STM Study of Au(111) Surface-Grafted Paramagnetic Macrocyclic Complexes [Ni2L(Hmba)](+) via Ambidentate Coligands.
Molecular anchoring and electronic properties of macrocyclic complexes fixed on gold surfaces have been investigated mainly by using scanning tunnelling microscopy (STM) and complemented with X-ray photoelectron spectroscopy (XPS). Exchange-coupled macrocyclic complexes [Ni2L(Hmba)](+) were deposited via 4-mercaptobenzoate ligands on the surface of a Au(111) single crystal from a mM solution of the perchlorate salt [Ni2L(Hmba)]ClO4 in dichloromethane. The combined results from STM and XPS show the formation of large monolayers anchored via Au-S bonds with a height of about 1.5 nm. Two apparent granular structures are visible: one related to the dinickel molecular complexes (cationic structures) and a second one related to the counterions ClO4(-) which stabilize the monolayer. No type of short and long-range order is observed. STM tip-interaction with the monolayer reveals higher degradation after 8 h of measurement. Spectroscopy measurements suggest a gap of about 2.5 eV between HOMO and LUMO of the cationic structures and smaller gap in the areas related to the anionic structures.
Leibniz Institute for Solid State and Materials Research (IFW-Dresden) , Helmholtzstrasse 20, 01171 Dresden, Germany.
Christian
C
Salazar
Institut für Anorganische Chemie, Universität Leipzig , 04103 Leipzig, Germany.
Jochen
J
Lach
Leibniz Institute for Solid State and Materials Research (IFW-Dresden) , Helmholtzstrasse 20, 01171 Dresden, Germany.
Florian
F
Rückerl
Leibniz Institute for Solid State and Materials Research (IFW-Dresden) , Helmholtzstrasse 20, 01171 Dresden, Germany.
Danny
D
Baumann
Leibniz Institute for Solid State and Materials Research (IFW-Dresden) , Helmholtzstrasse 20, 01171 Dresden, Germany.
Sebastian
S
Schimmel
Leibniz Institute for Solid State and Materials Research (IFW-Dresden) , Helmholtzstrasse 20, 01171 Dresden, Germany.
Martin
M
Knupfer
Institut für Anorganische Chemie, Universität Leipzig , 04103 Leipzig, Germany.
Berthold
B
Kersting
Leibniz Institute for Solid State and Materials Research (IFW-Dresden) , Helmholtzstrasse 20, 01171 Dresden, Germany.|Center for Transport and Devices, Technische Universität Dresden , 01069 Dresden, Germany.
Bernd
B
Büchner
Leibniz Institute for Solid State and Materials Research (IFW-Dresden) , Helmholtzstrasse 20, 01171 Dresden, Germany.|Center for Transport and Devices, Technische Universität Dresden , 01069 Dresden, Germany.
Christian
C
Hess