Fused-Fluoran Leuco Dyes with Large Color-Change Derived from Two-Step Equilibrium: iso-Aminobenzopyranoxanthenes.
Fluorans are popular leuco dyes that are used in various applications, such as carbonless-copy papers and thermal papers. Here, we describe unique leuco dyes in which two fluoran units are fused into a C2hstructure (iso-aminobenzopyranoxanthenes; iso-ABPXs). iso-ABPXs exhibited a large two-step color change (colorless/pink and pink/blue-green) due to opening-closing of two spirolactone rings. The two-step equilibrium among the colorless, pink, and blue-green forms could be well controlled by adjusting acid concentration, solvent, and/or temperature.
Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Yoshinao
Y
Shirasaki
Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Yuta
Y
Okamoto
Elements Chemistry Laboratory, RIKEN, and Advanced Elements Chemistry Research Team, RIKEN Center for Sustainable Resource Science (CSRS), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Atsuya
A
Muranaka
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University , 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.|Next-Generation Imaging Team, RIKEN Center for Life Science Technologies (CLST), 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
Shinichiro
S
Kamino
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University , 1-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan.|Next-Generation Imaging Team, RIKEN Center for Life Science Technologies (CLST), 6-7-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
Daisuke
D
Sawada
Materials Characterization Support Unit, RIKEN Center for Emerging Matter Science (CEMS), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Daisuke
D
Hashizume
Graduate School of Pharmaceutical Sciences, The University of Tokyo , 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.|Elements Chemistry Laboratory, RIKEN, and Advanced Elements Chemistry Research Team, RIKEN Center for Sustainable Resource Science (CSRS), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Masanobu
M
Uchiyama