阅读说明：本技术 一种c2对称性的荧光手性羧酸配体l-h2、制备方法与应用 (C2Symmetrical fluorescent chiral carboxylic acid ligand L-H2, preparation method and application ) 是由 朱成峰 李寒雪 李影 钱亦健 倪嘉豪 贾船儿 李有桂 吴祥 付延明 于 2021-10-22 设计创作，主要内容包括：本发明公开一种C-(2)对称性的荧光手性羧酸配体L-H-(2),涉及配位化学和手性化学技术领域,其结构式如下：本发明还提供上述配体的制备方法及应用。本发明的有益效果在于：本发明中的手性配体不但合成成本低廉、制备方法简单,而且其骨架同时含有发光的共轭基团、柔性的磺酰基团以及可配位的羧酸基团,特别是与锌离子反应能够制备具有开放手性纳米孔道(1.06nm×0.44nm)、丰富手性识别位点和独特荧光发射性质的锌基手性多孔配位聚合物材料。所制备的锌基手性多孔配位聚合物材料,不仅可用作手性吸附材料选择性地识别吸附氧化苯乙烯异构体,而且可用作手性荧光传感材料快速地识别R-构型的氧化苯乙烯。(The invention discloses a C 2 Symmetrical fluorescent chiral carboxylic acid ligand L-H 2 Relates to the technical field of coordination chemistry and chiral chemistry, and has the following structural formula: the invention also provides a preparation method and application of the ligand. The invention has the beneficial effects that: the chiral ligand in the invention has low synthesis cost and simple preparation method, and the framework of the chiral ligand simultaneously contains a luminescent conjugated group, a flexible sulfonyl group and a coordinatable carboxylic acid group, and particularly can be reacted with zinc ions to prepare a zinc-based chiral porous coordination polymer material with an open chiral nano-pore (1.06nm multiplied by 0.44nm), rich chiral recognition sites and unique fluorescence emission property. The prepared zinc-based chiral porous coordination polymer material not only can be used as a chiral adsorption material to selectively identify and adsorb styrene oxide isomers, but also can be used as a chiral fluorescent sensing material to rapidly identify R-configured styrene oxide.)

1. C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The method is characterized in that: the structural formula is as follows:

2. preparation of C as described in claim 1₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The method of (2), characterized by:

1) dissolving L-phenylalanine in absolute methanol, adding thionyl chloride, stirring at room temperature for reaction, then adding a low-concentration sodium hydroxide solution to adjust the pH of the mixed reaction solution to be alkaline, extracting an organic phase by using ethyl acetate, and then drying and concentrating to obtain a crude product of L-phenylalanine methyl ester;

2) dissolving L-phenylalanine methyl ester, pure naphthalene-1, 5-disulfonyl chloride and dry triethylamine in ultra-dry dichloromethane, reacting the obtained reaction mixed solution at room temperature, and purifying after the reaction is finished to obtain methyl esterified chiral ligand L-Me₂Putting into the next hydrolysis reaction;

3) methyl esterified chiral ligand L-Me₂Dissolving sodium hydroxide in tetrahydrofuran, methanol and water, reacting at room temperature for 4-6 hr, regulating pH to 2 with dilute hydrochloric acid, extracting organic phase with dichloromethane, filtering, drying, and concentrating to obtain C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂。

3. C according to claim 2₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The preparation method is characterized by comprising the following steps: the ratio of the amounts of the substances of L-phenylalanine and thionyl chloride in said step 1)Greater than or equal to 1: 1.

4. C according to claim 2₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The preparation method is characterized by comprising the following steps: the step 3) methyl esterified chiral ligand L-Me₂And sodium hydroxide in a ratio of 1:2 or less, wherein the volume ratio of tetrahydrofuran, methanol and water in the solvent is 1:1: 1.

5. Based on C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The zinc-based chiral porous coordination polymer is characterized in that: the zinc-based chiral porous coordination polymer takes zinc ions as a metal center and has L-H₂Is chiral ligand, 4, 4' -bipyridine is auxiliary ligand, the molecular formula of the zinc-based chiral porous coordination polymer is { [ Zn (L) ((bpy))]·DMF}_nThe structural formula of the zinc-based chiral porous coordination polymer is as follows:

wherein n is an integer.

