A six-toothed aminophenoxy rare earth complex substituted with a nitrogen-containing heterocycle, and a preparation method and application thereof

Abstract

The present invention discloses a class of nitrogen heterocycle-substituted hexa-dentate aminophenoxy rare earth complexes (I), a preparation method thereof, and an application thereof in the highly active catalytic ring-opening polymerization of lactones. The preparation method comprises the following steps: reacting a neutral ligand with a metal raw material compound in an organic medium, then adding an alcohol for reaction, and obtaining the target compound through filtration, concentration, and recrystallization. The nitrogen heterocycle-substituted hexa-dentate aminophenoxy rare earth complex of the present invention is a highly efficient catalyst for the ring-opening polymerization of lactones, and can be used for catalyzing the polymerization reaction of lactones such as lactide, and catalyzing the one-pot copolymerization of lactide and ε-caprolactone to obtain a multi-block copolymer. The nitrogen heterocycle-substituted hexa-dentate aminophenoxy rare earth complex of the present invention has good tolerance to impurities, has very high catalytic activity, and can obtain high molecular weight polyester materials. A has a structure shown in formula (II), (III), (IV) or (V); B has a structure shown in formula (VI) or (VII).

Description

Technical Field

[0001] The present invention relates to a class of six-toothed aminophenoxy rare earth complexes substituted with nitrogen heterocycles, a preparation method thereof, and the application of such complexes in lactide polymerization. Background Art

[0002] In recent years, with the improvement of people's living standards and environmental awareness, humans have begun to search for polyolefin substitutes that are convenient to synthesize and environmentally friendly. Among them, poly(lactic acid) (PLA) is widely sourced, and its final degradation products are water and carbon dioxide, making it a green and environmentally friendly polymer material. At the same time, PLA has high tensile strength and compressive modulus and has been widely used as a biomedical polymer in medical coatings, sustained-release drugs, surgical sutures, fracture fixation materials, etc. Therefore, the synthesis of poly(lactic acid) and the design of the required catalysts have been widely studied by scientists from all walks of life.

[0003] Lactide contains two chiral centers and thus has three isomers, meso-lactide (meso-LA), L-lactide (L-LA), and D-lactide (D-LA). When an equal proportion of L-lactide and D-lactide are mixed, it forms racemic lactide (L-LA:D-LA = 1:1, rac-LA). Catalyzing the polymerization of different configurations of lactide can obtain poly(lactic acid) with various microscopic stereostructures. The physical properties and processing properties of poly(lactic acid) are mainly determined by its stereoregularity. For example, isotactic poly(lactic acid) is a crystalline polymer material with a melting point of about 170 - 180 °C and good mechanical strength, and is commonly used as a bone fixation material. The stereocomplex formed by PDLA and PLLA has a higher melting point (220 - 240 °C) and exhibits good thermal stability. Heterotactic and atactic poly(lactic acid) are amorphous polymers. The heterotactic polymer has a lower melting point, while the atactic polymer has no melting point and is commonly used as a drug sustained-release body. In addition, the molecular weight of the polymer also affects its properties. Therefore, designing and synthesizing catalysts with both high activity and high selectivity to catalyze the polymerization of racemic lactide to obtain polymer materials with different stereoregularities is of great significance. Rare earth metal elements have different atomic structures and electron distributions from other metal elements and have unique properties and applications in the fields of organometallic chemistry and coordination chemistry. Designing and synthesizing highly active and highly stereoselective rare earth complexes to achieve the controllable synthesis of poly(lactic acid)-based polymers has become one of the current research hotspots.

[0004] From 2004 to 2011, the Carpentier group reported tetradentate claw-type aminophenoxy yttrium complexes, which have high activity in catalyzing the ring-opening polymerization of racemic lactide, and the highest heterotactic selectivity can reach P r= 0.96 (Chem. Commun., 2004, 330 - 331; Chem. Eur. J., 2006, 12: 169 - 179; Chem. Eur. J., 2011, 17: 1872 - 1883). In 2007, the group of Cui Dongmei reported a tetradentate claw-type aminophenoxo lanthanide metal complex of the same type of ligand, which had moderate catalytic activity for the polymerization of rac-LA, but very high heterotactic selectivity, P r = 0.95 - 0.99 (Organometallics, 2007, 26: 2747 - 2757). In 2006, the Okuda group reported a class of linear tetradentate sulfur-bridged phenoxo scandium complexes, and the highest heterotactic selectivity could reach P r = 0.96 (Angew. Chem. Int. Ed., 2006, 45: 7818 - 7821.). When the monomer was changed to meso-lactide, the syndiotacticity could reach P s = 0.93 (Macromolecules, 2010, 43: 10201 - 10203). In 2008, the Arnold group reported a class of C3-symmetric chiral phosphine oxide-substituted alkoxy rare earth complexes, which could catalyze the complete conversion of 200 equivalents of monomers in 10 min at -18 °C in dichloromethane to obtain multi-block isotactic poly(PLA) (P m = 0.81), which was the first rare earth complex reported in the literature with isotactic catalytic selectivity for the ring-opening polymerization of rac-LA (Angew. Chem. Int. Ed., 2008, 47: 6033 - 6036). In 2012, the Williams group reported a series of yttrium complexes with tetradentate phosphinimino-bridged phenolic ligands, which had high activity in catalyzing the polymerization of rac-LA and relatively high heterotactic selectivity, with the highest reaching P r = 0.88 (Inorg. Chem., 2012, 51: 2157 - 2169). After the group introduced an additional coordinating atom into the bridging group of the phosphinoaminophenol ligand, the complex catalyzed the polymerization of racemic lactide at room temperature to obtain poly(lactide) with medium isotacticity, P m = 0.77 (J. Am. Chem. Soc., 2012, 134: 20577 - 20580). In 2017, the Lu group reported a series of yttrium complexes with [OOOO]-type linear tetradentate bisphenol ligands coordinated with one molecule of tetrahydrofuran. This series of complexes had good activity and isotactic selectivity in catalyzing the polymerization of rac-LA, and was the rare earth complex with the highest reported isotactic selectivity in the literature (-15 °C, P i = 0.90; 25 °C, P i = 0.84) (Macromolecules, 2017, 50: 515 - 522).

[0005] The copolymerization of lactide with other lactones is also a research hotspot in the development of aliphatic polyester materials. It has been found that the copolymerization of lactide with ε-caprolactone (ε-CL) can improve the defects of single polymers in terms of material properties, making their advantages complementary and obtaining materials with controllable biodegradation rates and permeability (Angew. Chem. Int. Ed., 2011, 50: 9244-9246). Rare earths have natural advantages in the catalytic field, but there are few cases of using rare earth catalysts for the copolymerization of lactide with ε-caprolactone. In 2020, the group of Yao Yingming reported a yttrium complex with aminophenoxy ligand, which catalyzed the one-pot copolymerization of L-LA and ε-CL to obtain a random copolymer P(LA-sta-CL) (Dalton Trans., 2020, 49: 5842-5850).

[0006] At present, great breakthroughs have been made in the field of ring-opening polymerization of racemic lactide with rare earth metal complexes. The synthesis of poly(lactide) with different stereoconfigurations has been achieved to a certain extent by changing the metal center of the complex and adjusting the ligand structure. Among them, there are many rare earth complexes with heterotactic selectivity, but few rare earth metal complexes with isotactic selectivity. In addition, most rare earth metal complexes have low tolerance to impurities and are difficult to be applied industrially. Therefore, it is necessary to further develop the research on rare earth metal catalysts in order to develop rare earth catalysts with both high activity, high stereoselectivity and good impurity tolerance. Summary of the Invention

[0007] One of the purposes of the present invention is to disclose a class of hexadentate aminophenoxy rare earth complexes substituted with nitrogen-containing heterocycles.

[0008] Another purpose of the present invention is to disclose a preparation method of a class of hexadentate aminophenoxy rare earth complexes substituted with nitrogen-containing heterocycles.

[0009] A third purpose of the present invention is to disclose the application of a class of hexadentate aminophenoxy rare earth complexes substituted with nitrogen-containing heterocycles in lactone polymerization.

