Gawale Yogesh, Adarsh Nagappanpillai, Kalva Sandeep Kumar, Joseph Joshy, Pramanik Manojit, Ramaiah Danaboyina, Sekar Nagaiyan
Dyestuff Technology Department, Institute of Chemical Technology, Matunga, Mumbai, 400 019, India.
Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram, 695 019, Kerala, India.
Chemistry. 2017 May 11;23(27):6570-6578. doi: 10.1002/chem.201605702. Epub 2017 Apr 18.
Four new N-ethylcarbazole-linked aza-boron-dipyrromethene (aza-BODIPY) dyes (8 a,b and 9 a,b) were synthesized and characterized. The presence of the N-ethylcarbazole moiety shifts their absorption and fluorescence spectra to the near-infrared region, λ≈650-730 nm, of the electromagnetic spectrum. These dyes possess strong molar absorptivity in the range of 3-4×10 m cm with low fluorescence quantum yields. The triplet excited state and singlet oxygen generation of these dyes were enhanced upon iodination at the core position. The core-iodinated dyes 9 a,b showed excellent triplet quantum yields of about 90 and 75 %, with singlet oxygen generation efficiency of about 70 and 60 % relative to that of the parent dyes. Derivatives 8 a,b showed dual absorption profiles, in contrast to dyes 9 a,b, which had the characteristic absorption band of aza-BODIPY dyes. DFT calculations revealed that the electron density was spread over the iodine and dipyrromethene plane of 9 a,b, whereas in 8 a,b the electron density was distributed on the carbazole group and dipyrromethene plane of aza-BODIPY. The uniqueness of these aza-BODIPY systems is that they exhibit efficient triplet-state quantum yields, high singlet oxygen generation yields, and good photostability. Furthermore, the photoacoustic (PA) characteristics of these aza-BODIPY dyes was explored, and efficient PA signals for 8 a were observed relative to blood serum with in vitro deep-tissue imaging, thereby confirming its use as a promising PA contrast agent.
合成并表征了四种新型的 N-乙基咔唑连接的氮杂硼二吡咯亚甲基（aza-BODIPY）染料（8 a、b 和 9 a、b）。N-乙基咔唑部分的存在将它们的吸收光谱和荧光光谱转移到电磁光谱的近红外区域，λ≈650 - 730 nm。这些染料在 3 - 4×10 m cm 范围内具有很强的摩尔吸光率，但荧光量子产率较低。在核心位置进行碘化后，这些染料的三重激发态和单线态氧生成得到增强。核心碘化的染料 9 a、b 显示出约 90%和 75%的优异三重态量子产率，相对于母体染料，单线态氧生成效率约为 70%和 60%。与具有 aza-BODIPY 染料特征吸收带的染料 9 a、b 相比，衍生物 8 a、b 显示出双重吸收谱。密度泛函理论（DFT）计算表明，9 a、b 的电子密度分布在碘和二吡咯亚甲基平面上，而在 8 a、b 中，电子密度分布在氮杂硼二吡咯亚甲基的咔唑基团和二吡咯亚甲基平面上。这些氮杂硼二吡咯亚甲基体系的独特之处在于它们表现出高效的三重态量子产率、高单线态氧生成产率和良好的光稳定性。此外，还探索了这些氮杂硼二吡咯亚甲基染料的光声（PA）特性，通过体外深部组织成像观察到相对于血清，8 a 具有有效的 PA 信号，从而证实了它作为一种有前景的 PA 造影剂的用途。