6. The zinc-based chiral porous coordination polymer of claim 5, characterized in that: the unit cell parameters of the single crystal of the zinc-based chiral porous coordination polymer are as follows: α＝β＝γ＝90°,Z＝4。

7. a method of making a zinc-based chiral porous coordination polymer of claim 5, characterized in that: the method comprises the following steps:

1) preparing a reaction mixed solution: c is to be₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂Adding 4, 4' -bipyridine and zinc salt into a mixed solvent, and fully stirring and dissolving at normal temperature to obtain a reaction mixed solution;

2) and (3) crystallization reaction: and (2) reacting the reaction mixed solution prepared in the step 1) at 60-80 ℃ for 48-72 hours to obtain a colorless blocky crystal, and then filtering and washing to obtain the zinc-based chiral porous coordination polymer.

8. The method of claim 7, wherein the zinc-based chiral porous coordination polymer comprises: said C is₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The molar ratio of the 4, 4' -bipyridyl to the zinc salt is 1:1: 2.

9. Use of the zinc-based chiral porous coordination polymer of claim 5 in chiral resolution of styrene oxide isomers.

10. The application of the zinc-based chiral porous coordination polymer in claim 5 in fluorescence sensing recognition of styrene oxide isomers.

Technical Field

The invention relates to the technical field of coordination chemistry and chiral chemistry, in particular to C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂A preparation method and application thereof.

Background

The development of multifunctional chiral porous materials is always one of the hot points of research in the field of chiral science and technology, and especially, chiral porous materials having both chiral resolution and chiral sensing functions are more concerned by scientists. Porous Coordination Polymers (PCPs) are organic-inorganic hybrid crystalline materials with unique pore structures formed by coordination of functionalized organic ligands and metal ions, also called metal-organic framework Materials (MOFs), and the structures and functions of the materials can be realized by reasonably selecting and regulating the organic ligands and the metal ions, so that the PCPs become an ideal platform for constructing multifunctional chiral porous materials.

Although chiral porous coordination polymers have been reported in succession, few materials with chiral separation or chiral sensing functions are available, mainly because the construction of coordination polymer materials with both chiral porous structure and multiple recognition sites is very challenging. In view of the fact that chiral amino acid can be used as both a chiral source and a substrate recognition site, the chiral amino acid becomes one of ideal choices for constructing the porous coordination polymer with the chiral function. For example, patent application with publication number CN111621031A discloses a preparation method and application of a chiral MOF-based separation material, wherein the chiral separation material with the function of adsorbing and separating styrene oxide is constructed by using L-phenylalanine as a chiral source, but the chiral material only embodies a single chiral separation function and cannot simultaneously have a chiral fluorescence recognition function.

Disclosure of Invention

The invention aims to provide a C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The zinc-based chiral porous coordination polymer is a chiral supermolecule crystal with a unique two-dimensional network structure, can be used for adsorption separation and fluorescence sensing identification of chiral micromolecule styrene oxide isomers, and shows that the chiral porous coordination compound can be used as a potential multifunctional chiral material for rapid identification and separation of chiral molecules.

The invention solves the technical problems through the following technical means:

c₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The structural formula is as follows:

has the advantages that: c of the invention₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The skeleton of the chiral porous coordination polymer not only has carboxylic acid groups capable of coordinating with metal, but also has luminescent conjugated groups and flexible sulfonyl groups, and provides conditions for constructing the multifunctional chiral porous coordination polymer with a novel structure and chiral resolution and fluorescence functions.

