Syntheses,Structure Characterization And Photoelectrochemical Properties Of Ligand Functionalized Titanium-Oxo Clusters

Titanium-oxo clusters?TOCs?are important member of polyoxometalates?POMs?that have rich structure characters and physicochemical properties.Owing to their precise structure information at the atomic level,TOCs can be bregarded as the molecular structural model for TiO₂ semiconductor materials and bridgeb the gap between molecular materials and nano-materials.The research on the synthesis of TOCs and modulation on their structure and photoelectrochemical properties have attracted growing interests.In this thesis,a series of ligand-functionalized TOCs are designed and synthesized.Their structures are characterized by single crystal X-ray diffraction.The spectroscopic properties,electrochemistry,photoelectrochemical property and photocatalytic property of the TOCs are characterized.Theoretical calculations are carried out to give further understanding on the structure property relationship.The main results are summarized as follows:1.The ferrocenecarboxylate-,1-naphthoate-and 1-naphthylacetate-functionalized TOCs were synthesized,respectively.The introduction of of ferrocene groups into the titanium-oxo cluster significantly extends the visible absorption band and reduces the band gap?2.5 eV?.The much enhanced photoelectrochemical activity was observed for the ferrocenecarboxylate-functionalized clusters.2.The 4-dimethylaminobenzoate,1-adamantanecarboxylate,and dimethylma-lobnate functionalized TOCs were synthesized,respectively.As an organic dye with the donor–?-bridge-acceptor?D–?–A?structure,the introduction of 4-dimethylamin-obenzoate ligand into titanium-oxo cluster significantly reduces the band gap?2.5 eV?and improves the photoelectrochemical activity.3.A series of 4-chlorosalicylate-stabilized titanium-oxo clusters were synth-esized with the structure-directing effect of tetrazole.The photoelectrochemical and photocatalytic experiments show that Ti-oxo core structure has significant influence on the photophysical and photocatalytic properties of titanium-oxo clusters.4.A series of TOCs functionalized with 2,2'-biphenolato ligands were synthesized,and their structures were modulated by varying experimental conditions.The spectroscopic characterization show that the 2,2'-biphenolato ligands effectively reduce the band gap of TOCs.Photoelectrochemical experiments show that the larger cage-like core structure is more favorable for photocurrent response.