Co3簇基金属有机框架材料实现“一石二鸟”高效催化CO2转化为噁唑烷酮.pdf

Co3簇基金属有机框架材料实现“一石二鸟”高效催化簇基金属有机框架材料实现“一石二鸟”高效催化CO2转化为噁唑烷酮转化为噁唑烷酮 焦卓浩，赵心远，赵健，谢瑶，侯胜利*，赵斌*南开大学化学学院，先进能源材料化学教育部重点实验室，可再生能源转换和储存中心，天津 300071 摘要：摘要：噁唑烷酮是药物化学中重要的中间体，可以通过炔丙基胺类或氮杂环类化合物与CO2的环化获得。合成一种可以同时催化这两种反应的催化剂是一件有很强吸引力，但极具挑战性的工作。本文合成了一例独特的三维(3D)CO3簇金属-有机框架(MOF)(CH3NH2CH3)2CO3(BCP)26H2O4DMFn(1)并进行了表征，1表现出良好的溶剂稳定性和热稳定性。催化实验结果表明，1可以高效催化氮杂环或炔丙基胺类化合物与CO2反应来制备噁唑烷酮，并且催化剂对两种反应都具有广泛的底物普适性和良好的循环使用性。对照实验和核磁共振测试表明，1中路易斯酸和路易斯碱位点的共存是高效催化的原因。化合物1作为一种新型催化剂，成功实现了“一石二鸟”高效催化CO2转化为噁唑烷酮。关键词：关键词：金属有机框架材料；双功能催化剂；CO2利用；噁唑烷酮；可循环性 中图分类号：中图分类号：O643 1 Introduction With the proposal of carbon neutrality,the emission reduction and effective utilization of CO2 have become the focus of researches.CO2 as an inexpensive and readily available C1 feedstock,can be converted into a variety of high value-added products,including urea,formic acid,methanol,cyclic carbonates,oxazolidinones,and polymers through photo-catalysis,electro-catalysis,or thermos-catalysis 111.Among them,oxazolidinones as heterocyclic compounds have been widely used in synthesizing antibacterial drugs such as tedizolid,radezolid,and linezolid 12.And they also play an important role in serving as intermediates in organic synthesis and chiral auxiliary reagents 13,14.Heretofore,diverse methods have been proposed for the preparation of oxazolidinones,among which two of the most common and efficient approaches are the cycloaddition of CO2 with aziridines or carboxylation cyclization of CO2 with propargyl amines due to their high atom economy and simple procedure 15.Some catalysts have been applied in preparation of oxazolidinones by these two approaches,including amino acids 16,haloids 17,noble metal complexes 18,etc.However,high cost or complicated postprocessing procedures limit their large-scale industrial applications,and these studies only focus on one kind of reactionon account of the high thermodynamic stability and kinetic inertness of CO2.Hence,it is important to construct a heterogeneous catalyst that can catalyze these two kinds of reactions.Metal-organic frameworks(MOFs),as an emerging class of heterogeneous catalysts,have gained increasing attention due to their abundant metal active sites 1922,inherent porosity 2325,and easy functionalities 2629.In recent years,researches focused on MOFs for catalyzing the formation of oxazolidinones from CO2 with aziridines or propargyl amines,and many exciting works have been reported successively 30,31.However,these catalysts are usually used to catalyze only one type of these reactions because these two reactions are Lewis-acid and Lewis-base preferred reactions,respectively.In addition,due to the high stability of CO2,these reactions usually require harsh conditions such as high temperature or pressure.Hence,the construction of one MOF that can simultaneously catalyze these two types of reactions under mild conditions is desirable but challenging.The Co2+ion has been used to construct a variety of MOFs structures due to its diverse coordination modes,and its Lewis acidity also allows it to apply in numerous catalytic reactions 3237.In this contribution,we synthesized a unique 3D MOF(CH3NH2CH3)2Co3(BCP)26H2O4DMFn(1)by combining Co2+and a carboxylate ligand 5(2,6bis(4carboxyphenyl)pyri-din4yl)isophthalic acid(H4BCP)through solvothermal method,which has a large 1D channel with a size of 0.4 nm 0.9 nm.Experiment results reveal that 1 shows excellent catalytic performance for promoting the conversion of both aziridines and propargylic amines with CO2 into oxazolidinones,and it can be reused for five cycles and maintains high catalytic activity.In particular,1 