Carbon-based Biradicals: Structural and Magnetic Switching

Chemical Reviews, Год журнала: 2023, Номер 123(24), С. 13952 - 13965

Опубликована: Ноя. 10, 2023

Sterically hindered C═C double bonds often deform into a bent or twisted geometry. Thus, many overcrowded ethylenes anthraquinodimethanes can adopt multiple conformations, such as folded form form, which are interconvertible under the application of external stimuli. A perpendicular with biradical character also be adopted when designed to incorporate stable carbon-based radical unit, is involved in stimuli-responsive magnetic switching accompanied by structural change. This review focuses on recent advances development strained π-electron systems and reveals factors that affect mutual interconversion behavior. The energy barrier for conformational isomers affected tricyclic skeleton bulky substituents bonds, whereas relative stability increases additional insertion 9,10-anthrylene units bonds.

Язык: Английский

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Introducing Phosphorus into the Overcrowded Thiele’s hydrocarbon Family: Unveiling Contorted Main Group Diradicaloids with Dynamic Redox Behavior

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(47)

Опубликована: Авг. 19, 2024

Abstract Thiele's Hydrocarbons (THs) featuring a 9,10‐anthrylene core with switchable geometric and electronic configurations offer exciting possibilities in advanced functional materials. Despite significant advances main group‐based diradicaloids contemporary chemistry, group THs containing an anthrylene cores have remained elusive, primarily due to the lack of straightforward synthetic strategies inherent high reactivity these species. In this study, we utilize anthracene‐based phosphine synthon demonstrate, for first time, facile high‐yielding strategy robust P‐functionalized overcrowded ethylenes (OCEs) within TH family. These OCEs feature non‐symmetric environment, incorporating (thio) xanthyl phosphaalkene termini. We systematically probe structures derivatives illustrate impact isolobal motif on quinoidal/diradicaloid character. Notably, compounds exhibit dynamic redox behavior, leading orthogonally twisted conformational changes upon oxidation, kinetically locked redox‐couple.

Язык: Английский

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Open‐Shell States in Dynamic Diradicaloids

ChemPlusChem, Год журнала: 2025, Номер unknown

Опубликована: Март 18, 2025

Abstract The open‐shell organic and carbon‐based systems, with either a doublet, triplet or higher spin‐states, play key role in contemporary research, opening potential applicability for several crucial fields. Among those derivatives, specific attention has been given to p ‐phenylene‐based systems derived from the original Thiele hydrocarbon. These stabilize an diradicaloid resonance structure thermally accessible state are quinone‐benzene (Clar's sextet) equilibrium. In our discussion, we very carefully choose examples which focus on fundamental derivatives that merge diatropic subunits, ready two unpaired electrons via dynamic modulation of geometry. This process provides additional factor energy aromatics, mostly responsible stabilization electrons.

Язык: Английский

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[5]Cumulene Bridged Tri(9‐anthryl)Methyl Dimer

Chemistry - An Asian Journal, Год журнала: 2025, Номер unknown

Опубликована: Апрель 28, 2025

Abstract Toward the synthesis and evaluation of stable radical‐based 2D frameworks, a diacetylene‐bridged tri(9‐anthryl)methyl ( TAntM ) radical dimer was designed synthesized. X‐ray crystallographic analysis revealed strong spin–spin interaction between units through diacetylene linker, resulting in closed‐shell [5]cumulene structure as form. Variable‐temperature (VT) 1 H‐NMR measurements at high temperatures showed signal broadening for aromatic protons, indicating an increased population thermally excited triplet species metastable To facilitate spin‐state modulation by external stimuli, mechanical grinding solid state conducted. Due to its reactivity, partially induced structural changes state.

Язык: Английский

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Bis‐Olefin Based Crystalline Schlenk Hydrocarbon Diradicals with a Triplet Ground State

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(45)

Опубликована: Авг. 30, 2023

A modular approach for the synthesis of isolable crystalline Schlenk hydrocarbon diradicals from m-phenylene bridged electron-rich bis-triazaalkenes as synthons is reported. EPR spectroscopy confirms their diradical nature and triplet electronic structure by revealing a half-field signal. computational analysis state to be ground state. As proof-of-principle methodology, 4,6-dimethyl-m-phenylene was further utilized coupling unit between two alkene motifs. The steric conjunction 4,6-dimethyl groups substantially twists substituents at nonbonding electron bearing centers relative central motif. result, spin delocalization decreased exchange unpaired spins, hence, significantly reduced. Notably, 108 years after Schlenk's m-phenylene-bis(diphenylmethyl) diradical, first time we were able isolate its derivative with same spacer, i.e. m-phenylene, radical in form.

