Is the [9]Annulene Cation a Möbius Annulene?

Bucher, Götz; Huenerbein, Robert; Auer, Alexander A.; Mucke, Eva; Köhler, Felix; Siegwarth, Jan; Herges, Rainer

doi:10.1002/anie.200900886

Cited by 30 publications

(22 citation statements)

References 42 publications

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“…The geometry optimizations and single point calculations were performed at B3LYP/6–311 + G(d,p) and CCSD(T)/DZP levels, respectively. In 2009, Herges and coworkers presented high‐level coupled‐cluster calculations including corrections for solvent and vibrational contributions and they predict that the Hückel and the Möbius isomer of C 9

{normalH}_{9}^{+}

are quasi‐degenerate (the energy difference is only 0.04 kcal mol −1 ). Moreover, this work also contains the UV/Vis spectra of the [9] annulene cation measured in laser flash photolysis, which concludes that the Hückel structure is the most stable conformation since it is the unique conformer detected, although it was considered that the Möbius structure could exist in small concentrations below the detection limit.…”

Section: Resultsmentioning

confidence: 99%

Relevance of the DFT method to study expanded porphyrins with different topologies

et al. 2017

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Meso-aryl expanded porphyrins present a structural versatility that allows them to achieve different topologies with distinct aromaticities. Several studies appeared in the literature studying these topological switches from an experimental and theoretical point of view. Most of these publications include density functional theory calculations, being the B3LYP the most used methodology. In this work, we show that the selection of the functional has a critical role on the geometric, energetic, and magnetic results of these expanded porphyrins, and that the use of an inadequate methodology can even generate spurious stationary points on the potential energy surface. To illustrate these aspects, in this article we have studied different molecular distortions of two expanded porphyrins, [32]-heptaphyrin and [26]-hexaphyrin using 11 DFT functionals and performing single point energy calculations at the local pair natural orbital coupled cluster DLPNO-CCSD(T) method, which have been carried out for benchmarking purposes. For some selected functionals, the dispersion effects have also been evaluated using the D3-Grimme's dispersion correction with Becke-Johnson damping. Our results let us to conclude that the CAM-B3LYP, M05-2X, and M06-2X functionals are the methodologies that provide a more consistent description of these topological switches, while other methods, such as B3LYP, BPE, and BP86, show a biased description. © 2017 Wiley Periodicals, Inc.

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{normalH}_{9}^{+}

Section: Resultsmentioning

confidence: 99%

Relevance of the DFT method to study expanded porphyrins with different topologies

et al. 2017

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“…In 1971, the charged cyclic 8p-electron [9]annulene (C 9 H 9 ) +6 was the first experimental evidence for the aromatic Möbius system. The theoretical support regarding the aromaticity of the system was reported by Scheleyer et al 15 In 2009, the quasi-degenerate property of the Hückel and the Möbius isomers of (C 9 H 9 ) +1 was predicted by high level coupled cluster calculations 16 with an energy difference of only 0.04 kcal mol À1 . Experimentalists 16 detected Hückel structure as the unique and most stable conformer by considering the existence of Möbius structure in very small concentrations below the detection limit.…”

Section: Introductionmentioning

confidence: 87%

Triply twisted Möbius annulene: a new class of two-photon active material – a computational study

Kundi

Alam

Thankachan

2015

Phys. Chem. Chem. Phys.

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In the present work, we have studied the gas phase one- and two-photon absorption (OPA and TPA) properties of the first two excited states of the triply twisted Möbius annulene molecule (G. R. Schaller, et al., Nat. Chem. 2014, 6, 608) and five model systems substituted with different donor and acceptor groups. The main purpose of this study is to explore the OPA and TPA properties of this newly synthesized molecule and the unique π-conjugation provided by it. We have used the linear and quadratic response theory methods with the CAMB3LYP functional and the cc-pVDZ basis set for calculating the required parameters. Our results indicate that in the absence of any directive force (i.e. the donor-acceptor groups) the unsubstituted molecule is completely TP inactive. However, as soon as we insert the donor-acceptor group the system becomes TP active which can further be enhanced (up to 3640 GM in our case) by changing the donor-acceptor groups. We have explained the results by performing a two-state model calculation and by analyzing the TP tensor elements and the orbitals involved in the transition processes.

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“…In the search for a stable Mo¨bius annulenes, Herges, Grimme and their groups have looked at annulene cations. SCS-MP2 and CCSSD(T), and a variety of DFT computations of [9]annulene cation 18 reveal that the lowest energy Hu¨ckel (21h) and Mo¨bius (21m) structures, shown in Fig. 2, are very close in energy.…”

Section: Aromaticity and Antiaromaticitymentioning

confidence: 92%

Computational organic chemistry

Bachrach

2011

Annu. Rep. Prog. Chem., Sect. B: Org. Chem.

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Is the [9]Annulene Cation a Möbius Annulene?

Cited by 30 publications

References 42 publications

Relevance of the DFT method to study expanded porphyrins with different topologies

Relevance of the DFT method to study expanded porphyrins with different topologies

Triply twisted Möbius annulene: a new class of two-photon active material – a computational study

Computational organic chemistry

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