The invention also provides a compound C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The preparation method comprises the following steps:

1) dissolving L-phenylalanine in anhydrous methanol, adding redistilled and purified thionyl chloride, stirring at room temperature for reaction, then adding a sodium hydroxide solution to adjust the pH of the mixed reaction solution to be alkaline, extracting an organic phase by using ethyl acetate, and then drying and concentrating to obtain a crude product of L-phenylalanine methyl ester;

2) dissolving L-phenylalanine methyl ester, naphthalene-1, 5-disulfonyl chloride and anhydrous triethylamine in ultra-dry dichloromethane, reacting the obtained reaction mixed solution at room temperature, and after the reaction is finished, performing column separation and purification to obtain methyl-esterified chiral ligand L-Me₂Putting into the next hydrolysis reaction;

3) methyl esterified chiral ligand L-Me₂And sodium hydroxide in Tetrahydrofuran (THF), methanol (MeOH), water (H)₂O), reacting at room temperature for 4-6 hours, adjusting the pH of the reaction mixture to 1-3 with dilute hydrochloric acid, extracting the organic phase with dichloromethane, filtering, drying and concentrating to obtain C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂。

Has the advantages that: the chiral carboxylic acid ligand synthesized by the invention is obtained by using L-phenylalanine as a chiral raw material and naphthalene-1, 5-disulfonyl chloride as a luminescent element through three-step simple organic reaction, and the chiral carboxylic acid ligand is low in synthesis cost, simple in preparation method and simple in experimental operation, so that the large-scale preparation of the chiral carboxylic acid ligand is facilitated.

Preferably, the mass ratio of the L-phenylalanine to the thionyl chloride in the step 1) is greater than or equal to 1:1, and the thionyl chloride needs to be re-evaporated and purified.

Preference is given toIn the step 2), the ratio of the mass amounts of the L-phenylalanine methyl ester and the naphthalene-1, 5-disulfonyl chloride is 2:1, the triethylamine and the dichloromethane used need to be moisture-free, and the triethylamine and the dichloromethane which are not treated in an anhydrous manner can cause the chiral ligand L-Me of methyl esterification₂The synthesis yield of (2) is decreased.

Preferably, said step 3) methyl esterified chiral ligand L-Me₂The ratio of the amount of the substance to the sodium hydroxide is 1:2, Tetrahydrofuran (THF), methanol (MeOH), and water (H) in the solvent₂O) is 1:1:1, and the pH value of the hydrochloric acid adjusting solution cannot be more than 3.

The invention also provides a method based on the C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The chiral porous coordination polymer takes zinc ions as metal centers and has L-H₂4, 4' -bipyridine (bpy) is an auxiliary ligand for bridging the ligand, and the chemical formula of the zinc-based chiral porous coordination polymer is { [ Zn (L) (bpy)]·DMF}_nThe structural formula of the zinc-based chiral porous coordination polymer is as follows:

wherein n is an integer.

n represents the infinite periodicity of the structure.

Has the advantages that: the zinc-based chiral porous coordination polymer not only has The chiral nano-pore has a narrow, long and open chiral nano-pore which is suitable for the size of a reaction substrate, has rich chiral recognition sites such as amide groups, carbonyl groups, benzyl groups, naphthalene rings and the like, and has remarkable fluorescence property, thereby providing structural conditions for developing chiral resolution and fluorescence sensing performance of the chiral nano-pore.

Preferably, the unit cell parameters of the zinc-based chiral porous coordination polymer single crystal are as follows: α＝β＝γ＝90°, Z＝4。

the invention also provides a method based on C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The preparation method of the zinc-based chiral porous coordination polymer comprises the following steps:

1) preparing a reaction mixed solution: c is to be₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂Adding 4, 4' -bipyridine and zinc salt into a mixed solvent, and fully stirring and dissolving at normal temperature to obtain a reaction mixed solution;

2) and (3) crystallization reaction: and (2) reacting the reaction mixed solution prepared in the step 1) at 60-80 ℃ for 48-72 hours to obtain a colorless blocky crystal, and then filtering and washing to obtain the zinc-based chiral porous coordination polymer.

Has the advantages that: the method for preparing the zinc-based chiral porous coordination polymer is simple and easy to repeat, and has higher operability.

Preferably, said C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The molar ratio of the 4, 4 '-bipyridyl to the zinc salt is 1:1:2, and single crystals of the zinc-based chiral porous coordination polymer cannot be obtained by adjusting the proportion of the 4, 4' -bipyridyl to the zinc salt.

