A Near Infrared Dye that Undergoes Multiple Interconversions through Acid-Base Equilibria and Reversible Redox Processes

Papers published
K. Asai, A. Fukazawa, and S. Yamaguchi, Angew. Chem. Int. Ed., 2017, Early View. DOI: 10.1002/anie.201702140
  • A near-infrared (NIR) polymethine dye (1), consisting of a cyclohepta[1,2-b;4,3-b′]dithiophene and two phenol moieties, was synthesized. This dye exhibited pH-responsive changes in its photophysical properties due to a two-step acid–base equilibrium that produced a protonated cation (1H+) and an anion (1−). While 1H+ showed an intense fluorescence in the red region of the visible spectrum, 1− exhibited a strong absorption in the NIR region. The tropylium ion character in 1H+ induces high pKa1 and pKa2 values for 1. Moreover, a stable radical (1.) was prepared, which showed a NIR absorption band with a maximum at circa 1600 nm. The cyclic voltammogram of 1. revealed a two-step reversible redox process that produced 1− and the cation 1+, which is different from 1H+. These redox processes accompany drastic electrochromic changes in the vis–NIR region. Overall, 1 is susceptible to multiple interconversions between five forms, due to the multifaceted character of the cycloheptadithiophene skeleton.

Bookmark this on Hatena Bookmark
Hatena Bookmark - A Near Infrared Dye that Undergoes Multiple Interconversions through Acid-Base Equilibria and Reversible Redox Processes
Share on Facebook
Post to Google Buzz
Bookmark this on Yahoo Bookmark
Bookmark this on Livedoor Clip
Share on FriendFeed
[`tweetmeme` not found]
[`grow` not found]