RUI: New Porphyrinoid Architectures with Extended Conjugation Pathways

在美国国家科学基金会化学部化学合成项目的支持下，伊利诺伊州立大学的Timothy Lash教授正在探索类似天然卟啉的化合物的合成、表征和反应性。金属化卟啉广泛存在于自然界中，如血红素，在光合作用和氧气运输中起着至关重要的作用。卟啉在许多不同的领域也有许多应用，包括材料科学、催化和医学。卟啉在中心腔中有4个氮原子，使其结构能够结合金属离子。然而，一类重要的相关化合物，叫做碳卟啉，用一个碳原子代替了其中一个氮原子。碳卟啉具有修饰的性质，通常是对天然卟啉的补充。支持的工作是导致新的碳卟啉和相关的卟啉样系统的有效途径的发展，具有独特的反应性和不寻常的性质。这些结果增加了我们对基本化学概念的理解，如芳香性，这是分子的基本性质，可以提高稳定性。此外，这种类型的结构作为配体与重要的催化金属如钯和铑形成稳定的配合物。拉什教授和他的学生正在研究这些金属卟啉在精细化学品制备中的应用。此外，相关的此类复合物正在探索作为光敏剂在光动力治疗中的应用。这些项目不仅为培养本科生和硕士研究生从事科学、技术、工程和数学（STEM）领域的工作提供了良好的环境，而且还使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，新的卟啉类系统的合成路线正在开发中，包括使用环丙烷二醛的方法。麦克唐纳反应的“3 + 1”变体的应用将提供具有不同性质的扩展共轭结构。例如，具有融合芳香环的卟啉类结构，包括菲、芘和苊，将扩展平台，并有望大大改变这些体系的性质。其他独特卟啉的例子包括碳卟啉、羟基卟啉和三吡啶卟啉。所有这些分子都有独特的偶联途径，因此具有有趣的性质。合成这些底物的策略应该适用于几乎所有的融合芳香环体系。这些研究是非常基础的，提供了重要的新的类卟啉系统的途径，因此有可能对卟啉化学领域产生重大影响。该奖项反映了美国国家科学基金会的法定使命，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 support from the Chemical Synthesis program of the NSF Division of Chemistry, Professor Timothy Lash of Illinois State University is exploring the synthesis, characterization, and reactivity of compounds that resemble naturally occurring porphyrins. Metalated porphyrins are widespread in nature, e.g. hemes, and play crucial roles in photosynthesis and oxygen transport. Porphyrins also have numerous applications in a number of diverse areas, including materials science, catalysis, and medicine. Porphyrins have 4 nitrogen atoms within a central cavity that allow the structure to bind metal ions. However, an important class of related compounds, called carbaporphyrins, have a carbon atom in place of one of these nitrogens. Carbaporphyrins have modified properties that often complement those of naturally occurring porphyrins. The supported work is leading to the development of efficient routes to novel carbaporphyrins and related porphyrin-like systems that have unique reactivity and unusual properties. The results are increasing our understanding of fundamental chemistry concepts such as aromaticity, a fundamental property of molecules that leads to enhanced stability. Furthermore, structures of this type act as ligands to form stable complexes with important catalytic metals such as palladium and rhodium. Professor Lash and his students are studying applications of these metalloporphyrins in the preparation of fine chemicals. In addition, related such complexes are being explored for use as photosensitizers in photodynamic therapy. These projects are not only providing an excellent environment for training undergraduates and Masters level graduate students for careers in science, technology, engineering, and mathematics (STEM) but are also exposing these students to the multidisciplinary nature of modern scientific research.In this research, new synthetic routes to porphyrin-like systems are being developed, including methodology that makes use of cyclopropane dialdehydes. Applications of the “3 + 1” variant of the MacDonald reaction will provide structures having extended conjugation with alternative properties. For instance, porphyrin-like structures with fused aromatic rings, including phenanthrene, pyrene and acenaphthylene, will extend the platform and are expected to substantially alter the properties of these systems. Other examples of unique porphyrins include carboporphyrins hydroxyporphyrinoids, and tripyrrolic porphyrins. All these molecules have unique conjugation pathways and, as a result, interesting properties. The strategy to synthesize these substrates should be applicable to virtually all fused aromatic ring systems. These investigations are quite fundamental, providing access to important new porphyrinoid systems, and thus have the potential for major impact on 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.