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  11. Relationship Between Spatially Heterogeneous Reaction Dynamics And Photochemical Kinetics In Single Crystals Of Anthracene Derivatives.

Relationship between spatially heterogeneous reaction dynamics and photochemical kinetics in single crystals of anthracene derivatives.

Sogo Kataoka1, Daichi Kitagawa1, Hikaru Sotome2

  • 1Department of Chemistry and Bioengineering, Graduate School of Engineering, Osaka Metropolitan University 3-3-138 Sugimoto, Sumiyoshi-ku Osaka 558-8585 Japan kitagawa@omu.ac.jp kobatake@omu.ac.jp.

Chemical Science
|August 26, 2024

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View abstract on PubMed

Summary
This summary is machine-generated.

Photodimerization reactions in single crystals show varied progress, with some exhibiting reaction fronts and nonlinear kinetics. This behavior is linked to molecular structure and conformational changes, impacting material properties over time.

Area of Science:

  • Photochemistry and Materials Science
  • Solid-State Organic Chemistry

Background:

  • Controlling material properties requires understanding how physicochemical changes evolve with reaction kinetics.
  • Photodimerization of anthracene derivatives in single crystals is a model system for studying solid-state reactions.

Purpose of the Study:

  • To investigate the reaction kinetics and mechanisms of photodimerization in single crystals of various anthracene derivatives.
  • To correlate observed reaction patterns (e.g., reaction fronts, sigmoidal kinetics) with molecular structure and conformational changes.

Main Methods:

  • Crystallization of anthracene derivatives (9-cyanoanthracene, 9-anthraldehyde, 9-methylanthracene, 9-acetylanthracene).
  • In-situ monitoring of photodimerization using optical methods and absorbance changes.
  • Kinetic analysis employing the Finke-Watzky model to determine effective quantum yields.

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Main Results:

  • 9-cyanoanthracene and 9-anthraldehyde crystals showed reaction front propagation and pronounced sigmoidal absorbance changes, indicating heterogeneous conversion.
  • 9-methylanthracene and 9-acetylanthracene crystals exhibited spatially homogeneous conversion.
  • Kinetic analysis revealed a >10-fold change in effective quantum yield during reaction for 9-cyanoanthracene and 9-anthraldehyde, linked to reaction cooperativity.

Conclusions:

  • Reaction front propagation and nonlinear kinetics in anthracene derivative crystals are driven by differences in reaction cooperativity.
  • A mechanism involving conformational changes during reaction is proposed to explain heterogeneous progress in single crystals.
  • Findings provide insights into linking solid-state photochemical reaction dynamics to evolving physicochemical properties of materials.