TY  - JOUR
AU  - Linnenberg, Oliver
AU  - Moors, Marco
AU  - Solé-Daura, Albert
AU  - López, Xavier
AU  - Bäumer, Christoph
AU  - Kentzinger, Emmanuel
AU  - Pyckhout-Hintzen, Wim
AU  - Monakhov, Kirill
TI  - Molecular Characteristics of a Mixed-Valence Polyoxovanadate {V IV/V 18 O 42 } in Solution and at the Liquid–Surface Interface
JO  - The journal of physical chemistry  / C
VL  - 121
IS  - 19
SN  - 1932-7455
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2017-03870
SP  - 10419 - 10429
PY  - 2017
AB  - The understanding of the molecular state of vanadium-oxo clusters (polyoxovanadates, POVs) in solution and on surface is a key to their target application in catalysis as well as molecular electronics and spintronics. We here report the results of a combined experimental and computational study of the behavior of nucleophilic polyoxoanions [VIV10VV8O42(I)]5– charged balanced by Et4N+ in water, in a one-phase organic solution of N,N-dimethylformamid (DMF) or acetonitrile (MeCN), in a mixed solution of MeCN–water, and at the hybrid liquid–surface interface. The molecular characteristics of the compound (NEt4)5[V18O42(I)] (1) in the given environments were studied by microspectroscopic, electrochemical, scattering, and molecular mechanics methods. Contrary to the situation in pure water, where we observe great agglomeration with a number of intercalated H2O molecules between POVs that are surrounded by the Et4N+ ions, no or only minor agglomeration of redox-active POVs in an unprecedented cation-mediated fashion was detected in pure DMF and MeCN, respectively. An inclusion of 1% water in the MeCN solution does not have an effect significant enough to reinforce agglomeration; however, this leads to the POV···POV interface characterized by the presence of the Et4N+ ions and a small number of H2O molecules. Water amounts of ≥5% trigger the formation of higher oligomers. The deposition of compound 1 from MeCN onto an Au(111) surface affords nearly round-shaped particles (∼10 nm). The use of DMF instead of MeCN results in bigger, irregularly shaped particles (∼30 nm). This change of solvent gives rise to more extensive intermolecular interactions between polyoxoanions and their countercations as well as weaker binding of ion-pairing induced agglomerates to the metallic substrate. Lower concentration of adsorbed molecules leads to a submonolayer coverage and an accompanied change of the POV’s redox state, whereas their higher concentration results in a multilayer coverage that offers the pristine mixed-valence structure of the polyoxoanion. Our study provides first important insights into the reactivity peculiarities of this redox-responsive material class on a solid support.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000402024200020
DO  - DOI:10.1021/acs.jpcc.7b02138
UR  - https://juser.fz-juelich.de/record/830302
ER  -