In this article we discussed synthesis and catalytic applications of heterogeneous catalysts based on lacunary polyoxometalates (LPOMs) and transition metal substituted polyoxometalates (TMSPOMs), however exclusively the focus has been given to the mono LPOMs and mono-TMSPOMs. As the field of supported LPOMs/TMSPOMs is upcoming important field, some aspects about choice of support as well as methods of supporting have also been described. We also include a few of our new research results in order to understand the effect of support and active species as well as choice of organic transformation.

A novel heterogeneous catalyst comprising undecamolybdophosphate and hydrous zirconia was synthesized, characterized by various physicochemical techniques and used as an efficient heterogeneous catalyst for oxidation of styrene using H₂O₂ as an oxidant. The novelty of the present work lies in obtaining >99% conversion of styrene with >99% selectivity for benzaldehyde under solvent free mild reaction conditions.

Environmentally benign oxidation of alcohols and alkenes over transition metal substituted phosphomolybdates with molecular oxygen as an oxidant and TBHP as an initiator was carried out. The influence of different parameters on the conversion as well as the selectivity was investigated. All the catalysts showed good catalytic activity with excellent selectivity for the desired products as well as a higher TON. The system not only catalyzes the reaction but also avoids the use of organic solvents as it was carried out under solvent free conditions. Moreover, the catalysts could be recovered and reused four times without a significant loss in their activity and selectivity. A probable reaction mechanism was also proposed for the oxidation of alcohols and alkenes.