KR20060123970A - Porous metal-organic framework with coordinatively unsaturated sites, preparation method thereof and its uses as a molecule adsorber and a catalyst - Google Patents

Abstract

A porous metal-organic framework with coordinatively unsaturated sites, a preparation method thereof and its uses as a molecule adsorbent and a catalyst are provided to permanently preserve the porous properties, stably maintain the structure at high temperature, and perform the catalyst reaction. The porous metal-organic framework with coordinatively unsaturated sites represented by the formula(1): Mn_x (NDC)_y (Sol)_z in which x and y are independently an integer of above 1, z is an integer of above 0 and sol is solvent, wherein manganese ion and 2,6-naphthalene dicarboxylate(NDC) are coordinatively bound; the solvent is formamide, methylformamide, ethylformamide, propylformamide, butylformamide, dimethylformamide, diethylformamide, dipropylformamide, dibutylformamide, diethylether, methanol, ethanol, propanol, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, dimethyl sulfoxide, water, benzene, chlorobenzene, toluene, phenol or pyridine.

Description

Porous metal-organic framework with coordinatively unsaturated sites, preparation method according and its uses as a molecule adsorber and a catalyst}

1 (a) is an ORTEP diagram of [Mn (NDC) (DEF)], 1 (b) is a plan view of the [Mn (NDC) (DEF)] 3D skeleton, and 1 (c) is [Mn (NDC) ) (DEF)] Side view of the 3D framework.

2 (a) is an XRPD pattern of [Mn (NDC) (DEF)], 2 (b) is a simulated XRPD pattern based on single crystal X-ray data of [Mn (NDC) (DEF)], 2 (c) is the XRPD pattern of [Mn (NDC)], 2 (d) is the XRPD pattern after immersing [Mn (NDC)] in DEF, and 2 (e) shows [Mn (NDC)] in water vapor. XRPD pattern after exposure.

3 is a diffuse reflectance spectrum of [Mn (NDC) (DEF)] and [Mn (NDC)].

4 shows TGA and DSC results of [Mn (NDC) (DEF)].

Fig. 5A is a nitrogen gas adsorption isotherm of [Mn (NDC)], and 5 (b) is a hydrogen gas adsorption isotherm.

6 is an argon gas adsorption isotherm of [Mn (NDC)].

7 is a photograph showing the dissociation of hydrogen peroxide in [Mn (NDC)].

The present invention relates to a porous metal-organic framework having an empty coordination site, a method for preparing the same, and a use as a molecular adsorbent and a catalyst. More specifically, a manganese (II) ion and a 2,6-naphthalenedicarboxylate are coordinated. The manganese (II) ion may have an empty coordination site, and relates to a porous metal-organic framework having a three-dimensional structure with permanent porous properties, a method for preparing the same, and a use as a molecular adsorbent and a catalyst.

Metal-Organic Framework (MOF) is a recent research project because of its potential for application in the field of adsorption and separation of molecules such as ion exchange, catalysts, sensor technology and optoelectronics. Metal-organic frameworks are designed and assembled by selecting appropriate building blocks to form cavities or channels of various sizes and shapes. However, despite active research, there is not much information for designing metal-organic frameworks with permanent porosity. This is because, firstly, the metal-organic framework is not strong and often collapses when the guest molecule that fills the void is removed, and secondly, it is easily destroyed under vacuum at high or even low temperatures due to heat instability. Often they dissolve in solvents and dissociate into building blocks. Thus, its application is still limited compared to inorganic zeolites.

Various coordinating polymers have been prepared to build metal-organic frameworks, but coordinating polymers with permanent porosity are very rare [S. Takamizawa, E. Nakata, H. Yokoyama, K. Mochizuki, W. Mori, Angew. Chem. 2003 , 115 , 4467-4470; Angew. Chem . Int. Ed . 2003 , 42 , 4331-4334; EY Lee, MP Suh, Angew. Chem . 2004 , 116 , 2858-2861; Angew. Chem . Int. Ed. 2004 , 43 , 2798-2801; S. Kitagawa, R. Kitaura, S.-I. Noro, Angew. Chem . Int. Ed. 2004 , 43 , 2334-2375; Korean Laid-Open Patent Publication No. 2004-96545; Republic of Korea Patent Publication No. 2005-8749].

