Electrochemistry of Gadolinium-Polyoxometalate Complexes in Concentrated Salt Solutions

Lanthanide-polyoxometalate complexes have been recently shown to possess unique magnetic, luminescent, and catalytic properties. While their electrochemical behavior has been explored in literature to some degree, the role of metallic spe-cies within the POM and nature and concentration of counter-cations in solutions has not been fully explained. The cur-rent work seeks to address this by studying the Gd(OTf)3 – [H2W12O40]6-(MT) – Si(W12O40)-4 system in concentrated LiCl in N,N-dimethylformamide (DMF) using electrochemical and spectroscopic techniques. It was found that Gd3+ did not chem-ically bond to the POM species but interacted electrostatically through the Ot bonds of the MT POM but not Si based POM. Electrochemically, Gd3+ showed more reversible electrochemistry but was able to gain an additional electron in the pres-ence of the MT- species. The Si-POM did not show much electrochemical behavior in the presence of Li+ and Gd3+ likely due to its non-interaction with both species, found using FTIR. The current work presents a step forward in the under-standing of the role of metallic and cationic species in the electrochemical behavior of lanthanide-POM complexes.