POLYOXOMETALATES ENTRAPPED IN SOL-GEL MATRICES FOR REDUCING ELECTRON EXCHANGE COLUMN APPLICATIONS

Electron exchange columns are analogous to ion exchange columns and comprise entrapment of a strong redox reagent that performs oxidation/reduction cycles with the substrate passing through the columns. Such columns are reversible in nature and are more advantageous as the entrapped redox reagent do not contaminate the products. The electron exchange columns reported so far were designed for oxidation processes and have significant drawbacks, such as relatively small redox reagents that result in leaching, and some organic ligands are more procumbent to redox sensitivity and decomposed with time.^1-2 Therefore in order to overcome these drawbacks, a redox active polyoxometalate was entrapped in silica sol-gel matrices for electron exchange column applications. Polyoxometalates (POMs) are the most suitable candidates for this purpose having the ability to accept/release several electrons without decomposing and changing their structure and moreover are expected to have stability for many redox cycles.³ The properties of the columns strongly depend on the composition of the precursors used to prepare the matrices.⁴ The columns exhibit good reversibility and are the first reducing electron exchange columns ever prepared.

References:

1. Lavi, A. Burg, E. Maimon, D. Meyerstein, Chem. Eur. J., 2011, 17, 5188-5192.
2. Attia, A. Shames, E. Zilbermann, G. Goobes, E. Maimon, D. Meyerstein, Dalton Trans.,2014, 43,

103-110.

3. Xue, G. Chen, Z. Long, Y. Zhou, J. Wang, RSC Adv., 2015, 5, 19306-19314.
4. Sanchez, J. Mater. Chem., 2005, 15, 3557-3558.