A Near‐Infrared Emissive π‐Conjugated Polymer Consisting of an Excited‐State Intramolecular Proton Transfer Unit. Issue 9 (23rd July 2020)

• Record Type: Journal Article
• Authors: Suzuki, Naoya; Wakioka, Masayuki; Ozawa, Fumiyuki; Yamaguchi, Shigehiro
• Is Part Of: Asian journal of organic chemistry. Volume 9:Issue 9(2020)
• Page Start: 1326
• Page End: 1332
• Publication Date: 2020-07-23
• Subjects: ESIPT -- near infrared fluorescence -- π-conjugated polymer -- D-A type chromophore -- direct arylation; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; 547.005
• DOI: 10.1002/ajoc.202000234
• Languages: English
• ISSNs: 2193-5807

Abstract

Abstract: Near infrared (NIR)‐emissive polymers are attractive luminescent materials due to their utilities in biological, optoelectronic, and telecommunication applications. Herein we report the use of a dialkylamine‐strapped dithienylpyrrole (DTP) as an excited‐state intramolecular proton transfer (ESIPT) building block for producing NIR‐emissive π‐conjugated polymers. The study of a series of model compounds showed that the extension of π‐conjugation with a moderately electron‐accepting comonomer unit, dithientyl‐substituted thiazolo[5, 4‐d]thiazole (TzTz), effectively stabilizes the zwitterionic ESIPT state while increasing the oscillator strength for the electronic transition from the ESIPT state. Consequently, a polymer consisted of DTP and TzTz units exhibited a significantly red‐shifted emission, exceeding 750 nm, from the ESIPT state in polar solvents. Abstract : Upon excitation, dialkylamine‐strapped dithienylpyrrole undergoes the excited‐state intramolecular proton transfer (ESIPT), resulting in enhancement of the electron‐donating ability. An alternating polymer of this skeleton with an electron‐accepting thiazolo[5, 4‐ d ]thiazole unit retains the ESIPT behavior, and exhibits a NIR emission with a large Stokes shift in polar solvents.