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计划的支持下，伊利诺伊州立大学的蒂莫西·拉什教授正在探索类似自然生成的卟啉的化合物的合成、表征和反应活性。金属卟啉广泛存在于自然界中，如亚铁血红素，在光合作用和氧气运输中起着至关重要的作用。在许多不同的领域，包括材料科学、催化和医学，卟啉也有大量的应用。卟啉在中心空腔内有4个氮原子，使结构能够结合金属离子。然而，有一类重要的相关化合物，称为碳卟啉，它用碳原子代替其中的一个氮素。碳卟啉具有修饰的性质，这些性质通常是对自然产生的卟啉的补充。所支持的工作正在导致开发有效的路线，以获得具有独特反应性和不寻常性质的新型碳卟啉和相关的类似卟啉的系统。结果增加了我们对基本化学概念的理解，如芳香性，这是导致稳定性增强的分子的基本属性。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络合物。拉什教授和他的学生正在研究这些金属卟啉在制备精细化学品中的应用。此外，正在探索将相关的此类络合物用作光动力疗法中的光敏剂。这些项目不仅为培养科学、技术、工程和数学(STEM)的本科生和硕士研究生提供了良好的环境，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，正在开发合成类似卟啉的系统的新路线，包括利用环丙二醛的方法学。麦克唐纳反应的“3-1”变体的应用将提供具有替代性质的扩展共轭结构。例如，具有稠合芳环的类似卟啉的结构，包括菲、芘和庚，将扩展平台，并有望显著改变这些体系的性质。其他独特的卟啉的例子包括碳卟啉、羟基卟啉和三吡咯啉。所有这些分子都有独特的共轭途径，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稠合芳环体系。这些研究是非常基础的，提供了进入重要的新的卟啉系统的途径，因此有可能对卟啉化学领域产生重大影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.