Structure and electronic-state of the liquid-like cluster observed during solvent evaporative crystallization process

2021 Fiscal Year Final Research Report

• Project/Area Number: 19H02686
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 32020:Functional solid state chemistry-related
• Research Institution: Shinshu University
• Principal Investigator: Ito Fuyuki 信州大学, 学術研究院教育学系, 教授 (80403921)
• Co-Investigator(Kenkyū-buntansha): 坂本 章 青山学院大学, 理工学部, 教授 (90262146) ; 岡島 元 中央大学, 理工学部, 准教授 (20582654) ; 島田 林太郎 青山学院大学, 理工学部, 助教 (70548940)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 蛍光スペクトル / 有機結晶 / 液滴状クラスター / ハイパースペクトルカメラ / 低振動数ラマン分光

Outline of Final Research Achievements

We have previously reported the molecular dynamics of the crystallization process based on the fluorescence changes during the evaporative crystallization. These results support the two-step nucleation mechanism based on the fluorescence spectral changes from the monomer in solution to the crystal via an amorphous-like intermediate. In this study, we elucidate the structure and properties of the amorphous-like intermediate. The key intermediate liquid-like cluster state for the two-step nucleation mechanism is visualized by the fluorescence color changes of dibenzoylmethanatoboron difluoride derivatives. Three types of emissive species (Crystal, BG-aggregates, and Amorphous) are generated from monomers in solution via liquid-like clusters during solvent evaporation. In terms of crystallization dynamics, our results indicate that it is important not only to generate supersaturated states, but also to maintain the survival time of the liquid-like cluster.

Free Research Field

光化学

Academic Significance and Societal Importance of the Research Achievements

結晶生成に関する核形成機構で提案されてきている「二段階核形成機構」で想定されている液滴状クラスターの構造，物性に関する評価をすすめることができた．また，この中間体の保持時間が，結晶析出のみならず多形発現にも影響を与えていることを実証した．この結果は，有機結晶の関与する医薬品や機能性固体材料の合理的製造プロセスに重要な視座を与えるものである．また，不均一系の界面現象の実時間変化の観測に，ハイパースペクトルカメライメージング蛍光スペクトルイメージングを適用したことは，その汎用性を拡大させた意義をもつ．