Paradigm Shift for Observation of Phosphorescence-Derived Circularly Polarized Luminescence in the near infrared region

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K19063
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Keio University
• Principal Investigator: Hasobe Taku 慶應義塾大学, 理工学部(矢上), 教授 (70418698)
• Project Period (FY): 2018-06-29 – 2022-03-31
• Keywords: 円偏光発光

Outline of Final Research Achievements

A homoleptic zinc(II) helicate organized by a pair of achiral dipyrromethene ligands through zinc(II)-coordination were systematically synthesized to estimate the chiroptical properties. This zinc complex demonstrated strong exciton-coupled chiroptical responses from the helical configuration with a strong absorption dissymmetry factor |gabs| (up to 0.20). More importantly, an intense polarized luminescence in the far-red region (700-850 nm) with a fluorescence quantum yield ΦFL of 0.23 was observed for this helicate with a dissymmetry factor |glum| of 0.022, the largest value among the rare earth- and precious metal-free small molecules. These unprecedentedly large g values were supported by theoretical calculations. Additionally, singlet fission using acene derivatives for phosphorescence-derived circularly polarized luminescence in the near infrared region was also observed.

Free Research Field

光化学

Academic Significance and Societal Importance of the Research Achievements

円偏光発光（CPL）は3Dディスプレイだけでなく、セキュリティペイントや光通信を含む高度光情報プロセシングへの展開が期待されている。しかしながら、これらに必要な近赤外領域でのCPLの報告例は皆無である。本研究では非平面型ジピロメテン誘導体を用いて安定にキラル保持が可能な亜鉛錯体を合成し、円二色性吸収 (CD) およびCPL の各種測定を行った。異方性因子は赤色および近赤外の領域において、gabs : 0.22およびglum: 0.022を達成した。報告されている近赤外領域での有機低分子系のglumとしては最高値を示す結果が得られた。