[0010] Technical concept of the present invention:

[0011] Aminophenol ligands have the characteristics of readily available raw materials, simple synthesis, and adjustable structure. By changing the substituents to regulate the electronic effect and steric effect, the catalytic activity and stereoselectivity of metal catalysts can be effectively controlled. Different from other metals, rare earth metals have large orbital radii and many empty orbitals, and multidentate chelating ligands are required to stabilize the metal center. At present, there is no research report on the application of rare earth catalysts coordinated with hexadentate ligands in the ring-opening polymerization of racemic lactide. The present invention will provide a class of rare earth complexes of nitrogen heterocyclic substituted hexaaminophenoxy, by changing the types of nitrogen heterocycles and the ortho-substituents of phenoxy groups in the ligand, to adjust the Lewis acidity of the rare earth metal center and the steric hindrance around the metal center, in order to achieve the high activity and high stereoselectivity of rare earth complexes in catalyzing the ring-opening polymerization of racemic lactide. In addition, the present invention further applies this class of rare earth catalysts to the copolymerization of lactide and ε-caprolactone, and regulates the composition and properties of the copolymer by changing factors such as monomer ratio and temperature.

[0012] The rare earth complex (I) of nitrogen heterocyclic substituted hexaaminophenoxy provided by the present invention is characterized by having the following general formula:

[0013]

[0014] In formula (I):

[0015] R 1 ~R 2 respectively represent alkyl groups with a straight-chain, branched-chain or cyclic structure having C1 to C 20 alkyl groups substituted with C7 to C 30 mono- or poly-aryl;

[0016] A is a group having a structure shown in formula (II), (III), (IV) or (V):

[0017]

[0018] A coordinates with the metal center Re through its nitrogen atom; Re represents Y, La;

[0019] B is an alkylene bridge having a structure shown in formula (VI) or (VII):

[0020]

[0021] R 3 represents alkyl groups with a straight-chain, branched-chain or cyclic structure having C1 to C 10 alkyl groups substituted with C7 to C 20 mono- or poly-aryl.

[0022] In formula (I), R 1 ~R 2Preferably an alkyl group having a straight-chain, branched-chain or cyclic structure of C1-C8, a C7-C 20 alkyl group substituted with mono- or poly-aryl;

[0023] R 3 Preferably an alkyl group having a straight-chain, branched-chain or cyclic structure of C1-C6, a C7-C 13 alkyl group substituted with mono- or poly-aryl;

[0024] More characteristically, in formula (I), R 1 ~R 2 is preferably methyl, isopropyl, tert-butyl, cumyl, trityl; R 3 is preferably methyl, ethyl, isopropyl, tert-butyl, benzyl, 2-phenylethyl, 1-phenylethyl.

[0025] The preferred structure of the hexa-dentate aminophenoxy rare earth complex substituted with a nitrogen-containing heterocycle is:

[0026]

[0027]

[0028]

[0029] The preferred hexa-dentate aminophenoxy rare earth complex substituted with a nitrogen-containing heterocycle, its ligand typically has the following structure:

[0030]

[0031] For the hexa-dentate aminophenoxy rare earth complex substituted with a nitrogen-containing heterocycle described in the present invention, the synthetic route of its ligand (VIII) is as shown below:

[0032]

[0033] The diamine is subjected to reductive amination reaction with the aldehyde group-substituted nitrogen-containing heterocyclic compound shown in formula (X) to generate the corresponding di-secondary amine, and 2-bromomethyl-4,6-disubstituted phenol (IX) is added for reaction. The reaction temperature is 0-90 °C, and the reaction time is 2-72 hours. Then the ligand compound (VIII) is collected from the reaction product;

[0034] Among them, the synthesis of 2-bromomethyl-4,6-disubstituted phenol (IX) can be obtained by reacting 2,4-disubstituted phenol with paraformaldehyde in a 33% acetic acid solution of hydrogen bromide according to the reference method (Inorg. Chem., 2002, 41, 3656; J. Org. Chem., 1994, 59, 1939):

[0035]

[0036] The preparation method of the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex (I) according to the present invention is as follows:

[0037]

[0038] React the nitrogen heterocyclic substituted hexa-dentate aminophenol ligand compound shown in formula (VIII) with the rare earth metal raw material compound Re[N(SiMe3)2]3 in an organic medium, and then add alcohol R 3 OH to continue the reaction. The reaction temperature is 0-100 °C, and the reaction time is 2-24 hours. Then, collect the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth target complex (I) from the reaction product;

[0039] In the above preparation method, the substituents R 1 ~R 3 、A and B are consistent with the corresponding groups of the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex (I) satisfying the present invention.

[0040] The molar ratio of the nitrogen heterocyclic substituted hexa-dentate aminophenol ligand compound (VIII), the rare earth raw material compound Re[N(SiMe3)2]3 and the alcohol R 3 OH is 1:1.0-1.5:0.8-1.5, preferably 1:1.0-1.2:0.9-1.2; the organic medium is selected from one or two of tetrahydrofuran, ether, toluene, benzene, petroleum ether and n-hexane.

[0041] The nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to the present invention is an efficient lactone polymerization catalyst and can be used for the polymerization reactions of L-lactide, D-lactide, rac-lactide, meso-lactide, ε-caprolactone, β-butyrolactone and α-methyltrimethylene carbonate. The polymerization methods are solution polymerization and melt polymerization.

[0042] Using the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to the present invention as a catalyst, lactide is polymerized at -40-180 °C, preferably 0-130 °C; the molar ratio of the catalyst to the monomer during polymerization is 1:1-50000, preferably 1:200-15000.

[0043] Using the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to the present invention as a catalyst, ε-caprolactone is polymerized at -40-180 °C, preferably 0-130 °C; the molar ratio of the catalyst to the monomer during polymerization is 1:1-50000, preferably 1:200-15000.

[0044] Using the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex of the present invention as a catalyst, ε-caprolactone is copolymerized with lactide. The lactide is preferably one or more of L-lactide, D-lactide, rac-lactide and meso-lactide; the copolymerization temperature is -40 to 180 °C, preferably 0 to 130 °C; in the copolymerization reaction, the molar ratio of the rare earth catalyst to lactide is 1:50 to 5000, preferably 1:100 to 1500, and the molar ratio of the rare earth catalyst to ε-caprolactone is 1:1 to 5000, preferably 1:50 to 1500. The present invention has no special requirement for the molar ratio of lactide to ε-caprolactone, and it is only necessary to meet the requirements of the molar ratio of the catalyst to lactide and the molar ratio of the catalyst to ε-caprolactone.

[0045] Using the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex of the present invention as a catalyst, when catalyzing the polymerization of lactone, a certain amount of alcohol can be added as a chain transfer agent to regulate the molecular weight of the obtained polymer. The molar ratio of the catalyst to alcohol and monomer during polymerization is 1:1 to 50:1 to 50000, preferably 1:1 to 10:1 to 15000; the alcohol is an alkyl alcohol with a straight-chain, branched-chain or cyclic structure, a C7-C 10 alkyl alcohol with a straight-chain, branched-chain or cyclic structure, C7-C 20 alkyl alcohol substituted with a single or multiple aryl groups, preferably isopropanol and benzyl alcohol.

