posted on 2024-01-23, 02:03authored byZdeněk Jakub, Azin Shahsavar, Jakub Planer, Dominik Hrůza, Ondrej Herich, Pavel Procházka, Jan Čechal
The functionality
of 2D metal–organic frameworks (MOFs)
is crucially dependent on the local environment of the embedded metal
atoms. These atomic-scale details are best ascertained on MOFs supported
on well-defined surfaces, but the interaction with the support often
changes the MOF properties. We elucidate the extent of this effect
by comparing the Fe-TCNQ 2D MOF on two weakly interacting supports:
graphene and Au(111). We show that the Fe-TCNQ on graphene is nonplanar
with iron in quasi-tetrahedral sites, but on Au(111) it is planarized
by stronger van der Waals interaction. The differences in physical
and electronic structures result in distinct properties of the supported
2D MOFs. The dz2 center position
is shifted by 1.4 eV between Fe sites on the two supports, and dramatic
differences in chemical reactivity are experimentally identified using
a TCNQ probe molecule. These results outline the limitations of common
on-surface approaches using metal supports and show that the intrinsic
MOF properties can be partially retained on graphene.