Synthesis and Characterization of Nitrogen and Sulfur Donor-Acceptor Stenhouse Adducts

项目摘要/摘要 这项建议描述了利用基本化学性质来改变试剂的反应性 生物医学上重要化合物的合成。具体来说，C-S键的化学性质将是 用于合成新型的光开关，名为施主-受体-斯滕豪斯加合物，DASA。尽管 斯滕豪斯加合物于2014年推出，目前已在药物输送、动态相转移、 聚合物、液晶、选择性光开关和化学传感应用。尽管他们很有希望 尽管如此，可持续发展援助目前受到其结构多样性的限制。只有胺供体和两个受体是 目前通常在DASA系统中使用。因此，其物理性能和应用受到了限制。 首要目标是开发和表征具有窄HOMO-LUMO的新型DASA分子 这样，新开发的分子可以在650-1450 nm的生物窗口内被激活 灯。这样做将使可光切换分子进入挑战光药理学和特异性的领域 光发射应用。具体地说，DASA光开关的独特能力是从线性、不带电的 结构到环，两性离子中间体提供了一个机会渗透到血脑屏障和 开发有趣的热激活延迟荧光(TADF)物种。为了访问新的DASA 具有所需特性的分子，与硫、膦、氧的加合物和附加共轭 将会被调查。2-硫代苯甲醛取代C-O键形成较弱且较长的C-S键 对使用呋喃甲醛时无法在DASA中加入其他给体功能负责 材料；噻吩衍生物在碳原子上的电子密度也较低，使其成为完美的衬底 用于在缩合受体分子时开环。如果C-S键不够弱，则可极化的 硫磺将用亲硫的路易斯酸来活化。合成新型斯滕豪斯加合物1)提供了额外的 DASA以探索上述应用，2)使进一步研究这些新的化学性质 光开关，以及3)提供了开发其他用途的机会，如光药理学中列出的那些用途 以及光发射应用。

Project Summary/Abstract This proposal describes the use of fundamental chemical properties to alter the reactivity of reagents for the synthesis of biomedically important compounds. Specifically, the chemical properties of C–S bonds will be used for the synthesis of novel photoswitches named donor-acceptor Stenhouse adducts, DASAs. Though Stenhouse adducts were introduced in 2014, they have been explored in drug delivery, dynamic phase transfer, polymers, liquid crystals, selective photoswitching, and chemosensing applications. Despite their promising applications, DASAs are currently limited by their structural diversity. Only amine donors and two acceptors are generally used in DASA systems today. As a result, the physical properties and applications are limited. The overarching goal is to develop and characterize novel DASA molecules with a narrow HOMO-LUMO gap such that the newly developed molecules may be activated within the biological window of 650–1450 nm light. Doing so puts photoswitchable molecules into the realm of challenging photopharmacological and specific light-emission applications. Specifically, the unique ability for DASA photoswitches to go from linear, uncharged structures to cyclic, zwitterionic intermediates presents an opportunity to permeate the blood-brain barrier and to develop interesting thermally activated delayed fluorescence (TADF) species. In order to access new DASA molecules with the desired characteristics, adducts with sulfur, phosphine, oxygen, and additional conjugation will be investigated. 2-Thiophenecarboxaldehyde bears a weaker and longer C–S bond in place of the C–O bond responsible for the inability to incorporate other donor functionality in DASAs when using furfural as a starting material; thiophene derivatives also carry less electron density on the carbon atoms, making it a perfect substrate for ring opening upon condensing an acceptor molecule. If the C–S bond is not sufficiently weak, the polarizable sulfur will be activated using thiophilic Lewis acids. Synthesizing novel Stenhouse adducts 1) provides additional DASAs to explore applications listed above, 2) enables further research on the chemical properties of these new photoswitches, and 3) provides an opportunity to develop additional uses like those listed in photopharmacology and light emission applications.