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Driving Forces for Covalent Assembly of Porphyrins by Selective C–H Bond Activation and Intermolecular Coupling on a Copper Surface
Andrea Floris, Sam Haq, Mendel In’t Veld, David B. Amabilino, Rasmita Raval, and Lev Kantorovich, J. Am. Chem. Soc., 2016, 138 (18), pp 5837–5847
Abstract
Recent synthesis of covalent organic assemblies at surfaces has opened the promise of producing robust nanostructures for functional interfaces. To uncover how this new chemistry works at surfaces and understand the underlying mechanisms that control bond-breaking and bond-making processes at specific positions of the participating molecules, we study here the coupling reaction of tetra(mesityl)porphyrin molecules, which creates covalently connected networks on the Cu(110) surface by utilizing the 4-methyl groups as unique connection points. Using scanning tunneling microscopy (STM), state-of-the-art density functional theory (DFT), and Nudged Elastic Band (NEB) calculations, we show that the unique directionality of the covalent bonding is found to stem from a chain of highly selective C–H activation and dehydrogenation processes, followed by specific intermolecular C–C coupling reactions that are facilitated by the surface, by steric constraints, and by anisotropic molecular diffusion. These insights provide the first steps toward developing synthetic rules for complex two-dimensional covalent organic chemistry that can be enacted directly at a surface to deliver specific macromolecular structures designed for specific functions.
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Published by Andrea Floris
Dr Andrea Floris is a Lecturer at the School of Mathematics and Physics, College of Science, University of Lincoln (United Kingdom).
He is a computational condensed matter physicist with expertise in density functional theory (DFT), molecular self-assembly, computational superconductivity, vibrational properties, and nanostructured systems.
He obtained his Ph.D. in physics at the University of Cagliari (Italy) with a thesis focussed on the implementation and application of the DFT for Superconductors (SCDFT), a theory able to predict the critical temperature of conventional superconductors in the absence of empirical parameters.
In 2004 he moved to Freie Universität Berlin, where he worked several years in further developing and applying the SCDFT theory to many materials under different conditions of pressure and electron-phonon coupling.
In 2007-2013, he was also was visiting researcher at the University of Minnesota (USA), where he extended the DFT+U method to the density functional perturbation theory, to calculate phonons spectra of materials having a strong electronic correlation.
In 2010-2015, he worked first as Research Associate then as Visiting Lecturer at King´s College London, on the self-assembly of organic molecules on surfaces, which is his currently his main research field.
In 2015 he was Associate Researcher at CIC Energigune, Spain.
During many years of research activity, he established collaborations with theoretical and experimental groups in Europe, UK, USA and China. He also enjoyed doing experiences of mentoring and teaching, supervising Ph.D. and master students in Freie Universitaet Berlin, King’s College London and Wuhan University (China).
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Centre for Computational Physics 
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