| Vanadium-containing polyometalates(POMs)as a main class of POMs have aroused researcher?s attention owing to diverse structures and excellent properties fields of catalysis,magnetism,optics and medicinal chemistry.Vanadoborates and vanadium phosphates are two kinds of Vanadium-containing polyometalates.They are composed of different types of BO4/BO3,PO4and polyhedral VOxwith rich valence by vertex-sharing,edge-sharing or face-sharing.They have a variety of geometries:0-D,1-D,2-D and 3-D open-framework.In addition,the addition of alkali metal cations,organic amines,transition metal cations and their complexes not only further expands the structure of the system,but also brings more applications.Up to now,these two types of compounds has been widely reported up to now,only few vanadoborates with{V6B20/22}clusters and vanadium phosphates with[P2O7]4-have been reported.The study of proton conductivity and ionic conductivity is scarce.There is a strong connection between the material conductivity and its practical application.Therefore,it is signification to develop novel vanadoborates and vanadium phosphates with high proton and ionic conductivity.In this paper,four kinds of novel structures of compounds were successfully prepared by hydrothermal synthesis method with vanadium as the basic element.We analyzed their structural characteristics through various characterizations and further explored their properties.The main research results of this paper are as follows:1.Wepresenttwonovel3-Dvanadoborates[H3dien]2[V6B22O44(OH)10(H2O)0.5]·2H3O·12H2O(1)and Na3H10[Ni(H2O)2(VO)6(B10O22)2]·NH4·19H2O(2),which were successfully synthesized under hydrothermal conditions.Both of them have“lantern-shaped”anionic clusters{V6B22}/{V6B20}.In compound 2,the{V6B20}clusters are linked together through NiO6octahedral bridges,resulting in 1-D chains along the c-axis.The 1-D chains are further connected by Na O6polythdra to give rise to a 3-D open-framework structure.Furthermore,guest molecules interact with the skeleton forming the abundant three-dimensinoal hydrogen-bonds networks in the two compounds,which endow them good proton conductivity of 10-3S cm-1,which are comparable to many excellent proton conduction materials reported.2.Wereportedtwonew3-Dvanadoborates(NH4)6(H2en)2[V12B18O54(OH)6(H2O)0.5]·12.5H2O(3)and K8Cu(en)2[V12B18O54(OH)6(H2O)0.5]·14H2O(4),which were prepared by hydrothermal synthesis method.Both compounds have"A+B+A"type anion clusters of{V12B18}.Among of them,"A"represents the{V6O18}cluster and"B"represents{B18O42}unit.The{V12B18}clusters in compound 3 interacted with the guest moleculars through H-bonding networks and formed a three-dimensional(3D)structure with proton conductivity of 3.86×10-4S cm-1.For compound 4,adjacent{V12B18}clusters in the structure interact with each other through hydrogen-bonds and extend infinitely to form 1-D chains along the a-axis.These 1-D chains further interact with the cationic Cu(en)22+by hydrogen-bonds,forming 2-D layered structure with large channels.In addition,K+as counterweight ions dispersed in the channels of compound 4.Interestingly,the compound 4 showed a good adsorption capacity for methylene blue(MB)in alkaline solution,and the removal rate reached 95%.This work not only expands the vanadoborates system,but also enriches its application.3.Thefirst3-Dvanadium-nickelpyrophosphate(C6H14N2)[Ni V2O6H8(P2O7)2]·2H2O(5)and 1-D vanadium-pyrophosphate(C6H14N2)[VP2O8](6)with organic template have been hydrothermally synthesized and sturcturally characterized.Both compounds possess one-dimensional chains which build by P2O7group and VOn(n=5,6)polyhedron alternately linked together and infinitely extended.The 1-D chains in the compound 5 are cross-linked by vertex-sharing between NiO6and P2O7units into an infinite 3-D framework with intersecting 6-,8 and 12-rings channels along[100],[010]and[001]directions.The organic amines not only act as proton carriers,but also interact with anion skeletons to form a continuous hydrogen-bonding pathway which can provied a network for proton transport.Strikingly,compound 5 exhibited proton conductivity of 2.0×10-2S cm-1,which is comparable to that of the Nafion.And the activation energy is 0.38 e V.These characteristics endow compound 5 with great potential as a solid electrolyte material for hydrogen fuel cells and sensors in the future.4.One novel V/B/P system compounds KVBP2O9·H2O(7)was successfully prepared by the method of synthesis without organic template.In compound 7,PO4units and VO6octahedra through sharing?2-O atoms,forming“wavy-shaped”2-D layer structure.Then 2-D layers further give rise to the 3-D open-framework by tetrahedral BO4.The alkali metal cations K+fill the pores of the compound.In addition,the compounds show good ionic conductivity of 1.1×10-3S cm-1,making it potential candidates for superionic conductors and solid electrolyte materials.At the same time,the green synthesis method of this work,which provides a new idea for exploring novel compounds of V/B/P system. |
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