[0046] The catalyst provided by the present invention is easy to prepare, has stable properties and strong impurity tolerance. It can even directly use industrial-grade lactide without purification treatment for ring-opening polymerization and obtain a polymer with the same performance as that obtained by polymerizing with purified monomers; at the same time, the catalyst provided by the present invention has a certain stereoselectivity during the catalytic ring-opening polymerization of lactide, and adjusting the ligand structure can realize the transformation from heterotactic selectivity to isotactic selectivity polymerization; in addition, the catalyst provided by the present invention realizes for the first time the preparation of a multi-block copolymer of lactide and ε-caprolactone by a one-pot feeding method. The present invention will be further illustrated by examples below, but the present invention is not limited thereto. Detailed implementation mode

[0047] Example 1

[0048] The ligand L1 described in the present invention was synthesized according to the literature (RSC Adv., 2015, 5, 477):

[0049] (1) Synthesis of N,N'-bis[(pyridin-2-yl)-methyl]ethylenediamine

[0050]

[0051] Add 25 mL of methanol, ethylenediamine (10 mmol, 0.60 g), and pyridine-2-carboxaldehyde (20.0 mmol, 2.14 g) to a 50 mL three-necked flask. React at 70 °C in an oil bath for 10 h. Cool to room temperature, and slowly add sodium borohydride (30.0 mmol, 1.13 g) under a water bath. Continue to react at 70 °C in an oil bath for 12 h. Cool to room temperature, quench with saturated potassium carbonate solution, extract with dichloromethane, dry over anhydrous Na2SO4, and evaporate the solvent under reduced pressure to obtain a brown oil (2.32 g, yield about 96%). Without further purification, it is directly used for the next step.

[0052] (2) Synthesis of ligand L1

[0053]

[0054] Add 20 mL of dichloromethane to a 50 mL eggplant-shaped flask containing N,N'-bis[(pyridin-2-yl)methyl]ethylenediamine (about 9.21 mmol, 2.24 g). Then, add triethylamine (57.4 mmol, 5.81 g) and 2-bromomethyl-4,6-di-tert-butylphenol (18.4 mmol, 5.51 g) successively. React at room temperature for 12 h, quench with water, extract with dichloromethane, dry over anhydrous Na2SO4, evaporate the solvent under reduced pressure, add 30 mL of methanol, stir for 12 h, and then pour out the mother liquor and filter to obtain a milky white powder (5.66 g, 90.4%). 1 H NMR (400 MHz, CDCl3, 298 K) δ 10.47 (s, 2H, OH), 8.50 (d, 3 J = 4.8 Hz, 2H, ArH), 7.58 (td, 3 J = 7.7, 1.7 Hz, 2H, ArH), 7.23 (d, 3 J = 7.8 Hz, 2H, ArH), 7.18 (d, 4 J = 2.2 Hz, 2H, ArH), 7.13 (dd, 3 J = 6.7, 5.0 Hz, 2H, ArH), 6.79 (d, 4 J = 2.2 Hz, 2H, ArH), 3.70 (s, 8H, NCH2Ar,), 2.81 (s, 4H NCH2CH2N), 1.39 (s, 18H, C(CH3)3), 1.25 (s, 18H), C(CH3)3.

[0055] Example 2

[0056] Synthesis of ligand L2:

[0057]

[0058] Dissolve N,N'-bis[(pyridin-2-yl)-methyl]ethylenediamine (about 9.57 mmol, 2.32 g) in 20 mL of dichloromethane in a 50 mL eggplant-shaped flask. Then, successively add triethylamine (57.4 mmol, 5.81 g) and 2-(bromomethyl)-4,6-dicumylphenol (19.1 mmol, 8.08 g). React at room temperature for 12 h, quench with water, extract with dichloromethane, dry over anhydrous Na2SO4, and remove the solvent under reduced pressure. Then add 30 mL of methanol, stir for 12 h, pour out the mother liquor, and filter to obtain a yellow foamy powder (4.67 g, 52.6%). 1 H NMR (400 MHz, CDCl3, 298 K): δ 10.00 (br s, 2H, OH), 8.33 (d, 3 J = 4.8 Hz, 2H, ArH), 7.34 (td, 3 J = 7.7, 1.6 Hz, 2H, ArH), 7.19–7.26 (m, 7H, ArH), 7.01–7.08 (m, 12H, ArH), 7.09–7.01 (m, 5H, ArH), 6.67 (s, 2H, ArH), 6.56 (d, 3 J = 7.8 Hz, 2H, ArH), 3.48 (s, 4H, NCH2Ar), 3.38 (s, 4H, NCH2Ar), 2.45 (s, 4H, NCH2CH2N), 1.66 (s, 12H, C(CH3)2Ph), 1.63 (s, 12H, C(CH3)2Ph). 13 C{1H}NMR (101 MHz, CDCl3) δ 157.28, 153.40, 151.60, 151.40, 148.75, 140.22, 136.79, 135.33, 128.00, 127.75, 126.82, 126.15, 125.78, 125.52, 125.06, 124.79, 123.97, 122.26, 121.39, 58.99, 58.87, 49.87, 42.55, 42.09, 31.18, 29.55. Anal. Calcd. for C 64 H 70 N4O2: C, 82.90; H, 7.61; N, 6.04. Found: C, 82.87; H, 7.38; N, 5.70%.

[0059] Example 3

[0060] Synthesis of ligand L3

[0061] (1) Synthesis of N,N'-bis[(quinolin-2-yl)-methyl]ethylenediamine

[0062]

[0063] Except that the raw materials used were ethylenediamine (10 mmol, 0.60 g), quinoline-2-carbaldehyde (20.0 mmol, 3.14 g) and sodium borohydride (31.0 mmol, 1.18 g), the other operation steps were the same as those in Example 1. A red oil (3.44 g, yield approximately 100%) was obtained.

[0064] (2) Synthesis of ligand L3

[0065]

[0066] Except that the raw materials used were N,N'-bis[(quinolin-2-yl)methyl]ethylenediamine (about 10 mmol, 3.44 g), triethylamine (60 mmol, 6.07 g) and 2-(bromomethyl)-4,6-di-tert-butylphenol (20.0 mmol, 5.98 g), the other operations were the same as those in Example 1, and a light yellow solid (6.42 g, 82.4%) was obtained. 1 H NMR (400 MHz, CDCl3) δ 10.70 (br s, 2H, OH), 8.09 (d, 3 J = 8.4 Hz, 2H, ArH), 7.94 (d, 3 J = 8.5 Hz, 2H, ArH), 7.72 (d, 3 J = 8.1 Hz, 2H, ArH), 7.67 (t, 3 J = 7.1 Hz, 2H, ArH), 7.49 (t, 3 J = 7.5 Hz, 2H, ArH), 7.25 (d, 3 J = 8.4 Hz, 2H, ArH), 7.19 (d, 3 J = 2.3 Hz, 2H, ArH), 6.80 (d, 3 J = 2.2 Hz, 2H, ArH), 3.91 (s, 4H, NCH2Ar), 3.75 (s, 4H, NCH2Ar), 2.87 (s, 4H, NCH2CH2N), 1.41 (s, 18H, C(CH3)3), 1.23 (s, 18H, C(CH3)3). 13 C{ 11H NMR (101 MHz, CDCl3, 298 K): δ 158.33, 154.02, 147.58, 140.50, 136.65, 135.67, 129.64, 129.08, 127.58, 127.29, 126.41, 124.44, 123.19, 121.72, 121.05, 60.04, 59.10, 50.66, 35.04, 34.21, 31.84, 29.79. Anal. Calcd. for C 52 H 66 N4O2: C, 80.16; H, 8.54; N, 7.19. Found: C, 79.81; H, 8.36; N, 6.94%.

[0067] Example 4

[0068] Synthesis of ligand L4

[0069] (1) Synthesis of N,N'-bis[(N-methylimidazol-2-yl)-methyl]ethylenediamine

[0070]

[0071] Except that ethylenediamine (6.0 mmol, 0.36 g), N-methylimidazole-2-carboxaldehyde (12 mmol, 1.32 g) and sodium borohydride (13.2 mmol, 0.499 g) were used as raw materials, other operation steps were the same as those in Example 1. A brownish-red oily substance (0.49 g, yield about 33.0%) was obtained.

