Creating Elastic Organic Crystals of π‐Conjugated Molecules with Bending Mechanofluorochromism and Flexible Optical Waveguide. Issue 52 (21st November 2018)

• Record Type: Journal Article
• Authors: Hayashi, Shotaro; Yamamoto, Shun‐ya; Takeuchi, Daisuke; Ie, Yutaka; Takagi, Koji
• Is Part Of: Angewandte Chemie international edition. Volume 57:Issue 52(2018)
• Page Start: 17002
• Page End: 17008
• Publication Date: 2018-11-21
• Subjects: elastic organic crystals -- fibril lamella -- fluorescence -- mechanochromism -- optical waveguide; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201810422
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: To create low band‐gap, fluorescent, and elastic organic crystal emitters, we focused on an extended π‐conjugated system based on: a) a planar conformation, b) a rigid structure, and c) controlled intermolecular interactions. Herein, we report on two fluorescent and highly flexible organic crystals (1 and 2 ) which could bend under an applied stress. The bent crystals rapidly recover their straight shape upon release of the stress. Crystal 1 with a tetrafluoropyridyl terminal unit and a lower band‐gap energy (orange emission, λ em =573 nm, Φ F =0.50), showed no bending mechanofluorochromism and had superior performance as an optical waveguide with reddish orange emission. The waveguide performance of the crystal did not decrease under bending stress. For crystal 2 with a pentafluorophenyl terminal unit (green emission, λ em =500 nm, Φ F =0.38), the original waveguide performance decreased under an applied bending stress; however, this crystal showed a unique bending mechanofluorochromism. Abstract : Two elastic and fluorescent organic single crystals were successfully created based on an original molecular design. The crystals showed bending mechanofluorochromism and high performance as a flexible waveguide.