基于2-吡啶甲醛肟配体的Ni_%282%29%5E%28Ⅱ%29Zn_%282%29%5E%28Ⅱ%29簇配合物的合成、晶体结构、磁性及光催化性能%28英文%29.pdf

第39卷第11期2023年11月Vol.39 No.1122192230无机化学学报CHINESE JOURNAL OF INORGANIC CHEMISTRY收稿日期：20230321。收修改稿日期：20231001。陕西省自然科学基金(No.2022JZ49，2022NY071)、延安市重点产业链项目(No.2022SLZDCY001)、陕西省教育厅重点项目(No.23JY086)和陕西省大学生创新创业训练计划项目(No.S202210719111)资助。通信联系人。Email：yanghua_基于2吡啶甲醛肟配体的Ni2Zn2簇配合物的合成、晶体结构、磁性及光催化性能杨华符钰培乔丹董璐璐陈小莉崔华莉王记江(延安大学化学与化工学院，陕西省反应工程重点实验室，新能源新功能材料实验室，延安716000)摘要：在溶剂热条件下，以2吡啶甲醛肟(HL)为主配体，Zn(OAc)22H2O和NiCl26H2O为金属盐，合成了一个Ni2Zn2簇配合物Ni2Zn2(L)4Cl2(CH3O)2(1)，通过元素分析、红外光谱、单晶X射线衍射等对其结构进行了表征。研究了该配合物的磁性及光催化降解染料的性能，结果表明：配合物1属于正交晶系，Pna21空间群，其分子中包含2个Ni离子，2个Zn离子，4个L-配体，2个Cl-离子和2个CH3O-离子。磁性研究表明NiNi离子间存在弱的反铁磁相互作用。光催化降解染料的研究结果表明该配合物对甲基橙和罗丹明B有较好的降解活性，降解率分别达到83.9%和71.1%。进一步探讨了光催化降解染料的作用机理。关键词：2吡啶醛肟；晶体结构；磁性；光催化降解中图分类号：O614.81+3；O614.24+1文献标识码：A文章编号：10014861(2023)11221912DOI：10.11862/CJIC.2023.186Synthesis,crystal structure,magnetic properties,and photocatalytic activity ofNi2Zn2cluster complex based on 2pyridinealdoxime ligandYANG HuaFU YuPeiQIAO DanDONG LuLuCHEN XiaoLiCUI HuaLiWANG JiJiang(Shaanxi Key Laboratory of Chemical Reaction Engineering,Laboratory of New Energy and New Function Materials,School of Chemistry and Chemical Engineering,Yanan University,Yanan,Shaanxi 716000,China)Abstract:Under solvothermal conditions,the reaction of 2pyridinealdoxime(HL)with NiCl26H2O and Zn(OAc)22H2O has led to a Ni2Zn2cluster complex with composition Ni2Zn2(L)4Cl2(CH3O)2(1).This complex was characterized by elemental analysis,IR spectroscopy,singlecrystal Xray diffraction,etc.The results show that 1 belongsto the orthorhombic system with the Pna21space group.The structure of 1 contains two Niions,two Znions,twoCl-ions,four L-ligands,and two CH3O-anions.The magnetic properties and photocatalytic activity toward the degradation of dyes were investigated.Magnetic susceptibility measurements at 2300 K for the microcrystals of 1revealed antiferromagnetic NiNiinteractions.1 exhibited excellent photocatalytic capability in the degradationof methyl orange(MO)and rhodamine B(RhB)within 180 min under ultraviolet radiation.The degradation efficiencies reached 83.9%and 71.1%respectively.The mechanism of photocatalytic dye degradation was further discussed.CCDC:2205562.Keywords:2pyridinealdoxime;crystal structure;magnetism;photocatalytic degradation无机化学学报第39卷0IntroductionThe study of polynuclear 3dmetal complexes is ofcontinuous interest to scientists with various disciplines14.This interest is orignated from their applications in magnetic materials511,spintronics1213,magnetoelectronics14,biological systems1518,and photocatalyticactivity1920.Successfulstrategiesforbuildingsuch clusters include employing appropriate bridgingligands,developing simple and efficient syntheticmethods,and selecting suitable metal salt sources.One favorable method for synthesizing 3dmetalpolynuclear complexes is to use oximate ligands.Theoximates show a great ability to prepare polynuclearclusters,and the oximates could efficiently convey magnetic interactions2123.A plethora of clusters based onoximate ligands has been documented24.To our surprise,the clusters involving terminal coordinate orbridging chloroligands are extremely rare25.Chlorideion is a popular ligand in the preparation of molecularmagnets since the Cl bridge could transfer ferromagnetic interactions under certain conditions2628.Hence,the development of efficient approaches that can generate clusters involving both chloro and oximate ligandsis in high demand.We have recently attempted to synthesize polynuclear complexes in which chloride ions serve as the terminal coordinate or bridging ligand under solvothermalconditions.Our motivation is driven by the followingimportant reasons:the nuclearities of clusters arepartly dependent