[0072] (2) Synthesis of ligand L4

[0073]

[0074] Except that N,N'-bis[(N-methylimidazol-2-yl)-methyl]ethylenediamine (about 1.98 mmol, 0.49 g), triethylamine (12.0 mmol, 1.21 g) and 2-(bromomethyl)-4,6-di-tert-butylphenol (3.95 mmol, 1.18 g) were used as raw materials, other operations were the same as those in Example 1, and a light yellow solid (0.74 g, 54.1%) was obtained. 1 1H NMR (400 MHz, CDCl3, 298 K): δ 9.97 (s, 1H, OH), 7.19 (d, 3 J = 2.3 Hz, 2H, ArH), 6.90 (d, 3 J = 1.1 Hz, 2H, ArH), 6.80 (d, 3 J = 2.3 Hz, 2H, ArH), 6.75 (d, 3J = 1.0 Hz, 2H, ArH), 3.67 (s, 4H, NCH2Ar), 3.62 (s, 4H, NCH2Ar), 3.42 (s, 6H, NCH3), 2.88 (s, 4H, NCH2CH2N), 1.38 (s, 18H, C(CH3)3), 1.25 (s, 18H, C(CH3)3). 13 C{1H} NMR (101 MHz, CDCl3) δ 153.57, 143.75, 141.00, 135.65, 127.47, 124.30, 123.25, 121.64, 121.29, 58.84, 50.71, 49.18, 34.94, 34.22, 32.84, 31.73, 29.65. Anal. Calcd. for C 42 H 64 N6O2: C, 73.64; H, 9.42; N, 12.27. Found: C, 73.72; H, 9.28; N, 12.10%.

[0075] Example 5

[0076] Synthesis of Ligand L5

[0077] (1) Synthesis of (R,R)-N,N'-bis[(pyridin-2-yl)methyl]cyclohexanediamine

[0078]

[0079] Except that the starting materials used were (R,R)-cyclohexanediamine (10.0 mmol, 1.14 g), pyridine-2-carbaldehyde (20.0 mmol, 2.14 g) and sodium borohydride (31.0 mmol, 1.18 g), the other operation steps were the same as in Example 1. A yellowish-brown oily substance (2.55 g, yield about 86%) was obtained.

[0080] (2) Synthesis of Ligand L5

[0081]

[0082] Except that the starting materials used were (R,R)-N,N'-bis[(pyridin-2-yl)methyl]cyclohexanediamine (about 8.61 mmol, 2.55 g), triethylamine (51.7 mmol, 5.23 g) and 2-(bromomethyl)-4,6-di-tert-butylphenol (17.2 mmol, 5.16 g), the other operations were the same as in Example 1, and a light yellow solid (3.94 g, 62.5%) was obtained. 11H NMR (400 MHz, CDCl3, 298 K) δ 8.55 (s, 2H, ArH), 7.52 (s, 2H, ArH), 7.15 (s, 2H, ArH), 7.12 (s, 2H, ArH), 6.70 (s, 2H, ArH), 3.96 (d, 2 J = 11.7 Hz, 2H, ArCH2N), 3.77 (br s, 2H, NCHCHN), 3.54 (d, 4H, ArCH2N), 2.90 (s, 2H, ArCH2N), 2.15 (s, 2H, CH2 of cyclohexyl), 1.71 (s, 2H, CH2 of cyclohexyl), 1.29 (s, 18H, C(CH3)3), 1.23 (s, 18H, C(CH3)3), 1.07 (s, 4H, CH2 of cyclohexyl). Anal. Calcd. for C 48 H 68 N4O2: C, 78.64; H, 9.35; N, 7.64. Found: C, 78.74; H, 9.42; N, 7.34%.

[0083] Example 6

[0084] Synthesis of rare earth complex Y1

[0085] Under argon protection, ligand L1 (0.500 mmol, 339 mg) was added to a 50 mL Schlenk flask and dissolved in 15 mL of anhydrous tetrahydrofuran. Then Y[N(SiMe3)2]3 (0.500 mmol, 285 mg) was dissolved in 5 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 6 h. Then t BuOH (0.0 mmol, 37 mg) was dissolved in 2 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 8 h. A small amount of impurities was removed by filtration, and the solvent was removed under reduced pressure to obtain a yellow foamy solid. Recrystallization from toluene and n-hexane gave a pale yellow solid (218 mg, 52%).

[0086]

[0087] 1 1H NMR (400 MHz, C6D6, 298 K): δ 9.81 (d, 3 J = 4.3 Hz, 2H, ArH), 7.37 (d, 3J = 2.6 Hz, 2H, ArH), 6.88 (td, 3J = 7.7, 1.8 Hz, 2H, ArH), 6.76 (d, 3J = 2.6 Hz, 2H, ArH), 6.68–6.64 (m, 2H, ArH), 6.37 (d, 3J = 7.6 Hz, 2H, ArH), 3.99 (d, 2 J = 14.4 Hz, 2H, NCH2Ar), 3.33 (d, 2 J = 11.9 Hz, 2H, NCH2Ar), 2.87 (d, 2 J = 11.4 Hz, 2H, NCH2CH2N), 2.66 (d, 2J = 14.3 Hz, 2H, NCH2Ar), 2.33 (d, 2 J = 12.1 Hz, 2H, NCH2CH2N), 1.85 (s, 9H, OC(CH3)3), 1.50 (s, 18H, PhC(CH3)3), 1.40 (s, 18H, PhC(CH3)3). 13 C{ 1 H} NMR (100 MHz, C6D6, 298 K): δ 163.71, 158.21, 152.56, 138.13, 135.72, 134.21, 125.19, 123.71, 121.97 (all Ar-C), 70.83, 67.80 (THF) 62.81, 35.73, 35.36, 34.10, 32.51, 30.28, 25.72 (THF). Anal. Calcd. for C 48 H 69 N4O3Y·1.6C4H8O: C, 68.46; H, 8.64; N, 5.87. Found: C, 67.92; H, 8.19; N, 6.35%.

[0088] Example 7

[0089] Synthesis of rare earth complex La1

[0090] Under argon protection, ligand L1 (0.500 mmol, 339 mg) was added to a 50 mL Schlenk flask and dissolved in 15 mL of anhydrous tetrahydrofuran. Then La[N(SiMe3)2]3 (0.5 mmol, 310 mg) was dissolved in 5 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 6 h. Then BnOH (0.50 mmol, 54 mg) was dissolved in 2 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 8 h. A small amount of impurities was removed by filtration, and the filtrate was dried under reduced pressure to obtain a yellow foamy solid. Recrystallization from toluene and n-hexane gave a pale yellow solid (393 mg, 47%).

[0091]

[0092] 1 H NMR (400 MHz, C6D6, 298 K): δ 8.81 (d, 3J = 3.9 Hz, 2H, ArH), 7.97 (d, 3 J = 7.5 Hz, 2H, ArH), 7.52 (d, 4 J = 2.5 Hz, 2H, ArH), 7.41 (t, 3 J = 7.6 Hz, 2H, ArH), 7.2 (t, 3 J = 7.4 Hz, 1H, ArH), 7.13 (t, 2H, toluene), 7.08–6.99 (m, 3H, toluene), 6.90 (d, 4 J = 2.4 Hz, 2H, ArH), 6.82 (td, 3 J = 7.7, 1.4 Hz, 2H, ArH), 6.42 (t, 3 J = 6.2 Hz, 2H, ArH), 6.36 (d, 3 J = 7.7 Hz, 2H, ArH), 5.76 (s, 2H, PhCH2O), 3.94 (d, 2 J = 14.2 Hz, 2H, ArCH2N), 3.78 (d, 2 J = 12.0 Hz, 2H, ArCH2N), 2.94 (br s, 2H, NCH2CH2N), 2.40 (d, 2 J = 12.0 Hz, 2H, ArCH2N), 2.31 (d, 2 J = 14.2 Hz, 2H, ArCH2N), 2.10 (s, 3H, toluene), 2.02 (br s, 2H, NCH2CH2N), 1.45 (s, 18H, C(CH3)3), 1.43 (s, 18H, C(CH3)3). 13 C{ 1 H} NMR (100 MHz, C6D6, 298 K): δ 163.74, 158.20, 150.48, 148.95, 138.34, 136.11, 134.82, 129.3 (toluene), 128.6 (toluene), 126.78, 125.99, 125.7 (toluene), 124.41, 123.94, 123.20 (all Ar-C), 71.04, 63.02, 35.36, 34.19, 32.48, 30.06, 21.1 (toluene). Anal. Calcd. for: C 51 H 67 N4O3La·C7H8: C, 68.62; H, 7.45; N, 5.52. Found: C, 68.20; H, 7.89; N, 5.50%.