Accordingly, the present inventors have studied the metal-organic framework having permanent porosity, and the coordination of manganese (II) ion and 2,6-naphthalenedicarboxylate (2,6-naphthalenedicarboxylate = NDC)- Successful synthesis of the organic framework, and there may be an empty coordination site in the manganese (II) ions of the metal-organic framework, even if the solvent molecules are removed, the metal-organic framework does not collapse, permanent porous properties The discovery of superthermal stability has led to the completion of the present invention.

An object of the present invention is a coordination bond between manganese (II) ions and 2,6-naphthalenedicarboxylate, the manganese (II) ions may have an empty coordination site, and has a three-dimensional structure of permanent porous properties It is to provide a porous metal-organic framework, a method for producing the same and its use as a molecular adsorbent and a catalyst.

The present invention provides a porous metal-organic framework in which a manganese (II) ion and 2,6-naphthalenedicarboxylate are coordinated to each other, represented by the following formula.

[Mn _x (NDC) _y (Sol) _z ]

Wherein x and y are integers of at least 1 and z is an integer of at least 0;

NDC refers to 2,6-naphthalenedicarboxylate and Sol refers to solvent.)

The porous metal-organic framework of the present invention is a porous metal-organic framework in which a manganese (II) ion and 2,6-naphthalenedicarboxylate are coordinated (hereinafter, 'manganese (II) -naphthalenedicarboxylate porous metal- Organic framework). Since the empty coordination site may exist structurally in the manganese (II) ion, the structure does not collapse even when the solvent coordinating is removed. Thus, the porous metal-organic framework of the present invention is a porous metal-organic framework of three-dimensional structure with permanent porous properties with thermal stability.

The solvent (Sol) is not particularly limited as long as it can form a coordination bond with manganese (II) ions, for example, formamide, methylformamide, ethylformamide, propylformamide, butylformamide, dimethyl Formamide, diethylformamide, dipropylformamide, dibutylformamide, diethylether, methanol, ethanol, propanol, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, dimethyl sulfoxide Side, water, benzene, chlorobenzene, toluene, phenol and pyridine.

The most preferred example of the manganese (II) -naphthalenedicarboxylate porous metal-organic framework of the present invention is

[Mn (NDC) (DEF)]; or

[Mn (NDC)].

(In the formula, DEF refers to diethylformamide.)

In the manganese (II) -naphthalenedicarboxylate porous metal-organic framework according to the embodiment in which the solvent molecules of the present invention are coordinated, each carboxylate group may act as a bidentate or tridentate. . When the carboxylated group acts as a tridentate As shown in the binding mode of O (1) -CO (2) and Mn (1) of FIG. 1A, the carboxylated group is a manganese (II) and a square chelate ring. To form. In FIG. 1A the benzene ring of NDC ^2- is omitted to avoid complexity.

In the manganese (II) -naphthalenedicarboxylate porous metal-organic framework according to the embodiment in which the solvent molecules of the present invention are coordinated, each manganese (II) ion is coordinated with the binding atoms of four carboxylated groups and one solvent molecule. It combines to form a distorted octahedral. Manganese (II) ions are bridged by carboxylato groups, as shown in FIGS. 1A and 1 (a) and 1 (b) below. Thus, manganese (II) ions form one-dimensional manganese (II) chains extending in the a direction, as shown in FIG. 1C. And, the one-dimensional manganese (II) chain is connected to each other through the naphthalene ring of NDC ^2- .

The plane formed of the naphthalene ring of NDC ^2- connecting the manganese (II) chain is parallel to the (0 1 1) and (0 1 -1) planes, as shown in Figure 2 below. The plane intersects the one-dimensional manganese (II) chain to form a three-dimensional skeleton, and the three-dimensional skeleton is a one-dimensional rhombic aperture having a diagonal length of 21.5 Å and 10.5 Å Provide a channel. The channel is filled with solvent molecules coordinating to manganese (II) ions (FIGS. 1B, 1C).

On the other hand, the free volume evaluated by PLATON for the manganese (II) -naphthalenedicarboxylate porous metal-organic framework according to the embodiment in which the solvent molecule of the present invention is not coordinated is about 42.1%. The X-ray powder diffraction (XRPD) pattern (FIG. 2 (a)) of the porous metal-organic framework according to the embodiment in which the solvent molecules of the present invention are coordinated and the porosity according to the embodiment in which the solvent molecules of the present invention are not coordinated Comparing the XRPD pattern of the metal-organic framework (Fig. 2 (c)), it can be seen that there is a difference in both, the manganese (II)-naphthalenedicarboxylate porous metal of the present invention depending on the coordination of the solvent molecules It is confirmed that the structure of the organic framework is different.