Preferably, the zinc salt in the step 1) is Zn (NO)₃)₂·6H₂O, other zinc salts, do not allow to obtain single crystals of the zinc-based chiral porous coordination polymer of the invention.

Preferably, the mixed solvent in the step 1) is prepared by mixing N, N' -Dimethylformamide (DMF) and acetonitrile (MeCN), the volume ratio of the DMF to the acetonitrile is 1:1, and a single crystal of the zinc-based chiral porous coordination polymer cannot be obtained by changing the type of the solvent.

The invention also provides application of the zinc-based chiral porous coordination polymer in chiral resolution of styrene oxide isomers.

Has the advantages that: the zinc-based chiral porous coordination polymer can preferentially recognize and adsorb styrene oxide with R configuration, so that the zinc-based chiral porous coordination polymer can be used as a chiral resolution material.

The invention also provides application of the zinc-based chiral porous coordination polymer in fluorescent sensing recognition of styrene oxide isomers.

Has the advantages that: the zinc-based chiral porous coordination polymer can have intermolecular interaction with styrene oxide with R configuration remarkably, so that the fluorescence of the zinc-based chiral porous coordination polymer is quenched obviously, and the zinc-based chiral porous coordination polymer can be used as a chiral fluorescence sensing material.

The invention has the advantages that: c of the invention₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂On one hand, the chiral naphthalene derivative is obtained by taking L-phenylalanine as a chiral raw material and naphthalene-1, 5-disulfonyl chloride as a luminescent element through three-step simple organic reaction, and has the advantages of low synthesis cost, simple preparation method and simple experimental operation, thereby being beneficial to large-scale preparation; on the other hand, the skeleton of the chiral porous coordination polymer not only has carboxylic acid groups capable of coordinating with metal, but also has luminescent conjugated groups and flexible sulfonyl groups, and is favorable for preparing the multifunctional chiral porous coordination polymer with a novel structure and chiral resolution and fluorescence functions.

The zinc-based chiral porous coordination polymer prepared by the reaction of the ligand and zinc ions has 1.06nm multiplied by 0.44nm open chiral nanopores, abundant chiral recognition sites (amide groups, carbonyl groups, benzyl groups, naphthalene rings and the like) and remarkable fluorescence emission property, and can be used as a chiral resolution and fluorescence sensing material of styrene oxide isomers.

Drawings

FIG. 1 shows a graph C in example 1 of the present invention₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂Schematic diagram of the synthetic route of (1).

FIG. 2C of example 1 of the present invention₂Methyl esterification product L-Me of symmetric fluorescent chiral carboxylic acid ligand₂Nuclear magnetic resonance hydrogen spectrum of (a).

FIG. 3 is a crystal structure of zinc-based chiral porous coordination polymer in example 2 of the present invention.

FIG. 4 shows a one-dimensional chain structure of zinc-based chiral porous coordination polymer in example 2 of the present invention.

FIG. 5 shows two-dimensional network supramolecular structures formed by hydrogen bonding (hydrogen bonding is shown by dotted lines) in zinc-based chiral porous coordination polymers in example 2 of the present invention.

FIG. 6 shows three-dimensional network supramolecular structures formed by hydrogen bonding (hydrogen bonding is shown by dotted lines) in zinc-based chiral porous coordination polymers in example 2 of the present invention.

FIG. 7 is a high performance liquid chromatography of styrene oxide adsorption separation by zinc-based chiral porous coordination polymer in example 3 of the present invention.

FIG. 8 shows the fluorescent sensing of the zinc-based chiral porous coordination polymer for identifying styrene oxide isomers in example 4 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Test materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

The specific techniques or conditions not specified in the examples can be performed according to the techniques or conditions described in the literature in the field or according to the product specification.

