Ein N‐Heterozyklisches Chinodimethan: Eine starke organische Lewis‐Base mit Diradikal‐Charakter DOI Creative Commons
Jama Ariai,

Maya Ziegler,

Christian Würtele

et al.

Angewandte Chemie, Journal Year: 2023, Volume and Issue: 136(16)

Published: Dec. 13, 2023

Abstract Wir berichten über die Darstellung eines neuen organischen σ‐Donors mit einem C 6 H 4 ‐Linker zwischen N ‐heterozyklischen Carben (NHC) und einer exozyklischen Methylidengruppe, den wir als ‐heterozyklisches Chinodimethan (NHQ) bezeichnen. Die Aromatisierung des ‐Linkers liefert eine entscheidende Triebkraft für Reaktion NHQs Elektrophil macht das NHQ deutlich basischer analoge NHCs oder ‐heterozyklische Olefine (NHOs), wie DFT‐Berechnungen Konkurrenzexperimente zeigen. In Lösung findet beim unerwartete Kopf‐Kopf‐Dimerisierung unter formaler Wasserstofffreisetzung durch C−C‐Kopplung der Methylidengruppen statt. zeigen, dass diese einen offenschaligen Singulettpfad verläuft, was auf diradikalischen Charakter hinweist. Das Produkt dieser Dimerisierung kann konjugiertes Bis‐Chinodimethan beschrieben werden, laut zyklischer Voltammetrie ein starkes organisches Reduktionsmittel ist ( E 1/2 =−1.71 V vs. Fc/Fc + ) bemerkenswert kleine Singulett–Triplett‐Lücke von Δ S→T =4.4 kcal mol −1 aufweist.

Dianionic and Neutral Diboron-Centered Classical Diradicaloids DOI
Ayan Das, Benedict J. Elvers, Nicolas Chrysochos

et al.

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(13), P. 9004 - 9011

Published: March 19, 2024

Herein, we report the syntheses and electronic structures of crystalline dianionic as well neutral diboron-centered classical diradicaloids boron analogues Thiele, Chichibabin, Müller (this only for diradicaloids!) hydrocarbons. These are based on borane radical anion NHC-stabilized boryl spin carriers, respectively. All these exhibit triplet population at room temperature regardless π-conjugated spacer: p-phenylene, p,p′-biphenylene, or p,p″-terphenylene. In case diradicaloids, employed spacer plays a crucial role temperature: EPR inactive p-phenylene vs active p,p′-biphenylene. The findings emphasize importance carriers resulting ground-state: along with pivotal spin-coupler between two spins. Notably, 100 years (a century) after first by Krause triphenyl radical-anion, being isoelectronic to triphenylmethyl radical, convey anion-based diradicaloids. Furthermore, while donor-stabilized radicals were introduced in 1980s Giles Roberts, said concept is herewith extended radical-based

Language: Английский

Citations

5
Thermal Equilibrium Between Quinoid/Biradical Forms Enhancing Electrochemical Amphotericity DOI
Yusuke Ishigaki,

Shin‐ichi Mizuno,

Kazuma Sugawara

et al.

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(35)

Published: April 22, 2024

Upon dibenzo annulation on Thiele's hydrocarbon (tetraphenyl-p-quinodimethane), the quinoid form and biradical adopt quite different geometries, thus are no longer resonance structures. When these two forms can interconvert rapidly due to small energy barrier (ΔG

Language: Английский

Citations

4
Manipulating Aromaticity to Redirect Topochemical Polymerization Pathways DOI
Qingsong Zhang, Zhipeng Pei, Ah‐Young Song

et al.

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: unknown

Published: April 15, 2025

Topochemical polymerization (TCP) represents an essential route to create regio- and stereoregular polymers through solid-state transformations. Herein, we present innovative strategy for controlling topochemical pathways by tailoring the terminal group aromaticity in para-azaquinodimethane (AQM) ring system. Substituting phenyl groups with less aromatic furyl units extends significant spin density delocalization across conjugated core upon thermal activation, inducing diradicaloid characters at positions enabling unconventional reactivities both solution solid states. Thermal treatment toluene yields a unique cyclophane dimer formed via furyl-methine C-C coupling, confirmed X-ray crystallography, while reactions produce intercolumnar coupling intracolumnar methine-methine coupling. The spin-center-directed mechanism underlying these transformations is validated theoretical modeling isotopic labeling experiments. This study highlights prowess of modulation functional pro-aromatic systems, which enables synthesis main chain structures that are otherwise difficult access.

Language: Английский

Citations

0
Structural‐Change‐Induced Two‐Stage Redox Behavior of Pentacenebisquinodimethane with Tricolor Chromism DOI
Yusuke Ishigaki,

Shin‐ichi Mizuno,

Takashi Harimoto

et al.

