title: Benzo[c,d]indole-Containing Aza-BODIPY Dyes: Asymmetrization-Induced Solid-State Emission and Aggregation-Induced Emission Enhancement as New Properties of a Well-Known Chromophore.
abstract: A series of symmetric and asymmetric benzo[c,d]indole-containing aza boron dipyrromethene (aza-BODIPY) compounds was synthesized by a titanium tetrachloride-mediated Schiff-base formation reaction of commercially available benzo[c,d]indole-2(1H)-one and heteroaromatic amines. These aza-BODIPY analogues show different electronic structures from those of regular aza-BODIPYs, with hypsochromic shifts of the main absorption compared to their BODIPY counterparts. In addition to the intense fluorescence in solution, asymmetric compounds exhibited solid-state fluorescence due to significant contribution of the vibronic bands to both absorption and fluorescence as well as reduced fluorescence quenching in the aggregates. Finally, aggregation-induced emission enhancement, which is rare in BODIPY chromophores, was achieved by introducing a nonconjugated moiety into the core structure.
authors.affiliation: Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 819-0395 (Japan). ssoji@cstf.kyushu-u.ac.jp.|Center for Molecular Systems (CMS), Kyushu University, Fukuoka 819-0395 (Japan). ssoji@cstf.kyushu-u.ac.jp.
authors.forename: Soji
authors.initials: S
authors.lastname: Shimizu
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan).
authors.forename: Ai
authors.initials: A
authors.lastname: Murayama
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan).
authors.forename: Takuya
authors.initials: T
authors.lastname: Haruyama
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan).
authors.forename: Taku
authors.initials: T
authors.lastname: Iino
authors.affiliation: Division of Material Science, Advanced Research Support Center, Ehime University, Matsuyama 790-8577 (Japan).
authors.forename: Shigeki
authors.initials: S
authors.lastname: Mori
authors.affiliation: Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, Fukuoka 819-0395 (Japan).|Center for Molecular Systems (CMS), Kyushu University, Fukuoka 819-0395 (Japan).
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Furuta
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan). nagaok@m.tohoku.ac.jp.|Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567 (Japan). nagaok@m.tohoku.ac.jp.
authors.forename: Nagao
authors.initials: N
authors.lastname: Kobayashi
keywords: aggregation; dyes/pigments; fluorescence; nitrogen heterocycles; solid-state emission