Competitive hydrosilylation in carbon nanoreactors: probing the effect of nanoscale confinement on selectivity.

Platinum nanoparticles (PtNP) either imbedded within (PtNP@GNF) or adsorbed on the surface (PtNP/GNF) of hollow graphitised carbon nanofibres catalyse hydrosilylation reactions inside or outside the nanoreactor respectively. Comparison of the products formed using PtNP@GNF and PtNP/GNF reveals that nanoreactors create an environment promoting the formation of aromatic over aliphatic products in the competitive hydrosilylation of phenylacetylene with a mixture of triethylsilane and dimethylphenylsilane reactants. Quantification of the distribution of reaction products indicates a three- to four-fold increase in the concentration of aromatic reactants within GNF depending on the dimensions of the carbon nanoreactor. The altered local concentrations of reactants in PtNP@GNF combined with stabilisation of the reaction intermediates by interactions with the nanoreactor interior cause significant changes in the pathways of chemical transformations. The effects of nanoscale confinement on the reactivity of molecules can be harnessed for preparative synthesis in carbon nanoreactors.