DOI: 10.1002/asia.201300283 Self-Assembly of a Halogenated Molecule on Oxide-Passivated CuACHTUNGTRENNUNG(110) Mohamed El Garah,* [a] Josh Lipton-Duffin, [a] Jennifer M. MacLeod, [a] Rico Gutzler, [b] Frank Palmino, [c] Vincent Luzet, [c] FrØdØric ChØrioux, [c] and Federico Rosei* [a, d] Introduction On-surface noncovalent intermolecular interactions can drive supramolecular organization in two dimensions, which can lead to the stabilization of structures that may be used as active layers in organic electronic devices. [1] Known ex- amples of 2D self-assembled molecular networks are stabi- lized by several interactions, such as hydrogen bonds, [2] van der Waals forces, [3] metal–organic coordination, [4] and halo- gen bonds. [5] Other interactions based on electrostatic forces between molecules and the support surfaces can offer addi- tional pathways for molecular self-assembly. [6] A number of structures that are based on these intermolecular interac- tions have been investigated on metal surfaces under ultra- high vacuum (UHV) and the wide range of available sub- strates provides possibilities for enhancing or impeding the molecule–surface interactions and, by extension, affecting the structural and electronic properties of the supramolec- ular structures. [7] Most studies of this nature have focused on the use of bare substrates; only a handful have reported the differences between the growth modes of organic molecules on passivated surfaces. [8] Most of the results show that sur- face passivation decreases reactivity and favors the forma- tion of large self-assembled and ordered structures, whereas the corresponding bare surfaces cause the molecules to chemisorb in a disordered geometry, such as terephthalic acid (TPA) on SiACHTUNGTRENNUNG(111)-7  7. [8a] Some species may even be destroyed by certain surfaces, owing to dissociative adsorp- tion, such as 3,4,9,10-perylene-tetracaboxylic-dianhydride (PTCDA) on NiACHTUNGTRENNUNG(111). [9] However, the passivation of Ni with oxygen decreases its reactivity and allows PTCDA to form an ordered network. [10] By contrast, some reports have sug- gested oxidation may even increase a given substrate’s reac- tivity, such as the self-metalation of porphyrins on Cu- ACHTUNGTRENNUNG(001). [11] The {110} facet of copper is a model surface for the study of molecular adsorption and self-assembly, owing to its high anisotropy and moderate reactivity. This facet possesses a strong ability to template molecular orientation and to direct epitaxial growth, as in the case of pentacene. [12] More- over, CuACHTUNGTRENNUNG(110) can also act as a catalyst for the Ullmann de- halogenation of organic molecules at room temperature, as has been demonstrated for diiodo- and dibromobenzene, [13] as well as for larger and more-complicated precursors. [14] However, the mitigation of this catalytic effect by passiva- tion has not been reported so far. The CuACHTUNGTRENNUNG(110) ÀOACHTUNGTRENNUNG(21) sur- face can be used as a template for supramolecular self-as- sembly, [8b, 12, 15] on which the adsorbed oxygen species lead to a passivation of the bare CuACHTUNGTRENNUNG(110) surface. [8b] The OACHTUNGTRENNUNG(21) overlayer has the advantage of being well-ordered (as op- posed to having only local order, as found in the oxidations [a] Dr. M. El Garah, Dr. J. Lipton-Duffin, Dr. J. M. MacLeod, Prof. Dr. F. Rosei Centre Énergie, MatØriaux et TØlØcommunication Institut National de la Recherche Scientifique UniversitØ du QuØbec 1650 boulevard Lionel-Boulet Varennes, QC J3X 1S2 (Canada) Fax: (+ 1) 450-929-8102 E-mail: elgarah@emt.inrs.ca [b] Dr. R. Gutzler Max Planck Institute for Solid State Research Heisenbergstraße 1, 70569 Stuttgart (Germany) [c] Prof.Dr. F. Palmino, V. Luzet, Dr. F. ChØrioux Institut FEMTO-ST UniversitØ de Franche-ComtØ, CNRS, ENSMM 32 Avenue de l’Observatoire F-25044 Besancon cedex (France) [d] Prof. Dr. F. Rosei Center for Self-Assembled Chemical Structures McGill University H3A 2K6, MontrØal, QC (Canada) E-mail: rosei@emt.inrs.ca Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/asia.201300283. Abstract: The supramolecular self-as- sembly of brominated molecules was investigated and compared on CuACHTUNGTRENNUNG(110) and CuACHTUNGTRENNUNG(110) À OACHTUNGTRENNUNG(21) surfaces under ul- trahigh vacuum. By using scanning tun- nelling microscopy, we show that bro- minated molecules form a disordered structure on CuACHTUNGTRENNUNG(110), whereas a well- ordered supramolecular network is ob- served on the CuACHTUNGTRENNUNG(110) À OACHTUNGTRENNUNG(21) surface. The different adsorption behaviors of these two surfaces are described in terms of weakened molecule–substrate interactions on CuACHTUNGTRENNUNG(110) À OACHTUNGTRENNUNG(21) as op- posed to bare CuACHTUNGTRENNUNG(110). The effect of oxygen-passivation is to suppress de- bromination and it can be a convenient approach for investigating other self- assembly processes on copper-based substrates. Keywords: copper · dehalogena- tion · scanning tunneling microsco- py · self-assembly · template synthesis Chem. Asian J. 2013, 8, 1813 – 1817  2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 1813 FULL PAPER