RUI: Aromaticity, Tautomerization and Metalation of Carbaporphyrinoid Systems

有了这个奖项，NSF化学部的化学合成计划正在支持伊利诺伊州州立大学的Timothy Lash教授的研究，以探索类似于一类称为“卟啉”的分子的化合物的合成，表征和反应性。卟啉化合物具有许多有价值的性质，在材料科学、催化和医学等领域有着广泛的应用。它们在自然界中也有一系列令人印象深刻的功能，从氧气运输到光合作用。卟啉含有4个氮原子，相关的系统称为碳卟啉，其中一个氮原子被一个碳原子取代。这些分子通常具有补充天然存在的卟啉的性质。支持的工作是导致有效的路线，以新颖的碳卟啉和相关系统，具有独特的反应性和光谱特性。获得新的卟啉类似物类别正在提高我们对基本化学概念的理解，例如芳香性，这是化学中的一个基本概念，可以提高分子的稳定性。此外，这些类型的结构通常与钯、铑和其他重要的金属催化剂形成稳定的络合物。Lash教授和他的学生正在研究这些分子在精细化学品制备中的应用，因为这些衍生物改变了结合金属的催化活性。此外，相关化合物正在探索用作光动力疗法中的光敏剂。这些项目不仅为有机合成领域的本科生和硕士研究生的培养提供了良好的环境，还让这些学生接触到现代科学研究的多学科性质。在这项研究中，正在开发新的类卟啉体系的合成路线，包括非那利卟啉、喹啉和氨甲胆碱。麦克唐纳反应的“3 + 1”变体的进一步应用是提供并入非那烯、喹啉和许多相关杂环单元的结构。芳香族羟基卟啉类化合物和非芳香族酮互变异构体之间的竞争可能特别有见地，这些过程正在使用光谱技术进行探测。真二氢卟酚被广泛研究，部分原因是它们显示出作为光敏剂的应用潜力。含有碳环代替吡咯单元之一的氨甲酰氯通常比母体四吡咯结构更稳定，并且可以具有同样有用的性质。然而，卡巴胆碱迄今为止研究甚少，开发新的路线，这些二氢卟啉类化合物将具有重要价值。在碳卟啉结构上引入稠合芳环为进一步修饰这些化合物的性质提供了机会，并且正在开发一种制备具有稠合萘、蒽和相关结构单元的碳卟啉的新方法。这种方法也被应用于合成更大的二聚体系统，预计质子化后表现出较强的电子相互作用。因此，这些研究揭示了重要的新卟啉系统，并将在卟啉化学领域产生重大影响。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With this award, the Chemical Synthesis program of the NSF Division of Chemistry is supporting the research of Professor Timothy Lash at Illinois State University to explore the synthesis, characterization, and reactivity of compounds that resemble a class of molecules called "porphyrins". Porphyrins possess many valuable properties and have applications in material science, catalysis and medicine. They also have an impressive array of functions in nature that range from oxygen transportation to photosynthesis. Porphyrins contain 4 nitrogen atoms, and related systems, called carbaporphyrins, have a carbon atom in place of one of the nitrogens. These molecules often have properties that complement those of naturally occurring porphyrins. The supported work is leading to efficient routes to novel carbaporphyrins and related systems that have unique reactivity and spectroscopic properties. Access to new classes of porphyrin analogues are improving our understanding of fundamental chemistry concepts such as aromaticity, a fundamental concept in chemistry which can lead to the enhanced stability of molecules. Furthermore, these types of structures commonly form stable complexes with palladium, rhodium and other important metal catalysts. Professor Lash and his students are studying applications of these molecules in the preparation of fine chemicals, as these derivatives modify the catalytic activity of bound metals. In addition, related compounds are being explored for use as photosensitizers in photodynamic therapy. These projects are not only providing an excellent environment for training undergraduates and Master's level graduate students in the field of organic synthesis, they are also exposing these students to the multidisciplinary nature of modern scientific research.In this research, synthetic routes to new porphyrin-like systems, including phenaliporphyrins, quiniporphyrins and carbachlorins, are being developed. Further application of the "3 + 1" variant of the MacDonald reaction is providing structures that incorporate phenalene, quinoline and numerous related heterocyclic units. The competition between aromatic hydroxyporphyrinoids and nonaromatic keto-tautomers can be particularly insightful, and these processes are being probed using spectroscopic techniques. True chlorins are widely studied, in part because they show the potential for applications as photosensitizers. Carbachlorins, which contain a carbocyclic ring in place of one of the pyrrole units, are generally more stable than the parent tetrapyrrolic structures and may have equally useful properties. However, carbachlorins have been little studied to date, and the development of new routes to these dihydroporphyrinoids will be of significant value. The introduction of fused aromatic rings onto carbaporphyrin structures offers the opportunity to further modify the properties of these compounds, and a new methodology to prepare carbaporphyrins with fused naphthalene, anthracene and related structural units is being developed. This approach is also being applied to be synthesis of larger dimeric systems that are expected to exhibit strong electronic interactions upon protonation. Hence, these investigations are revealing important new porphyrinoid systems and will have a major impact in the field of Porphyrin Chemistry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.