Application Of A Two-Step Reaction Method Based On 3D Printing Technology In Synthesizing POMOFs Materials

3D printing technology has a lot ofadvantagessuch as low cost,short cycle time,and the out-and-outcustomizable process.In the field of chemistry,this technology has been used to build any reaction device required for experiment,which will give researchers a great degree of convenience and freedom.Through customized reactor and reasonable experimentscheme,researcherscan complete a compound and ingenious chemistry experiment.In recent years,metal-organic framework materials(MOFs)have attracted a great deal of attentions from researchers owing to their diverse porous framework structures and the application value in the fields of catalysis,gas storage/separation,and molecular recognition.Introducingthe polyoxometalates(POMs)with high negative charge and good multifunctional catalytic properties into the framework of MOFs can lead to the formation of POM-based MOF materials(POMOFs)with various structures and excellent functions.The traditional synthesis of POMOF uses one-pot hydrothermal method and solvent diffusion method,which have many limitations such as harsh reaction conditions,poor predictability of structure,miscellaneous conditional selecting,and long reaction cycle.How to controllably and efficiently obtain novel and functional POMOFs is current major challenge.In this thesis,by using the two-chamber reactor designed and manufactured via 3D printing technology,we successfullysynthesized two crystal structures that could not be obtained by the traditional one-pot reaction method.Then we further explore the influence of the parameters in the two-step reaction method on the structure of POMOFs.First of all,three kinds of novel MOFs with entangled network structure were synthesized by using flexible cationic carboxylic acid ligands(1,4-bis(pyridinil-3-carboxylato)-1,4-dimethylbenzene,L1)and simple carboxylic acid ligands:Co4(L1)(BTC)2(H2O)4 · 4H2O(1),Cd2(L1)(AIP)2(H2O)2·2H2O(2)and Cd2(L1)(atpt)2(H2O)2(3),BTC =trimesic acid,AIP = 5-Aminoisophthalic acid,atpt = 2-aminoterephthalic acid.Whereafter,by introducedK4[a-SiW12O40]·17H2O(?-SiW12)and Na3[CrMo6O24H6]·8H2O(CrMo6)into the network of flexible ligand L1 and metal ion Co2+ via two-step reaction method,we obtainedaOD structure:Co2(L1)2(?-SiW12)(H2O)8·DMF(4),and a 3D network structure:[Co(L1)NaCrMo6(H2O)2]·2H2O(5).At last,in order to further explore the influence of two-step reaction parameters on the crystal structure,we synthesized four new structures based on the compounds 4 and 5 by modulating reaction parameters.By changing the singlesolvent environment of the POMs during the synthesis of the compound 4,we obtained a1D structure:CO2(L1)2(?-SiW]2)(H2O)8·2H2O(6),By changing the synthesis method of CrMo6 in the synthesis of compound 5,we obtained a2D structure:Na[Co(MeOH)2(DMF)2(H2O)2](L1)(CrMo6)(7).By designing a custom three-chamber two-step reactor that places the reactants ofa-SiW12 and CrMo6 in a competitively coordinated environment,we obtained an interesting 2Dcurved surface structure:Na3(L,)2(CrMo6)(H20)10·2H20(8).By replacing L1 with L2(1,4-bis(pyridinil-4-carboxylato)-1,4-dimethylbenzene)during the synthesis of compound5,we obtained a different 2D layered structure:Na2(L2)(CrMo6)(H2O)4·6H2O(9).The above result proves that the two-step reaction method based on 3D printing indeed can expand the crystal structure diversity of POMOFs.Through the two-step method,we synthesized not only the crystal structures that cannot be obtained by the one-pot reaction method,but also additional crystal structures by adjusting the parameters of two-step method.This result indicates that POMOFs framework structures hopefully can be controlled and designed more directionally through this two-step reaction method.