The present invention also provides a method for producing a manganese (II) -naphthalenedicarboxylate porous metal-organic framework.

The preparation method of the present invention comprises the step of mixing nitrate, chloride, or acetate salt of manganese (II) with 2,6-naphthalenedicarboxylic acid in a solvent. This step produces a manganese (II) -naphthalenedicarboxylate porous metal-organic framework according to an embodiment in which solvent molecules are coordinated.

The solvent (Sol) is not particularly limited as long as it can form a coordination bond with manganese (II) ions, for example, formamide, methylformamide, ethylformamide, propylformamide, butylformamide, dimethyl Formamide, diethylformamide, dipropylformamide, dibutylformamide, diethylether, methanol, ethanol, propanol, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, dimethyl sulfoxide Side, water, benzene, chlorobenzene, toluene, phenol and pyridine.

The preparation method of the present invention is carried out by desolvating the manganese (II) -naphthalenedicarboxylate porous metal-organic framework according to the embodiment in which the solvent molecules obtained as described above are coordinated with the manganese according to the embodiment in which the solvent molecules are not coordinated ( II) -naphthalenedicarboxylate porous metal-organic frameworks may also be obtained.

The desolvation step may include heating the manganese (II) -naphthalenedicarboxylate porous metal-organic framework in which the solvent molecules are coordinated at 200-450 ° C. under reduced pressure. The decompression conditions are appropriately 10 ⁻⁴ to 10 ⁻⁶ Torr in view of the efficiency of desolvation. If the temperature is lower than 200 ° C., desolvation does not occur well. If the temperature is higher than 450 ° C., decomposition of the compound occurs.

Manganese (II) -naphthalenedicarboxylate porous metal-organic frameworks in which the solvent molecules of the form [Mn _x (NDC) _y ] (x and y are integers of 1 or more) are not coordinated, as mentioned (II) Since an empty coordination site exists around the ion, it can be used as a reversible molecular adsorbent. Examples of the molecule include nitrogen, hydrogen or argon.

In addition, manganese (II) -naphthalenedicarboxylate porous metal-organic frameworks in which the solvent molecules of the form [Mn _x (NDC) _y ] (x and y are integers of 1 or more) are not coordinated as mentioned. As such, since an empty coordination group exists around manganese (II) ions, it can be used as a heterogeneous catalyst. For example, manganese (II) -naphthalenedicarboxylate porous metal-organic frameworks in which the solvent molecules according to the present invention are not coordinated can be used as catalysts for the decomposition reaction of hydrogen peroxide.

The present invention will be described in more detail with reference to the following examples. The following examples are intended to illustrate the invention and are not intended to limit the scope of the invention.

In the examples below, all compounds and solvents used in the synthesis were reagent grade and used without further purification. IR spectra were obtained using a Perkin Elmer Spectrum One FT-IR spectrophotometer. UV / vis diffuse reflectance spectra were obtained using a Perkin Elmer Lambda 35 UV / vis spectrophotometer. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed using a TA Instruments TGAQ50 and DSCQ10 at a scan rate of 5 ° C / min under nitrogen gas. Elemental analysis was conducted at the Institute of Basic Sciences, Seoul National University. X-ray powder diffraction (XRPD) data was recorded with a Bruker D5005 diffractometer at a scan rate of 5 ° / min and step size of 0.02 ° in 2θ for Cu Kα (λ = 1.5406 kV) at 40 kV, 40 mA. Gas sorption data was obtained with a Quantachrome Autosorb-1 gas sorption unit.

