Fundamental difference between simple arenes and PAHs found in <i>o</i>-PAH-connected porphyrins

Ko, Min-Sung; Hong, Jung-Ho; Desale, Pradeep P.; Roh, Tae-Ho; Cho, Dong-Gyu

doi:10.1039/d3qo01549a

Cited by 2 publications

(1 citation statement)

References 31 publications

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“…group, was more reliable than that at C18 for assessing the global aromaticity. This issue is well recognized in the literature, and inner and outer Hs are carefully chosen for obtaining experimental aromaticity . In addition, the chemical shifts of β-pyrrolic CHs (averaged values) upfield-shifted in the order of the strength of the E.W.…”

Section: Resultsmentioning

confidence: 99%

Effects of Electron-Withdrawing and Electron-Donating Groups on Aromaticity in Cyclic Conjugated Polyenes

Ko,

Roh,

Desale

et al. 2024

J. Am. Chem. Soc.

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Determining the aromaticity of various fluorinated benzenes is challenging as easily obtained experimental aromaticity [Δδ(H outer − H inner )] necessitates the chemical shifts of inner and outer protons. This issue was addressed in porphyrinoids by replacing the electron-withdrawing (E.W.) groups at the mesopositions of porphyrins and allyliporphyrins. Electronic effects on aromaticity in porphyrinoids have not been thoroughly examined in the literature. In porphyrins, the effect of E.W. groups is minimal, making it difficult to establish a clear relationship between the aromaticity strength and E.W. groups. Conversely, in allyliporphyrins, stronger E.W. groups, such as indandione (IND) derivatives, significantly reduce the aromaticity of the parent structure. The IND derivatives disrupted the aromatic pathway of allyliporphyrin more effectively than those attached to porphyrins. This is attributed to the absence of β-carbons in allyliporphyrins. The effect of electron-donating (E.D.) groups on porphyrins and allyliporphyrins was further investigated. Contrary to the initial assumption that the E.D. groups might enhance aromaticity owing to their ability to increase electron density, as the strength of the E.D. groups increased, the aromaticity of the porphyrinoids decreased. Despite the modest reduction in aromaticity, any form of electron perturbation reduces aromaticity. The aromaticity of various fluorinated benzenes is expected to parallel our observations of porphyrinoids as representative aromatic polyenes.

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Section: Resultsmentioning

confidence: 99%

Effects of Electron-Withdrawing and Electron-Donating Groups on Aromaticity in Cyclic Conjugated Polyenes

Ko,

Roh,

Desale

et al. 2024

J. Am. Chem. Soc.

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Two Different Clar’s Sextets: Clar’s Rule Does Not Necessarily Contradict the Global Pathway of Conjugated Macrocycles

Desale,

Ko,

Roh

et al. 2024

J. Am. Chem. Soc.

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Fundamental difference between simple arenes and PAHs found in o-PAH-connected porphyrins

Abstract: Simple arenes and PAHs are distinguishable, but identifying their unique differences poses a challenge. This manuscript reveals, for the first time, how these differences manifest in global aromaticity within porphyrinoids.

Cited by 2 publications

References 31 publications

Effects of Electron-Withdrawing and Electron-Donating Groups on Aromaticity in Cyclic Conjugated Polyenes

Effects of Electron-Withdrawing and Electron-Donating Groups on Aromaticity in Cyclic Conjugated Polyenes

Two Different Clar’s Sextets: Clar’s Rule Does Not Necessarily Contradict the Global Pathway of Conjugated Macrocycles

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