structures are formed. The introduction of cadmium metal ions makes the metal-organic frameworks have good fluorescence properties. The fluorescence spectrum of the prepared helical cadmium metal-organic framework fluorescent material, that is, 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal-organic framework, shows that the target metal-organic framework has stable fluorescence properties and can be used as a fluorescent Functional materials are used in the field of luminescent materials science. Thermogravimetric analysis showed that the target metal-organic framework collapsed at 309°C, indicating that it had good thermal stability, which provided a guarantee for its further application as a fluorescent material.

Description of drawings

Fig. 1 is the cell figure of the cadmium metal organic framework fluorescent material containing helix prepared in embodiment 1;

Fig. 2 is the two-dimensional network diagram of the helix-containing cadmium metal organic framework fluorescent material prepared in Example 1;

Fig. 3 is the powder diffraction pattern of the cadmium metal organic framework fluorescent material containing helix prepared in embodiment 1;

Fig. 4 is the thermal gravimetric curve diagram of the cadmium metal organic framework fluorescent material containing helix prepared in embodiment 1;

FIG. 5 is a solid-state fluorescence spectrum diagram of the helical cadmium metal organic framework fluorescent material prepared in Example 1. FIG.

detailed description

A helix-containing cadmium metal-organic framework fluorescent material and a preparation method thereof, the method is simple, the prepared material contains a helix structure, has excellent luminescence performance, the synthesis method is simple, the operation is convenient, the yield is high, and the reproducibility is good, etc. advantage.

The technical solution adopted by the present invention to solve the above technical problems is: a helical cadmium metal organic framework fluorescent material, which is self-entangled helical 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal Organic framework, the chemical formula is {[Zn(bmb)(m-ada)]·1.5H ₂ O} _n , where n is greater than one, bmb is 1,4-dibenzyl(2-methylbenzimidazole), m- ada is 1,3-adamantanediacetate anion; the simplified structure of bmb and mH ₂ ada is as follows:

bmb mH ₂ ada

The 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal organic framework belongs to the monoclinic crystal system, the space group is P2/c, and the unit cell parameter is a = 9.3237 (19) , b = 10.479(2) , c = 17.961(5) , α = 90°, β = 108.80(3)°, γ = 90°, V = 1661.2(7) ³ .

The basic structure of the 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal organic framework is that the central metal Cd(II) ion of the target metal organic framework is in an octahedral coordination environment, with two symmetrical The carboxyl oxygen atom on the sex-related m-ada ^2- anion is coordinated with the two nitrogen atoms of the two symmetry-related bmb ligands. Cd–O bond lengths are 2.319(2) and 2.377(2) , the Cd–N bond length is 2.293(3) ; Ligand bmb adopts a symmetrical trans conformation, N _donor ··· N–C _sp3 ···C _sp3 torsion angle is 110.977°; Cd(II) ion coordinates with bmb to form a meso-helix with a pitch of 17.961 , corresponding to the length of the c-axis; the two free acetate groups of the flexible m-ada ^2- anion adopt a bidentate chelating coordination mode, and the Cd/bmb meso _- helical The chains form a 2D structure whose sides reveal elliptical channels; adjacent 2D layers are stacked in an overlapping manner.

The preparation method of the helix-containing cadmium metal organic framework fluorescent material comprises the following steps: combining cadmium nitrate tetrahydrate, 1,4-dibenzyl (2-methylbenzimidazole), 1,3-adamantane diacetic acid , sodium hydroxide and distilled water are mixed to obtain a mixed solution A, so that the molar concentration of cadmium nitrate tetrahydrate in the gained mixed solution A is 0.1-0.8 mmol/L, 1,4-dibenzyl (2-methylbenzimidazole) The molar concentration is 0.1-0.8 mmol/L, the molar concentration of 1,3-adamantane diacetic acid is 0.1-0.8 mmol/L, and the molar concentration of sodium hydroxide is 0.4-1.6 mmol/L; then the mixed solution A is moved to In a stainless steel reaction kettle lined with polytetrafluoroethylene, keep the temperature at 170°C for three days, and then slowly lower it to room temperature at a rate of 5°C per hour to obtain colorless prism crystals, which are washed, filtered, and dried. The helical cadmium metal organic framework fluorescent material is obtained.

The molar concentration of sodium hydroxide in the mixed solution A is preferably twice the molar concentration of 1,3-adamantanediacetic acid.

The drying method is vacuum drying or blast drying.

The following examples further illustrate the present invention.

Example 1: Combine Cd(NO ₃ )·4H ₂ O (61.7 mg, 0.2 mmol), bmb (36.6 mg, 0.1 mmol), mH ₂ ada (33.2 mg, 0.2 mmol) and NaOH (16.0 mg, 0.4 mmol) and 10 mL of distilled water, then transferred to a 25 mL stainless steel reactor with a polytetrafluoroethylene liner, kept at 170°C for three days, and then slowly lowered to room temperature at a rate of 5°C per hour to obtain a colorless prism The crystal is a helical cadmium metal organic framework fluorescent material. The crystals are washed, filtered, and dried, and the yield of the final product is about 60%.

