B3 - On-surface synthesis and electronic structure of topological PCLs

Principal investigator: Prof. Dr. Sabine Maier, FAU Erlangen, [webpage]
Doctoral researcher Shreya Garg

In the past decade, on-surface synthesis on metallic substrates revealed many novel carbon materials with atomically precise structures and intriguing electronic properties. The on-surface coupling reactions take advantage of the catalytic properties of metal surfaces. Thereby, the construction of high-quality low-dimensional carbon nanostructures requires steering the reaction pathway by a clever precursor design and applying substrate templating effects. One of the challenges is the fabrication of long-range ordered two-dimensional covalent organic frameworks (2D COFs) via on-surface reactions in ultra-high vacuum due to the irreversible structure formation. Another essential aspect is preserving the intriguing electronic properties of 2D COFs using advanced physical and electronic decoupling schemes.

© Sabine Maier
Macrocyle with full arm-chair edge, porous CNR, honeycomb 2D COF, honeycomb 2D MOF.
Figure: Macrocyle with full arm-chair edge,[1] porous CNR,[2] honeycomb 2D COF,[3] honeycomb 2D MOF.[4]

We aim to unravel the structural and electronic properties of novel topological and heteroatom doped graphene nanoribbons (GNRs) and 2D Dirac metal-organic frameworks (MOFs) and COFs fabricated by on-surface synthesis using high-resolution scanning probe microscopy/spectroscopy (STM,nc-AFM, and STS) at low temperatures.

Thesis topic: Topological GNRs: On-surface synthesis and electronic structure

We will study the on-surface synthesis of novel 1D GNRs and 2D Dirac materials on metal surfaces. Using high-resolution scanning probe microscopy/spectroscopy, we aim to understand the effect of heteroatom-doping and incorporation of non-six-membered rings on the electronic structure.

[1] F. Xiang, S. Maisel, S. Beniwal, V. Akhmetov, C. Ruppenstein, M. Devarajulu, A. Dörr, O. Papaianina, A. Görling, K.Y. Asharov, S. Maier, “Planar π-extended cycloparaphenylenes featuring all-armchair edge topology” Nat. Chem. 2022, 14, 871–876.
[2] M. Ammon, T. Sander, S. Maier, “On-surface synthesis of porous carbon nanoribbons from polymer chains”, J. Am. Chem. Soc. 2017, 139, 12976–12984.
[3] C. Steiner, J. Gebhardt, M. Ammon, Z. Yang, A. Heidenreich, N. Hammer, A. Görling, M. Kivala, S. Maier, “Hierarchical on-surface synthesis and electronic structure of carbonyl-functionalized one- and two-dimensional covalent nanoarchitectures”, Nat. Commun. 2017, 8, 14765.
[4] Z. Yang, T. Sander, J. Gebhardt, T.A. Schaub, J. Schönamsgruber, H. Soni, A. Görling, M. Kivala, S. Maier, “Metalated Graphyne-Based Networks as 2D Materials: Crystallization, Topological Defects, Delocalized Electronic States and Site-Specific Doping”, ACS Nano 2020, 14, 16887-16896.