Example 1

C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The synthetic route of (1) is shown in figureThe method comprises the following specific steps:

1) dissolving L-phenylalanine and thionyl chloride at a mass ratio of 1:1 in anhydrous methanol, and reacting at room temperature with stirring for 12 hours with 1 mol. L^-1Adjusting the pH value of the reaction mixed solution to 8 by using a sodium hydroxide solution, extracting an organic phase by using ethyl acetate, drying and concentrating to obtain a crude product of the L-phenylalanine methyl ester, wherein the purity of the reaction product can be directly used for the next reaction; wherein thionyl chloride needs to be steamed and purified again, otherwise, the reaction is incomplete, so that the yield is reduced;

2) dissolving naphthalene-1, 5-disulfonyl chloride in CH₂Cl₂Adding 2.2 times of equivalent of triethylamine, stirring at room temperature, adding L-phenylalanine methyl ester, wherein the mass ratio of naphthalene-1, 5-disulfonyl chloride to L-phenylalanine methyl ester is 1:2, and continuously reacting for 12 hours at room temperature; the crude reaction product is passed through CH₂Cl₂Extracted, anhydrous Na₂SO₄Drying, concentrating under reduced pressure, and separating by chromatography to obtain white solid ligand esterification product L-Me₂。

In this step, 0.32g (1.0mmol) of naphthalene-1, 5-disulfonyl chloride was dissolved in 100mL of ultra-dry CH₂Cl₂Adding 0.30mL of anhydrous treated triethylamine, stirring at room temperature for 0.5h, slowly adding 0.36g (2mmol) of L-phenylalanine methyl ester, and continuing to react at room temperature for 12 h; the crude reaction product is passed through CH₂Cl₂Extracted, anhydrous Na₂SO₄Drying, concentration under reduced pressure and chromatography gave 0.52g of L-Me₂The yield was 85%. It is noteworthy that the use of ultra-dry CH is required in the condensation reaction₂Cl₂Solvents and anhydrous treated triethylamine reagent, which otherwise leads to a decrease in yield. FIG. 2 shows the ligand methyl esterification product L-Me₂The hydrogen spectrum of nuclear magnetic resonance shows that the product is successfully synthesized.

3) 0.29g (0.5mmol) of L-Me₂Dissolving in 100mL of mixed solvent of tetrahydrofuran, methanol and water (volume ratio is 1:1: 1), adding 0.40g (1.0mmol) of sodium hydroxide, and reacting at room temperature for 6 h; concentrating the reaction mixture under reduced pressure, dissolving with water, adjusting pH to 2 with 1mol/L hydrochloric acid, and regulating pH to CH₂Cl₂Extracting the organic phase with anhydrous Na₂SO₄Drying, concentrating, and separating by column chromatography to obtain 0.25g pure chiral ligand L-H₂The yield was 90%. The hydrochloric acid adjusted solution pH in this step may be between 1 and 3, and if the pH is greater than 3, this will result in the hydrolysis product not being transferred to the organic phase and thus product loss.

¹H-NMR (600MHz, DMSO-d6, delta, ppm) delta: 12.69(s,2H), 8.72(d, J ═ 9.2Hz,2H), 8.64(d, J ═ 8.7Hz,2H), 7.88(d, J ═ 7.3Hz,2H), 7.50(t, J ═ 8.0Hz,2H), 6.98-6.87 (m,10H), 3.84(td, J ═ 9.5,4.9Hz,2H), 2.90(dd, J ═ 13.7,5.1Hz,2H), 2.66(dd, J ═ 13.7,9.9Hz, 2H). IR (KBr pellet, v/cm)^-1)：3353(m),3340(m),3073(m)3055(m),3019(w),2933(w),2593(w),1712(s),1640(s),1530(s),1445(m),1390(m),1324(m),1251(m),1214(m),1099(w),1074(w),1038(m),1020(m),917(m),874(m)728(m),697(m),694(m),624(w),540(w),473(w)。

