From Pentalene to Dicyclopenta[b,g]naphthalene, or the Change towards Delocalized Structures

Abstract

Using triples-corrected coupled-cluster methods as well as other high-level theoretical approximations, the optimized parameters and isomerization barriers of the family of compounds cyclopentadiene-(benzene)x-cyclopentadiene (x = 0, 1, 2) are computed. In contrast to previous studies, s-indacene presents a localized C(2h) geometry. Also, the localized structure of pentalene is found to be the most stable, but when two benzene rings are intercalated between the five-member rings of pentalene, the resulting molecule preferably adopts a delocalized D(2h) conformation.

Theoretical insights into the host-guest interactions between [6]cycloparaphenyleneacetylene and its anthracene-containing derivative and fullerene C70

“…However, the previous studies only focus on the fine-tuning deformation of the host without noting that of guest. [33,47,48] The calculations here clearly revealed that the induced mutual-fit interaction not merely comes from the contribution of [6]CPPA host, but also that of C 70 guest. This simultaneously suggests that both [6] CPPA and C 70 are highly elastic molecules.…”

“…The calculated lengths of the long axis and short axis in the isolated [6]CPPA are 13.31 and 12.90 Å, respectively, in good agreement with ab initio results. [33,34] It can be seen from Table 1 that among all the configurations of the complexes, the two centers of the host and guest are not overlapping with the distances between two centers, d c-c , in the range of 1.0~2.8 Å. The d c-c in the two standing isomers are relative small and in the range of 1.0~1.1 Å, but these of lying and half-lying isomers are larger and in the range of 2.1~2.8 Å.…”

“…As a consequence, the dispersion force that is favored by quadrupolar-quadrupolar interaction between the electrostatically different concave and convex surfaces would play an important role in the spontaneous formation of complexes between CNRs host and fullerene guest. [33,47] In short, van der Waals force in a planar π-π interaction system derived from dispersion force, but that in the curved π-π interaction system may be more strengthened by the polarization existing in the curved surfaces. So, it is reasonable that the equilibrium interfacial distance between convex and concave faces is not always equal to that of planar π-π interaction like between graphite sheets.…”

“…In spite of significant progresses, the experimental determination of such interactions for those CNRs-fullerenes supramolecular compounds is complicated or at least rather cumbersome. [33] From this point of view, it is necessary to deeply investigate the host-guest of CNRs-fullerene complexes via theoretical calculations. Zhao and Truhlar [34] studied the supramolecular interactions between the hydrocarbon nanoring host, [6]CPPA, and six guests including hexamethylbenzene, fullerenes (C 60 and C 70 ), and three armchair-type nanotubes: (3,3), (4,4), and (5,5) by using M06-L [35] and M06-2X [36] density functionals.…”

Noncovalent interactions between O6‐corona[6]arene nanorings and fullerenes C60 and C70: atypical ring ball‐shaped host‐guest systems

“…Generally and qualitatively speaking, if the frontier orbitals are obviously extended across the 2 or more fragments of a complex or a supramolecular system, charge transfer (CT) between the fragments is suggested; otherwise, CT can be excluded. [44] As shown in Figure 3, it is clear that the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the host-guest complexes are completely localized on the C 60 or C 70 guest but independent of T3 or P3 nanorings. Similar results without crossing the 2 moieties can be found for the other complexes (see Figure S1 and Figure S2 of the Supporting Information), indicating the lack of obvious CT between O 6 -corona [6]arene nanoring and fullerene.…”