Theoretical studies on a carbonaceous molecular bearing: association thermodynamics and dual-mode rolling dynamics

Isobe, Hiroyuki; Nakamura, Kôsuke; Hitosugi, Shunpei; Sato, Sota; Tokoyama, Hiroaki; Yamakado, Hideo; Ohno, Koichi; Kono, Hirohiko

doi:10.1039/c5sc00335k

Cited by 54 publications

(56 citation statements)

References 63 publications

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“…[29] We hope that the exploration of the structural chemistry of nanohoops will be further stimulated by the present molecular systems that give persistent belts with the smallest acene (naphthalene) units.…”

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confidence: 99%

Belt‐Shaped Cyclonaphthylenes

et al. 2015

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The recent development of cyclo-para-phenylenes has demonstrated the feasibility of radial π systems in nanohoop structures, especially in the crystalline state. However, in contrast to macrocyclic molecules with benzene units, which have a several-decades-long history, macrocycles composed solely of naphthylene units (the smallest acene) have been much less explored. Although two examples of cyclonaphthylenes have been reported to date, neither possesses a radial π system. We herein report the first example of belt-shaped cyclonaphthylenes with curved π systems. The molecule, [8]cyclo-amphi-naphthylene, is linked at the 2,6-positions of the naphthylene units, thus affording belt-shaped molecules. Although the molecular structures are flexible, which allows for rotation of the naphthylene units in solution, they can be rigidified with the aid of methylene bridges to afford persistent molecular structures in solution.

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confidence: 99%

Belt‐Shaped Cyclonaphthylenes

et al. 2015

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“…[1][2][3] Fundamental developments have discovered fascinating phenomena and enabled a wealth of applications in the gas phase, [4][5][6][7][8] in solution, 4,[9][10][11] in crystals, 4,12 on surfaces, [4][5][6][13][14][15] and in biosystems. 16 Here we use a molecular model rotor to demonstrate the way from molecular quantum dynamics to explicitly time dependent statistical thermodynamics.…”

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confidence: 99%

From coherent quasi-irreversible quantum dynamics towards the second law of thermodynamics: The model boron rotor B13+

2018

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The planar boron cluster B13+ provides a model to investigate the microscopic origin of the second law of thermodynamics in a small system. It is a molecular rotor with an inner wheel that rotates in an outer bearing. The cyclic reaction path of B13+ passes along thirty equivalent global minimum structures (GMi, i = 1, 2, ..., 30). The GMs are embedded in a cyclic thirty-well potential. They are separated by thirty equivalent transition states with potential barrier Vb. If the boron rotor B13+ is prepared initially in one of the thirty GMs, with energy below Vb, then it tunnels sequentially to its nearest, next-nearest etc. neighbors (520 fs per step) such that all the other GMs get populated. As a consequence, the entropy of occupying the GMs takes about 6 ps to increases from zero to a value close to the maximum value for equi-distribution. Perfect recurrences are practically not observable.

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“…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).…”

Section: Crystal Structuresmentioning

confidence: 85%

“…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).…”

Section: Introductionmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Matsuno

Nakai

Maniwa

et al. 2019

Chemistry An Asian Journal

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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.

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Theoretical studies on a carbonaceous molecular bearing: association thermodynamics and dual-mode rolling dynamics

Abstract: The dynamics of a carbonaceous molecular bearing were investigated by DFT methods to reveal dual-mode motions with a minute energy barrier.

Cited by 54 publications

References 63 publications

Belt‐Shaped Cyclonaphthylenes

Belt‐Shaped Cyclonaphthylenes

From coherent quasi-irreversible quantum dynamics towards the second law of thermodynamics: The model boron rotor B13+

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

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