Publication Date: 2023/02/16
Abstract: Preyssler Polyoxometalate (POM) is a doughnut shaped heteropolytungstate constructed from five PW6O22 units, each of which is derived from the lacunary fragment of Keggin anion, α-[PW12O40]3-. They are the first examples of POMs with an internal cavity within which remains encrypted a sodium cation. This sodium cation can be replaced for trivalent lanthanide cations and other cations of similar size. Hence, Preyssler POM is also called inorganic crown ethers or inorganic cryptrates. Preyssler POM is a redox active cluster which is active over a wide range of pH from 0 to 10. As said, the encrypted lanthanide is usually in +III oxidation state. However, Europium and Cerium encrypted POMs shows certain behaviour that lead the chemists to predict +II and +IV Oxidation states respectively . However, XANES, EXAFS, CV confirmed an oxidation state of +III in the above cases. Cyclic voltammetry reveals an extensive redox chemistry of the lanthanide encrypted POMs. Dyprosium and Holmiun encrypted POMs are found to exhibit single molecular magnetism. The study on the surface of Preyssler POM is highly explored and has ruled almost a decade. Various reseachers employed various techniques like layer-by-layer mechanism and Ionic self-Assembly process for the construction of multilayer composites and nanostructures and subjected them to the study of electrochromism. Preyssler POM has been for lesser number of times employed as a building block for the construction of extended strutures, owing to the discrepancy in obtaining single crystal. A handful of examples have been elucidated below. The example of the lacunary Preyssler POM and an extended structure based on it have also been set up. Preyssler POM has been observed to make its most remarkable contribution in the field of catalysis. Preyssler POM is found to be a green catalyst and has efficiently catalysed a huge number of organic reactions. The medicinal value of Preyssler POM has also been established. A number of theoretical studies have also been performed.
Keywords: Preyssler, Polyoxometalates, Cryptohydration, Hysterysis, Electrochromism
DOI: https://doi.org/10.5281/zenodo.7645911
PDF: https://ijirst.demo4.arinfotech.co/assets/upload/files/IJISRT23FEB214.pdf
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