Nanoaggregates of simple Mn porphyrin complexes as catalysts for the selective oxidation of hydrocarbons

Article abstract of DOI:10.1002/ejic.201201437

A stable suspension of simple manganese(III) meso-tetraphenylporphyrin nanoaggregates was prepared by a host-guest procedure, in which ethanol and water are used as "green" solvents. The organic nanoparticles were studied by dynamic light scattering (DLS), AFM, and UV/Vis and fluorescence spectroscopy. The results indicate that the nanoaggregates have a spherical morphology with sizes between 15-40 nm. The epoxidation of olefins and oxygenation of saturated hydrocarbons by PhI(OAc)₂ were efficiently enhanced with excellent selectivity under the influence of simple Mn(TPP)OAc (TPP = meso-tetraphenylporphyrin) nanoparticles. Enhanced stabilities and activities were achieved with nanostructured Mn catalysts compared to those of the individual counterparts in solution according to turnover numbers and UV/Vis studies. The title nanocatalyst facilitates a greener reaction because the reaction solvent is a water/ethanol mixture and PhI(OAc)₂ is safe to use. The efficiency of the oxidation system depends critically upon the steric hindrances and electronic structures of both nitrogen donor ligands and porphyrin nanoparticles. Copyright