Yasuchika Hasegawa

Graduate School of Engineering, Hokkaido University

Research AreasPhotochemistry, Coordination Chemistry
Participating Group (2020-2021)

Soft-crystal and photophysical transformations from lanthanide complex to coordination polymer

Luminescence, Soft Crystal, Lanthanide Complex, Lanthanide Coordination Polymer
Co-Researcher: Yuichi Kitagawa (Hokkaido University Institute for Chemical Reaction Design and Discover, Lecturer)

Research Outline

Luminescence properties of lanthanide complexes are strongly depended on their coordination geometrical structures (Laporte allowed transitions). In this study, new-type soft crystal transformation based on the changeable lanthanide coordination number and geometry under out-triggers is demonstrated. In particular, soft crystal transformation from seven- to eight-coordinated europium(III) complexes under out-trigger (addition/removement of pyridine derivatives) are investigated. The reversible soft crystal transformation in solid state are characterized using X-ray analyses, photophysical measurements (emission spectral analyses, emission quantum yields, emission lifetimes, radiative rate analyses, LMCT (ligand to Eu(III) charge transfer) analyses etc.). The soft crystal transformation and photophysical analysis (excited energy transfer process in transformed intermediates) from seven-coordinated lanthanide complex to eight-coordinated lanthanide coordination polymer are also studied.

Soft crystal transformation from lanthanide complex to coordination polymer
Transition state in soft crystal transformation
Participating Group (2018-2019)

Synthesis and Photo-functional Characterization of Chiral Lanthanide Coordination Polymer with Soft Crystals Transformation

Glass Transformation, Chiral, Lanthanide Complex, Luminescence
Co-Researcher: Takayuki Nakanishi (Graduate School of Industrial Science and Technology, Tokyo University of Science, Lecturer)
Co-Researcher: Yuichi Kitagawa (Hokkaido University Institute for Chemical Reaction Design and Discover, Lecturer)

Research Outline

Lanthanide complexes with chiral ligands shows circularly polarized luminescence (CPL) with large dissymmetry factor. The photo-functional properties of aggregations composed of chiral lanthanide coordination polymers open up a frontier field of science. In this study, synthesis and photo-functional characterization of chiral lanthanide coordination polymer with crystal-phase transition (soft crystals transformation) are explored. The chiral lanthanide coordination polymers are prepared by the complexation of chiral Eu(III) complexes with phosphine oxides with ethynyl groups. Their transformed structures and photophysical properties are characterized using X-ray analysis, circular dichroism (CD) and CPL spectra. The photosensitized energy transfer process of chiral Eu(III)/Tb(III)coordination polymers is also evaluated using Arrhenius analysis.

Chiral Lanthanide Coordination Polymer with Crystal-phase transitions
Lanthanide Coordination Polymer with ethynyl groups


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