on the addition of inorganic anionand on the types of the anion2930.Except that the chloro bridge could transmit ferromagnetic interactions,the involvement of chloride ions in oximatechemistry may result in clusters with an unrevealed nuclearity.Solvothermal techniques are rarely used inthe coordination chemistry of oximate ligands31.Thesuccessful preparation of Mn6and Ni6wheels32,which were not accessible via conventional coordination chemistry techniques,suggests that the combination of the solvothermal technique with the employmentof chloro ligand may generate the expected complexes.Studies on the degradation of organic dyes by polynuclear complexes have rarely been reported1920.Under these considerations,we chose 2pyridinealdoxime(HL),which is a favorable ligand in the preparation of singlechain magnets33as the ligand,NiCl26H2O and Zn(OAc)22H2O as the metal and chloroligand sources,and performed the reaction under solvothermal conditions.A complex with the formula Ni2Zn2(L)4Cl2(CH3O)2(1)was prepared.Although the utilization of the L-ligand had led to the formations of aseries of Ni234,Ni335,NiCr 36,NiMn 37,Ni938,and Ni1439,1 is the only Ni2Zn2cluster based on theL-ligand.At present,many organic dyes are utilized in academic laboratories and industries such as cosmetics,plastics,and pharmaceuticals40.These organic dyesnot only seriously pollute the environment but alsocause harmful damage to human health4142.Therefore,the degradation of organic dyes is attracting intensiveattention.Recently,many studies on the removal oforganic dyes using Znand Nicomplexes as photocatalysts have been carried out due to the low cost,lowtoxicity,and good photocatalytic performance of thesecomplexes4346.Thus,the photocatalytic activity towardthe degradation of dyes and magnetic properties of 1were reported in this work.1Experimental1.1Reagents and characterizationAll experiments were carried out under aerobicconditions.The solvents and reagents are purchasedfrom the chemical companies and used without furtherpurification.The C,H,and N analyses were conductedin a CarloErba EA 1110 CHNOS microanalyzer.IRspectra of the ligand and complex 1(4 000400 cm-1)were measured in a Nicolet MagNaIR 500 FTIR spectrometer.Powder Xray diffraction(PXRD)pattern of 1was recorded on a Bruker D8 Advance diffractometer(Cu K,=0.154 06 nm,2=550,U=40 kV,I=40mA).Thermoanalysis of complex 1 was performed in aNetzsch STA 449C thermogravimetric analyzer from 30to 800 at a 10 min-1rate for heating.Magneticsusceptibility data(2300 K)were measured using aQuantum Design MPMS7 SQUID magnetometer.Diamagnetic corrections were performed using Pascals2220第11期constants.The UVVis spectra(200800 nm)were measured using a Shimadzu UVVis spectrometer at roomtemperature.1.2Synthesis of complex 1In the 8 mL Pyrex tube,NiCl26H2O(0.023 7 g,0.1 mmol),Zn(OAc)22H2O(0.043 9 g,0.2 mmol),HL(0.039 6 g,0.2 mmol),and MeOH/EtOH(2 mL,1 1,V/V)were added.The glass tube was sealed and heated inan oven at 120 for 48 h.The tube was then cooled ata rate of 5 h-1to room temperature.Brownishredcrystals of the product were obtained.The yield of theproduct was 54%based on HL.Anal.Calcd.forC26H26Cl2N8Ni2Zn2O6(%):C,36.08;H,3.03;N,12.95.Found(%):C,35.66;H,3.40;N,12.62.1.3Photocatalysis experimentComplex 1(10 mg)was mixed with methyl orange(MO,20 mgL-1)or rhodamine B(RhB,20 mgL-1),respectively,to obtain suspensions.The suspensionsolution was stirred in the dark for about 15 min toensure the establishment of adsorption equilibrium before irradiation.Then,the solution was conducted onan XPA7type photochemical reactor equipped with a500 W Xenon lamp,and the reaction temperature wasmaintained at about 25 by circulating cooling water.A certain volume of samples was collected and separated by