Conjugation Paths in Monosubstituted 1,2- and 2,3-Naphthoquinones

Shahamirian, Mozhgan; Cyrański, Michał K.; Krygowski, Tadeusz M.

doi:10.1021/jp2036179

Cited by 14 publications

(15 citation statements)

References 25 publications

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“…We followed the conjugation path method applied in Ref. to characterize structural aromaticity of the studied DHPR and DHPC systems. In that study, the HOMA index was not used as an aromaticity index, but rather as a measure of delocalization at the given conjugation path.…”

Section: Resultsmentioning

confidence: 99%

On the incorporation effect of the ring-junction heteroatom. The sEDA(III) and pEDA(III) Descriptors

Mazurek

Dobrowolski

2014

J. Phys. Org. Chem.

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Descriptors of the heteroatom incorporation effect in the ring-junction position, sEDA(III) and pEDA(III), are introduced for the first time. They express the change in the σ and π valence electron population produced by the heteroatom. The sEDA(III) descriptor is a good measure of electronegativity of ring-junction incorporants. Unexpectedly, the pEDA(III) descriptor does not correlate with π-electron characteristics because the 'aromatic' bond pattern in the considered fused ring systems depends on the incorporants' change within the group or period of the periodic system. We found that the HOMA aromaticity index of conjugated paths is useful to trace π-electron flows in heteroatom-incorporated polycyclic (aromatic) systems.

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Section: Resultsmentioning

confidence: 99%

On the incorporation effect of the ring-junction heteroatom. The sEDA(III) and pEDA(III) Descriptors

Mazurek

Dobrowolski

2014

J. Phys. Org. Chem.

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“…In addition to the important conclusions presented above, when the HOMA values of the ring of the studied systems are plotted against substituent constants, the linear regression has a good correlation (cc = − 0.930): the stronger electron donating substituent, the higher value of HOMA. onosubstituted 1,2-and 2,3-naphthoquinone derivatives have been the subject of studies on conjugated paths between CO groups and the substituents (X = NO, NO 2 , CN, CHO, Me, OMe, OH, NH 2 , NHMe, and NMe 2 ) [158]. The applications of the π-electron delocalization characteristics, such as FLU, DI, and HOMA, as well as changes in the CO bond lengths and SESE calculation, allowed for a better recognition of the problem.…”

Section: Polysubstituted π-Electron Systemsmentioning

confidence: 99%

“…To characterize π-electron delocalization HOMA, FLU, SA (Shannon aromaticity) [162] and Table 4 Statistics of regression (y = a × σ + b) of bond lengths and DI values for both carbonyl groups, SESE, HOMA, and FLU values of the rings on substituent constants for 2,3-naphthoquinone derivatives, correlation coefficients (R) taken as modulo value (from ref. [158] NICS(1)zz aromaticity indices were used. Both in the case of isolated monomers and H-bonded complexes, excellent linear correlations (R 2 ≥ 0.97) were found between aromaticity indices and the substituent constants.…”

Section: Polysubstituted π-Electron Systemsmentioning

confidence: 99%

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On the relations between aromaticity and substituent effect

2019

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Aromaticity/aromatic and substituent/substituent effects belong to the most commonly used terms in organic chemistry and related fields. The quantitative description of aromaticity is based on energetic, geometric (e.g., HOMA), magnetic (e.g., NICS) and reactivity criteria, as well as the properties of the electronic structure (e.g., FLU). The substituent effect can be described using either traditional Hammett-type substituent constants or characteristics based on quantum-chemistry. For this purpose, the energies of properly designed homodesmotic reactions and electron density distribution are used. In the first case, a descriptor named SESE (energy stabilizing the substituent effect) is obtained, while in the second case cSAR (charge of the substituent active region), which is the sum of the charge of the ipso carbon atom and the charge of the substituent. The use of the above-mentioned characteristics of aromaticity and the substituent effect allows revealing the relationship between them for mono-, di-, and polysubstituted π-electron systems, including substituted heterocyclic rings as well as quasi-aromatic ones. It has been shown that the less aromatic the system, the stronger the substituent influence on its π-electron structure. In all cases, when the substituent changes number of π-electrons in the ring in the direction of 4N+2, its aromaticity increases. Intramolecular charge transfer (a resonance effect) is privileged in cases where the number of bonds between the electron-attracting and electron-donating atoms is even. Quasi-aromatic rings, when attached to a truly aromatic hydrocarbon, simulate well the Boriginal^aromatic rings, alike the benzene. For larger systems, a long-distance substituent effect has been found.

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“…In the case of ortho-benzoquinone, many aromaticity indices such as HOMA [6,7], MCI [8,9] or FLU [10] indicated antiaromatic properties of the ring [11] in contrast to benzene ring known as the archetypic aromatic π-electron system [12][13][14][15]. Moreover, the HOMA [6,7] values for the ring with the two CO groups are −1.353 and −1.277 for 1,2-and 2,3-naphthoquinone [16], respectively, indicating antiaromaticity, whereas HOMA for the ring in naphthalene amounts to 0.811 [17].…”

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Why 1,2-quinone derivatives are more stable than their 2,3-analogues?

et al. 2015

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In this work, we have studied the relative stability of 1,2- and 2,3-quinones. While 1,2-quinones have a closed-shell singlet ground state, the ground state for the studied 2,3-isomers is open-shell singlet, except for 2,3-naphthaquinone that has a closed-shell singlet ground state. In all cases, 1,2-quinones are more stable than their 2,3-counterparts. We analyzed the reasons for the higher stability of the 1,2-isomers through energy decomposition analysis in the framework of Kohn–Sham molecular orbital theory. The results showed that we have to trace the origin of 1,2-quinones’ enhanced stability to the more efficient bonding in the π-electron system due to more favorable overlap between the SOMOπ of the ·C4n−2H2n–CH·· and ··CH–CO–CO· fragments in the 1,2-arrangement. Furthermore, whereas 1,2-quinones present a constant trend with their elongation for all analyzed properties (geometric, energetic, and electronic), 2,3-quinone derivatives present a substantial breaking in monotonicityThis work has been supported by the European Union in the framework of European Social Fund through the Warsaw University of Technology Development Programme. O.A. S., H. S. and T.M. K. gratefully acknowledge the Foundation for Polish Science for supporting this work under MPD/2010/4 project "Towards Advanced Functional Materials and Novel Devices-Joint UW and WUT International PhD Programme" and the Interdisciplinary Center for Mathematical and Computational Modeling (Warsaw, Poland) for providing computer time and facilities. Thanks are also to the Ministerio de Economia y Competitividad of Spain (Projects CTQ2011-23156/BQU and CTQ2011-25086) and the Generalitat de Catalunya (project numbers 2014SGR931, Xarxa de Referencia en Quimica Teorica i Computacional, and ICREA Academia 2014 prize for MS

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Conjugation Paths in Monosubstituted 1,2- and 2,3-Naphthoquinones

Cited by 14 publications

References 25 publications

On the incorporation effect of the ring-junction heteroatom. The sEDA(III) and pEDA(III) Descriptors

On the incorporation effect of the ring-junction heteroatom. The sEDA(III) and pEDA(III) Descriptors

On the relations between aromaticity and substituent effect

Why 1,2-quinone derivatives are more stable than their 2,3-analogues?

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