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A Highly Efficient Near‐Infrared‐Emissive Copolymer with a N=N Double‐Bond π‐Conjugated System Based on a Fused Azobenzene–Boron Complex
Author(s) -
Gon Masayuki,
Tanaka Kazuo,
Chujo Yoshiki
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201803013
Subject(s) - conjugated system , azobenzene , copolymer , homo/lumo , boron , photoluminescence , materials science , double bond , photochemistry , electron acceptor , acceptor , electron deficiency , chemistry , polymer chemistry , crystallography , polymer , molecule , organic chemistry , optoelectronics , physics , condensed matter physics , composite material
Fused azobenzene–boron complexes (BAzs) show highly efficient near‐infrared (NIR) emission from the nitrogen–nitrogen double bond (N=N) containing π‐conjugated copolymer. Optical measurements showed that BAz worked as a strong electron acceptor because of the intrinsic electron deficiency of the N=N double bond and the boron–nitrogen (B−N) coordination which dramatically lowered the energy of the lowest unoccupied molecular orbital (LUMO) of the azobenzene ligand. The simple donor–acceptor (D–A) type copolymer of bithiophene (BT) and BAz exhibited intense photoluminescence (PL) in the NIR region both in the dilute solution ( λ PL =751 nm, Φ PL =0.25) and in the film ( λ PL =821 nm, Φ PL =0.038). The BAz monomer showed slight PL in the dilute solution, and aggregation‐induced emission (AIE) was detected. We proposed that N=N double bonds should be attractive and functional building blocks for designing π‐conjugated materials.