centrifugation to remove the residual catalystparticles.Then the solution was analyzed by using aShimadzu UVVis spectrometer.The concentration ofMO and RhB were estimated by the absorbance at462 and 552 nm,characteristic of MO and RhB,respectively.1.4Xray crystallographySingle crystals of complex 1 were obtained fromMeOH/EtOH under solvothermal conditions.Brownbulk crystals(0.20 mm0.15 mm0.15 mm)wereselected and placed in a single crystal diffractometer.Diffraction data were measured on Bruker Smart Apex CCDC diffractometers equipped with a graphitemonochromator utilizing Mo K(=0.07 073 nm)radiation at 293(2)K.The diffraction intensity data were corrected using the SADABS program by semiempiricalabsorption.The structures were solved by direct methods using the SHELXS97 package.All nonhydrogenatoms and anisotropy parameters were refined usingthe full matrix least squares on F2method by theSHELXL97 program.The coordinates of all hydrogenatoms were obtained through theoretical hydrogenation.Crystallographic data together with refinement detailsfor 1 are summarised in Table 1.Selected bond lengthsand bond angles for the complex are listed in Table 2.CCDC:2205562.Table 1Crystallographic data for complex 1ParameterEmpirical formulaFormula weightCrystal systemSpace groupa/nmb/nmc/nmV/nm3ZDc/(gcm-3)1C26H26Cl2N8Ni2Zn2O6865.61OrthorhombicPna211.957 26(16)0.912 86(7)1.795 41(17)3.207(5)41.792ParameterF(000)range/()Limiting indicesReflection collected,uniqueData,restraint,number of parametersGOFR1,wR2I2(I)R1,wR2(all data)Largest diff.peak and hole/(enm-3)11 7441.54-25.00-23 h 15,-9 k 10,-10 l 2121 202,4 1534 153,1,4181.1140.035 6,0.079 40.045 7,0.087 7670,-260Table 2Selected bond lengths(nm)and bond angles()of complex 1Ni1N1Ni1N2Ni1N6Ni1N80.211(7)0.205(7)0.208(9)0.205(7)Ni2N4Ni2N5Ni2N7Ni2O50.206(7)0.207(7)0.211(9)0.210(6)Zn1O5Zn1Cl1Zn2O2Zn2O40.201(6)0.219(4)0.196(6)0.199(7)杨华等：基于2吡啶甲醛肟配体的Ni2Zn2簇配合物的合成、晶体结构、磁性及光催化性能2221无机化学学报第39卷2Results and discussion2.1Synthesis of complex 1Complex1wassynthesizedinEtOH/MeOH(Eq.1)under solvothermal conditions.The 1 1 2 reaction among NiCl26H2O,Zn(OAc)22H2O and HL gavetetranuclear 1.We have also attempted the synthesis of1 by conducting the experiments at room temperatureat 101.325 kPa.The reaction of NiCl26H2O,HL,andZn(OAc)22H2O in EtOH under 101.325 kPa and roomtemperature resulted in a known complex Ni(L)Cl247.Ni1O5Ni1O6Ni2N3N1Ni1O5N1Ni1O6N2Ni1N1N2Ni1O5N2Ni1O6N2Ni1N6N2Ni1N8N6Ni1N1N6Ni1O5N6Ni1O6N8Ni1N1N8Ni1O5N8Ni1N6N8Ni1O60.213(6)0.212(6)0.212(7)167.4(2)93.7(3)78.8(3)92.4(3)100.8(3)89.3(3)163.5(3)96.1(3)92.7(3)167.1(3)91.1(3)99.5(2)78.7(3)92.8(3)Ni2O6Zn1O1Zn1O3O6Ni1O5N3Ni2O6N4Ni2N5N4Ni2N7N4Ni2N3N4Ni2O5N4Ni2O6N5Ni2N3N5Ni2N7N5Ni2O5N5Ni2O6N7Ni2O6N7Ni2N3O5Ni2N30.212(6)0.197(6)0.197(7)79.0(2)165.7(2)162.8(3)91.3(3)78.3(3)101.1(3)91.1(3)89.8(3)78.3(3)91.8(3)102.5(2)90.2(3)99.5(3)92.9(3)Zn2O6Zn2Cl2O5Ni2O6O5Ni2N7O1Zn1O3O1Zn1O5O1Zn1Cl1O3Zn1O5O3Zn1Cl1O5Zn1Cl1O2Zn2Cl2O2Zn2O4O2Zn2O6O4Zn2Cl2O4Zn2O6O6Zn2Cl20.202(6)0.219(4)79.6(2)164.1(3)95.8(3)103.4(2)121.2(2)104.8(3)115.6(2)113.3(2)117.3(2)98.8(3)102.4(2)116.8(2)104.2(3)114.9(2)Continued Table 1HL+NiCl26H2O+Zn(OAc)2H2OMeOH/EtOH,T,pNi2Zn2(L)4Cl2(CH3O)2(1)2.2Description of the structureThe coordination environment of complex 1 isshown in Fig.1.1 crystallizes in the orthorhombic crystal system of the Pna21space group.In the structure of1,there are two Niions,two Znions,four L-ligands,two Cl-ions,and two CH3O-anions.The two Niandtwo Znions are linked together by four L-ligands andtwo CH3O-anions to form a butterfly like structure.The Ni1(Ni2)ion is sixcoordinated by four nitrogenatoms from two L-ligands,and two oxygen atoms(3O)from two deprotonated methanol molecules,forming adistorted octahedron geometry.The Zn1(Zn2)ion istetra coordinated by two