Structure of cyclooctatetraene at 129 K

Claus, K. H.; Krüger, Carl

doi:10.1107/s0108270188005840

Cited by 57 publications

(60 citation statements)

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“…It is known from electron [139][140][141] and X-ray diffraction [142,143] data and recent results of femtosecond spectroscopy [144] that the molecule adopts a tub-shaped structure of D 2d symmetry, as shown in Figure 12.…”

Section: Cyclooctatetraene: a Non Planar Cyclic Conjugated Systemmentioning

confidence: 96%

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Gellini

Salvi

2010

Symmetry

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The paper introduces general considerations on structural properties of aromatic, antiaromatic and non-aromatic conjugated systems in terms of potential energy along bond length alternation and distortion coordinates, taking as examples benzene, cyclobutadiene and cyclooctatetraene. Pentalene, formally derived from cyclooctatetraene by cross linking, is also considered as a typical antiaromatic system. The main interest is concerned with [n]annulenes and model [n]annulene molecular systems, n ranging from 10 to 18. The rich variety of conformational and configurational isomers and of dynamical processes among them is described. Specific attention is devoted to bridged [10]-and [14]annulenes in the ground and lowest excited states as well as to s-indacene and biphenylene. Experimental data obtained from vibrational and electronic spectroscopies are discussed and compared with ab initio calculation results. Finally, porphyrin, tetraoxaporphyrin dication and diprotonated porphyrin are presented as annulene structures adopting planar/non-planar geometries depending on the steric hindrance in the inner macrocycle ring. Radiative and non-radiative relaxation processes from excited state levels have been observed by means of time-resolved fluorescence and femtosecond transient absorption spectroscopy. A short account is also given of porphycene, the structural isomer of porphyrin, and of porphycene properties.

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Section: Cyclooctatetraene: a Non Planar Cyclic Conjugated Systemmentioning

confidence: 96%

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Gellini

Salvi

2010

Symmetry

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“…Experimental geometry by electron diffraction 49 and by X-ray diffraction 50 shows a non-planar (tub-shaped) structure and a substantial CC bond length alternation. Planarization of COT may be reached by a partial rehybridization at the carbon atom due to a forced decrease of the HCC bond angles at carbon atoms forming the double bond.…”

Section: Introductionmentioning

confidence: 98%

Substituent effects in mono- and disubstituted 1,3,5,7-cyclooctatetraene derivatives in natural and planar conformations

Palusiak

Krygowski

2009

New J. Chem.

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Substituent effect in cyclooctatetraene (COT) has been investigated by means of quantum-chemical (DFT-B3LYP) calculations. Two substituents, nitroso (p-electron-withdrawing) and hydroxy (p-electron-donating), have been examined and compared with monosubstituted and unsubstituted systems. Additionally, both the natural (tub-shaped) and the planar geometries of the COT have been taken into account. The behavior of COT ring, being the antiaromatic 4n p-electron system, has been compared with that of the benzene ring, being the aromatic 4n + 2 system. The 1,4-substitution differs significantly from the 1,3-and 1,5-substitution, which corresponds to an analogous situation found for benzene derivatives (para vs. meta substitution). Substituents influence COT more effectively in its planar geometry as compared with the tub-shaped geometry. This is due to the better overlapping of the p z orbitals of the carbon atoms within the ring in its planar conformation. As far as the p-electron communication between the substituents is concerned, the behavior of both 4n and 4n + 2 systems is in some way similar. Both systems tend to keep their p-electronic structures. Nevertheless, benzene ring, i.e. 4n + 2 system seems to be a clearly worse medium for transmission of the substituents communication than its 4n counterpart.

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“…To achieve amolecular motion-driven thermo-responsive molecular crystal with high thermal stability,w ep lanned to connect flexible and mobile p units by hydrogen bonding interaction of carboxylic acid and designed tetra- [2,3]thienylene tetracarboxylic acid (1)a sac andidate thermo-responsive crystalline material with aH OF structure ( Figure 1). Te tra [2,3]thienylene (X) [19] is an expanded cyclooctatetraene (COT) derivative [20] which forms at wisted tubshape structure [21] due to the 8p electronic nature of the COT ring. COT shows dynamic ring inversion in solution, [22] and we considered that this could be the source of bulk mechanical force.H ydrogen bonding interactions could stabilize the molecular assembly even under molecular motion to suppress melting.…”

Section: Introductionmentioning

confidence: 99%

Jumping Crystal of a Hydrogen‐Bonded Organic Framework Induced by the Collective Molecular Motion of a Twisted π System

2019

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There is alimited number of reports on mechanically responsive molecular crystals,i ncluding thermo-responsive and light-responsive crystals.Rigid ordered molecular crystals with aclose-packing structure are less able to accept distortion, which hampers the development of such molecular crystals. The thermosalient effect, or "crystal jumping", refers to athermo-responsive system that converts heat into mechanical force by thermally induced phase transition. While they have recently attracted attention as potential highly efficient molecular actuators,less than two dozens of thermosalient molecular crystals have been reported to date,a nd the design of such molecules as well as how they assemble to express at hermosalient effect are unknown. Herein, we demonstrate how the cooperative molecular motion of twisted p units could serve to develop at hermo-responsive jumping molecular crystal with ah ydrogen-bonded organic framework (HOF) of tetra-[2,3]thienylene tetracarboxylic acid (1). The cooperative change in the molecular structure triggered by the desolvation of THF in the channel of the HOF structure induced not only ac hangei nt he structure of HOF but also mechanical force. Hydrogen bonding interactions contributed significant thermal stability to maintain the HOF assembly even with ad ynamic structural change.

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Structure of cyclooctatetraene at 129 K

Cited by 57 publications

References 3 publications

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Structures of Annulenes and Model Annulene Systems in the Ground and Lowest Excited States

Substituent effects in mono- and disubstituted 1,3,5,7-cyclooctatetraene derivatives in natural and planar conformations

Jumping Crystal of a Hydrogen‐Bonded Organic Framework Induced by the Collective Molecular Motion of a Twisted π System

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