Example 1 Preparation of [Mn (NDC) (DEF)]

Manganese nitrate (Mn (NO ₃ ) ₂ nH ₂ O) (0.18 g, 1.0 mmol) and 2,6-naphthalenedicarboxylic acid (H ₂ NDC, 0.22 g, 1.0 mmol) are dissolved in DEF (7 mL) I was. The solution was placed in a Teflon vessel in an autoclave, heated at 105 ° C. for 24 hours and then cooled to room temperature. The pale yellow block-form crystals formed were filtered, washed with DEF and dried in air. Yield: 88%. FT-IR (KBr): ν = 3065 (s), 2981 (s), 2940 (s), 1942 (s), 1651 (s), 1613 (s), 1573 (s), 1556 (s), 1494 (s), 1446 (s), 1360 (s) cm ⁻¹ ; UV / vis (FIG. 3, diffuse reflectance, λ _max ): 330, 285 nm. Elemental Analysis: MnC ₁₇ H ₁₇ NO ₅ (%), Theoretical Values C 55.15, H 4.63, N 3.78; Found C 55.17, H 4.71, N 3.50.

X-ray Crystallography : Single crystals of [Mn (NDC) (DEF)] were sealed in a glass capillary along with a mother liquid. Diffraction data were collected at 153K from graphite-short wavelength Mo-Kα radiation (λ = 0.71073 μs) on an Enraf Nonius Kappa CCD diffractometer. Crystal structure was solved by direct method using SHELXS-97, and refined by full-matrix least-squares method using SHELXL-97 included in WinGX program package. The positions of all hydrogen atoms were placed in ideal positions. In the refining process, anisotropic thermal parameters were applied to all non-hydrogen atoms and isotropic thermal parameters were applied to hydrogen atoms.

Determination data: MnC ₁₇ H ₁₇ NO ₅ , M r = 370.26, monoclinic, space group P 2 ₁ / a , a = 7.535 (5), b = 21.513 (5), c = 10.466 (5) Å , β = 96.666 (5), V = 1685.1 (14) Å ³ , Z = 4, T = 153 K, R ₁ = 0.0457 ( I > 2σ ( I )), wR ₂ ( F ² ) = 0.1108 ( I > 2σ ( I )), GOF = 0.95.

Example 2 Preparation of [Mn (NDC)]

[Mn (NDC) (DEF)] was placed in a Schlenck tube and heated at 220 ° C. under vacuum for 18 hours. FT-IR (KBr pellets): ν = 3263 (s), 1603 (s), 1564 (s), 1538 (s), 1504 (s), 1385 (s), 1312 (s) cm ⁻¹ ; UV / vis (FIG. 3, diffuse reflectance, λ _max ): 357, 289 nm. Elemental Analysis: MnC ₁₂ H ₆ O ₄ (%), Theoretical Values C 53.56, H 2.25; Found C 52.54, H 2.43.

Experimental Example 1 Measurement of X-ray Powder Diffraction Characteristics

X-ray powder diffraction measurement characteristics measurement results for [Mn (NDC) (DEF)] and [Mn (NDC)] are shown in FIG. 2. The XRPD pattern (FIG. 2 (a)) for the [Mn (NDC) (DEF)] powder is simulated data based on X-ray data for the single crystal of [Mn (NDC) (DEF)] (FIG. 2 (b)). Matches This means that the bulk sample has a structure like a single crystal. On the other hand, the XRPD pattern (FIG. 2 (c)) for [Mn (NDC)] from which the solvent was removed is different from the XRPD pattern of [Mn (NDC) (DEF)]. This is because the structural change of the framework occurs when the DEF that is coordinated is removed. Next, even after immersing [Mn (NDC)] in DEF for 24 hours, the XRPD pattern (Fig. 2 (d)) did not change. This indicates that once the coordinating solvent in the metal has been removed it does not revert back to its original structure even when immersed in the solvent. In addition, the XRPD pattern (FIG. 2 (e)) when [Mn (NDC)] was exposed to water vapor for 3 days was different from the XRPD patterns of [Mn (NDC) (DEF)] and [Mn (NDC)]. different. This indicates that the skeletal structure changed due to the coordination of water molecules in the empty coordination site of manganese (II).

Experimental Example 2 TGA and DSC Analysis

The analysis results by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for [Mn (NDC) (DEF)] are shown in FIG. 4. Heating [Mn (NDC) (DEF)] to 250 ° C. removed all coordinated solvents (theoretical value: 27.3 wt%, measured value: 26.6 wt%). Solvent free [Mn (NDC)] did not pyrolyze to 450 ° C.

Experimental Example 3 Measurement of Gas Sorption Characteristics

Gas sorption characteristics were measured with a Quantachrome Autosorb-1 instrument. Accurately measured amounts of [Mn (NDC)] were introduced into the gas sorption apparatus and treated at 230 ° C. and 10 ⁻⁵ Torr to remove all coordinating solvents. N ₂ gas sorption isotherms of desolvated solids were measured by static method at each equilibrium pressure and at 77K. In the same manner, the H ₂ and Ar gas sorption isotherms of the solids desolvated at 77K were measured.

