COMMUNICATION 1704321 (1 of 10) www.small-journal.com small NANO MICRO © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Functionalized Graphdiyne Nanowires: On-Surface Synthesis and Assessment of Band Structure, Flexibility, and Information Storage Potential Florian Klappenberger,* Raphael Hellwig, Ping Du, Tobias Paintner, Martin Uphoff, Liding Zhang, Tao Lin, Bahare Abedin Moghanaki, Mateusz Paszkiewicz, Ivana Vobornik, Jun Fujii, Olaf Fuhr, Yi-Qi Zhang, Francesco Allegretti, Mario Ruben, and Johannes V. Barth DOI: 10.1002/smll.201704321 (CNTs), [1] graphene sheets, [2] and gra- phene nanoribbons. [3,4] Recently, sig- nificant interest in their graphyne and graphdiyne-related counterparts incorpo- rating both sp 2 - and sp-hybridized carbon atoms is quickly emerging. [5–8] Notably, theoretical investigations predict prom- ising characteristics suitable for a broad variety of applications including molecular electronics, energy storage, gas filtering, and light harvesting. [9–13] However, the experimental realization of the targeted materials remains challenging and, so far, solution-based synthesis approaches only afforded multilayered materials with significant amounts of impurities and unknown structural properties. [14] Various routes to the fabrication of high-quality carbon materials are cur- rently being investigated, [15] of which the epitaxial growth on well-defined metal substrates under ultrahigh vacuum (UHV) conditions is considered one of the most promising. Combining it with the cova- lent on-surface synthesis from rationally designed organic precursors [16] paved the way to the engineering of stable [17] and atom-precise nanostructures, [18] amongst them various types of conjugated polymer wires [19–21] and gra- phene nanoribbons. [4,18,22,23] In this context, the homocoupling reaction of terminal alkyne tectons has raised great hopes for the construction of graphdiyne-related nanostructures. [8,24,25] However, the intricate Carbon nanomaterials exhibit extraordinary mechanical and electronic proper- ties desirable for future technologies. Beyond the popular sp 2 -scaffolds, there is growing interest in their graphdiyne-related counterparts incorporating both sp 2 and sp bonding in a regular scheme. Herein, we introduce carbonitrile- functionalized graphdiyne nanowires, as a novel conjugated, one-dimensional (1D) carbon nanomaterial systematically combining the virtues of covalent coupling and supramolecular concepts that are fabricated by on-surface synthesis. Specifically, a terphenylene backbone is extended with reactive terminal alkyne and polar carbonitrile (CN) moieties providing the required functionalities. It is demonstrated that the CN functionalization enables highly selective alkyne homocoupling forming polymer strands and gives rise to mutual lateral attraction entailing room-temperature stable double-stranded assemblies. By exploiting the templating effect of the vicinal Ag(455) surface, 40 nm long semiconducting nanowires are obtained and the first experimental assessment of their electronic band structure is achieved by angle-resolved photoemission spectroscopy indicating an effective mass below 0.1m 0 for the top of the highest occupied band. Via molecular manipulation it is showcased that the novel oligomer exhibits extreme mechanical flexibility and opens unexplored ways of information encoding in clearly distinguishable CN-phenyl trans–cis species. Thus, conformational data storage with density of 0.36 bit nm -2 and temperature stability beyond 150 K comes in reach. Carbon Materials Dr. F. Klappenberger, Dr. R. Hellwig, T. Paintner, M. Uphoff, L. Zhang, Dr. T. Lin, B. Abedin Moghanaki, M. Paszkiewicz, Dr. Y.-Q. Zhang, Dr. F. Allegretti, Prof. J. V. Barth Physik-Department E20 Technische Universität München 85748 Garching, Germany E-mail: florian.klappenberger@tum.de The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.201704321. Dr. P. Du, Dr. O. Fuhr, Prof. M. Ruben Institute für Nanotechnologie Karlsruher Institut für Technologie (KIT) 76344 Eggenstein-Leopoldshafen, Germany Dr. I. Vobornik, Dr. J. Fujii Istituto Officina dei Materiali (IOM)-CNR Laboratorio TASC Area Science Park, I-34149 Trieste, Italy Prof. M. Ruben IPCMS-CNRS Université de Strasbourg F-67034 Strasbourg, France Carbon-based materials exhibit extraordinary mechanical and electronic properties. They are a central research topic in the 21st century and promising candidates for future nanotech- nology applications. A plethora of nanomaterials is based on established sp 2 -hybridized scaffolds such as carbon nanotubes Small 2018, 14, 1704321