Example 2

Based on C₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The synthesis method of the zinc-based chiral porous coordination polymer specifically comprises the following steps:

reacting L-H₂(11.8mg,0.02mmol)、Zn(NO₃)₂·6H₂O (11.9mg,0.04mmol) and 4, 4 '-bipyridine (bpy) (3.12mg,0.02mmol) were dissolved in 5mL of a mixed solvent of N, N' -Dimethylformamide (DMF) and acetonitrile (MeCN) (v_DMF：v_MeCN1:1) sealed in a 20mL explosion-proof glass bottle, and heated at 60 ℃ for 36 hours to obtain colorless blocky crystals of the zinc-based chiral porous coordination polymer, wherein the yield is 60%. IR (KBr pellet, v/cm)^-1): 3358(m),3339(m),3073(m)3055(m),3012(w),2909(w),2344(w),1633(s),1533(s),1433(m),1396(m),1342(m),1256(m),1220(m),1190(m),1081(w),1062(w),1038(m),1008(m),977(m),899(m)770(m),694(m),674(m),619(w),533(w),472 (w). When the kind of the metal salt, the kind of the solvent or L-H is changed₂、Zn(NO₃)₂·6H₂The single crystal of the zinc-based chiral porous coordination polymer can not be obtained by the proportion of O and bpy.

Experimental data and characterization:

for the base C obtained in example 2₂Symmetrical fluorescent chiral carboxylic acid ligand L-H₂The crystal structure of the zinc-based chiral porous coordination polymer is measured.

The determination method comprises the following steps: selecting a single crystal sample with proper size, placing the single crystal sample on a single crystal diffractometer, collecting diffraction data, utilizing APEX3 software to restore the obtained diffraction data, utilizing SHELXS-2014 program to analyze and refine the crystal structure, and utilizing a full-matrix least square method (full-matrix least-squares defined on F)²) All non-hydrogen atoms were defined and anisotropic refinement of the atoms was accomplished. In addition chiral ligands L-H₂And the hydrogen atom in bpy is completed by theoretical hydrogenation.

And (3) measuring results: the crystal cell parameters of the zinc-based chiral porous coordination polymer single crystal are α＝β＝γ＝90°, Z＝4。

By analyzing the single crystal data of the zinc-based chiral porous coordination polymer of the invention, the crystal is proved to be in the orthorhombic chiral P2₁2₁2₁A space group, the asymmetric unit of which comprises 1 zn (ii) ion, 1 molecule of ligand L, 1 molecule of bpy and 1 molecule of DMF guest. As shown in FIG. 3, the central metallic Zn (II) ion coordinates 2 carboxyl oxygen atoms from the same ligand L and 2 pyridine nitrogen atoms from different bpy molecules, forming a distorted tetrahedral configuration. The length of the coordination bond around the metal center is respectively Andthe coordinate bond angle around the metal center is 94.351(1) ° to 120.75(2) °.

The ligand L shows high flexibility due to the existence of sulfonyl bonds, so that two carboxyl groups of the ligand L can be coordinated with Zn ions head to form a ring-shaped ZnL structure, and then a W-shaped one-dimensional chain structure shown in figure 4 is formed through the bridging action of bpy molecules; the adjacent one-dimensional chains then passing intermolecularOperatively connected into a two-dimensional layered structure as shown in figure 5; with adjacent layer structures further passing between aromatic ringsThe action is stacked into a porous three-dimensional supermolecular structure, and the calculation of PLTON software shows that the pore space capable of accommodating guest molecules in the zinc-based chiral porous coordination polymer accounts for 35.9 percent of the total volume; in particular, a dimension ofAs shown in fig. 6, wherein the amide group, carbonyl group, naphthalene ring and benzyl group are all oriented towards the open channels, thereby providing rich sites for recognition of chiral guest molecules.

Example 3

Experiment for adsorbing styrene oxide by chiral recognition

In view of the existence of open chiral nanometer pore canals and rich chiral recognition sites in the zinc-based chiral porous coordination polymer, the capability of selectively recognizing different enantiomers of the zinc-based chiral porous coordination polymer is researched by using styrene oxide as a substrate.

