General Graph Theory of Superaromaticity

Aihara, Jun‐ichi

doi:10.1246/bcsj.66.57

Cited by 134 publications

(393 citation statements)

References 22 publications

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“…If a π-system contains three or more rings, one or more terms are necessary in the expansion of P G (X) like eq 19, which represent additional contributions from two or more disjoint circuits. We previously derived the following approximate but amazing formulas to interpret the total π-binding energy E π and TRE for a neutral conjugated hydrocarbon in terms of molecular geometry: 71,72 E % 6:0846 log 10 jP G ðiÞj ð24Þ E % 6:0846 log 10 jR G ðiÞj ð25Þ TRE % 6:0846 log 10 jP G ðiÞj À 6:0846 log 10 jR G ðiÞj ð26Þ where i is the square root of ¹1. The function value «P G (i)« was proposed as a generalized expression for Hosoya's z* index.…”

Section: Visualization Of Aromatic Stabilizationmentioning

confidence: 99%

“…4,56 Therefore, we can only say that aromatic species have a greater probability of being kinetically more stable than non-or antiaromatic ones. 57 It, nevertheless, is generally true that highly antiaromatic molecules are too reactive to isolate. As for PAHs, TRE per π-electron is roughly linear in the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO).…”

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confidence: 99%

“…In our view, the TRE concept is safely applicable to cyclic conjugated molecules, as far as simple HMO theory describes well the π-systems. It seems that the aromaticity of cyclic bicalicene (57), 67,68 which consists of two calicene units, is also overestimated to some extent.…”

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Graph Theory of Aromatic Stabilization

Aihara¹

2016

BCSJ

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Aromaticity is very sensitive to the geometry of the π-system. Topological resonance energy (TRE), defined graphtheoretically, represents an aromatic stabilization energy (ASE) arising from cyclic conjugation in the π-system. TRE can be calculated for not only ground-state but also excited-state species. The TRE concept has since been extended analytically to solve many different problems concerning aromaticity and reactivity. Bond resonance energy (BRE), defined in harmony with TRE, is an excellent probe for exploring kinetic stability of cyclic π-systems. It represents the contribution of individual π-bonds to global aromaticity. The well-known isolated pentagon rule (IPR) for fullerenes was verified in terms of BRE. Superaromatic stabilization energy (SSE) defined for macrocyclic π-systems finally confirmed the absence of macrocyclic aromaticity in kekulene. A novel local aromaticity index for polycyclic aromatic hydrocarbons (PAHs) was devised by reinterpreting the definition of SSE. We then found that aromatic properties of some PAHs are not compatible with Clar's aromatic sextet rule. We now feel that many fundamental problems with regard to aromatic stabilization and related phenomena have been solved conceptually.

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Section: Visualization Of Aromatic Stabilizationmentioning

confidence: 99%

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Graph Theory of Aromatic Stabilization

Aihara¹

2016

BCSJ

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“…Only a few studies on the optical characterization of the molten CT complexes have been reported. 831 In the following we describe a drastic decrease in resistivity by a factor of 10 5 -10 6 upon the melting of a neutral alternating CT complex, C 7 TET-TTF Á TCNQ (Chart 15). Syntheses and characterizations of C n TET-TTF have been studied by Otsuka, Saito, et al 832 The molecules with intermediate alkyl chain lengths exhibited considerably low melting points owing to the increased fusion entropy (Fig.…”

Section: Reticulate Doped Polymer (Rdp) Filmsmentioning

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Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

Saito¹,

Yoshida²

2007

Bulletin of the Chemical Society of Japan

370

127

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“…Aihara (17) reported the vapor pressure of benzil as a function of temperature. From his correlation equation…”

Section: Resultsmentioning

confidence: 99%

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Abraham

2002

Journal of Solution Chemistry

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The Abraham general solvation model is used to calculate the numerical values of the solute descriptors for benzil from experimental solubilities in organic solvents. The mathematical correlations take the formwhere C S and C W refer to the solute solubility in the organic solvent and water, respectively, C G is a gas-phase concentration, R 2 is the solute excess molar refraction, V x is the McGowan volume of the solute, fi H 2 and fl H 2 are measures of the solute hydrogenbond acidity and basicity, … H 2 denotes the solute dipolarity/polarizability descriptor, and L [16] is the solute gas-phase dimensionless Ostwald partition coefficient into hexadecane at 25 • C. The remaining symbols in the above expressions are known solvent coefficients, which have been determined previously for a large number of gas/solvent and water/solvent systems. We estimate R 2 as 14.45 cm 3 -mol −1 and calculate V x as 163.74 cm 3 -mol −1 , and then solve a total of 51 equations to yield … H 2 = 1.59, fl H 2 = 0.620 and log L [16] = 7.6112. These descriptors reproduce the 51 observed log(C S /C W ) and log(C S /C G ) values with a standard deviation of only 0.115 log units.

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General Graph Theory of Superaromaticity

Cited by 134 publications

References 22 publications

Graph Theory of Aromatic Stabilization

Graph Theory of Aromatic Stabilization

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

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