%0 Journal Article
%A Linnenberg, Oliver
%A Moors, Marco
%A Solé-Daura, Albert
%A López, Xavier
%A Bäumer, Christoph
%A Kentzinger, Emmanuel
%A Pyckhout-Hintzen, Wim
%A Monakhov, Kirill
%T Molecular Characteristics of a Mixed-Valence Polyoxovanadate {V IV/V 18 O 42 } in Solution and at the Liquid–Surface Interface
%J The journal of physical chemistry  / C
%V 121
%N 19
%@ 1932-7455
%C Washington, DC
%I Soc.
%M FZJ-2017-03870
%P 10419 - 10429
%D 2017
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000402024200020
%R 10.1021/acs.jpcc.7b02138
%U https://juser.fz-juelich.de/record/830302