Example 2: As described in Example 1, under the same other conditions, the amount and ratio of raw materials were changed, and the specific operation was as follows: Cd(NO ₃ )·4H ₂ O (92.6 mg, 0.3 mmol), bmb (36.6 mg, 0.1 mmol), mH ₂ ada (33.2 mg, 0.2 mmol) and NaOH (16.0 mg, 0.4 mmol) and 10 mL of distilled water were mixed, and the subsequent operations were the same as in Example 1 to obtain colorless prism crystals. After the crystals are washed, filtered and dried, the helical cadmium metal organic framework fluorescent material is obtained, and the yield is about 55%.

Example 3: As described in Example 1, under the same other conditions, the amount and ratio of raw materials were changed, and the specific operation was as follows: Cd(NO ₃ )·4H ₂ O (154.3 mg, 0.5 mmol), bmb (36.6 mg, 0.1 mmol), mH ₂ ada (33.2 mg, 0.2 mmol) and NaOH (16.0 mg, 0.4 mmol) and 10 mL of distilled water were mixed, and the subsequent operations were the same as in Example 1 to obtain colorless prism crystals. After the crystals are washed, filtered and dried, the helical cadmium metal organic framework fluorescent material is obtained, and the yield is about 53%.

Example 4: As described in Example 1, under the same other conditions, the amount and ratio of raw materials were changed, and the specific operation was as follows: Cd(NO ₃ )·4H ₂ O (246.9 mg, 0.8 mmol), bmb (36.6 mg, 0.1 mmol), mH ₂ ada (33.2 mg, 0.2 mmol) and NaOH (16.0 mg, 0.4 mmol) and 10 mL of distilled water were mixed, and the subsequent operations were the same as in Example 1 to obtain colorless prism crystals. After the crystals are washed, filtered and dried, the helical cadmium metal organic framework fluorescent material is obtained, and the yield is about 54%.

Example 5: As described in Example 1, under the same other conditions, the amount and ratio of raw materials were changed, and the specific operation was as follows: Cd(NO ₃ )·4H ₂ O (92.6 mg, 0.3 mmol), bmb (108.9 mg, 0.3 mmol), mH ₂ ada (33.2 mg, 0.2 mmol) and NaOH (16.0 mg, 0.4 mmol) and 10 mL of distilled water were mixed, and the subsequent operations were the same as in Example 1 to obtain colorless prism crystals. After the crystals are washed, filtered and dried, the helical cadmium metal organic framework fluorescent material is obtained, and the yield is about 59%.

Example 6: As described in Example 1, under the same other conditions, the amount and ratio of raw materials were changed, and the specific operation was as follows: Cd(NO ₃ )·4H ₂ O Cd(NO ₃ )·4H ₂ O (154.3 mg, 0.5 mmol), bmb (108.9 mg, 0.3 mmol), mH ₂ ada (66.4 mg, 0.4 mmol) and NaOH (32.0 mg, 0.8 mmol) and 10 mL of distilled water were mixed, and the subsequent operations were the same as in Example 1, Colorless prismatic crystals were obtained. After the crystals are washed, filtered and dried, the helical cadmium metal organic framework fluorescent material is obtained, and the yield is about 62%.

Example 7: As described in Example 1, under the same other conditions, the amount and ratio of raw materials were changed, and the specific operation was as follows: Cd(NO ₃ )·4H ₂ O Cd(NO ₃ )·4H ₂ O (154.3 mg, 0.5 mmol), bmb (108.9 mg, 0.3 mmol), mH ₂ ada (123.8 mg, 0.8 mmol) and NaOH (64.0 mg, 1.6 mmol) and 10 mL of distilled water were mixed, and the later operation was the same as in Example 1, and Colorless prismatic crystals were obtained. After the crystals are washed, filtered and dried, the helical cadmium metal organic framework fluorescent material is obtained, and the yield is about 57%.

The helix-containing cadmium metal organic framework fluorescent material obtained in Example 1 is further characterized as follows:

(1) Determination of the crystal structure of helical cadmium metal organic framework fluorescent materials

The crystals were collected by Bruker Apex II X-ray single crystal diffractometer. At 293 K, Mo _Ka rays (λ=0.071073nm) were monochromated by a graphite monochromator, and the scanning method was φ–ω scanning. The crystal diffraction data were restored using the TEXSAN program, and the crystal structure analysis was performed on a PC with the SHELX-97 program system. The diffraction intensity data were corrected by Lp factor and empirical absorption, and the primary structure was obtained by direct method analysis. After several rounds of difference Fourie synthesis, all non-hydrogen atoms are found. Coordinates and anisotropy temperature factors for all non-hydrogen atoms were refined using full-matrix least squares. The hydrogen atoms on the water molecules were obtained by the difference Fourier synthesis method and fixed on the parent atom for refinement, and the hydrogen atoms on the carbon atoms were obtained by the geometric hydrogenation method. Detailed crystal determination data are shown in Table 1; important bond length and bond angle data are shown in Table 2. The crystal structure is shown in Figure 1 and Figure 2.

