Altering the electronic properties of diamondoids through encapsulating small particles.

The stability, optimized structure, and electronic gap of four diamondoid complexes, adamantane, C(10)H(16), diamantane, C(14)H(20), triamantane, C(18)H(24) and the T(d)-symmetry isomer of pentamantane, C(26)H(32), incorporating cage-centered small atoms and ions (X@cage, where X = H(+), Li(0,+), Be(0,+,2+), Na(0,+), Mg(0,2+), He, Ne, and F(-)) have been studied at the B3LYP hybrid level of theory. All adamantane complexes, except those encapsulating H(+) and Mg, are endohedral minima. In contrast no diamantane complexes are minima. A wide variety of atoms and ions can be encapsulated by triamantane and pentamantane molecules. The complexes are more stable for smaller and more highly charged metallic guest species. The electronic HOMO-LUMO gaps of diamondoid complexes are significantly affected by the inclusion of charged particles. The stability of the structures, the amount of the charges which are transferred between small particles and diamondoids cages, and the change in the HOMO-LUMO gaps of diamondoids are nearly the same for the corresponding possible complexes. All these features mostly depend on the charge, the size and the type of the encapsulated particle, and not on the type of diamondoid.