Reply to the ‘Comment on “Theoretical studies on a carbonaceous molecular bearing: association thermodynamics and dual-mode rolling dynamics”’ by E. M. Cabaleiro-Lago, J. Rodriguez-Otero and A. Gil, Chem. Sci., 2016, 7, DOI: 10.1039/C5SC04676A

Abstract

We reply to the comments raised by Cabaleiro-Lago et al. on our article (H. Isobe et al., Chem. Sci., 2015, 6, 2746–2753).

Concyclic CH-π arrays for single-axis rotations of a bowl in a tube

“…With a methyl-substituted model of Me-[4]CC⊃COR, we first screened the level of theory among representative DFT methods for the reproducibility of the association enthalpy. Taking account of previous DFT investigations of the [4]CC host for a fullerene guest 17 , 18 , we adopted a common basis set of 6-311 G(d) with nine methods with long-range corrections. Despite the wide range of association energies between +0.43 and –32.2 kcal mol –1 (Supplementary Fig.…”

Regulated Single‐Axis Rotations of a Carbonaceous Guest in a van der Waals Complex with an Entropy Cost

“…The guests were slightly inclined in the host, and the tilt angles of C 70 ,w hich were measured as the angle between the C 5 axis of C 70 and the C 4 axis of [4]CC, were 278 and 208 for these two structures, respectively.I nt he 278tilted structure, the C 5 axes were located at the single-bond linkageso ft he [4]CC host. We believe that these variations of orientationss uggest that the C 70 guest in [4]CC rotates in at ilted precession manner, [10,11] which explains the minor discrepancy of the experimental q valuesf rom the ideal q values of the single-axis rotation (see above). We believe that these variations of orientationss uggest that the C 70 guest in [4]CC rotates in at ilted precession manner, [10,11] which explains the minor discrepancy of the experimental q valuesf rom the ideal q values of the single-axis rotation (see above).…”

“…The chemical shifts were calibrated with the resonance of C 60 as an external reference (143 ppm), and the values were used as the reference chemical shift (d iso )o fl ine-shape simulations. [21,22] Under the singleaxis rotation of C 70 around the C 5 axis, the principal values of chemical shift tensor of static molecules (d 11 [21,22] which determines the anisotropy splitting in arelationship of For the simulation of the spectrum of single-axis rotations of C 70 (Figure 1a nd Figure S4), we adopted am ethod reported in the literature.…”

“…For instance,c arbonaceousf ullerenem olecules (C 60 /C 70 )r otate in a solid, [7,8] and the dynamics are under the influence of face-toface intermolecular contacts. By realizing that such quantitative, well-decomposed measures of configurational entropy can provide an important basis to resolve ap oint of frequent dispute about molecular assembly, [10][11][12][13] we decidedt oe lucidate the solid-state dynamics of host-guest systems. [9] The host, (P)- (12,8)- [4]cyclo-2,8-chrysenylene ([4]CC), was composed of hydrogen and carbon atoms andw as suitable fore xplorations of the solid-stated ynamics in detail.I tw as determinedt hat the rotations of C 60 in the [4]CC'C 60 complex were dictated mainly by the enthalpy barrier (DH rot°) o f+ 1.96 AE 0.08 kcal mol À1 , which was accompanied by am inor barrier from the entropy change (DS rot°= À1.46 AE 0.32 cal mol À1 K À1 )( Figure1).…”

“…Upon complexation with as egment of carbon nanotubes as ah ost throughv an der Waalsi nteractions, the dynamics of the guest C 60 molecule are further liberatedt or ealize inertialr otations in as olid. This system, which comprises two rigid molecules assembled solely by van der Waals forces, is rare because it has an ideal host-guests tructure to derive rotational (orientational) entropyc hanges [10,11] and to perform solid-state investigations of dynamics that allow us to separatethe orientational entropy from other entropy contributionss uch as translational (positional) and solvente ntropy. This quantitative information on the rotational dynamics is unique and rare;t hus, it can deepen our understanding of molecular assembly,s pecifically in relation to entropyc hanges.…”