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Toward a Reversible Isolation of a C20 Fullerene Inside a Tetraureacalix[4]arene Dimer. A Theoretical Study
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posted on 2006-08-03, 00:00 authored by Grygoriy Dolgonos, Oleg Lukin, Marcus Elstner, Gilles H. Peslherbe, Jerzy LeszczynskiThe potential stabilization of normally unstable C20, the smallest fullerene, via its encapsulation inside a
tetraureacalix[4]arene dimer has been analyzed using molecular mechanics calculations with different force
fields, the self-consistent-charge density-functional tight-binding with dispersion correction (SCC-DFTB-D)
model, and standard density-functional-theory (DFT) calculations. The interaction energies obtained for the
C20 complex have been compared with analogous values calculated for numerous complexes of the
tetraureacalix[4]arene dimer with other guests. Results of the calculations with all force fields and SCC-DFTB-D predict that the binding of C20 occurs with the highest selectivity. On the other hand, standard DFT
calculations fail to correctly describe the stabilization of the complexes under study as standard DFT generally
does not treat dispersion interactions properly. Predicted relative stabilities of the complexes are discussed in
conjunction with available experimental data. Molecular dynamics simulations reveal the instability of the
guest-free capsular dimer, which decomposes on a 1-ns time scale, while dimeric complexes with guests
remained intact during the 5-ns simulation time, indicating the guest-driven formation of the molecular capsule.