McNamara Louis E, Rill Tana A, Huckaba Aron J, Ganeshraj Vigneshraja, Gayton Jacqueline, Nelson Rachael A, Sharpe Emily Anne, Dass Amala, Hammer Nathan I, Delcamp Jared H
Department of Chemistry and Biochemistry, University of Mississippi, 322 Coulter Hall, University, MS, 38677, USA.
Chemistry. 2017 Sep 12;23(51):12494-12501. doi: 10.1002/chem.201702209. Epub 2017 Aug 9.
The development of deep red and near infrared emissive materials with high quantum yields is an important challenge. Several classes of squaraine dyes have demonstrated high quantum yields, but require significantly red-shifted absorptions to access the NIR window. Additionally, squaraine dyes have typically shown narrow Stokes shifts, which limits their use in living biological imaging applications due to dye emission interference with the light source. Through the incorporation of indolizine heterocycles we have synthesized novel indolizine squaraine dyes with increased Stokes shifts (up to >0.119 eV, >50 nm increase) and absorptions substantially further into the NIR region than an indoline squaraine benchmark (726 nm versus 659 nm absorption maxima). These materials have shown significantly enhanced water solubility, which is unique for squaraine dyes without water-solubilizing substituents. Absorption, electrochemical, computational, and fluorescence studies were undertaken and exceptional fluorescence quantum yields of up 12 % were observed with emission curves extending beyond 850 nm.
开发具有高量子产率的深红色和近红外发光材料是一项重大挑战。几类方酸菁染料已显示出高量子产率，但需要显著红移吸收才能进入近红外窗口。此外，方酸菁染料通常具有较窄的斯托克斯位移，由于染料发射会干扰光源，这限制了它们在活体细胞成像应用中的使用。通过引入中氮茚杂环，我们合成了新型中氮茚方酸菁染料，其斯托克斯位移增加（高达>0.119 eV，增加>50 nm），并且吸收比吲哚啉方酸菁基准物质更深入近红外区域（吸收最大值分别为726 nm和659 nm）。这些材料显示出显著增强的水溶性，这对于没有水溶性取代基的方酸菁染料来说是独一无二的。我们进行了吸收、电化学、计算和荧光研究，观察到高达12%的优异荧光量子产率，发射曲线延伸至850 nm以上。