(2) Table 1 The main crystallographic data of helical cadmium metal organic framework fluorescent materials: ^a

Remark:

(3) Table 2 Main bond lengths of helical cadmium metal-organic framework fluorescent materials ( ) and bond angle (゜)

S symmetrical code: #1 -x,-y-1,-z #2 -x+1,y,-z+1/2 #3 -x,y,-z+1/2.

(4) PXRD phase purity characterization of helical cadmium metal organic framework fluorescent materials

The PXRD characterization of the helical cadmium metal organic framework fluorescent material shows that it has a high phase purity, which provides a purity guarantee for its application as a fluorescent material, as shown in Figure 3. (Instrument model: Bruker/D8 Advance).

(5) Thermal stability characterization of helical cadmium metal organic framework fluorescent materials

The thermogravimetric curve of the helical cadmium metal organic framework fluorescent material shows that its framework can still exist stably at about 309 °C, and has a certain thermal stability, which provides a thermal stability guarantee for its further development and application as a fluorescent material, as shown in Figure 4 . (Instrument model: Bruker/D8 Advance)

(6) Solid-state fluorescence properties of helical cadmium metal-organic framework fluorescent materials

The solid-state fluorescence test was carried out on the sample of the helical cadmium metal organic framework fluorescent material after the enrichment treatment: through the analysis of the fluorescence spectrum, it was found that the helical cadmium metal organic framework fluorescent material was excited by light at 288nm, and there was a strong light at 305nm. Fluorescence absorption peak. Accordingly, the helical cadmium metal organic framework fluorescent material can be further applied as a fluorescent material, as shown in FIG. 5 . (Instrument model: HITACHI/F-4500).

Claims (4)

1. A helical cadmium metal organic framework fluorescent material, characterized in that: the helical cadmium metal organic framework fluorescent material is self-entangled helical 1,4-dibenzyl (2-methylbenzo imidazole) cadmium metal-organic framework with the chemical formula {[Zn(bmb)(m-ada)]·1.5H ₂ O} _n , where n is greater than one and bmb is 1,4-dibenzyl(2-methylbenzimidazole ), m-ada is 1,3-adamantane diacetate anion; wherein bmb and mH ₂ ada have the following structural formulas: bmb mH ₂ ada The 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal organic framework belongs to the monoclinic crystal system, the space group is P2/c, and the unit cell parameter is a = 9.3237 (19) , b = 10.479(2) , c = 17.961(5) , α = 90°, β = 108.80(3)°, γ = 90°, V = 1661.2(7) ³ ; The basic structure of the 1,4-dibenzyl (2-methylbenzimidazole) cadmium metal organic framework is that the central metal Cd(II) ion of the target metal organic framework is in an octahedral coordination environment, with two symmetrical The carboxyl oxygen atom on the sex-related m-ada ^2- anion is coordinated by the two nitrogen atoms of the two symmetry-related bmb ligands; the Cd–O bond lengths are 2.319(2) and 2.377(2) , the Cd–N bond length is 2.293(3) ; Ligand bmb adopts a symmetrical trans conformation, N _donor ··· N–C _sp3 ···C _sp3 torsion angle is 110.977°; Cd(II) ion coordinates with bmb to form a meso-helix with a pitch of 17.961 , corresponding to the length of the c-axis; the two free acetate groups of the flexible m-ada ^2- anion adopt a bidentate chelating coordination mode, and the Cd/bmb meso _- helical The chains form a 2D structure whose sides reveal elliptical channels; adjacent 2D layers are stacked in an overlapping manner. 2. the preparation method of the helical cadmium metal organic framework fluorescent material as claimed in claim 1, is characterized in that: comprise the following steps: with tetrahydrate cadmium nitrate, 1,4-dibenzyl (2-methylbenzimidazole ), 1,3-adamantane diacetic acid, sodium hydroxide and distilled water are mixed, obtain mixed solution A, make the molar concentration of cadmium nitrate tetrahydrate in the gained mixed solution A be 0.1-0.8mmol/L, 1,4-dibenzyl The molar concentration of (2-methylbenzimidazole) is 0.1-0.8 mmol/L, the molar concentration of 1,3-adamantanediacetic acid is 0.1-0.8 mmol/L, and the molar concentration of sodium hydroxide is 0.4-1.6 mmol /L; then move the mixed solution A to a stainless steel reaction kettle with a polytetrafluoroethylene lining, keep the temperature at 170°C for three days, and then slowly drop to room temperature at a rate of 5°C per hour to obtain colorless prism crystals After separating, washing, filtering and drying the colorless prismatic crystals, the helical cadmium metal organic framework fluorescent material is obtained. 3. the preparation method of the helix-containing cadmium metal organic framework fluorescent material as claimed in claim 2, is characterized in that: the molar concentration of sodium hydroxide in the described mixed solution A is 1,3-adamantane diacetic acid molar concentration 2 times. 4 . The preparation method of helical cadmium metal organic framework fluorescent material as claimed in claim 2 , characterized in that: the drying method is vacuum drying or blast drying.