title: Water-tunable solvatochromic and nanoaggregate fluorescence: dual colour visualisation and quantification of trace water in tetrahydrofuran.
abstract: While investigating the unique optical properties of aminobenzopyranoxanthenes (ABPXs), organic fluorescent dyes with the fusion of two rhodamines, we have found that the spirolactone form of ABPXs exhibited solvatochromic fluorescence in organic solvents. Detailed spectrophotometric and theoretical analyses showed that the solvatochromic fluorescence of ABPXs originated from the photo-excited charge separation in solvents of different dipolarities. Further studies revealed that fluorescent nanoaggregates were also formed in highly concentrated solution. The intriguing dual fluorescence properties of ABPXs were tunable in response to the water content, and served as a new detection principle for naked-eye visualisation (above 0.5 wt%) and quantification (0.010-0.125 wt%) of water in tetrahydrofuran.
authors.affiliation: Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama-shi, Okayama 700-8530, Japan. skamino@okayama-u.ac.jp dsawada@okayama-u.ac.jp.
authors.forename: Masaru
authors.initials: M
authors.lastname: Tanioka
authors.affiliation: Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama-shi, Okayama 700-8530, Japan. skamino@okayama-u.ac.jp dsawada@okayama-u.ac.jp and Next-Generation Imaging Team, RIKEN-CLST, Kobe-shi, Hyogo 650-0047, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Kamino
authors.affiliation: Advanced Elements Chemistry Research Team, RIKEN-CSRS, and Elements Chemistry Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan.
authors.forename: Atsuya
authors.initials: A
authors.lastname: Muranaka
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Shirasaki
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan.
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Ooyama
authors.affiliation: Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama-shi, Okayama 700-8530, Japan. skamino@okayama-u.ac.jp dsawada@okayama-u.ac.jp.
authors.forename: Masashi
authors.identifier: http://orcid.org/0000-0001-7027-1568
authors.initials: M
authors.lastname: Ueda
authors.affiliation: Advanced Elements Chemistry Research Team, RIKEN-CSRS, and Elements Chemistry Laboratory, RIKEN, Wako-shi, Saitama 351-0198, Japan and Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Uchiyama
authors.affiliation: Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama-shi, Okayama 700-8530, Japan. skamino@okayama-u.ac.jp dsawada@okayama-u.ac.jp and Next-Generation Imaging Team, RIKEN-CLST, Kobe-shi, Hyogo 650-0047, Japan.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Enomoto
authors.affiliation: Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama-shi, Okayama 700-8530, Japan. skamino@okayama-u.ac.jp dsawada@okayama-u.ac.jp and Next-Generation Imaging Team, RIKEN-CLST, Kobe-shi, Hyogo 650-0047, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Sawada