Chemistry - An Asian Journal, Journal Year: 2024, Volume and Issue: 19(17)

Published: May 31, 2024

Tricolor electrochromism was realized through the interconversion among neutral (yellow), dicationic (green), and tetracationic (blue) states, even though only one kind of chromophore is generated upon oxidation. Both states were isolated as stable salts, their different colors come from effective inter-chromophore interaction in state but not state. Despite negligible Coulombic repulsion with four cyanine-type chromophores, pentacenebisquinodimethane undergoes stepwise two-stage two-electron oxidation when radical-stabilizing 5-(4-octyloxyphenyl)-2-thienyl groups are attached on exomethylene bonds. A contribution biradical form reason for observed negative cooperativity during electrochemical

Language: Английский

Citations

3
An N‐Heterocyclic Quinodimethane: A Strong Organic Lewis Base Exhibiting Diradical Reactivity DOI Creative Commons
Jama Ariai,

Maya Ziegler,

Christian Würtele

et al.

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 63(16)

Published: Dec. 13, 2023

We report the preparation of a new organic σ-donor with C

Language: Английский

Citations

5
N‐Heterocyclic Carbene Analogues of Wittig Hydrocarbon DOI Creative Commons
Henric Steffenfauseweh, Yury V. Vishnevskiy, Beate Neumann

et al.

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(26)

Published: March 4, 2024

N-Heterocyclic carbene (NHC) analogues of Wittig hydrocarbon, [(NHC)(Stil)(NHC)] (3a-c) (NHC = SIPr (1a) C[N(Dipp)CH

Language: Английский

Citations

1
Molecular Insights into [2.2]Paracyclophane‐Based Functional Materials: Chemical Aspects Behind Functions DOI Creative Commons
Zahid Hassan

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: 34(47)

Published: April 15, 2024

Abstract Many of the functions and features practically useful materials are province molecular‐level chemistry their modulation at different length‐scale. This report illustrates behind [2.2]paracyclophane‐based with a particular focus on most recent explorations through‐space conjugated small‐molecule organic emitters, π‐stacked macrocyclic molecules polymers, poly(p‐phenylenevinylene)s featuring well‐defined donor‐acceptors sequence control, surface engineering technologically‐relevant parylenes that finds broad applications across field chemical science technology. largely deals potential opportunities associated molecular planar chirality, conformational behaviors, strain‐induced non‐planarity aromatics, profound impacts conjugation π‐electron interactions/delocalization optoelectronic properties π‐conjugated polymers extended structures consisting cyclophanes. A special is put concept supramolecular using chemically‐programmed chiral cyclophanes via non‐covalent stacking controlled arrangements. Illustrating cyclophane as precursors/monomers fabrication strategies for incorporation in structurally‐controlled (poly( p ‐xylylene)s formed vapor deposition polymerization post‐deposition interface described. Demonstrating rather approach electronically‐dictated ring‐opening metathesis employing strained cyclophane‐diene precursors generate poly( ‐phenylenevinylene)s (i.e., low dispersity) donor‐acceptor control also discussed. will serve an indispensable one‐stop reference organic, polymer chemists, well material scientists working research innovations.

Language: Английский

Citations

1
Interception and Synthetic Application of Diradical and Diene Forms of Dual‐Nature Azabicyclic o‐Quinodimethanes Generated by 6p‐Azaelectrocyclization DOI Creative Commons

Shankar Majji,

Daniel J. Lee,

Supuni I. N. Hewa Inaththappulige

et al.

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(41)

Published: July 18, 2024

We demonstrate that 2-alkenylarylaldimines and ketimines undergo thermal 6π-azaelectrocyclization to generate a wide range of azabicyclic o-quinodimethanes (o-QDMs). These o-QDMs exist as hybrid diene benzylic diradical. The diradical nature was confirmed by their ability dimerization react with H-atom donor, 2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) O

Language: Английский

Citations

1
Radical versus Non-Radical Reactivity in ortho- and para-Quinonedimethides and Implications for Cycloaddition Mechanisms DOI
Zhipeng Pei,

Kieran P. E. Connor,

Nicholas L. Magann

et al.

Organic Letters, Journal Year: 2024, Volume and Issue: 26(38), P. 8110 - 8114

Published: Sept. 16, 2024

The latent singlet diradical character of the parent

Language: Английский

Citations

1
Gated off-site radical injection: Bidirectional conductance modulation in single-molecule junctions DOI Creative Commons

Hanjun Zhang,

Lichuan Chen, Xiaodong Liu

et al.

Science Advances, Journal Year: 2024, Volume and Issue: 10(44)

Published: Nov. 1, 2024

Uncovering the effects of radical injection into responsive organic molecules is a long-sought goal, and single-molecule junctions provide unique way to investigate molecular conductance evolution during injection. We can modulate main channel by using electronic from off-site neutral radicals acting as gating terminals. Two families cyclopentadienone derivatives were synthesized, featuring inter-pyridyl inter-radical paths that are linear (FCF) or cross conjugated (PCP). Using scanning tunneling microscope break junction technique, we find mono- diradicals in PCP system unexpectedly decreases regarding closed-shell analog, while FCF systems increases. Through-bond through-space mechanisms found series, respectively, jointly overall charge transmission. This concept offers promising approach for developing devices manipulating electrical junctions.

Language: Английский

Citations

1