Multifunctional metal-doped carbon nanocapsules

We present an ab initio study of carbon fullerenes, such as C-20, C-36, C-56, C-60, and C-68, that are substitutionally doped with transition metals coordinated to several nitrogen atoms. These capsules with porphyrinlike metal sites have remarkable electronic and spin polarizations. Additional doping by boron increases their highest occupied molecular orbital-lowest unoccupied molecular orbital gap, stabilizes their electronic structure, and causes their ground states to have higher spin multiplicity, where the spin density is spread over the capsule. These capsules could be applied in molecular electronics, catalysis, light harvesting, and nanomechanics.