Crystal Structures And Properties Of Titanium-oxo Clusters

Titanium(Ti)based photocatalytic materials are widely used in photocatalytic oxidation and reduction,organic synthesis,degradation of environmental pollutants,photocatalytic H2 generation from water splitting,sensing and solar cells,etc.In recent years,researchers in chemistry and materials have paid much attention on titanium(Ti)based photocatalytic materials.Titanium dioxide is one of the most important semiconductor photocatalytic materials with high catalytic activity,low toxicity and low cost.However,its wide band gap and low utilization of solar energy limit its application in the field of photoelectrochemistry.Compared with titanium dioxide,titanium coordination compounds(Titanium Metal Organic Frameworks Ti-MOFs and Titanium-oxo Clusters TOCs)can exhibit equivalent or superior performance in catalytic applications,which can overcome the disadvantages of low porosity and low efficiency of titanium dioxide and improve the corresponding performance with the modification of structures.In addition,their precise structure information can be obtained by X-ray diffraction technology.which is beneficial to the development of new functional materials by studying the relationship between properties and structures.Among them,titanium-oxo clusters have gradually become a research hotspot due to their novel structures and excellent properties.Increasing attention has been paid to the synthesis of novel titanium-oxo clusters and obtaining their structural information and properties.The purpose of this thesis is to synthesize novel titanium oxide clusters by solvothermal method and to explore their crystal structures and properties by choosing suitable ligands.The details are as follows:(1)Selecting p-aminobenzoic acid as the ligand and titanium isopropoxide as the titanium source,a 32-nucleus ring-like titanium oxide nanocluster compound 1 Ti32(?2-O)8(?3-O)8(L)16(gly)32(glyH)16·12(glyH2)·29(IPA)was synthesized by mild solvothermal reaction,in which L stands for p-aminobenzoic acid,IPA for isopropanol,and glyH2 for glycol The cluster compound 1 underwent an irreversible desolvation under natural air-drying conditions to generate a stable compound 1-Dry Ti32(?2-O)8(?3-O)8(L),6(gly)32(glyH)16·12(glyH2).The metastable-to-stable transition of compound 1 was successfully captured by X-ray single crystal diffraction technology.The experimental results show that the stable compound 1-Dry not only can be stable in various solvents such as 1,4-dioxane,water,acetone,methanol,acetonitrile and isopropanol,but also effectively adsorpt N2 and CO2 selectively.(2)By altering the types of organic ligands,salicylic acid ligands such as salicylic acid(C7H6O3),2,5-dihydroxybenzoic acid(C7H6O4)and titanium isopropoxide were selected to synthesize zero-dimensional titanium oxide clusters compound 2 Ti14(?2-O)14(?3-O)8(C7H4O3)7(C7H5O3)(OiPr)18 and compound 3 Ti16(?2-O)8(?3-O)10(C7H3O4)4(OiPr)14(H2O)2·2HOiPr.In addition to the accurate characterization of their structures,their solvent stability and acid-base stability were also determined.The research content of this paper can provide useful information for the synthesis of novel titanium-oxo clusters,and their potential applications should be investigated in the near future.