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

Abstract

In at ight host-guest complex assembled solely by nondirectional van der Waals forces, unique motionso ft he guest, such as solid-state inertial rotations, emerge. The regulation of dynamic motions is an important element to be explored for novel functions of such complexes,w hich may be seemingly difficult to achieve because of the nondirectionality of the assembling forces. Ar egulated, single-axis rotation was made possible by choosing an appropriate shape of the guest in the tubular host. Specifically,a ne llipsoidal guest was made to stand along ac ylinder axis of the host, which consequently resulted in single-axis rotations of the guest in the solid. The rotational frequency was considerably high for solid-stater otations but was suppressed to 10 GHz, which was 1/20 of the isotropic rotationo faspherical guest. In-depth kinetic analyses quantitativelyr evealed that the entropy cost was ad etermining factor that regulated the dynamics. Results and DiscussionSolid-state 13 CN MR spectraThe van der Waals complexo f[ 4]CC'C 70 was previously prepared to reveal the tight associationinsolution. [14,15] Alarge association constant of K a = 3.8 10 9 m À1 was recorded in o-dichlorobenzene along with the thermodynamics parameters (DH = À10.1 kcal mol À1 , DS =+10.0 cal mol À1 K À1 ), which were comparable to those of [4]CC'C 60 in the same medium (K a = 4.4 10 9 m À1 ; DH = À7.7kcal mol À1 , DS =+17.6 cal mol À1 K À1 ).Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Ineffective OH Pinning of the Flipping Dynamics of a Spherical Guest within a Tight‐Fitting Tube

“…[18] Four chrysene panels within as ingle [4]CC host were spectroscopically equivalent in the 1 HNMR spectra, thus showing the presence of singleaxis rotations of the guest ( Figure S10). [4,6,9] Thep recise two-wheeled structures of [4]CC'(C 59 N) 2 &- [4]CC were revealed by crystallography.The crystal structure showed that the dumbbell-shaped (C 59 N) 2 guest was encapsulated and two rotated disordered orientations were found along the dumbbell axis.T he cylindrical [4]CC hosts were nearly aligned in parallel, and the cylinders were tilted against the dumbbell-shaped guest ( Figure 3a). Thet ilt angle was measured to be 358 8 ( Figure S13), which was identical to that observed with nonpolar [4]CC'(C 60 ) 2 & [4]CC.…”

“…Forschungsartikel rotational dynamics of spherical guests in cylindrical hosts. [6] Explorations of the functions of the present nitrogen-doped systems are currently under investigation, including by solidstate dynamics. [34]…”

“…[5] Although challenging,m odulations of such unique dynamics were partly achieved by changing the molecular shapes of the guest. Fore xample,a n oval shape rendered the C 70 guest (7.1 7.1 7.9 3 )b iased toward single-axis rotations, [6] and similar single-axis rotations were also made possible by ashaft-like substituent pinned on C 60 . [4,7] Intrigued by the interesting dynamic behavior of the vdW complexes,w es tarted exploring the doping of the molecular peapods with heteroatoms to modulate the dynamic and electronic properties.Replacing ac arbon atom of C 60 should intrinsically bias the moment of inertia as well as charge distribution over the spherical structure.W eh erein report the supramolecular assembly of as eries of molecular peapods with heteroatom-doped guests in the [4]CC host, which led to unexpected observations in terms of the unique, fundamental dynamics.After establishing an oxidative bisect- ing route for ac ation-in-tube complex ( Figure S1), we found interesting chemical methods to tweak the flipping dynamics.…”

Ineffective OH Pinning of the Flipping Dynamics of a Spherical Guest within a Tight‐Fitting Tube

“…rotational dynamics of spherical guests in cylindrical hosts. [6] Explorations of the functions of the present nitrogen-doped systems are currently under investigation, including by solidstate dynamics. [34]…”