Covalent Bonding in Surface-Confined Ullmann Polymerization

Surface polymerization is of great interest as it enables the realization of graphene-like layers with tunable properties by simply modifying the architecture of the molecular building blocks used as precursors. We focus on some open points concerning the fundamentals of surface-catalyzed dehalogenative polymerization based on Ullmann coupling, widely used over the past decade to obtain 1D and 2D polymers on surfaces. M. Di Giovannantonio et al. ACS Nano 7 (9), 8190 (2013)
http://pubs.acs.org/doi/abs/10.1021/nn4035684

1,4-dibromobenzene molecules were used as precursors, forming poly(para-phenylene) polymers by Ullmann coupling on Cu(110). Chemically sensitive techniques such as x-ray photoelectron spectroscopy (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy allow to unequivocally identify the existence of an organometallic intermediate product of reaction and the of a final extended conjugated structure. Scanning tunneling microscopy (STM), low energy electron diffraction (LEED) and first-principles calculations provide a deeper insight into the intermediate organometallic phase and on the fundamental role of the halogen in stabilizing specific structures. Fast-XPS analysis of the system during the transformation from organometallic chains to polymers unveils the exact transition temperature for this process. Retrieve article
Insight into Organometallic Intermediate and Its Evolution to Covalent Bonding in Surface-Confined Ullmann Polymerization, Marco Di Giovannantonio, Mohamed El Garah, Josh Lipton-Duffin, Vincent Meunier, Luis Cardenas, Yannick Fagot Revurat, Albano Cossaro, Alberto Verdini, Dmitrii F. Perepichka, Federico Rosei and Giorgio Contini. ACS Nano 2013, 7 (9), pp 8190-8198
DOI: 10.1021/nn4035684
http://pubs.acs.org/doi/abs/10.1021/nn4035684
Ultima modifica il Martedì, 17 Dicembre 2013 16:03