Selective Noble Gas Inclusion in Pentagon-Dodecahedral X₂₀-Cages

Using DFT-based computational chemistry calculations (ωB97XD/def2-tzvp//ωB97XD/def2-svp/svpfit + ZPE(ωB97XD/def2-svp/svpfit)), binding energies of noble gases encapsulated in a series of dodecahedrane molecules (general formula: X₂₀H₂₀ where X = C, Si, Ge, Sn and Pb, and X₂₀ where X = N, P, As, Sb and Bi) were calculated to learn about the noble gas selectivity. Based on calculated binding energies, the Sn₂₀H₂₀ cage can best accommodate noble gases with a medium size radius (Ar and Kr), while the Pb₂₀H₂₀ dodecahedrane cage is best suited for noble gases with the larger radii (Xe and Rn). On the other hand, from the elements of the V main group of the periodic table, the Bi₂₀ cage has shown the best results to selectively encapsulate Ar and Kr, with the amounts of energy being released being -5.24 kcal/mol and -6.13 kcal/mol, respectively. By monitoring the geometric changes of all here-reported host cages upon encapsulating the noble gas guest, the host has shown minor to no flexibility, testifying to the high rigidity of the dodecahedrane structure which was further reflected in very high encapsulating energies.