Gon Masayuki, Tanaka Kazuo, Chujo Yoshiki
Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.
Chem Rec. 2021 Jun;21(6):1358-1373. doi: 10.1002/tcr.202000156. Epub 2021 Jan 4.
Azomethine (C=N) and azo (N=N) scaffolds are a part of structural units in poly(p-phenylene azomethine) (PAM) and poly(p-phenylene azo) (PAZ), respectively. Poly(p-phenylene vinylene) (PPV) is known to be one of luminescent π-conjugated polymers, meanwhile PAM and PAZ, which are the aza-substituted PPV analogues, are regarded as weak or no emissive materials. However, by the boron complexation, intense emission can be induced. Furthermore, environment-sensitivity and stimuli-responsivity were also observed. In this review, we demonstrate unique and versatile luminescent properties based on "flexible and bendable" π-conjugated systems composed of the boron-fused azomethine and azobenzene complexes (BAm and BAz) with the O,N,O-type tridentate ligands. The "flexible and bendable" luminophores showed intriguing optical behaviors, such as thermosalient effect, aggregation-induced emission (AIE) and crystallized-induced emission (CIE). Moreover, highly efficient emissions both in solution and film states were observed from the polymers. We illustrate the results and mechanisms on these luminescent properties from the series of our recent studies with BAm and BAz complexes and polymers.
甲亚胺（C=N）和偶氮（N=N）支架分别是聚对苯撑甲亚胺（PAM）和聚对苯撑偶氮（PAZ）结构单元的一部分。聚对苯撑乙烯撑（PPV）是已知的发光π共轭聚合物之一，而作为氮杂取代PPV类似物的PAM和PAZ则被视为弱发光或无发光材料。然而，通过硼络合可以诱导强烈的发射。此外，还观察到了环境敏感性和刺激响应性。在这篇综述中，我们展示了基于由硼稠合甲亚胺和偶氮苯络合物（BAm和BAz）与O，N，O型三齿配体组成的“柔性且可弯曲”π共轭体系的独特且通用的发光特性。这些“柔性且可弯曲”的发光体表现出有趣的光学行为，如热致变色效应、聚集诱导发光（AIE）和结晶诱导发光（CIE）。此外，从聚合物中观察到了溶液态和薄膜态的高效发射。我们通过一系列关于BAm和BAz络合物及聚合物的近期研究来说明这些发光特性的结果和机制。
