Benzo-thia-fused [n]thienoacenequinodimethanes with small to moderate diradical characters: the role of pro-aromaticity versus anti-aromaticity

Shi, Xueliang; Quintero, Estefanía; Lee, Sangsu; Jing, Linzhi; Herng, Tun Seng; Zheng, Bin; Huang, Kuo‐Wei; Navarrete, Juan T. López; Ding, Jun; Kim, Dongho; Casado, Juan

doi:10.1039/c5sc04706d

Cited by 44 publications

(27 citation statements)

References 83 publications

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“…Additionally, the NMR signals of oxidized NDI‐2 appeared at 6.07 and 8.99 ppm as temperature was decreased to 213 K (Figure S3 in the Supporting Information). This feature has been observed in many other singlet diradical systems, which is originated from the existence of thermally excited triplet species due to a small singlet‐triplet energy gap …”

Section: Methodsmentioning

confidence: 58%

“…This feature has been observed in many other singlet diradical systems, which is originated from the existence of thermally excited triplet species due to as mall singlet-tripletenergy gap. [33][34][35] To furthers upport the electronic structures of both radical and diradical, we measured electron paramagnetic resonance (EPR) spectra in CH 2 Cl 2 solutions( Figure S4 in the Supporting Information). Well-resolved EPR signals with a g-factoro f 2.0029 were observed in oxidized NDI-1 and NDI-2.I np articular,t he intensity of EPR signals in oxidized NDI-2 was increased as temperature wasi ncreased, indicating that oxidized NDI-2 has singlet ground state.…”

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confidence: 99%

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Radical and Diradical Formation in Naphthalene Diimides through Simple Chemical Oxidation

et al. 2017

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We successfully synthesized, for the first time, a naphthalene diimide (NDI) radical and diradical by simple chemical oxidation using lead(IV) dioxide. The formation of the (di)radical is confirmed by UV/Vis/NIR absorption, H NMR, and electron paramagnetic resonance (EPR) measurements. In particular, temperature-dependent EPR, SQUID (superconducting quantum interference device) measurements, and quantum calculations demonstrated that the generated NDI diradical has a singlet diradical character of y=0.69 in the ground state. Subsequent characterization of this (di)radical revealed its stabilities, large two-photon absorption cross-section, and short excited-state lifetime.

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Section: Methodsmentioning

confidence: 58%

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confidence: 99%

Radical and Diradical Formation in Naphthalene Diimides through Simple Chemical Oxidation

et al. 2017

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“…These observations indicated the ground states of all three rubicene diradicals are singlet, while Se-rubicene may have smallest singlet-triplet energy gap (ΔE ST ). 10 Page 9 of 17 CCS Chemistry Furthermore, magnetic properties of O-, S-, and Se-rubicenes solids were measured via EPR and SQUID.…”

Section: Fig 2 the Torsion Angles (A) Packing Modes (B) Multicentered...mentioning

confidence: 99%

“…First, this conversion is required to conform to the rule that aromaticity driving force surpasses the energy of breaking double bonds. [9][10][11] Second, endowing a PAH diradical with long air stability needs to elongate the distance between two radicals to lower the interaction, 12 since short-distance radical species tend to be reactive. To meet above requirements is either designing PAHs with large fused π moieties or introducing bulky groups to protect radicals.…”

Section: Introductionmentioning

confidence: 99%

Air Stable Chalcogen-Doped Rubicenes with Diradical Character

Ma¹,

Wang²,

Li³

et al. 2022

CCS Chem

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Air stable diradicaloid polycyclic aromatic hydrocarbons (PAHs) materials possess unique electronic and magnetic properties for various applications. In general, it is required to elongate conjugated distances between two radicals center to improve the air stability, complexing the synthetic procedures. Herein, the chalcogen containing rubicenes (O-, S-, and Se-rubicenes) were systematically investigated to understand the chalcogen effects on their physicochemical properties. Impressively, these rubicenes presented unprecedented diradical characters within one simple benzene ring and excellent air stabilities. Their diradical characters are manifested by single-crystal X-ray studies, variable temperature-nuclear magnetic resonance

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“…An important intrinsic factor is the ability of a molecule to switch its electronic structure from a pro-aromatic structure to an aromatic one upon excitation. [5][6][7] Now, aromaticity and antiaromaticity are concepts that come in various forms.…”

Section: Introductionmentioning

confidence: 99%

Guidelines for Tuning the Excited State Hückel-Baird Hybrid Aromatic Character of Pro-Aromatic Quinoidal Compounds

Escayola¹,

Tonnelé²,

Luis³

et al. 2020

Preprint

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<p>The present study aims to provide a solid ground for the identification, characterization and controlled design of pro-aromatic quinoidal organic compounds holding conjugated rings with Hückel and/or Baird (singlet and triplet) excited state aromatic character, and expects to become a reference work for future studies on Baird-aromaticity. Concretely, we explore a wide range of compounds with a central conjugated ring of different sizes and symmetric exocyclic substitutions. We employ a combination of different computational tools and we also introduce a new energy-based approach for the quantification of the Baird-aromatic character. </p> <p> </p> The key findings of this study indicate that Baird aromaticity is achieved in pro-aromatic quinoidal compounds having small anionic rings or in electron deficient rings with the proper exocyclic substitution. Low-lying states of these systems show very strong hole/electron overlaps, implying that their aromaticity cannot be related to intramolecular charge transfer.

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Benzo-thia-fused [n]thienoacenequinodimethanes with small to moderate diradical characters: the role of pro-aromaticity versus anti-aromaticity

Abstract: Pro-aromatic Thn-TIPS exhibits distinctly different physical properties from anti-aromatic Sn-TIPS.

Cited by 44 publications

References 83 publications

Radical and Diradical Formation in Naphthalene Diimides through Simple Chemical Oxidation

Radical and Diradical Formation in Naphthalene Diimides through Simple Chemical Oxidation

Air Stable Chalcogen-Doped Rubicenes with Diradical Character

Guidelines for Tuning the Excited State Hückel-Baird Hybrid Aromatic Character of Pro-Aromatic Quinoidal Compounds

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