Electron Delocalization Pathways in Porphyrin Nanostructures

高效电子设备的发展，如计算机芯片和led，一直是无数技术进步的推动力。我们现在已经达到了传统材料（金属和硅）所能达到的极限，进一步的小型化需要利用纳米级的量子现象。Anderson小组专注于构建基于卟啉的纳米结构（带和环），其行为类似于金属，表现出诸如小带隙，超快能量离域和纳米级环电流的奇异特性。在某些情况下，它们的导电性可以通过量子干涉来控制。这使它们成为分子线、晶体管、光吸收或发光器件的优秀候选者。这个项目提出了卟啉纳米结构的量子力学模拟，目的是理解和预测它们的行为。我们的第一个目标是确定描述这些系统的适当方法。然后，我们将回答难以通过实验探索的问题，例如：芳香性的限制是什么？电流通过哪些化学键流动？电子、光学和磁性是如何取决于分子结构和金属中心（及其自旋）的？我们可以通过电子离域路径来预测量子干涉吗？最后，我们将系统地筛选具有不同连接和金属中心的卟啉基聚合物的性能，确定合适的分子线候选材料。该项目将展示如何准确描述分子电子学感兴趣的纳米级系统，为扩展共轭系统中的电子离域和量子干涉提供新的视角，并确定分子线和电路的新合成目标。它将为超快能量迁移和纳米级芳香性等现象提供基本的理解。

The development of efficient electronic devices, such as computer chips and LEDs, has been the driving force of countless technological advances. We have now reached the edge of what is possible with conventional materials (metals and silicon), and further miniaturization requires exploitation of quantum phenomena at the nanoscale. The Anderson group is focused on building porphyrin-based nanostructures (tapes and rings) which behave similar to metals, exhibiting exotic properties such as small band gaps, ultrafast energy delocalization, and nanoscale ring currents. In some cases, their electrical conductivity can be controlled by quantum interference. This makes them excellent candidates for molecular wires, transistors, and light-absorbing or light-emitting devices. This project proposes quantum-mechanical simulations of porphyrin nanostructures with the goal of understanding and predicting their behavior. Our first objective is to identify proper methods for describing these systems. Then, we will answer questions that are difficult to explore experimentally, such as: What are the limits of aromaticity? Through which chemical bonds does the electrical current flow? How do the electronic, optical, and magnetic properties depend on the molecular structure and the metal center (and its spin)? Can we predict quantum interference by following electron delocalization pathways? Finally, we will systematically screen the properties of porphyrin-based polymers with different linkers and metal centers, determining suitable candidates for molecular wires. The project will show how to accurately describe nanoscale systems of interest to molecular electronics, give a new perspective on electron delocalization and quantum interference in extended conjugated systems, and identify new synthetic targets for molecular wires and electrical circuits. It will provide fundamental understanding of phenomena such as ultrafast energy migration and nanoscale aromaticity.