Rhodizonic acid on noble metals : surface reactivity and coordination chemistry
author:
Kunkel Donna A., Simpson Scott, Beniwal Sumit, Morrow Katie L., Smith Douglas C., Cousins Kimberley, Ducharme Stephen, Zurek Eva, Hooper James , Enders Axel
A study of the two-dimensional crystallization of rhodizonic acid on the
crystalline surfaces of gold and copper is presented. Rhodizonic acid, a cyclic oxocarbon
related to the ferroelectric croconic acid and the antiferroelectric squaric acid, has not been
synthesized in bulk crystalline form yet. Capitalizing on surface-assisted molecular self-
assembly, a two-dimensional analogue to the well-known solution-based coordination
chemistry, two-dimensional structures of rhodizonic acid were stabilized under ultrahigh
vacuum on Au(111) and Cu(111) surfaces. Scanning tunneling microscopy, coupled with
fi
rst-principles calculations, reveals that on the less reactive Au surface, extended two-
dimensional islands of rhodizonic acid are formed, in which the molecules interact via
hydrogen bonding and dispersion forces. However, the rhodizonic acid deprotonates into
rhodizonate on Cu substrates upon annealing, forming magic clusters and metal
−
organic
coordination networks with substrate adatoms. The networks show a 2:1 distribution of
rhodizonate coordinated with 3 and 6 Cu atoms, respectively. The stabilization of
crystalline structures of rhodizonic acid, structures not reported before, and their transition into metal
−
organic networks
demonstrate the potential of surface chemistry to synthesize new and potential useful organic nanomaterials.
affiliation:
Wydział Chemii : Zakład Chemii Teoretycznej im. K. Gumińskiego