Dataset of Regioselective sulfonation of diaza [4] and [6]helicene dyes for far-red electrochemiluminescence in water

There is a very rapid development of new organic electrochemiluminescence (ECL) dyes with a large variety of electronic properties enabled by playing with structural variations achieved by organic chemistry. However, a major limitation is their water solubility while keeping their ECL capabilities. Here, the synthesis and optical, electrochemical and ECL properties of a series of four original water-soluble helicene dyes operating in physiological conditions are reported. Those species were prepared using diaza [4] and [6]helicenes as structural cores functionalized for the purpose of this study with sulfonate groups in various positions, which significantly improves their water solubility. Synthetically, thanks to strongly acidic conditions, regioselective sulfonylation reactions were enabled and occurred at defined position(s) of the outer rim of the helical cores. In terms of optical properties, such functional groups induce a red-shift of the absorption and emission properties up to the near-infrared in the [4]helicene series. The fluorescence ranges typically in the red to far-red (660-710 nm) and spanning towards the near-infrared region. The electrochemical characterization evidenced an irreversible oxidation, whereas the reduction could be reversible depending on the dye. This series of molecules were investigated as ECL emitters in aqueous media using tri-n-propylamine as a sacrificial co-reactant and revealed to be efficient ECL luminophores in these conditions. Such a study on these water-soluble π-conjugated dyes presenting different core structures may guide the design and analytical applications of new ECL dyes with a strong efficiency in physiological conditions.

近年来，借助有机化学手段调控分子结构变体，具有多样电子特性的新型有机电致化学发光（electrochemiluminescence，ECL）染料开发速度极快。然而，此类染料在保留ECL性能的同时，水溶性不足是其主要发展局限。本研究报道了一系列共四种原创性水溶性螺烯（helicene）染料的合成方法，以及其在生理条件下的光学、电化学与ECL性能。此类染料以二氮杂[4]螺烯（diaza [4]helicenes）与二氮杂[6]螺烯（diaza [6]helicenes）为结构核心，并在不同位置引入磺酸根基团（sulfonate groups）以大幅提升水溶性。从合成路径来看，通过强酸性反应条件可实现区域选择性磺酰化（regioselective sulfonylation）反应，且反应精准发生在螺旋核心外缘的指定位点。就光学性能而言，此类官能团可使吸收与发射光谱发生红移（red-shift），在[4]螺烯系列中红移幅度可达近红外（near-infrared）波段。其荧光发射通常位于红光至远红光区间（660~710 nm），并可延伸至近红外区域。电化学表征结果显示，此类染料的氧化过程为不可逆过程，而还原过程则因染料分子结构差异而可能表现出可逆性。本研究以三正丙胺（tri-n-propylamine）作为牺牲共反应物（sacrificial co-reactant），在水相介质中对该系列分子作为ECL发光体（luminophores）的性能进行了测试，结果表明此类染料在该条件下具备高效的ECL发光能力。此项针对具有不同核心结构的水溶性π共轭染料（π-conjugated dyes）的研究，可为设计并开发在生理条件下具备高发光效率的新型ECL染料提供指导，并助力其在分析检测领域的应用。