Related Experiment Video
Updated: Jan 3, 2026
Fabricating van der Waals Heterostructures with Precise Rotational Alignment
Published on: July 5, 2019
Regulated Single-Axis Rotations of a Carbonaceous Guest in a van der Waals Complex with an Entropy Cost
Taisuke Matsuno1,2, Yusuke Nakai3, Yutaka Maniwa4
1Department of Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Abstract:
In a tight host-guest complex assembled solely by nondirectional van der Waals forces, unique motions of the 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, which may be seemingly difficult to achieve because of the nondirectionality of the assembling forces. A regulated, single-axis rotation was made possible by choosing an appropriate shape of the guest in the tubular host. Specifically, an ellipsoidal guest was made to stand along a cylinder 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-state rotations but was suppressed to 10 GHz, which was 1/20 of the isotropic rotation of a spherical guest. In-depth kinetic analyses quantitatively revealed that the entropy cost was a determining factor that regulated the dynamics.
Related Concept Videos
01:24Van der Waals Interactions
01:10Van der Waals Equation
First, the attractive forces between molecules, which are stronger at higher densities and reduce the pressure, are considered by adding to the pressure a term equal to the square of the molar density multiplied by a positive coefficient a. Second, the volume...
03:00Standard Entropy Change for a Reaction
02:02Chair Conformation of Cyclohexane
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
02:11Conformations of Cyclohexane
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...
02:18Conformations of Ethane and Propane
Staggered conformation is a low energy and more stable conformation with the C-H bonds on the front carbon placed at 60°dihedral angles relative to the C-H bonds on the back carbon, leading to a reduced torsional strain. In staggered...