[0093] Example 8

[0094] Synthesis of rare earth complex La2

[0095] Under argon protection, ligand L2 (0.500 mmol, 463 mg) was added to a 50 mL Schlenk flask and dissolved in 15 mL of anhydrous tetrahydrofuran. Then, La[N(SiMe3)2]3 (0.500 mmol, 310 mg) was dissolved in 5 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 6.5 h. Then, BnOH (0.50 mmol, 54 mg) was dissolved in 2 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was continued at room temperature for 8 h. A small amount of impurities was removed by filtration, and the solvent was removed under reduced pressure to obtain a yellow foamy solid. Recrystallization from toluene, dichloromethane, and n-hexane gave a pale yellow solid (341 mg, 58%).

[0096]

[0097] 1 H NMR (400 MHz, C6D6, 298 K) δ 8.69 (s, 2H, ArH), 7.79 (d, 4 J = 6.8 Hz, 2H, ArH), 6.87–6.82 (m, 2H, ArH), 6.72–6.82 (m, J = 6.8 Hz, 2H, ArH), 6.59 (s, 2H, ArH), 6.43 - 6.51 (m, 2H, ArH), 6.25 (d, 4 J = 7.6 Hz, 2H, ArH), 5.48 (s, 2H, PhCH2O), 4.25 (s, 0.6H, CH2Cl2) 3.19 (d, 2 J = 13.3 Hz, 2H ArCH2N), 2.66 - 2.87 (m, 4H, ArCH2N), 2.45 (d, 2 J = 13.7 Hz, 2H, ArCH2N), 2.18 (d, 2 J = 14.9 Hz, 4H, NCH2CH2N), 2.00, (s, 6H, C(CH3)2Ph), 1.72 (s, 6H, C(CH3)2Ph), 1.70 (s, 6H, C(CH3)2Ph), 1.62 (s, 6H, C(CH3)2Ph). 13 C{ 1 H}NMR (100 MHz, C6D6, 298 K): δ 163.31, 158.27, 152.83, 127.23 (all Ar-C), 53.5 (CH2Cl2) 42.40, 31.56. Anal. Calcd. for: C 71 H 75N4O3La·0.3CH2Cl2: C, 71.56; H, 6.37; N, 4.68. Found: C, 71.14; H, 6.44; N, 4.44%.

[0098] Example 9

[0099] Synthesis of rare earth complex La3

[0100] Under argon protection, ligand L3 (0.500 mmol, 390 mg) was added to a 50 mL Schlenk flask, dissolved in 5 mL of anhydrous tetrahydrofuran, and then La[N(SiMe3)2]3 (0.500 mmol, 310 mg) was dissolved in 5 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 6.5 h. Then, BnOH (0.50 mmol, 54 mg) was dissolved in 2 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was continued at room temperature for 8 h. A small amount of impurities was removed by filtration, and the solvent was removed under reduced pressure to obtain a yellow foamy solid. Recrystallization from toluene and n-hexane gave a pale yellow solid (402 mg, 79%).

[0101]

[0102] 1 H NMR (400 MHz, C6D6, 298 K): δ 10.10 (d, 3 J = 8.6 Hz, 2H, ArH), 8.13 (d, 3 J = 7.5 Hz, 2H, ArH), 7.53–7.42 (m, 6H, ArH), 7.33 (d, 3 J = 8.4 Hz, 2H, ArH), 7.25 (dd, 3 J = 13.9, 6.9 Hz, 2H, ArH), 7.12–7.05 (m, 2H, ArH), 6.84 (d, 4 J = 2.4 Hz, 2H, ArH), 6.54 (d, 3 J = 8.3 Hz, 2H, ArH), 6.00 (s, 1H, PhCH2O), 4.30 (d, 2 J = 14.9 Hz, 2H, ArCH2N), 3.96 (d, 2 J = 12.4 Hz, 2H, ArCH2N), 3.50 (d, 2 J = 9.4 Hz, 2H, NCH2CH2N), 2.29 (m, 4H, ArCH2N), 1.58 (d, J = 10.6 Hz, 2H, NCH2CH2N), 1.41 (s, 18H, C(CH3)3), 1.21 (s, 18H, C(CH3)3). 13 C{ 11H NMR (100 MHz, C6D6, 298 K): δ 13C NMR (101 MHz, C6D6) δ 163.48, 159.25, 148.04, 138.74, 136.57, 135.14, 131.38, 130.35, 128.55, 127.60, 127.39, 127.15, 126.24, 125.97, 123.96, 123.83, 121.30, 62.43, 50.40, 35.18, 34.21, 32.38, 29.58. Anal. Calcd. for: C 59 H 11 N4O3La: C, 69.26; H, 6.99; N, 5.48. Found: C, 69.02; H, 7.04; N, 5.68%.

[0103] Example 10

[0104] Synthesis of rare earth complex La4

[0105] Under argon protection, ligand L4 (0.500 mmol, 342 mg) was added to a 50 mL Schlenk flask and dissolved in 20 mL of anhydrous tetrahydrofuran. Then La[N(SiMe3)2]3 (0.500 mmol, 310 mg) was dissolved in 5 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 10 h. Then BnOH (0.50 mmol, 54 mg) was dissolved in 2 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 12 h. A small amount of impurities were removed by filtration, and the filtrate was dried under vacuum to obtain a yellow foamy solid. Recrystallization with tetrahydrofuran, dichloromethane, and n - hexane gave a light yellow powder (349 mg, 75%).

[0106]

[0107] 1 1H NMR (400 MHz, C6D6, 298 K): δ 7.54 (d, 4 J = 2.4 Hz, 2H), 7.53–7.50 (m, 4H, ArH and H of imidazole), 7.30–7.23 (m, 5H, ArH and H of imidazole), 6.93 (d, 4 J = 2.4 Hz, 2H, ArH), 5.85 (s, 2H, PhCH2O), 4.97 (s, 4H, NCH2), 4.03 (d, 2 J = 12.8 Hz, 2H), 3.52 (d, 2 J = 12.8 Hz, 2H), 2.39 (d, 2J = 12 Hz, 4H), 2.26 (s, 6H, NCH3), 1.49 (s, 18H, C(CH3)3), 1.45 (s, 18H, C(CH3)3). The solubility of the product is too poor to be analyzed by 13 CNMR. Anal. Calcd. for: C 49 H 69 N6O3La·1CH2Cl2: C, 59.23; H, 7.06; N, 8.29. Found: C, 59.16; H, 7.45; N, 8.39%.

[0108] Example 11

[0109] Synthesis of Rare Earth Complex La5

[0110] Under argon protection, ligand L5 (0.500 mmol, 367 mg) was added to a 50 mL Schlenk flask, dissolved in 5 mL of anhydrous tetrahydrofuran, and then La[N(SiMe3)2]3 (0.500 mmol, 310 mg) was dissolved in 5 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was carried out at room temperature for 6.5 h. Then BnOH (0.50 mmol, 54 mg) was dissolved in 2 mL of anhydrous tetrahydrofuran and slowly added dropwise. The reaction was continued at room temperature for 7 h. A small amount of impurities were removed by filtration, and the solvent and free silylamine were removed by vacuum distillation to obtain a light yellow foamy solid. Recrystallization from toluene and n - hexane gave a pale yellow solid (201 mg, 41%).

