Department of Chemistry and Biochemistry , University of Mississippi , University , Mississippi 38677 , United States.
Department of Chemistry , University of Kentucky , Lexington , Kentucky 40506 , United States.
J Org Chem. 2019 Jan 18;84(2):687-697. doi: 10.1021/acs.joc.8b02521. Epub 2018 Dec 26.
Molecular engineering strategies designed to red-shift cyanine dye absorptions and emissions further into the near-infrared (NIR) spectral region are explored. Through the use of a novel donor group, indolizine, with varying cyanine bridge lengths, dye absorptions and emissions, were shifted deeper into the NIR region than common indoline-cyanines. Stokes shifts resulting from intramolecular steric interactions of up to ∼60 nm in many cases were observed and explained computationally. Molecular brightnesses of up to 5800 deep into the NIR region were observed. Structure-property relationships are explored for the six indolizine-cyanine dyes with varying cyanine bridge length and indolizine substituents showing broad absorption and emission tunability. The dyes are characterized by crystallography, and the photophysical properties are probed by varying solvent for absorption and emission studies. Computational data show involvement of the entire indolizine π-system during light absorption, which suggests these systems can be tunable even further into the NIR region through select derivatizations.
探索设计用于将花菁染料的吸收和发射进一步红移到近红外（NIR）光谱区域的分子工程策略。通过使用具有不同花菁桥长度的新型供体基团吲哚嗪，将染料的吸收和发射进一步移至近红外区域，超过了常见的吲哚啉-花菁。在许多情况下，观察到并通过计算解释了来自分子内空间位阻相互作用的斯托克斯位移高达约 60nm。在深达近红外区域的 5800 处观察到分子亮度。通过对具有不同花菁桥长度和吲哚嗪取代基的六种吲哚嗪-花菁染料进行结构-性质关系的探索，显示出广泛的吸收和发射可调谐性。通过结晶学对染料进行表征，并通过改变溶剂来研究吸收和发射研究来探测光物理性质。计算数据表明，在光吸收过程中涉及整个吲哚嗪π-体系，这表明通过选择衍生化，这些体系甚至可以进一步调谐到近红外区域。
