Synthesis And Characterization Of Open-framework Borates And Transition Metal Borates

Borate materials have been an active field among the research of microporous materials in the past decades due to their rich structural chemistry and potential applications in nonlinear optical properties,luminescence,semiconducting materials and mineralogy.The rich structure types of borates originate from that the B atom can be coordinated with three O atoms or four O atoms to form BO3 triangles or BO4 tetrahedra,and further these triangles and tetrahedra can connect each other through sharing O atoms to form various fundamental building blocks(FBBs)of borates.These FBBs may exist as isolated anionic clusters or further polymerize into infinite chains,sheets and frameworks.In recent years,the introduction of heteroatoms,like main group metals and transition metals,into borate backbones has been proved to be an effective way to rich structure types of borates and obtain borate materials with novel structures and excellent properties.In this work,we make an effort to explore the synthesis of new borates and transition metal borates applying hydrothermal or solvothermal synthesis methods in the solvent system of water,ethanol and organic amines.Four novel borates or transition metal borates were obtained and characterized by means of single crystal X-ray diffraction,powder X-ray diffraction,IR,UV-vis,TG and elemental analysis.[C4H11N2][C2H5OH]0.5[B5O6(OH)4]·O.5H2O(2-1)[HN(C2H5)3]2[Zn4B2(C4H2O6)4(H2O)3]·0.5H2O(2-2)[HN(C2H5)3][Zn2B(C4H206)2(H20)](2-3)Zn6(H2NC2H4OH)2[(H2NC2H4)2(B3O7)](BO3)3·2H2O(2-4)Compound 2-1 is an isolated pure borate,which crystallizes in the monoclinic space group C2/c with an anionic FBB,[B5O6(OH)4]-.The FBBs of compound 2-1 connect with each other through hydrogen bonding interactions to form a three-dimensional network with supramolecular channels in different directions.Compounds 2-2 and 2-3 crystallize in the triclinic space group P-1 and monoclinic space group P21/c,respectively.The two compounds possess the same organic-inorganic hybrid Zn2B(C4H2O6)2 FBBs.These FBBs connect with tartaric acid into linear chains.The different orientation and arrangements of the chains lead to the formation of two sorts of topologically similar corrugated layers.Protonated triethylamine molecules as templates stay in the interlayer void spaces and link with backbones by hydrogen bonds.Compound 2-4 is a novel organic-inorganic hybrid pillar-layered zincoborate.The compound crystallizes in monoclinic space group P21/c and possesses a rare two-dimensional[Zn2BO3]? layer with boron atoms as inserts,forming a graphene-like structure.The adjacent layers are pillared by organic-inorganic hybrids derived from condensation between boron-oxygen clusters(B3O7)and ethanolamines.Furthermore,there also exist ethanolamines grafting onto both sides of the layers with one end unbonded.