[0111]

[0112] 1 H NMR (400 MHz, C6D6, 298 K) δ 7.76 (d, 3 J = 6.7 Hz, 2H, ArH), 7.48 (dd, 3,4 J = 7.2, 2.2 Hz, 2H, ArH), 7.40–7.28 (m, 2H, ArH), 7.24 (t, 3 J = 7.6 Hz 1H), 7.07–6.93 (m, 2H, ArH), 6.89–6.81 (m, 2H, ArH), 6.53 (br s, 2H, ArH), 6.45 (d, 2 J = 7.8 Hz, 1H, ArH), 6.39 (d, 2 J = 7.8 Hz, 1H, ArH), 5.41 (s, 2H, PhCH2O), 3.91 (d, 2 J = 14.0 Hz, 1H, NCH2Ph), 3.83 (d,2 J = 14.0 Hz, 1H, NCH2Ph), 3.73 (d, 2 J = 8.8 Hz, 1H, NCH2Ph), 3.64 (d, 2 J = 12.8 Hz, 1H, NCH2Ph), 3.12 (m, Hz, 2H, NCH2Ph), 2.88 (d, 2 J = 9.2 Hz, 1H, NCH2Ph), 2.81 (d, 2 J = 14.4 Hz, 1H, NCH2Ph), 2.78 (d, 2 J = 12.8 Hz, 1H, NCH2Ph), 2.56 (d, 2 J = 12.0 Hz, 1H, NCH2Ph), 1.68–1.56 (m, 4H, CH2 of cyclohexyl), 1.54 - 1.49 (m, 4H, CH2 of cyclohexyl), 1.44 (s, 18H, C(CH3)3), 1.43 (s, 18H, C(CH3)3), 1.43 (s, 18H, C(CH3)3), 1.35 (s, 18H, C(CH3)3). Anal. Calcd. for: C 55 H 73 N4O3La: C, 67.61; H, 7.53; N, 5.73. Found: C, 67,96; H, 7.45; N, 5.29%.

[0113] Example 12

[0114] Under argon protection, racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.5 mL of toluene. 0.5 mL of the toluene solution of catalyst Y1 was added to the polymerization flask. [rac-LA]0 = 1.0 M, [Y]0 = 0.005 M, [Y]0: [rac-LA]0 = 1:200. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was carried out for 4 hours. Petroleum ether was added to terminate the reaction. The solvent was removed by pumping, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. Vacuum drying was carried out for 24 h. Conversion rate: 94%, M n = 3.38×10 4 g / mol, polydispersity index PDI = 1.38, heterotacticity P r = 0.76.

[0115] Example 13

[0116] Except that the solvent was changed to tetrahydrofuran, other operations were the same as in Example 12. After reacting for 70 hours, the conversion rate was 67%, M n = 5.93×10 4g / mol, the molecular weight distribution PDI = 1.08, the heterotacticity P r = 078.

[0117] Example 14

[0118] Under argon protection, add racemic lactide (0.144 g, 1.0 mmol) into the polymerization flask and dissolve it with 0.5 mL of toluene. Measure 0.5 mL of the toluene solution of catalyst La1 and add it to the polymerization flask. [rac-LA]0 = 1.0 M, [La]0 = 0.002 M, [La]0: [rac-LA]0 = 1:500. Control the reaction temperature at 25 ± 1 °C, react for 21 seconds, and add petroleum ether to terminate the reaction. Evacuate the solvent, dissolve the residue with dichloromethane, and add methanol to precipitate the polymer. Dry in vacuum for 24 h. Conversion rate: 90%, M n = 6.32×10 4 g / mol, the molecular weight distribution PDI = 1.03, the isotacticity P m = 0.55.

[0119] Example 15

[0120] Except that the solvent is changed to tetrahydrofuran, other operations are the same as in Example 14. After reacting for 35 seconds, the conversion rate: 97%, M n = 6.29×10 4 g / mol, the molecular weight distribution PDI = 1.10, the isotacticity P m = 0.55.

[0121] Example 16

[0122] Except that the solvent is changed to dichloromethane, other operations are the same as in Example 14. After reacting for 26 seconds, the conversion rate: 92%, M n = 8.49×10 4 g / mol, the molecular weight distribution PDI = 1.26, the isotacticity P m = 0.58.

[0123] Example 17

[0124] Except that the catalyst is changed to La2, other operations are the same as in Example 14. After reacting for 202 seconds, the conversion rate: 94%, M n = 7.93×10 4 g / mol, the molecular weight distribution PDI = 1.05, the isotacticity P m = 0.58.

[0125] Example 18

[0126] Except that the catalyst is changed to La2 and the solvent is changed to tetrahydrofuran, other operations are the same as in Example 14. After reacting for 154 seconds, the conversion rate: 94%, Mn = 7.04×10 4 g / mol, the molecular weight distribution PDI = 1.19, the isotacticity P m = 0.59.

[0127] Example 19

[0128] Except that the catalyst was changed to La2 and the solvent was changed to dichloromethane, other operations were the same as in Example 14. After reacting for 180 seconds, the conversion rate was 98%, M n = 8.01×10 4 g / mol, the molecular weight distribution PDI = 1.08, the isotacticity P m = 0.60.

[0129] Example 20

[0130] Except that the catalyst was changed to La3, other operations were the same as in Example 14. After reacting for 726 seconds, the conversion rate was 94%, M n = 7.62×10 4 g / mol, the molecular weight distribution PDI = 1.10, the isotacticity P m = 0.33.

[0131] Example 21

[0132] Except that the catalyst was changed to La3 and the solvent was changed to tetrahydrofuran, other operations were the same as in Example 14. After reacting for 900 seconds, the conversion rate was 87%, M n = 5.29×10 4 g / mol, the molecular weight distribution PDI = 1.02, the heterotacticity P r = 0.71.

[0133] Example 22

[0134] Except that the catalyst was changed to La3 and the solvent was changed to dichloromethane, other operations were the same as in Example 14. After reacting for 773 seconds, the conversion rate was 97%, M n = 7.69×10 4 g / mol, the molecular weight distribution PDI = 1.02, the isotacticity P r = 0.71.

[0135] Example 23

[0136] Except that the catalyst was changed to La4, other operations were the same as in Example 14. After reacting for 37 seconds, the conversion rate was 93%, M n = 9.94×10 4 g / mol, the molecular weight distribution PDI = 1.64, the isotacticity P m = 0.56.

[0137] Example 24

[0138] Except that the catalyst was changed to La4 and the solvent was changed to tetrahydrofuran, other operations were the same as in Example 14. After reacting for 36 seconds, the conversion rate was 99%, M n = 7.04×10 4 g / mol, the molecular weight distribution PDI = 1.26, and the isotacticity P m = 0.57.

[0139] Example 25

[0140] Except that the catalyst was changed to La4 and the solvent was changed to dichloromethane, other operations were the same as in Example 14. After reacting for 37 seconds, the conversion rate was 99%, M n = 6.97×10 4 g / mol, the molecular weight distribution PDI = 1.33, and the isotacticity P m = 0.58.

[0141] Example 26

[0142] Except that [La]0 = 0.0005M and [La]0: [rac-LA]0 = 1:2000, other operations were the same as in Example 14. After reacting for 90 seconds, the conversion rate was 82%, M n = 1.95×10 5 g / mol, the molecular weight distribution PDI = 1.14, and the isotacticity P m = 0.58.

[0143] Example 27

[0144] Except that [La]0 = 0.00022M and [La]0: [rac-LA]0 = 1:4500, other operations were the same as in Example 14. After reacting for 331 seconds, the conversion rate was 84%, M n = 5.14×10 5 g / mol, the molecular weight distribution PDI = 1.18, and the isotacticity P m = 0.59.

[0145] Example 28

[0146] Except that [La]0 = 0.00011M and [La]0: [rac-LA]0 = 1:9000, other operations were the same as in Example 14. After reacting for 618 seconds, the conversion rate was 49%, M n = 3.13×10 5 g / mol, the molecular weight distribution PDI = 1.20, and the isotacticity P m = 0.60.

[0147] Example 29

[0148] Except that [La]0 = 0.0000083 M and [La]0: [rac-LA]0 = 1:12000, other operations are the same as in Example 14. After reacting for 1049 seconds, the conversion rate is 57%, M n = 4.76×10 5 g / mol, the molecular weight distribution PDI = 1.15, and the isotacticity P m = 0.58.

[0149] Example 30

[0150] Except that the monomer is changed to L-lactide, other operations are the same as in Example 14. After reacting for 20 seconds, the conversion rate is 62%, M n = 8.65×10 4 g / mol, the molecular weight distribution PDI = 1.04.

[0151] Example 31

[0152] Except that the monomer is changed to D-lactide, other operations are the same as in Example 14. After reacting for 30 seconds, the conversion rate is 91%, M n = 1.11×10 5 g / mol, the molecular weight distribution PDI = 1.24.

