Lanthanide Complex with Thermostability

In this thesis, the control of coordination structures and functionalization of luminescent lanthanide(lll) complexes with LVF hfa and phosphine oxide ligands were investigated. In particular, the author constructed (1) lanthanide coordination polymer with thermostability and thermosensing ability and (2) lanthanide complexes with novel asymmetric coordination structures to improve their emission quantum yields. 

The luminescence and thermal properties of lanthanide(III) complexes can be manipulated and enhanced by designing organic ligands which coordinate to lan-thanide(III) ions. In this thesis, molecular designs for the enhancement of the luminescence properties and functionalization (thermostability and temperature-sensing ability) of lanthanide complexes with LVF phosphine oxide ligands have been described. The results obtained in this study were briefly summarized as follows. 

In this thesis, luminescent lanthanide complexes with specific coordination structures are introduced by Dr. Kohei Miyata. Specific coordination structures result in lanthanide complexes with remarkable photophysical properties. This thesis provides academic studies of specific coordination structures (mono-capped square-antiprism, dodecahedron, and coordination-polymer structures) of luminescent lanthanide complexes. Dr. Miyata has also successfully prepared thermostable and thermosensing luminophores composed of lanthanide ions and characteristic organic ligands. I believe that his studies contribute to successfid exploration of new science and technology in our future. 

As mentioned above, design of coordination structures of lanthanide complexes enable precise manipulations of the electron transitions in f orbitals. The geometrical, vibrational, and steric structures of lanthanide complexes are directly linked to luminescence properties such as emission quantum yield, radiative, and nonradiative rate constants. The control of the coordination structures of lanthanide complexes is expected to provide desirable emission properties. Lanthanide polynuclear complexes and coordination polymers have been also studied from the viewpoint of thermostability of complexes. However, the correlation between coordination structures and photophysical properties of lanthanide complexes has been scarcely investigated, and the optimum coordination environment for strong-luminescent properties has been still unclear. Additionally, lanthanide coordination polymer with both high thermostability and strong-luminescent properties has not been previously reported. 

Here, the author considers that the introduction of low-vibrational frequency (LVF) ligands as a linker part in the polymer chains would result in the preparation of a lanthanide coordination polymer with strong luminescence properties. Strongly liuninescent lanthanide complexes composed of LVF hfa and bidentate phosphine oxide ligands have been described in former chapters. The author also proposes that the introduction of aromatic aryl groups in the linker part of lanthanide coordination polymer is effective for the construction of thermostable luminophores with intermolecular interactions, such as CH/F, n-n, and CWn interactions. 

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