Novel Diaryliodonium Salts as One-Component Photopolymerisation Agents

计划研究利用一锅法高效制备一系列基于已知光吸收基序（如氟酮、芘、蒽醌、方英酮和二氧化硫氧杂蒽酮）的三氟化二芳基碘鎓（方案1）。这种方法对基于缺电子芳烃的碘盐的有效性尚未报道。随着我们从一系列芳香族和杂芳香族化合物中形成二芳基碘鎓盐的新稳健程序的建立，将进行比以前合成的化合物在更长的波长上吸收的化合物的制备。通过明智地剪裁这些新化合物的取代模式，预计在近红外区域的吸收最大值。幸运的是，一系列的碘芳烃和碘杂芳烃，如碘吲哚和碘噻吩，都是商业上可用的，这些底物都有可能被利用，从而提供现成的结构多样性。在大多数情况下，这些碘化合物的吸收光谱未被报道。此外，这些吸光芳香族核心可以很容易地通过传统和现代合成化学策略进行修饰。我们提出的与碘芳烃的反应可以将许多商业上可用的染料转化为二芳基碘鎓盐。例如，油蓝N是一种市售的蒽醌衍生物，吸收超过600纳米。商用染料的其他例子包括硫代靛蓝、靛蓝和间甲酚紫。硫代靛蓝将是这些化合物中最容易利用的，因为它是中性的，不含任何氢键供体。一旦这些新的碘盐被制备出来，它们的紫外-可见-近红外光谱将被评估。我们将很快建立一幅图，哪些芳烃和碘芳烃导致易于分离和处理的碘盐，哪些部分是最适合影响吸收最大值的红移。此外，我们将评估在适当波长（bbb - 400 nm）照射下对阳离子和自由基的光解速率，并通过气相色谱法跟踪反应。光分解产物的结构将被表征，从而使光破碎的精确模式得以建立；这些知识对于开发光聚合应用是必不可少的。有了长波吸收二芳基碘鎓盐系列，它们在环氧环己烯或丙烯酸酯等简单单体聚合中的功效将被评估。聚合物的分子量分布将由多角度激光散射测定。

It is planned to investigate the use of a one-pot method to efficiently prepare a range of diaryliodonium triflates based on known light absorbing motifs such as fluorenones, pyrenes, anthraquinones, squaraines and thioxanthone dioxides (Scheme 1). The effectiveness of this approach to iodonium salts based on electron-deficient arenes has not been reported. With our new robust procedures in place for the formation of diaryliodonium salts from a range of aromatic and heteroaromatic compounds, the preparation of compounds that are expected to absorb at longer wavelength than those previously synthesised will be undertaken. By judicious tailoring of the substitution pattern of these new compounds absorption maxima in the near IR region is anticipated. Fortuitously a range of iodoarenes and iodoheteroarenes, e.g. iodoindoles and iodothiophenes, are commercially available and these substrates can all potentially be harnessed thus offering ready structural diversity. In most cases, the absorption spectra of these iodo-compounds are unreported. In addition, these light absorbing aromatic cores can be easily modified by both traditional and modern synthetic chemistry strategies. There are many commercially available dyes that are known to absorb above 500 nm that can be converted into diaryliodonium salts by our proposed reaction with iodoarenes. For example, Oil Blue N is a commercially available anthraquinone derivative which absorbs above 600 nm. Other examples of commercially available dyes include thioindigo, indigo and m-cresol purple. Thioindigo will be the easiest of these compounds to utilise as it is neutral and does not contain any hydrogen bond donors.As soon as these new iodonium salts are prepared, their UV-vis-NIR spectra will be assessed. We will quickly build up a picture of which arenes and iodoarenes lead to easily isolable and handleable iodonium salts and which moieties are optimal for effecting red-shifts in absorption maxima. In addition, we will assess the rates of photolysis to cationic and radical species by irradiation at suitable wavelengths (>400 nm) and follow the reactions by gas chromatography. The structures of the photodecomposition products will be characterised thus enabling the precise mode of photo-fragmentation to be established; this knowledge is essential for developing photopolymerisation applications.With the series of long wavelength absorbing diaryliodonium salts in hand, their efficacies in the polymerisation of simple monomers such as cyclohexene oxide or acrylates will be assessed. The molecular weight distributions of the polymers will be determined by multi-angle laser light scattering.