[0153] Example 32

[0154] Except that the catalyst is changed to La5, other operations are the same as in Example 14. After reacting for 120 seconds, the conversion rate is 75%, M n = 7.27×10 4 g / mol, the molecular weight distribution PDI = 1.44, and the isotacticity P m = 0.63.

[0155] Example 33

[0156] Except that the monomer is changed to L-lactide, other operations are the same as in Example 32. After reacting for 16 seconds, the conversion rate is 77%, M n = 12.1×10 4 g / mol, the molecular weight distribution PDI = 1.24, and the isotacticity P m = 1.0.

[0157] Example 34

[0158] Except that the monomer is changed to D-lactide, other operations are the same as in Example 32. After reacting for 18 seconds, the conversion rate is 34%, M n = 5.20×10 4 g / mol, the molecular weight distribution PDI = 1.22, and the isotacticity P m = 1.0.

[0159] Example 35

[0160] Under argon protection, unpurified industrial-grade racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.5 mL of toluene. 0.5 mL of the toluene solution of catalyst La1 was measured and added to the polymerization flask. [rac-LA]0 = 1.0 M, [La]0 = 0.005 M, [La]0:[rac-LA]0 = 1:200. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was carried out for 71 seconds. Petroleum ether was added to terminate the reaction. The solvent was removed by pumping, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. Vacuum drying was carried out for 24 h. Conversion rate: 79%, M n = 2.98×10 4 g / mol, polydispersity index PDI = 1.13, isotacticity P m = 0.58.

[0161] Example 36

[0162] Except that the catalyst was changed to La4, other operations were the same as in Example 35. After the reaction for 121 seconds, the conversion rate was: 93%, M n = 2.22×10 4 g / mol, polydispersity index PDI = 1.07, isotacticity P m = 0.58.

[0163] Example 37

[0164] Except that the monomer was changed to ε-caprolactone, other operations were the same as in Example 14. After the reaction for 13 seconds, the conversion rate was: 100%, M n = 1.55×10 5 g / mol, polydispersity index PDI = 1.62.

[0165] Example 38

[0166] Except that the catalyst was changed to La2, other operations were the same as in Example 37. After the reaction for 14 seconds, the conversion rate was: 100%, M n = 1.41×10 5 g / mol, polydispersity index PDI = 1.49.

[0167] Example 39

[0168] Under argon protection, in a polymerization flask, add racemic lactide (0.144 g, 1.0 mmol), ε-caprolactone (0.114 g, 1.0 mmol), and dissolve them with 1 mL of toluene. Measure 1 mL of the toluene solution of catalyst La1 and add it to the polymerization flask. [rac-LA]0 = 0.5 M, [ε-CL]0 = 0.5 M, [La]0 = 0.001 M, [La]0:[rac-LA]0:[ε-CL]0 = 1:500:500. Control the reaction temperature at 25 ± 1 °C, react for 14 minutes, and add petroleum ether to terminate the reaction. Remove the solvent, dissolve the residue with dichloromethane, and add methanol to precipitate the polymer. Dry it in vacuo for 24 h. Conversion of lactide: 100%, conversion of ε-caprolactone: 80%, lactide linkages in the polymer: 55%, caprolactone linkages: 45%, average chain length of poly(lactide): 3.64 units, average chain length of poly(caprolactone): 2.98 units, M n = 1.27×10 5 g / mol, polydispersity index PDI = 1.74.

[0169] Example 40

[0170] Except for ε-caprolactone (0.274 g, 2.4 mmol), [ε-CL]0 = 1.2 M, [La]0:[rac-LA]0:[ε-CL]0 = 1:500:1200, other operations are the same as in Example 38. After reacting for 8 minutes, conversion of lactide: 100%, conversion of ε-caprolactone: 80%, lactide linkages in the polymer: 35%, caprolactone linkages: 65%, average chain length of poly(lactide): 2.52 units, average chain length of poly(caprolactone): 4.69 units, M n = 1.83×10 5 g / mol, polydispersity index PDI = 1.76.

[0171] Example 41

[0172] Except that racemic lactide is replaced with L-lactide, other operations are the same as in Example 38. After reacting for 85 seconds, conversion of lactide: 100%, conversion of ε-caprolactone: 45%, lactide linkages in the polymer: 68%, caprolactone linkages: 32%, average chain length of poly(lactide): 12.8 units, average chain length of poly(caprolactone): 6.01 units, M n = 1.44×10 5 g / mol, polydispersity index PDI = 1.7.

[0173] Example 42

[0174] Except for replacing the racemic lactide with D-lactide, other operations were the same as in Example 38. After reacting for 150 seconds, the conversion rate of lactide was 100%, the conversion rate of ε-caprolactone was 78%, the lactide linkages in the polymer were 57%, the caprolactone linkages were 43%, the average chain length of polylactide was 8.34 units, the average chain length of polycaprolactone was 6.29 units, M n = 1.27×10 5 g / mol, and the molecular weight distribution PDI = 1.89.

[0175] Example 43

[0176] Except for ε-caprolactone (0.136 g, 1.2 mmol), [ε-CL]0 = 0.6 M, [La]0:[rac-LA]0:[ε-CL]0 = 1:500:600, other operations were the same as in Example 40. After reacting for 88 seconds, the conversion rate of lactide was 100%, the conversion rate of ε-caprolactone was 36%, the lactide linkages in the polymer were 67%, the caprolactone linkages were 33%, the average chain length of polylactide was 12.5 units, the average chain length of polycaprolactone was 6.18 units, M n = 10.7×10 4 g / mol, and the molecular weight distribution PDI = 1.71.

[0177] Example 44

[0178] Except for ε-caprolactone (0.182 g, 1.6 mmol), [ε-CL]0 = 0.8 M, [La]0:[rac-LA]0:[ε-CL]0 = 1:500:800, other operations were the same as in Example 40. After reacting for 80 seconds, the conversion rate of lactide was 100%, the conversion rate of ε-caprolactone was 36%, the lactide linkages in the polymer were 64%, the caprolactone linkages were 36%, the average chain length of polylactide was 10.6 units, the average chain length of polycaprolactone was 5.96 units, M n = 1.11×10 5 g / mol, and the molecular weight distribution PDI = 1.71.

[0179] Example 45

[0180] Except for ε-caprolactone (0.228 g, 2 mmol), [ε-CL]0 = 1 M, [La]0:[rac-LA]0:[ε-CL]0 = 1:500:1000, other operations were the same as in Example 40. After reacting for 78 seconds, the conversion rate of lactide was 100%, the conversion rate of ε-caprolactone was 29%, the lactide linkages in the polymer were 64%, the caprolactone linkages were 36%, the average chain length of polylactide was 10.9 units, the average chain length of polycaprolactone was 6.14 units, M n = 1.06×10 5g / mol, the polydispersity index of the molecular weight distribution PDI = 1.72.

[0181] Example 46

[0182] Except for ε-caprolactone (0.274 g, 2.4 mmol), [ε-CL]0 = 1.2 M, [La]0:[rac-LA]0:[ε-CL]0 = 1:500:1200, other operations are the same as in Example 40. After reacting for 125 seconds, the conversion rate of lactide is 100%, the conversion rate of ε-caprolactone is 44%, the lactide link in the polymer is 48%, the caprolactone link is 52%, the average link length of poly(lactide) is 6.89 units, the average link length of poly(caprolactone) is 7.46 units, M n = 1.57×10 5 g / mol, the polydispersity index of the molecular weight distribution PDI = 1.77.

[0183] Example 47

[0184] Except for changing the catalyst to La2, other operations are the same as in Example 45. After reacting for 79 seconds, the conversion rate of lactide is 100%, the conversion rate of ε-caprolactone is 31%, the lactide link in the polymer is 58%, the caprolactone link is 42%, the average link length of poly(lactide) is 9.69 units, the average link length of poly(caprolactone) is 7.02 units, M n = 1.24×10 5 g / mol, the polydispersity index of the molecular weight distribution PDI = 1.68.