enables“two birds with one stone”in the synthesis of oxazolidinones by CO2,which represents a rarely reported catalyst for preparing oxazolidinones through two pathways.2 Experimental and computational section 2.1 Preparation of(CH3NH2CH3)2Co3(BCP)26H2O 4DMFn(1)Co(NO3)26H2O(99.99%,15 mg)and H4BCP(20 mg)were mixed with N,Ndimethylformamide(DMF,99.5%,2.5 mL)and deionized water(0.5 mL).Then 200 L of nitric acid(65.0%68.0%)was dropped in the mixture to adjust the pH.Subsequently,the mixture was transferred to a 25 mL Teflon-lined stainless-steel vessel and heated at 145 C for 72 h under autogenous pressure.After cooling to room temperature 物理化学学报 Acta Phys.-Chim.Sin.2023,39(11),2301018(3 of 8)naturally,dark purple lamellar crystals were collected.The resultant crystals were washed with DMF and H2O several times to remove the residual metal salts or ligands.Elemental analysis of crystal 1,calculated results:C 51.33%,H 4.83%,N 6.84%.Tested results:C 51.93%,H 4.79%,N 6.89%.CCDC number:2160038.2.2 Catalyst characterization Powder Xray diffraction(PXRD)patterns were measured on an Ultima IV diffractometer(Rigaku,Japan)using Cu K as radiation sources with a 5()min1 scanning speed.Xray photoelectron Spectrometer(XPS)analysis was carried out on an ESCALAB 250Xi spectrometer(ThermoFisher,USA)using Mono Al K radiation,and the internal standard carbon is 284.8 eV.1H NMR chemical shifts were measured on 400 MHz spectrometer(ASCEND 400,Bruker,Germany)using CDCl3 as internal standard.13C NMR chemical shifts were carried out on a AVANCE III HD 400 spectrometer(101 MHz,Bruker,Germany).The metal content was tested by Aglient 5110(USA)inductively coupled plasma optical emission spectrometer(ICPOES).Typically,100 L of reaction mixture obtained by centrifugation is decomposed by aqua regia and then diluted to 5 mL by deionized water.The resultant sample was measured by ICP-OES.Infrared spectra(IR)were measured by a Bruker Tensor 27(Germany)spectrophotometer.The thermogravi-metric analysis(TGA)data were measured on thermal gravimetric analyzer(NETZSCH TG209,Germany)under air atmosphere.Singlecrystal Xray diffraction was performed on a SuperNova Single Crystal diffractometer(Rigaku,Japan)with Mo K radiation(=0.71073,1 =0.1 nm).The obtained data was analyzed by Olex2 software to get the structure 38.Due to the highly disordered state of solvent molecules in frameworks,we use PLATON/SQUEEZE programs to remove the disordered solvent molecules 39,and the number of free solvent molecules was determined by elemental analysis and TGA.Detail of single crystal data and structure refinement for 1 were recorded in Table S1 in Supporting Information.2.3 Catalytic experiments Cycloaddition of CO2 with aziridines:Compound 1(10 mg),aziridine substrates(0.5 mmol)and cocatalyst TBAB(32.4 mg,0.1 mmol)were sealed in an autoclave.After purging with 0.5 MPa CO2,the autoclave was placed in water bath of 30 C and stirred for 9 h.When the reaction was completed,the catalyst was separated by centrifugation and filtration.The filtrate was dissolved in 0.5 mL CH2Cl2(99.9%),and then the yields of corresponding products(2x and 3x)were analyzed by 1H NMR with 1,3,5trimethoxybenzene(99.9%)as an internal standard.Carboxylation cyclization of CO2 with propargylic amines:Compound 1(10 mg),propargylic amines(0.5 mmol)and additive 1,8-diazabicyclo-5.4.0undec-7-ene(DBU,98%,19 mg,0.125 mmol)were mixed in CH3CN(99.7%,0.5 mL).After adding the mixture in a 15 mL Schlenk tube and purging 0.1 MPa of CO2,the tube was placed in oil bath at 80 C and kept stirred for 10 h.The mixture was separated by centrifugation and filtration when