Department of Chemistry and Biochemistry, Graduate School of, Engineering, Kyushu University, Fukuoka, 819-0395, Japan.
Spectroscopy Laboratory for Functional π-Electronic Systems, Department of Chemistry, Yonsei University, Seoul 03722, Korea.
Chemistry. 2021 Mar 17;27(16):5259-5267. doi: 10.1002/chem.202005360. Epub 2021 Feb 19.
A bright near-infrared (NIR) fluorescent molecule was developed based on the donor-acceptor-donor (D-A-D) approach using an aza-BODIPY analog called pyrrolopyrrole aza-BODIPY (PPAB) as an electron-accepting chromophore. Directly introducing electron-donating triphenylamine (TPA) to develop a D-A-D structure caused redshifts of absorption and emission of PPAB into the NIR region with an enhanced fluorescence brightness of up to 5.2×10 m cm , whereas inserting a phenylene linker between the TPA donor and the PPAB acceptor induced solvatochromic behavior in emission. Transient absorption spectra and theoretical calculations revealed the presence of a highly emissive hybridized locally excited and charge-transfer state in the former case and the contribution of the dark charge-separated state to the excited state in the latter case. The bright D-A-D PPAB as a novel emitter resulted in a NIR electroluminescence with a high external quantum efficiency of 3.7 % and a low amplified spontaneous emission threshold of ca. 80 μJ cm , indicating the high potential for NIR optoelectronic applications.
一种基于给体-受体-给体（D-A-D）策略的明亮近红外（NIR）荧光分子被开发出来，该策略使用一种称为吡咯并吡咯氮杂 BODIPY（PPAB）的aza-BODIPY 类似物作为电子受体发色团。直接引入供电子三苯胺（TPA）来开发 D-A-D 结构，导致 PPAB 的吸收和发射红移到 NIR 区域，荧光亮度高达 5.2×10 m cm ，而在 TPA 供体和 PPAB 受体之间插入一个亚苯基连接体则会导致发射的溶剂化变色行为。瞬态吸收光谱和理论计算表明，在前一种情况下存在一个高发射的杂化局部激发和电荷转移态，而在后一种情况下则存在暗电荷分离态对激发态的贡献。作为一种新型发射器的明亮 D-A-D PPAB 产生了具有高外量子效率 3.7％和低放大自发发射阈值约 80 μJ cm 的 NIR 电致发光，表明其在近红外光电应用方面具有很高的潜力。
