Tailoring Large Pores of Porphyrin Networks on Ag(111) by Metal-Organic Coordination.
The engineering of nanoarchitectures to achieve tailored properties relevant for macroscopic devices is a key motivation of organometallic surface science. To this end, understanding the role of molecular functionalities in structure formation and adatom coordination is of great importance. In this study, the differences in formation of Cu-mediated metal-organic coordination networks based on two pyridyl- and cyano-bearing free-base porphyrins on Ag(111) are elucidated by use of low-temperature scanning tunneling microscopy (STM). Distinct coordination networks evolve via different pathways upon codeposition of Cu adatoms. The cyano-terminated module directly forms 2D porous networks featuring fourfold-coordinated Cu nodes. By contrast, the pyridyl species engage in twofold coordination with Cu and a fully reticulated 2D network featuring a pore size exceeding 3 nm2only evolves via an intermediate structure based on 1D coordination chains. The STM data and complementary Monte Carlo simulations reveal that these distinct network architectures originate from spatial constraints at the coordination centers. Cu adatoms are also shown to form two- and fourfold monoatomic coordination nodes with monotopic nitrogen-terminated linkers on the very same metal substrate-a versatility that is not achieved by other 3d transition metal centers but consistent with 3D coordination chemistry. This study discloses how specific molecular functionalities can be applied to tailor coordination architectures and highlights the potential of Cu as coordination center in such low-dimensional structures on surfaces.
Physik Department E20, Technische Universität München, 85748, Garching, Germany.
Felix
F
Bischoff
Physik Department E20, Technische Universität München, 85748, Garching, Germany.|Institute for Advanced Study, Technische Universität München, 85748, Garching, Germany.
Yuanqin
Y
He
Physik Department E20, Technische Universität München, 85748, Garching, Germany.
Knud
K
Seufert
Department of Chemistry and Namur Research College, University of Namur, Belgium.
Daphné
D
Stassen
Department of Chemistry and Namur Research College, University of Namur, Belgium. bonifazid@cardiff.ac.uk.|School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. bonifazid@cardiff.ac.uk.
Davide
D
Bonifazi
Physik Department E20, Technische Universität München, 85748, Garching, Germany.
Johannes V
JV
Barth
Physik Department E20, Technische Universität München, 85748, Garching, Germany. wau@tum.de.
Willi
W
Auwärter
Monte Carlo simulations; porous materials; porphyrins; scanning tunneling microscopy; supramolecular chemistry