Synthesis,Structures And Properties Of Metal Borates Under Hydrothermal/Solvothermal Conditions

Crystalline open-framework borates are important types of inorganic microporous materials for their architectures and potential applications in catalysis,adsorption,ion-exchange and nonlinear optical crystal.Up to now,researchers has synthesis main group metal borates,transition metal borates and rare earth metal borates under hydrothermal/solvothermal,borate melting and high temperature solid state method.Germanium can build framework via tetrahedral,trigonal bipyramid,tetragonal pyramid and octahedral.A series of new metal or organically template borogermanates have been synthesized during the past 2 decades.Rare earth metal borates are of considerable interest new functional material because of their applications in fluorescence,non-linear optics,laser and ionic conductions.In this paper,we synthesized two borogermanates compounds used organic amine as templates under hydrothermal conditions:(C2H6NH2)2[B3Ge5O15(OH)](1)and(CH3NH3)2[GeB4O9](2).Seven rare earth metal borates via solvothermal conditions:Er(C03)[B(OH)4](3),RE2(HCOO)[B205(OH)]·H2O[RE = Y(4),Dy(5),Er(6)],RE3(HCOO)[B3O8(OH)]·H2O[RE = Y(7),Er(8),Dy(9)].Compounds 4-6 display similar 3D network structure,compounds 7-9 are isomorphic.These structures were determined by single-crystal X-ray diffraction and characterized by powder X-ray diffraction,thermo gravimetric analysis,FTIR,UV-vis-NIR diffuse reflectance spectra.Compound(C2H6NH2)2[B3Ge5O15(OH)]crystallizes in the triclinic space group P-1.Two BO4 tetrahedra and one BO2(OH)triangle are connected by corner-sharing 0 atoms to give a B3O7(OH)cluster.The B3O7(OH)cluster with five corner-shtaring GeO4 tetrahedra give a unique basket-shaped Ge5B3O18(OH)cluster.Each Ge5B3O18(OH)cluster connects with five nearest neighbors via Ge-O-Ge bonds to give the final double layer anionic open-framework.The guest[dima]+ cations are found in the layers and adjacent layers,play a role in charge balance and structural stability.Compound(CH3NH3)2[GeB4O9]crystallizes in the monoclinic space group P21.It is shows a diamond type net built by GeO4 and B4O9 unit Compound 2 exhibits the largest second harmonic generation(SHG)response(3 x KH2PO4)among reported BGOs,with the UV cutoff edge below 190 nm.Compound Er(CO3)[B(OH)4]crystallizes in the orthorhombic space group Pbca.It is a new structure mixed borate and carbonate,Rare earth metal Er and CO32-are connected by corner-sharing O atoms to give a layer,layer and B(OH)4 connects with each other via O-B-O bonds to give the final open-framework.Compounds 4-6 are isomorphic and belong to the space group Cmca.Rare earth metal and B2O5(OH)are connected by corner-sharing O atoms to give a single layer,single layer and single layer connects with each other via BO4 to give double layer.Then double layer and double layer are conneted by HCOO-to give the final open-framework.H2O are found in the double layers and djacent double layers.Compounds 7-9 crystallizes in the cubic space group Fm-3c.They are display similar 3D network structures.Each four rare earth metal connected with four HCOO-to give a cubic-type structure.Six cubic-type structure and B20O36(OH)12 are connected to give a 24 rare earth metal cluster.Each 24 rare earth metal cluster connected with B20 cluster to give final open-framework.It is.The work of this paper enriches the contents of synthetic and structural chemistry in borates,and opens up a new path to prepare functional borates materials,which are of significance to the exploitation of the borates materials.