oxygen atoms from two L-ligands,one terminal chloride ion,and one oxygen atom(3 O)from one CH3O-anion,exhibiting a distortedtetrahedron configuration.The four L-ligands all display 1122coordination mode.The ring skeletonof the two Niand two Znions of 1 is shown in Fig.2.Ellipsoidal probability:25%.Fig.1Coordination environment of complex 12222第11期The stacking diagram of 1 is shown in Fig.3.Thelayers are interconnected by C3HO3(0.254 nm)and C21HO4(0.241 nm)bonds,while the layersare interconnected by C11HO1(0.248 nm)bondsto form a 2D planar structure,and the faces are interconnected by CH bonds,expanding into a 3Dstructure.Fig.2Ring skeleton of two Niand two Znions of complex 1Fig.3Structure stacking diagram of complex 12.3IR spectraThe IR spectra of HL and complex 1 were determined in a range of 4 000 400 cm-1.As shown inFig.4a,the stretching vibration peak of OH in oxime(HL)appeared at 3 188 cm-1,and the peak moved to3 429 cm-1in 1.A C=N bending vibration absorptionpeak in HL appeared at 1 593 cm-1,and the peakmoved to 1 610 cm-1in 1.These signals show that thenickel ion is coordinated with the hydroxyl group in theHL ligand.In the IR spectrum of 1(Fig.4b),the CHabsorption peaks of pyridine were found at 3 077 and3 005 cm-1.The signal at 1 540 cm-1is assigned to thestretching vibration absorption peak of the aromaticring.These results revealed that the skeleton structureof the HL ligand remains intact during the coordinationprocess.2.4Thermal properties and PXRD analysisTo identify the thermal stabilities of complex 1,thermogravimetry(TG)measurements were performed.杨华等：基于2吡啶甲醛肟配体的Ni2Zn2簇配合物的合成、晶体结构、磁性及光催化性能2223无机化学学报第39卷The TG curve of 1 is shown in Fig.5a.The weight lossof 3.81%around 100 may be the loss of solventwater in 1.Then,1 lost weight dramatically at 294,and the weight loss was about 34.5%,due to the removal of the pyridine ring in the complex(Calcd.36.5%).The third weight losses occurred in the interval from330 to 796 ,8.2%and 19.5%respectively,whichmay be due to the removal of the coordinated alkoxygroup(OCH3)and the remaining structure(C=N,Cl-)(Calcd.7.1%,20.2%).Finally,the remaining 33.7%may be a mixture of ZnO and NiO(Calcd.36.0%).Theplateau appearing at 294 330 may be due to theabsorption of energy by alkoxy groups during the bondbreaking process.The PXRD pattern was measured at room temperature to confirm the purity of the phase of 1.The experimental and simulated PXRD patterns are shown inFig.5b.The simulated PXRD pattern was in good agreement with that of the experimental ones,proving thephase purity of 1.Fig.4IR spectra of HL(a)and complex 1(b)Fig.5TG curve(a)and simulated and experimental PXRD patterns(b)of 12.5Magnetic propertiesMagnetic property investigations on transition metal complexes continue to attract interest from scientists.These studies can provide fundamental factorscontrolling their magnetic properties.The dc magneticproperties for complex 1 were measured at an appliedmagnetic field of 1 kOe in a temperature range of 2300 K(Fig.6).At 300 K,the MT product of 1 was determined tobe 1.99 cm3mol-1K.This value was very close to thecalculated value for the two Ni ions(2.00 cm3mol-1K).Cooling down the sample of 1 over the whole temperature range,the MT value decreased and reached0.02 cm3mol-1K at 2 K,revealing the antiferromagnetic interactions between two Ni ions.The magneticproperties were analyzed by the reported equation48for2224第11期two S=1 metal centers.Two parameters,g=2.08 and J=-4.22 cm-1,were given.The magnetic data of M-1vs Tfrom 45300 K(linear part)were also fitted by the CurieWeiss law,which yields C=2.005 cm3mol-1K and=-11.366 K,confirming the presence of antiferromagnetic exchange coupling interactions among the metalcenters.2.6Photocatalytic propertiesIn recent y