Kang Hungu, Daaoub Abdalghani H S, Sangtarash Sara, Jang Jiung, Lee Kangsik, Sadeghi Hatef, Yoon Hyo Jae
Department of Chemistry, Korea University, Seoul, 02841, South Korea.
Device Modelling Group, School of Engineering, University of Warwick, Coventry, CV4 7AL, UK.
Small. 2025 Jul;21(27):e2501303. doi: 10.1002/smll.202501303. Epub 2025 May 23.
Coordination-driven supramolecular assemblies are promising for nanometer-sized electronic devices due to the potential to manipulate metal-ligand interactions and thereby control charge transport via tunneling through these assemblies. Cross-plane charge tunneling is investigated in assemblies of metalloporphyrins and pillar molecules, specifically palladium(II) and zinc(II) octaethylporphyrin (PdOEP and ZnOEP) monolayers and bilayers with bidentate (DABCO) and monodentate (ABCO) pillar ligands on highly oriented pyrolytic graphite (HOPG). Junction measurements and quantum-chemical calculations reveal that metal-ligand interactions significantly influence charge transport via tunneling and thermoelectric effects. Weak interactions in PdOEP assemblies create isolated molecular orbitals on interior pillar ligands, compressing the HOMO-LUMO gap and enhancing tunneling currents with unusual, inverted attenuation behavior and high thermopower. Conversely, strong interactions in ZnOEP assemblies induce localized orbitals on the porphyrin, leading to conventional tunneling decay behavior and low thermopower. The study highlights the potential of metal-ligand interactions as a strategy to engineer molecular orbital distribution, enhancing quantum transport efficiency in molecular-scale devices.
配位驱动的超分子组装体对于纳米级电子器件具有很大的潜力，因为其有可能操控金属-配体相互作用，进而通过这些组装体的隧穿来控制电荷传输。在金属卟啉和柱芳烃分子的组装体中研究了平面电荷隧穿，具体是在高度取向的热解石墨（HOPG）上，由双齿（DABCO）和单齿（ABCO）柱芳烃配体与钯（II）和锌（II）八乙基卟啉（PdOEP和ZnOEP）形成的单层和双层组装体。结测量和量子化学计算表明，金属-配体相互作用通过隧穿和热电效应显著影响电荷传输。PdOEP组装体中的弱相互作用在内部柱芳烃配体上产生孤立的分子轨道，压缩了HOMO-LUMO能隙，并增强了具有异常的、反向衰减行为和高热功率的隧穿电流。相反，ZnOEP组装体中的强相互作用在卟啉上诱导出局域轨道，导致传统的隧穿衰减行为和低热功率。该研究突出了金属-配体相互作用作为一种设计分子轨道分布的策略的潜力，可提高分子尺度器件中的量子传输效率。