Respectively carrying out solvent exchange treatment on the crystal of the zinc-based chiral porous coordination polymer by methanol and acetone for 2 hours, putting 20mg of the crystal into an ethanol solution of racemic styrene oxide with the concentration of 1.0mg/mL, and measuring the enantiomeric excess value (ee.) of the styrene oxide in the supernatant at the time of 0h, 1h, 2h and 3h by using high performance liquid chromatography

The experiment and the result of the chiral adsorption separation of styrene oxide are shown in figure 7, and the contact time of the zinc-based chiral porous coordination polymer and the styrene oxide is changed. Ee. values of styrene oxide in the supernatant at 0h, 1h, 2h and 2h were found to be 0%, 51%, 64% and 65%, respectively; the supernatant is excessive in S-configuration styrene oxide isomer by comparison with a standard sample; while chiral carboxylic acid ligand L-H with the same equivalent weight as that in zinc-based chiral porous coordination polymer₂After 3 hours of mixing with an equal amount of styrene oxide, the ee value of the solution phase is almost zero. The comparative experiment results show that the zinc-based chiral porous coordination polymer can preferentially identify and adsorb styrene oxide with R configuration in 2h and can reach adsorption balance in 2 h. Further researching the microscopic chiral environment of the zinc-based chiral porous coordination polymer, finding that hydrophilic carbonyl, sulfonyl, hydrophobic benzyl, naphthalene ring and the like are periodically embedded in the wall of the open chiral pore channel, and the groups face the chiral pore channel, so that intermolecular forces with different strengths, such as hydrogen bonds, pi-pi stacking effect and the like, can be generated between the chiral pore channel and two enantiomers of styrene oxide, and thus, the enantioselectivity recognition and adsorption of different isomers of styrene oxide are realized.

The comparison experiment shows that the separation effect of the crystal of the zinc-based chiral porous coordination polymer is lower than 65% only by using methanol for exchange or using acetone for exchange or changing the sequence of the methanol and the acetone, probably because the high boiling point solvent molecules in the chiral pore channels of the crystal can be fully removed by using the methanol for exchange and then using the acetone for exchange, otherwise, the DMF molecules which are not removed occupy the limited space of the chiral pore channels, thereby influencing the separation effect.

Example 4

Experiment for identifying styrene oxide by fluorescence sensing

The zinc-based chiral porous coordination polymer shows strong fluorescence emission (Ex 265nm) at 335nm due to the existence of conjugated units such as benzene rings, naphthalene rings and the like, and therefore, the capability of the zinc-based chiral porous coordination polymer for sensing and identifying styrene oxide by fluorescence is continuously researched.

2.0mg of crystal of zinc-based chiral porous coordination polymer is respectively placed in ethanol solutions of R and S-configuration styrene oxide (c is 10mmol/mL, V is 2mL) and 2mL of ethanol blank solvent, and after the mixture is uniformly stirred for 1 hour, the fluorescence intensities of the three are respectively detected.

As shown in FIG. 8, when S-configuration styrene oxide is added to an ethanol suspension of zinc-based chiral porous coordination polymer crystals, the fluorescence is quenched by about 11.5%, and when R-configuration styrene oxide is added, the fluorescence is quenched by as much as 60%. This result indicates that chiral complex 1 is capable of intermolecular interaction with two enantiomers of styrene oxide, so that fluorescence is quenched to some extent; but the zinc-based chiral porous coordination polymer has stronger interaction with an R-configured styrene oxide molecule, so that the fluorescence of the zinc-based chiral porous coordination polymer is quenched more remarkably and quickly. The results of the fluorescence sensing experiment and the chiral recognition adsorption experiment simultaneously show that the zinc-based chiral porous coordination polymer with the fluorescence performance constructed based on the L-phenylalanine can preferentially and selectively recognize the R-configured styrene oxide, so that the zinc-based chiral porous coordination polymer can be used as a potential chiral fluorescence sensing material and a chiral separation material for rapidly recognizing and separating the chiral small-molecule epoxy compound.

The contrast experiment shows that the crystal of the zinc-based chiral porous coordination polymer is exchanged only by methanol or acetone or the sequence of the two is changed, no obvious phenomenon exists in the experiment of identifying styrene oxide by fluorescence sensing, and the high-boiling-point solvent molecules in the crystal pore channel of the zinc-based chiral porous coordination polymer can be effectively removed only by methanol and acetone, so that the chiral identification function is realized.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.