The structure-directed synthesis of cyclacene and polyacene derivatives

Girreser, Ulrich; Giuffrida, Daniele; Kohnke, Franz H.; Mathias, John P.; Philp, Douglas; Stoddart, J. Fraser

doi:10.1351/pac199365010119

Cited by 74 publications

(40 citation statements)

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“…The targeting units of the present study, a series of n -cyclacenes, consisting of n fused benzene rings forming a closed loop (see Fig. 1), are the shortest ( n , 0) zigzag CNTs with hydrogen passivation, which have attracted considerable interest in the research community due to their fascinating electronic properties1215161718192021222324252627. As n -cyclacenes belong to the category of cata-condensed aromatics (i.e., molecules that have no carbon atoms belonging to more than two rings), each carbon atom is on the periphery of the conjugated system17.…”

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confidence: 99%

Electronic Properties of Cyclacenes from TAO-DFT

Lee

Chai

2016

Sci Rep

105

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Owing to the presence of strong static correlation effects, accurate prediction of the electronic properties (e.g., the singlet-triplet energy gaps, vertical ionization potentials, vertical electron affinities, fundamental gaps, symmetrized von Neumann entropy, active orbital occupation numbers, and real-space representation of active orbitals) of cyclacenes with n fused benzene rings (n = 4–100) has posed a great challenge to traditional electronic structure methods. To meet the challenge, we study these properties using our newly developed thermally-assisted-occupation density functional theory (TAO-DFT), a very efficient method for the study of large systems with strong static correlation effects. Besides, to examine the role of cyclic topology, the electronic properties of cyclacenes are also compared with those of acenes. Similar to acenes, the ground states of cyclacenes are singlets for all the cases studied. In contrast to acenes, the electronic properties of cyclacenes, however, exhibit oscillatory behavior (for n ≤ 30) in the approach to the corresponding properties of acenes with increasing number of benzene rings. On the basis of the calculated orbitals and their occupation numbers, the larger cyclacenes are shown to exhibit increasing polyradical character in their ground states, with the active orbitals being mainly localized at the peripheral carbon atoms.

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confidence: 99%

Electronic Properties of Cyclacenes from TAO-DFT

Lee

Chai

2016

Sci Rep

105

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“…They consist of benzene hexagons closed to cylinder and possess D nh group of symmetry. Considerable number of references concerning [C n ] 1 called n-cyclacenes are posted in the literature [11,12]. Experimental results on synthesis of n-cyclacenes are discussed in [11,12].…”

Section: The Initial Hydrocarbons [C N ]mentioning

confidence: 99%

“…Considerable number of references concerning [C n ] 1 called n-cyclacenes are posted in the literature [11,12]. Experimental results on synthesis of n-cyclacenes are discussed in [11,12]. It is postulated that the synthesis of ncyclacenes is still elusive and a majority of methods are based on the Diels-Alder reaction.…”

Section: The Initial Hydrocarbons [C N ]mentioning

confidence: 99%

Lithium mobility in complexes Li[C_n]₁ (n = 5−21): PES analysis in different stationary points

Balashov

Ermilov

Scherbinin

2008

Int J of Quantum Chemistry

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The equilibrium geometries of the cylinder-like lithium hydrocarbon complexes Li[C n ] 1 (n ϭ 7-12) are calculated within Density Functional Theory(DFT) with PBE0 exchange-correlation potential. The 6-31 G* basis was set on carbon and lithium atoms while STO-3G one was chosen for hydrogens. The tendencies found for complexes with n ϭ 7-12 gets broken and transforms to asymptotic behavior in range of n Ͼ 13. The large complexes possess the structure where lithium is placed at the carbon hexagon center area and close to C 2v symmetry. Opposite, for n ϭ 5-6 lithium is placed on the high symmetry axis of initial hydrocarbon. Several stationary points of complexes with n ϭ 8 -21, defined by lithium location under the hexagon center (1), under the COC bond center (2) and at the hydrocarbon skeleton center (3) were found. The migration barriers between stationary points (1)-(3) were estimated. The type (3) structures are distinctly higher of energy than (1) and (2), at that the difference is increased according to growing of n. The complexes with n Ͻ 13 are characterized by usual charge transfer from metal to hydrocarbon skeleton, for n Ն 13 the molecular-like solution is occurred.

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“…1). Hydrocarbons [C n ] q are considered as perspective precursors for pointed synthesis of the specified CNTs, but difficulties of their synthesis have not been overcome yet [7]. Cluster modeling allows to concentrate attention on details of CNTs electronic structure related to local environment.…”

Section: Introductionmentioning

confidence: 99%

The electronic terms of the finite‐length nanotubes, generated by edge states: A CASSCF study

Павлов

Ermilov

2011

Int J of Quantum Chemistry

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Low-lying electronic terms of the hydrocarbons [C 7 ] q (q ¼ 1,3…9) were calculated within CASSCF approach. The [C 7 ] q are H-terminated finite fragment of zigzag carbon nanotube (7,0) containing q cyclacene units. Each [C 7 ] q with odd q has D 7h point symmetry. All systems [C n ] q with arbitrary n and q have a specific set of the one-electron states characterized by the exponential decay along the cylinder axis that has been estimated within the Huckel model. These MOs are localized near bases of the cylinder and they are frontier in all systems [C n ] q . By hypothesis, the low-lying electronic terms of the hydrocarbons [C 7 ] q (q ¼ 1,3…9) are defined by four quasidegenerate MOs e 3 0 , e 3 00 , which were included in the active space CASSCF. Low-lying electronic terms possess tier structure and systems with various q have the same order of states. The distance between tiers tends to asymptotic limit with increasing q. In this case, states in each tier become quasi-degenerate. The lowest tier consists of close set of states, and each is characterized by single occupation of the localized MOs. Ground state of [C 7 ] q is singlet; values of splitting are well described by Heisenberg hamiltonaian. The calculation results can be interpreted as reducing interaction of states localized on opposite cylinder bases with increasing fragment length. According to CASSCF, this interaction reduces exponentially in exact accordance with the similar characteristics of the localized MOs. There is a reason to believe that the value of splitting decreases less rapidly with increasing q if level of calculation is improved.

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The structure-directed synthesis of cyclacene and polyacene derivatives

Abstract: Abstract

Cited by 74 publications

References 1 publication

Electronic Properties of Cyclacenes from TAO-DFT

Electronic Properties of Cyclacenes from TAO-DFT

Lithium mobility in complexes Li[C_n]₁ (n = 5−21): PES analysis in different stationary points

The electronic terms of the finite‐length nanotubes, generated by edge states: A CASSCF study

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The structure-directed synthesis of cyclacene and polyacene derivatives

Abstract: Abstract

Cited by 74 publications

References 1 publication

Electronic Properties of Cyclacenes from TAO-DFT

Electronic Properties of Cyclacenes from TAO-DFT

Lithium mobility in complexes Li[Cn]1 (n = 5−21): PES analysis in different stationary points

The electronic terms of the finite‐length nanotubes, generated by edge states: A CASSCF study

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Lithium mobility in complexes Li[C_n]₁ (n = 5−21): PES analysis in different stationary points