  A green and facile synthetic protocol for the preparation of photoactive gold
nanoparticle-soft oxometalates (AuNP-SOM) using a unique Keplarate type
oxomolybdate cluster viz. {Mo$_{132}$}, is reported. The as synthesized
AuNP-SOMs are fully characterized by Electronic absorption spectroscopy, Raman
spectroscopy and High resolution transmission electron microscopy (HR-TEM). We
further demonstrate that by merely tuning the ratio of the precursors in
solution it is possible to control the morphology of AuNP-SOM nanostructures.
Moreover, these photoactive AuNP-SOMs are employed as photocatalysts for the
photopolymerization of styrene to generate colloidal monodisperse polystyrene
microspheres in a controllable way in the absence of any external co-initiator
or inert atmosphere. Effect of styrene concentration on the size of
microspheres is studied using DLS and optical microscopy. Finally, the role of
AuNP-SOMs as efficient photocatalyst is established through several control
experiments and a reaction pathway is proposed.
