Cyanine dyes are an interesting class of near infrared (NIR) dyes that have captured the interest of the scientific community. The NIR cyanine dye of interest, heptamethine cyanine dye NIR-1, exhibits characteristics that satisfy the qualifications as an acceptor in a Fluorescence Resonance Energy Transfer (FRET) biosensor [Wher, 1976]. Applications of FRET systems include structure determination and conformation of proteins [Hammer et al., 2002], receptor/ligand interactions [Hammer et al., 2002], and the cellular exposure to environmental toxins [Schwartz and Ulfelder, 1992]. This research stems from an interdepartmental collaboration to develop a NIR FRET biosensor, with significant advantages over the existing systems. A critical component of this endeavor is the development of an efficient environmentally conscious synthesis of novel NIR cyanine dyes utilizing microwave technology. Herein, we report the microwave synthesis of NIR-1. 2,3,3-Trimethyl-1-ethyl-3H-indolium iodide (I) synthesis is advantageous over the reported synthesis due to the significantly reduced reaction time of450 s from 15 h and a decrease in the amount of iodoethane from 5 eq. to 3 eq. The condensation of heterocyclic salt I and bisaldehyde II has been accomplished in 220 s in 85% yield in the microwave oven; benzene has been eliminated from the condensation reaction procedure. Spectral characteristics of NIR-1 were determined and compared to commercially available NIR-1. A significant absence of asymmetry at the broad peak associated with the maximum absorbance wavelength, a slight increase in quantum yield (+—.02) and the blue shift of the maximum absorbance wavelength (—5 nm) was observed.

中文翻译：

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近红外七甲炔花青染料的微波合成

花青染料是一类有趣的近红外 (NIR) 染料，引起了科学界的兴趣。感兴趣的 NIR 花青染料，七甲炔花青染料 NIR-1，表现出满足作为荧光共振能量转移 (FRET) 生物传感器 [Wher, 1976] 中受体的资格的特性。FRET 系统的应用包括蛋白质的结构测定和构象 [Hammer et al., 2002]、受体/配体相互作用 [Hammer et al., 2002] 以及细胞暴露于环境毒素 [Schwartz and Ulfelder, 1992]。这项研究源于部门间合作开发 NIR FRET 生物传感器，与现有系统相比具有显着优势。这项努力的一个关键组成部分是利用微波技术开发高效的、具有环保意识的新型 NIR 花青染料合成方法。在此，我们报告了 NIR-1 的微波合成。2,3,3-Trimethyl-1-ethyl-3H-indolium iodide (I) 合成优于报道的合成，因为反应时间从 15 小时显着减少了 450 秒，并且碘乙烷的量从 5 eq 减少。到 3 eq。杂环盐Ⅰ与双醛Ⅱ在微波炉中220秒内缩合，收率85%；苯已从缩合反应过程中消除。确定了 NIR-1 的光谱特性，并将其与市售 NIR-1 进行了比较。在与最大吸收波长相关的宽峰处明显不存在不对称性，