Department of Chemistry and Biochemistry, University of Mississippi, University, MI 38677, USA.
Materials and Manufacturing Directorate, Air Force Research Laboratory, 2230 Tenth Street Area B Building 655, Wright-Patterson AFB, Dayton, OH 45433, USA.
Molecules. 2023 Jan 29;28(3):1287. doi: 10.3390/molecules28031287.
Fluorescent organic dyes that absorb and emit in the near-infrared (NIR, 700-1000 nm) and shortwave infrared (SWIR, 1000-1700 nm) regions have the potential to produce noninvasive high-contrast biological images and videos. BODIPY dyes are well known for their high quantum yields in the visible energy region. To tune these chromophores to the NIR region, fused nitrogen-based heterocyclic indolizine donors were added to a BODIPY scaffold. The indolizine BODIPY dyes were synthesized via microwave-assisted Knoevenagel condensation with indolizine aldehydes. The non-protonated dyes showed NIR absorption and emission at longer wavelengths than an aniline benchmark. Protonation of the dyes produced a dramatic 0.35 eV bathochromic shift (230 nm shift from 797 nm to 1027 nm) to give a SWIR absorption and emission (λ = 1061 nm). Deprotonation demonstrates that material emission is reversibly switchable between the NIR and SWIR.
吸收和发射近红外（NIR，700-1000nm）和短波红外（SWIR，1000-1700nm）区域的荧光有机染料具有产生非侵入性高对比度生物图像和视频的潜力。BODIPY 染料以其在可见光区的高量子产率而闻名。为了将这些生色团调谐到近红外区域，将融合氮基杂环吲哚啉供体添加到 BODIPY 支架中。通过微波辅助的 Knoevenagel 缩合反应，用吲哚啉醛合成了吲哚啉 BODIPY 染料。未质子化的染料在比苯胺基准更长的波长处显示出近红外吸收和发射。染料的质子化产生了显著的 0.35eV 红移（从 797nm 到 1027nm 的 230nm 位移），从而产生了 SWIR 吸收和发射（λ=1061nm）。去质子化表明材料发射在近红外和 SWIR 之间是可可逆切换的。
