Isolation and Characterization of the Cycloparaphenylene Radical Cation and Dication

Kayahara, Eiichi; Kouyama, Takahiko; Kato, Tatsuhisa; Takaya, Hikaru; Yasuda, Nobuhiro; Yamago, Shigeru

doi:10.1002/anie.201306881

Cited by 105 publications

(103 citation statements)

References 49 publications

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“…The assignments were consistent with our previous works. 68,70,71 The calculated λ max shifted bathochromically as the ring size increased. The plot of the transition energy obtained from the calculated λ max values against 1/n showed good linear correlations ( Figure 2).…”

Section: Articlementioning

confidence: 96%

Synthesis and Characterization of [n]CPP (n = 5, 6, 8, 10, and 12) Radical Cation and Dications: Size-Dependent Absorption, Spin, and Charge Delocalization

et al. 2015

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Radical cations and dications of [n]cyclo-p-phenylenes ([n]CPPs, n = 5, 6, 10, and 12), which are the models of those of linear oligo-p-phenylenes without a terminus, were synthesized as hexafluoroantimonate salts by the one- and two-electron chemical oxidation of CPP by NOSbF6 or SbF5. The radical cations, [n]CPP(•+), and dications, [n]CPP(2+), exhibited remarkable bathochromic shifts in their UV-vis-NIR absorption bands, suggesting that [n]CPP(•+) and larger [n]CPP(2+) exhibit longer polyene character than the shorter analogues. The larger bathochromic shift was consistent with the narrower HOMO-SOMO and HOMO-LUMO gaps in larger [n]CPP(•+) and [n]CPP(2+), respectively. In [n]CPP(•+), the spins and charges were equally and fully delocalized over the p-phenylene rings of the CPPs, as noted by ESR. (1)H NMR revealed that the hydrogen of [n]CPP(2+) shifted to a high magnetic field from the neutral compounds due to the diamagnetic ring current derived from the in-plane aromaticity of [n]CPP(2+). The single resonances observed in all [n]CPP(2+) strongly suggest the complete delocalization of the charges over the CPPs. Furthermore, the contribution of biradical character was clarified for [10]- and [12]CPP by VT-NMR experiment and theoretical calculation.

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Section: Articlementioning

confidence: 96%

Synthesis and Characterization of [n]CPP (n = 5, 6, 8, 10, and 12) Radical Cation and Dications: Size-Dependent Absorption, Spin, and Charge Delocalization

et al. 2015

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“…12 This result is consistent with our previous assignment, based on TDDFT calculations, that this absorption band arises from the transition from the doubly degenerate HOMOs to the nondegenerate LUMO ( Figure 2a). 5 The MCD intensity for the visible absorption band was considerably weaker than that for the near-IR band, but a clear MCD signal with a negative Faraday A term was observed. This result is also consistent with the TDDFT-based attribution of the band to transition from the HOMOs to nondegenerate LUMO+1.…”

Section: Introductionmentioning

confidence: 95%

“…5 Figure 1 shows the electronic absorption and MCD spectra of [8]CPP 2+ (SbF 6 -) 2 and [8]CPP in dichloromethane at room temperature. The most prominent feature of the MCD spec-…”

Section: Introductionmentioning

confidence: 99%

In-Plane Aromaticity in Cycloparaphenylene Dications: A Magnetic Circular Dichroism and Theoretical Study

et al. 2014

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The electronic structures of [8]cycloparaphenylene dication ([8]CPP(2+)) and radical cation ([8]CPP(•+)) have been investigated by magnetic circular dichroism (MCD) spectroscopy, which enabled unambiguous discrimination between previously conflicting assignments of the UV-vis-NIR absorption spectral bands. Molecular orbital and nucleus-independent chemical shift (NICS) analysis revealed that [8]CPP(2+) shows in-plane aromaticity with a (4n + 2) π-electron system (n = 7). This aromaticity appears to be the origin of the unusual stability of the dication. Theoretical calculations further suggested that not only [8]CPP(2+) but also all [n]CPP (n = 5-10) dications and dianions exhibit in-plane aromaticity.

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“…3 In 2008, Jasti, Bertozzi, and co-workers reported the synthesis of [9]-, [12]-, and [18]cycloparaphenylenes ([9]CPP, [12]CPP, and [18]CPP). Recently, Isobe reported tubular macrocycles, [4] Quite recently, the synthesis of CPPs was developed very rapidly and extensively by the groups of Itami, 12 Yamago, 13 Jasti, 14 and Müllen, 15 independently, and [5]- [16]CPPs and their derivatives were newly synthesized to explore characteristic properties. Recently, Isobe reported tubular macrocycles, [4] Quite recently, the synthesis of CPPs was developed very rapidly and extensively by the groups of Itami, 12 Yamago, 13 Jasti, 14 and Müllen, 15 independently, and [5]- [16]CPPs and their derivatives were newly synthesized to explore characteristic properties.…”

Section: Oligophenylene Macrocyclesmentioning

confidence: 99%

“…Recently, Isobe reported tubular macrocycles, [4] Quite recently, the synthesis of CPPs was developed very rapidly and extensively by the groups of Itami, 12 Yamago, 13 Jasti, 14 and Müllen, 15 independently, and [5]- [16]CPPs and their derivatives were newly synthesized to explore characteristic properties. 16,17 Furthermore, the cavity of CPPs acts as a host for p-conjugated molecules, and C 60 was selectively encapsulated by [10]CPP, forming a 1 : 1 complex, [10]CPP*C 60 (Fig. Interestingly, [8]CPP 2+ showed in-plane aromaticity with 30p-electrons.…”

Section: Oligophenylene Macrocyclesmentioning

confidence: 99%

Multifunctional π-expanded oligothiophene macrocycles

2015

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This tutorial review summarizes recent progress in the design, synthesis, and multifunctional properties of fully conjugated macrocyclic π-systems. We focus on the π-expanded oligothiophene macrocycles after a short survey of macrocyclic conjugated loops and belts such as [n]cycloparaphenylenes, cyclic[n]para-phenylacetylenes, [4]cyclo-2,8-crysenylenes, and cyclo[n]thiophenes. Fully conjugated π-expanded oligothiophene macrocycles possess shape-persistent but sometimes pliable π-frames, and the electronic and optoelectronic properties of the macrocycles largely depend on the π-systems inserted into the oligothiophene macrocycles. Among them, the π-expanded oligothiophene macrocycle composed of 2,5-thienylenes, ethynylenes, and vinylenes is one of the most widely applicable macrocycles for constructing multifunctional π-systems. These π-expanded oligothiophene macrocycles from small to very large ring sizes can be prepared via a short step procedure, and their various solid state structures can be determined by X-ray analysis. Since these macrocycles have inner and outer domains, specific information concerning structural, electronic, and optical properties is expected. Furthermore, π-expanded oligothiophene macrocycles with alkyl substituents exhibit various morphologies depending on nanophase separation of molecules, and a morphological change is observed for the molecular switch.

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Isolation and Characterization of the Cycloparaphenylene Radical Cation and Dication

Cited by 105 publications

References 49 publications

Synthesis and Characterization of [n]CPP (n = 5, 6, 8, 10, and 12) Radical Cation and Dications: Size-Dependent Absorption, Spin, and Charge Delocalization

Synthesis and Characterization of [n]CPP (n = 5, 6, 8, 10, and 12) Radical Cation and Dications: Size-Dependent Absorption, Spin, and Charge Delocalization

In-Plane Aromaticity in Cycloparaphenylene Dications: A Magnetic Circular Dichroism and Theoretical Study

Multifunctional π-expanded oligothiophene macrocycles

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