N ₂ gas sorption characteristics for [Mn (NDC)] are shown in FIG. 5 (a). [Mn (NDC)] showed a reversible type I isotherm by adsorbing N ₂ gas, suggesting the removal of DEF molecules in [Mn (NDC) (DEF)] resulting in permanent porosity in the solid. do. The Langurr surface area calculated from the isotherm is 191 m ² / g, which corresponds to about 240 m ² / g of Mn (HCO ₂ ) ₂ / 3C ₄ H ₈ O ₂ . The pore volume calculated by the Dubinin-Radushkevich formula is 0.07 cm ³ / g. In addition, [Mn (NDC)] adsorbed H ₂ gas up to 0.56 wt% at 77 K (FIG. 5 (b)), and also adsorbed argon gas (FIG. 6).

Experimental Example 4 Hydrogen Peroxide Decomposition Catalysis

To investigate the catalysis of the decomposition reaction of hydrogen peroxide, 5 mL of 30% hydrogen peroxide solution was added to 44.4 mg (0.12 mmol) of [Mn (NDC) (DEF)] and 33.2 mg (0.12 mmol) of [Mn (NDC)] at room temperature. ) Respectively.

When hydrogen peroxide was added to [Mn (NDC)], O ₂ gas was violently generated as shown in FIG. 7. However, no reaction occurred when hydrogen peroxide was added to [Mn (NDC) (DEF)]. In addition, after the decomposition reaction with excess hydrogen peroxide occurred, hydrogen peroxide was added to the recovered [Mn (NDC)] again to cause hydrogen peroxide decomposition. Therefore, it can be seen that [Mn (NDC)] acts as a catalyst in the hydrogen peroxide decomposition reaction.

Therefore, the manganese (II) -naphthalenedicarboxylate porous metal-organic framework of the present invention may have an empty coordination site, and thus have permanent porous properties, maintain its structure stably even at high temperatures, and catalyze It can be used in various fields such as molecular adsorption, separation process, ion exchange, heterogeneous catalyst, sensor.

Claims (8)

A porous metal-organic framework in which a manganese (II) ion and 2,6-naphthalenedicarboxylate are coordinated to each other, represented by the following Formula 1. <Formula 1> [Mn _x (NDC) _y (Sol) _z ] Wherein x and y are integers of at least 1 and z is an integer of at least 0; NDC refers to 2,6-naphthalenedicarboxylate and Sol refers to solvent.) The method of claim 1, wherein the solvent is formamide, methylformamide, ethylformamide, propylformamide, butylformamide, dimethylformamide, diethylformamide, dipropylformamide, dibutylformamide, diethyl ether , Methanol, ethanol, propanol, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, dimethylsulfoxide, water, benzene, chlorobenzene, toluene, phenol and pyridine Porous metal-organic framework. The method of claim 1, [Mn (NDC) (DEF)]; or Porous metal-organic framework, characterized in that [Mn (NDC)]. (Wherein DEF refers to diethylformamide) A method for producing a porous metal-organic framework comprising mixing a nitrate, chloride, or acetate salt of manganese (II) with 2,6-naphthalenedicarboxylic acid in a solvent to obtain a porous metal organic framework. The method of claim 4, further comprising desolvating the obtained porous metal organic framework. 6. The method of claim 5, wherein the desolvating is performed at 10 ⁻⁴ to 10 ⁻⁶ Torr and 200 to 450 ° C. ⁷ . A molecular adsorbent comprising a porous metal-organic framework in which a manganese (II) ion and 2,6-naphthalenedicarboxylate are coordinated to each other, represented by Formula 2 below. <Formula 2> [Mn _x (NDC) _y ] Wherein x and y are integers of at least 1; NDC refers to 2,6-naphthalenedicarboxylate.) A heterogeneous catalyst comprising a porous metal-organic framework in which a manganese (II) ion and 2,6-naphthalenedicarboxylate are coordinated to each other, represented by the following Chemical Formula 2. <Formula 2> [Mn _x (NDC) _y ] Wherein x and y are integers of at least 1; NDC refers to 2,6-naphthalenedicarboxylate.)

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