Department of Chemistry, Faculty of Natural & Mathematical Sciences, King's College London, Britannia House, 7 Trinity Street, London, SE1 1DB, UK.
Current address: Molecular Spectroscopy Department, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
Angew Chem Int Ed Engl. 2020 Oct 19;59(43):19193-19201. doi: 10.1002/anie.202007237. Epub 2020 Aug 24.
Nature has developed supramolecular constructs to deliver outstanding charge-transport capabilities using metalloporphyrin-based supramolecular arrays. Herein we incorporate simple, naturally inspired supramolecular interactions via the axial complexation of metalloporphyrins into the formation of a single-molecule wire in a nanoscale gap. Small structural changes in the axial coordinating linkers result in dramatic changes in the transport properties of the metalloporphyrin-based wire. The increased flexibility of a pyridine-4-yl-methanethiol ligand due to an extra methyl group, as compared to a more rigid 4-pyridinethiol linker, allows the pyridine-4-yl-methanethiol ligand to adopt an unexpected highly conductive stacked structure between the two junction electrodes and the metalloporphyrin ring. DFT calculations reveal a molecular junction structure composed of a shifted stack of the two pyridinic linkers and the metalloporphyrin ring. In contrast, the more rigid 4-mercaptopyridine ligand presents a more classical lifted octahedral coordination of the metalloporphyrin metal center, leading to a longer electron pathway of lower conductance. This works opens to supramolecular electronics, a concept already exploited in natural organisms.
自然界已经开发出超分子结构，利用基于金属卟啉的超分子阵列来实现出色的电荷输运能力。在此，我们通过金属卟啉的轴向配位将简单的、受自然启发的超分子相互作用纳入纳米级间隙中单分子线的形成中。轴向配位连接体的微小结构变化导致基于金属卟啉的线的输运性质发生显著变化。与更刚性的 4-吡啶硫醇配体相比，由于额外的甲基，吡啶-4-基-甲硫醇配体的灵活性增加，使得吡啶-4-基-甲硫醇配体能够在两个结电极和金属卟啉环之间采用意想不到的高导电性堆叠结构。DFT 计算揭示了由两个吡啶连接体和金属卟啉环的移位堆叠组成的分子结结构。相比之下，更刚性的 4-巯基吡啶配体呈现出更经典的金属卟啉金属中心的提升八面体配位，导致更长的电子路径和更低的电导率。这项工作为超分子电子学开辟了道路，这一概念已经在自然生物中得到了应用。
