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Herein is reported a metamorphosis taking place in a gold nanosized system. The observed phenomenon of shape and size transformations was found to be completely reversible. Unlike most procedures in the literature where shape and size control occur in the synthetic step by adding growth- and shape-controlling agents such as surfactants or polymers, in this system postsynthetic changes in shape and size can be carried out simply by changing the ratio of reactive, competing reagents, more specifically, alkylthiols versus tetralkylammonium salts. Interestingly, the transfer of gold metal occurs (large prismatic particles to small particles and vice versa) under the influence of reagents that do not cause such interactions with bulk gold. All intermediate steps of the morphology change were observed using HRTEM and electron diffraction. The processes of breaking down and “welding back” solid metal nanoparticles occur under mild conditions and are remarkable examples of the unique chemical properties of nanomaterials. The described process is expected to be relevant to other nanoscale systems where similar structural circumstances could occur.

Nanocyrstals of MgO having 4 nm average crystallite sizes with 450–550 m2/g surface area were prepared by the Aero-gel preparation method (AP-MgO). Dehydrohalogenation of 1-chlorobutane was performed using AP-MgO as a catalyst; And 1-butene is the selective product formed even after several cycles of 1-chlorobutane injections. AP-MgO was allowed to react with Cl2, which resulted in the formation of a highly reactive adduct which has a capability to selectively chlorinate propane.