title: Color Tuning of the Aggregation-Induced Emission of Maleimide Dyes by Molecular Design and Morphology Control.
abstract: Aggregation-induced emission (AIE)-active maleimide dyes, namely, 2-p-toluidino-N-p-tolylmaleimide, 3-phenyl-2-toluidino-N-p-tolylmaleimide, 2-p-thiocresyl-3-p-toluidino-N-p-tolylmaleimide, and 2,3-dithiocresyl-N-arylmaleimides, were synthesized by facile synthetic procedures. The dyes show intense emission in the solid state, and emission colors were controlled from green (λmax =527 nm) to orange (λmax =609 nm) by varying the substituents at the 2- and 3-positions of the maleimide and the packing structures in the solid state. 2,3-Disubstituted maleimide dyes effectively underwent redshifts of their emission wavelength. Furthermore, some of the dyes exhibited mechanochromism and polymorphism, and their emission properties were dramatically dependent on the morphology of the solid samples. The mechanisms of the emission behaviors were investigated by X-ray diffraction. The substituent of the nitrogen atom of the maleimide ring affected the intermolecular interactions and short contacts, which were observed by single crystal X-ray crystallography, to result in completely different emission properties.
authors.affiliation: Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan).
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Imoto
authors.affiliation: Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan).
authors.forename: Kohei
authors.initials: K
authors.lastname: Kizaki
authors.affiliation: Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553 (Japan).
authors.forename: Seiji
authors.initials: S
authors.lastname: Watase
authors.affiliation: Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553 (Japan).
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Matsukawa
authors.affiliation: Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology, Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585 (Japan). kenaka@kit.ac.jp.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Naka
keywords: aggregation; dyes/pigments; luminescence; mechanochromism; polymorphism