A Stable Neutral Hydrocarbon Radical:  Synthesis, Crystal Structure, and Physical Properties of 2,5,8-Tri-<i>tert</i>-butyl-phenalenyl

Goto, Kosaburo; Kubo, Takashi; Yamamoto, Kagetoshi; Nakasuji, Kazuhiro; Sato, Kazunobu; Shiomi, Daisuke; Takui, Takeji; Kubota, Mari; Kobayashi, Tunetoshi; Yakusi, Kyuya; Ouyang, Jianyong

doi:10.1021/ja9836242

Cited by 468 publications

(402 citation statements)

References 14 publications

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“…Phenalenyl (PNL) is a carbon-centered neutral π-radical with a delocalized spin structure. [12][13][14][15][16][17][18][19] Several PNL derivatives form π-dimers, and exhibit absorption bands around 600 nm. [15][16][17] In a few cases, 1D π-stacking columns are formed with large intermolecular separations of~3.78 (ref.…”

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confidence: 99%

Near-infrared absorption of π-stacking columns composed of trioxotriangulene neutral radicals

et al. 2017

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A long-wavelength photoabsorption of organic molecules has been noticed because of the potential as materials. In addition to the extension of π conjugation, molecular aggregation has been utilized to realize the elongation of absorption wavelength. We report strong near-infrared absorptions of trioxotriangulene neutral radicals in the crystalline state and large-scale theoretical calculations of the radical assemblies interpreting the mechanism of optical properties. Polarized absorption spectra and X-ray diffraction of the crystals clarified that an unusual π-stacking column consisting of π-dimers is key for this absorption. Quantum chemical calculations based on time-dependent density functional theory revealed that the π-dimer shows an electronic transition between frontier orbitals generated by strong coupling of the delocalized singly occupied orbitals of monomers. The interdimer interaction of transition dipole moments, which are parallel to the column, elucidated the increase of absorption wavelength. The divide-andconquer Green function method enabled the large-scale time-dependent density functional theory calculation up to a 60mer, where the maximum number of atoms is 4380, reproducing the near-infrared absorptions of trioxotriangulene crystals. The present method to investigate the mechanism of the long-wavelength photoabsorption is useful for developing organic materials consisting of stable neutral radicals.

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confidence: 99%

Near-infrared absorption of π-stacking columns composed of trioxotriangulene neutral radicals

et al. 2017

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“…The schematic geometric structure of the R 1 /D 25 /R 1 stack is shown in Fig. 2(a) bold, experiment data in italic 17) , and previous theoretical data 18) ); (c) The spin polarization on R 1 (Color code: dark for spin up, light for spin down; the density at the surface = 0.03 e/Å 3 ). diamagnetic molecule is preserved in the R 1 /D 25 /R 1 stack.…”

Section: Resultsmentioning

confidence: 99%

“…In this study, geometric structure, electronic structure, and magnetic properties of several forms of graphene-based magnetic materials, i.e. perinaphthenyl radicals C 13 H 9 (R 1 ) [15][16][17][18] , dimers [R 1 ] 2 , and alternating stacks of R 1 radicals and diamagnetic molecules, have been investigated using densityfunctional theory with dispersion correction and full geometry optimization. Our calculated results show that the R 1 radical has a spin of 1/2.…”

Section: Introductionmentioning

confidence: 99%

Ligand-Driven Exchange Coupling in Graphene-Based Magnetic Materials

et al. 2016

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Several forms of graphene-based magnetic materials have been investigated via density-functional theory utilizing dispersion correction and full geometry optimization. Our calculated results show that the perinaphthenyl radical (R 1 ) has a spin of 1/2. However, in its [R 1 ] 2 dimer structure, the net spin becomes zero due to an antiferromagnetic spin-exchange between radicals. To avoid antiferromagnetic spin-exchange of identical face-to-face radicals, the alternating stack of composition R 1 /D 25 /R 1 (with D 25 = graphene-based diamagnetic molecule C 34 H 16 ) has been designed and investigated. As expected, our calculated results con rm that the alternating stack R 1 /D 25 /R 1 has a ferromagnetic spin-exchange between two R 1 radicals with the spin-exchange coupling of J/k B = 277 K, and the spin moment of m = 2 μ B (Bohr magneton unit). In order to explore ways to tailor spin-exchange coupling in stacks, ve other R 1 /D 25 /R 1 -based alternating stacks with different ligand con gurations of R 1 have been designed and investigated. Interestingly, ferromagnetic spin-exchange in stacks can be enhanced by substituting ligands having a weak electron af nity for H atoms of a R 1 molecule, while it can be weakened by substituting ligands having high electron af nity for H atoms of a R 1 radical. These results can be explained in terms of the competitive hybridization between the HOMO (highest occupied molecular orbital) of radicals and the HOMO and LUMO (lowest unoccupied molecular orbital) of diamagnetic molecules. These results would give some indication for how the spin-exchange coupling in graphene-based alternating stacks can be tailored.

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“…It was first proposed in 1975 that phenalenyl has the potential to serve as a building block for molecular conductors [13][14][15]. Since then synthetic efforts have led to the crystallization and characterization of several types of PLY derivatives by chemical modification [16][17][18][19][20][21][22][23]. Heteroatom functionalization of neutral radicals such as thio-substituted PLY [24][25][26], azaphenalenyls [12,27,28], and bisphenalenyl boron complexes [29,30] have played a crucial role in the recent progress in phenalenyl chemistry and the important developments in heterocyclic radicals [31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structure and Solid State Properties of Cyclohexanemethylamine Substituted Phenalenyl Based Molecular Conductor

et al. 2012

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Abstract:We report the preparation, crystallization and solid state characterization of a cyclohexanemethylamine substituted spirobiphenalenyl radical; in the solid state the compound is iso-structural with its dehydro-analog (benzylamine-substitued compound), and the molecules packed in a one-dimensional fashion that we refer to as a π-step stack. Neighboring molecules in the stack interact via the overlap of one pair of active (spin bearing) carbon atoms per phenalenyl unit. The magnetic susceptibility measurement indicates that in the solid state the radical remains paramagnetic and the fraction of Curie spins is 0.75 per molecule. We use the analytical form of the Bonner-Fisher model for the S = 1/2 antiferromagnetic Heisenberg chain of isotropically interacting spins with intrachain spin coupling constant J = 6.3 cm −1 , to fit the experimentally observed paramagnetism [χ p (T)] in the temperature range 4-330 K. The measured room temperature conductivity (σ RT = 2.4 × 10 -3 S/cm) is comparable with that of the iso-structural benzyl radical, even though the calculated band dispersions are smaller than that of the unsaturated analog.

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A Stable Neutral Hydrocarbon Radical: Synthesis, Crystal Structure, and Physical Properties of 2,5,8-Tri-tert-butyl-phenalenyl

Cited by 468 publications

References 14 publications

Near-infrared absorption of π-stacking columns composed of trioxotriangulene neutral radicals

Near-infrared absorption of π-stacking columns composed of trioxotriangulene neutral radicals

Ligand-Driven Exchange Coupling in Graphene-Based Magnetic Materials

Synthesis, Structure and Solid State Properties of Cyclohexanemethylamine Substituted Phenalenyl Based Molecular Conductor

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