[0185] Example 48

[0186] Except for [La]0 = 0.002 M, [La]0:[L-LA]0:[ε-CL]0 = 1:250:250, other operations are the same as in Example 41. After reacting for 65 seconds, the conversion rate of lactide is 100%, the conversion rate of ε-caprolactone is 99%, the lactide link in the polymer is 54%, the caprolactone link is 46%, the average link length of poly(lactide) is 5.89 units, the average link length of poly(caprolactone) is 5.02 units, M n = 8.07×10 4 g / mol, the polydispersity index of the molecular weight distribution PDI = 1.81.

[0187] Example 49

[0188] Except for changing the temperature to -50 ± 1 °C, other operations are the same as in Example 14. After reacting for 4 hours, the conversion rate is 37%, M n = 3.45×10 4 g / mol, the polydispersity index of the molecular weight distribution PDI = 1.05, the isotacticity P r = 0.68.

[0189] Example 50

[0190] Under argon protection, add racemic lactide (0.144 g, 1.0 mmol) into the polymerization flask, and then add 0.1 mL of La1 solution. Keep [La]0: [rac-LA]0 = 1:5000. Control the temperature at 110 °C ± 1 °C, react for 30 seconds, and add petroleum ether to terminate the reaction. Remove the solvent, dissolve the residue in dichloromethane, and add methanol to precipitate the polymer. Dry in vacuum for 24 h. Conversion rate: 87%, M n = 1.87×10 5 g / mol, polydispersity index PDI = 1.56, isotacticity P m = 0.56.

[0191] Example 51

[0192] Under argon protection, add racemic lactide (0.144 g, 1.0 mmol) into the polymerization flask, and dissolve it with 0.5 mL of toluene solution of benzyl alcohol. Measure 0.5 mL of toluene solution of catalyst La1 and add it to the polymerization flask. [rac-LA]0 = 1.0 M, [La]0 = 0.001 M, [La]0: [BnOH]0: [rac-LA]0 = 1:1:1000. Control the reaction temperature at 25 ± 1 °C, react for 27 seconds, and add petroleum ether to terminate the reaction. Remove the solvent, dissolve the residue in dichloromethane, and add methanol to precipitate the polymer. Dry in vacuum for 24 h. Conversion rate: 91%, M n = 6.79×10 4 g / mol, polydispersity index PDI = 1.07, isotacticity P m = 0.56.

[0193] Example 52

[0194] Under argon protection, add racemic lactide (0.144 g, 1.0 mmol) into the polymerization flask, and dissolve it with 0.5 mL of toluene solution of benzyl alcohol. Measure 0.5 mL of toluene solution of catalyst La1 and add it to the polymerization flask. [rac-LA]0 = 1.0 M, [La]0 = 0.0005 M, [La]0: [BnOH]0: [rac-LA]0 = 1:2:2000. Control the reaction temperature at 25 ± 1 °C, react for 45 seconds, and add petroleum ether to terminate the reaction. Remove the solvent, dissolve the residue in dichloromethane, and add methanol to precipitate the polymer. Dry in vacuum for 24 h. Conversion rate: 85%, M n = 8.06×10 4 g / mol, polydispersity index PDI = 1.05, isotacticity P m = 0.58.

[0195] Example 53

[0196] Under argon protection, racemic lactide (0.144 g, 1.0 mmol) was added to a polymerization flask and dissolved in 0.5 mL of a toluene solution of benzyl alcohol. 0.5 mL of a toluene solution of catalyst La1 was added to the polymerization flask. [rac-LA]0 = 1.0 M, [La]0 = 0.0002 M, [La]0:[BnOH]0:[rac-LA]0 = 1:5:5000. The reaction temperature was controlled at 25 ± 1 °C, and the reaction was carried out for 92 seconds. Petroleum ether was added to terminate the reaction. The solvent was removed by pumping, and the residue was dissolved in dichloromethane. Methanol was added to precipitate the polymer. It was dried in vacuo for 24 h. Conversion: 89%, M n = 9.87×10 4 g / mol, polydispersity index PDI = 1.02, isotacticity P m = 0.57.

Claims

1. A six-toothed aminophenoxy rare earth complex (I) substituted with a nitrogen-containing heterocycle, characterized in that, It has the following general formula: In formula (I): R 1 ~R 2 respectively represent an alkyl group having a linear, branched or cyclic structure of C1 to C8, a C7 to C 20 alkyl group substituted with a single or multiple aryl groups; A is a group having a structure shown in formula (II), (III), (IV) or (V): A coordinates with the metal center Re through its nitrogen atom; Re represents Y, La; B is an alkylene bridge having a structure shown in formula (VI) or (VII); R 3 represents an alkyl group having a straight-chain, branched-chain or cyclic structure of C1-C6, C7-C 13 alkyl group substituted with mono- or poly-aryl groups.

2. The hexa-dentate aminophenoxo rare earth complex (I) substituted by nitrogen heterocycle according to claim 1, characterized in that, R 1 ~R 2 is methyl, isopropyl, tert-butyl, cumyl, trityl; R 3 is methyl, ethyl, isopropyl, tert-butyl, benzyl, 2-phenylethyl, 1-phenylethyl.

3. The preparation method of the nitrogen-containing heterocyclic substituted hexa-dentate aminophenoxy rare earth complex (I) according to any one of claims 1 to 2, comprising the following steps: Performing reductive amination reaction on diamine and the aldehyde group-substituted nitrogen-containing heterocyclic compound shown in formula (X) to generate the corresponding secondary diamine, adding 2-bromomethyl-4,6-disubstituted phenol (IX), with the reaction temperature being 0-90 °C and the reaction time being 2-72 hours, and then collecting the nitrogen-containing heterocyclic substituted hexa-dentate aminophenol ligand compound (VIII) from the reaction product; Optionally, react the nitrogen heterocyclic substituted hexa-dentate aminophenol ligand compound shown in formula (VIII) with the rare earth metal raw material compound Re[N(SiMe3)2]3 in an organic medium, and then add alcohol R 3 OH and continue the reaction. The reaction temperature is 0 to 100 °C, and the reaction time is 2 to 24 hours. Then, collect the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex (I) from the reaction product; Substituent R in the above preparation method 1 ~R 3 、A and B are the same as the corresponding groups of the hexa-dentate aminophenoxo rare earth complex (I) substituted by a nitrogen-containing heterocycle as described in any one of claims 1 to 2.

4. The method according to claim 3, wherein The six-toothed aminophenol ligand compound (VIII) substituted by nitrogen heterocycles, the rare earth metal raw material compound Re[N(SiMe3)2]3, and the alcohol R 3 The molar ratio of OH is 1:1.0 to 1.5:0.8 to 1.5; the organic medium is selected from one or two of tetrahydrofuran, diethyl ether, toluene, benzene, petroleum ether, and n-hexane.

5. Use of the nitrogen heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to any one of claims 1 to 2, characterized in that For ring-opening polymerization of lactones.

6. The application according to claim 5, wherein The lactones are selected from L-lactide, D-lactide, rac-lactide, meso-lactide, ε-caprolactone, β-butyrolactone, α-methyltrimethylene carbonate.

7. The application according to claim 5, wherein Using the nitrogen-containing heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to any one of claims 1 to 2 as a catalyst to polymerize lactide, and the molar ratio of the rare earth complex catalyst to the monomer during polymerization is 1:1-50000.

8. The application according to claim 5, wherein Using the nitrogen-containing heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to any one of claims 1 to 2 as a catalyst to polymerize ε-caprolactone, and the molar ratio of the rare earth complex catalyst to the monomer during polymerization is 1:1-50000.

9. The application according to claim 5, wherein Using the nitrogen-containing heterocyclic substituted hexa-dentate aminophenoxy rare earth complex according to any one of claims 1 to 2 as a catalyst to copolymerize ε-caprolactone and lactide, and in the copolymerization reaction, the molar ratio of the rare earth complex catalyst to lactide is 1:50-5000, and the molar ratio of the rare earth complex catalyst to ε-caprolactone is 1:1-5000.

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