the reaction was completed,and the filtrate was analyzed by 1H NMR with 1,3,5trimethoxybenzene as an internal standard.Cycle experiments:The filter residue was washed with fresh CH3CN three times and dried under vacuum at 60 C.The recovered catalyst was used for the next catalytic experiments.3 Results and discussion 3.1 Characterization According to singlecrystal Xray diffraction analysis,compound 1 crystallizes in a triclinic system with P1 space group.The asymmetric unit contains one and a half Co2+ions,one independent BCP4 ligand,and one dimethylamine cation(CH3)2NH2+).There are two types of Co ions(denoted as Co1 and Co2),and both of them are coordinated with six oxygen atoms from the carboxyl group of ligands(O1,O1A,O3,O3A,O7,O7A for Co1,and O3,O5,O9 O12,O13,O16 for Co2)(Fig.S1).One Co1 and two Co2 ions are bridged by the carboxyl group to form a Co3 cluster(Fig.1a).Each ligand coordinates with four Co3 clusters,expanding into a 3D anion framework(Fig.1b,c).(CH3)2NH2+acts as counterion to balance the charge which may generate from the decomposition of DMF and its existence was confirmed by structural analysis 40.By considering the Co3 clusters and H4BCP ligands as nodes,the structure can be rationalized to a 4,8connected net with flu topology(Fig.1d).Along the aaxis direction,a rectangular channel about 0.4 nm 0.9 nm is present in the framework,and the total potential pore volume of the structure is estimated to be 39.6%by PLATON software(Fig.1e).According to the analysis of infrared spectroscopy(IR),the OH vibration peak of the carboxyl group in the ligand is located at 29403300 cm1,while it disappears in the spectrum of 1 41.Meanwhile,the peak at 1672.8 cm1 which belongs to the stretching vibration of CO shifted to 1656.4 cm1 in that of 1,Fig.1 (a)The 8-connected Co3 cluster SBU;(b)coordination mode of H4BCP;(c)3D structure of the framework along the aaxis;(d)flu topology of 1;(e)the rectangular channel of 1 along the a-axis direction.物理化学学报 Acta Phys.-Chim.Sin.2023,39(11),2301018(4 of 8)which demonstrates the coordination of carboxyl groups to the Co ions(Fig.S2)42.XPS analysis shows the fitting peak at the binding energy of 531.78 eV in O 1s spectrum corresponds to COCo in the framework,conforming the coordination interaction between carboxyl groups and Co ions(Fig.S3c)43.In Co 2p spectrum,the peaks located at 781.7 and 797.4 eV belong to Co 2p3/2 and Co 2p1/2 of Co2+,while the binding energy of 786.2 and 802.0 eV is in accordance with the satellite peaks of Co2+(Fig.S3d)44.The PXRD peaks of 1 are identical to those of the simulated one,demonstrating the satisfactory phase purity of synthesized crystals(Fig.S4a).After immersing the crystals in several common solvents(DMF,N,Ndimethylacetamide,methanol,ethanol,acetonitrile,dichloromethane,dioxane,Nmethylpyrrolidone)for 24 h,the patterns still agree with that of synthesized samples and standard patterns,which confirms the excellent solvent stability of 1(Fig.S4b).In addition,the thermal stability was explored by performing the thermogravimetric analysis(TGA)at 30700 C(Fig.S5).As the temperature rises,there is a weight loss about 25.05%before 330 C,which is assigned to the escape of free solvent molecules(H2O and DMF,calculated 25%).Then the framework begins to gradually collapse and decompose.Meanwhile,PXRD test was performed under different temperatures(Fig.S6).Combined with TGA and PXRD results,1 can maintain its structure integrity under 200 C,which indicates that this compound has good thermal stability.The favorable thermal and solvent stabilities provide a guarantee for compound 1 to be used for therma