Язык: Английский

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Cation‐Stacking Approach Enabling Interconversion between Bis(xanthylium) and its Reduced Species

Chemistry - A European Journal, Год журнала: 2024, Номер 30(47)

Опубликована: Май 23, 2024

Cyclophane-type dications with two units of xanthylium were designed, the expectation that intramolecular interaction between cation could induce changes in absorption and redox behavior. The desired synthesized via macrocyclic diketone as a key intermediate, which was efficiently obtained by stepwise etherification. X-ray UV/Vis measurements revealed cyclophane-type adopt stacking structure both crystal solution. Due to caused π-π units, considerable blue shift compared corresponding monocations two-stage one-electron reduction process observed dications. Furthermore, upon electrochemical dications, formation biradicals radical species demonstrated spectroscopy several isosbestic points at stages. Therefore, cation-stacking approach is promising way provide novel properties due perturbation their molecular orbitals stabilize reduced even though they have open-shell characters.

Язык: Английский

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Von bis‐Olefin‐abgeleitete kristalline, diradikalische Schlenk‐Kohlenwasserstoffe mit einem Triplett‐Grundzustand

Angewandte Chemie, Год журнала: 2023, Номер 135(45)

Опубликована: Авг. 30, 2023

Abstract Beschrieben wird ein modularer Ansatz für die Synthese von kristallinen, diradikalischen Schlenk‐Kohlenwasserstoffen ausgehend m‐ Phenylen‐verbrückten, elektronenreichen bis‐Triazaalkenen. Das Auftreten eines Halbfeldsignals im EPR‐Spektrum bestätigt diradikalische Natur sowie den Triplett‐Zustand der Spezies. Dass auch dem Grundzustand entspricht, durch eine computergestützte Analyse untermauert. Um Modularität des Ansatzes zu belegen, wurde zudem 4,6‐Dimethyl‐ m ‐Phenylen‐Brücke als Verbindung zwischen beiden Alken‐Motiven untersucht. Der sterische Anspruch 4,6‐Dimethyl‐Gruppen führt einer substantiellen Rotation Substituenten an radikalischen Zentren relativ zum koppelnden ‐Phenylen‐Motiv. Daraus ergibt sich Verringerung Spin‐Delokalisierung, was in signifikant reduzierten Austauschkopplung ungepaarten Spinzuständen resultiert. Bemerkenswerterweise, konnten wir erstmalig und dies 108 Jahre nach ‐Phenylen‐Bis(Diphenylmethyl)‐Diradikals Schlenk Derivat mit gleichen zwei kristalliner Form isolieren.

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Introducing Phosphorus into the Overcrowded Thiele’s hydrocarbon Family: Unveiling Contorted Main Group Diradicaloids with Dynamic Redox Behavior

Angewandte Chemie, Год журнала: 2024, Номер 136(47)

Опубликована: Авг. 19, 2024

Abstract Thiele's Hydrocarbons (THs) featuring a 9,10‐anthrylene core with switchable geometric and electronic configurations offer exciting possibilities in advanced functional materials. Despite significant advances main group‐based diradicaloids contemporary chemistry, group THs containing an anthrylene cores have remained elusive, primarily due to the lack of straightforward synthetic strategies inherent high reactivity these species. In this study, we utilize anthracene‐based phosphine synthon demonstrate, for first time, facile high‐yielding strategy robust P‐functionalized overcrowded ethylenes (OCEs) within TH family. These OCEs feature non‐symmetric environment, incorporating (thio) xanthyl phosphaalkene termini. We systematically probe structures derivatives illustrate impact isolobal motif on quinoidal/diradicaloid character. Notably, compounds exhibit dynamic redox behavior, leading orthogonally twisted conformational changes upon oxidation, kinetically locked redox‐couple.

Язык: Английский

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Heptannulated Perylene Diimides: Formation and Reactivity of Electron‐Deficient Tropylium Cations and Heptafulvenes

Angewandte Chemie, Год журнала: 2024, Номер unknown

Опубликована: Ноя. 15, 2024

Abstract The development of new π‐conjugated motifs opens pathways to previously unexplored classes organic semiconductors and functional dyes. In this study, five‐ seven‐membered carbocycles were fused at the ortho bay regions electron‐deficient perylenes, starting from a common dialdehyde precursor. Structural analysis resulting perylene tetraesters, dianhydrides, diimides (PDIs) revealed three distinct ring‐fusion patterns defined stereochemistry. PDI cycloheptatrienes demonstrated susceptibility acid‐catalyzed transarylation, involving tropylium cation intermediates, which can be used preparatively. Under superacidic conditions, cations directly observed shown undergo hydride‐transfer reductions. Additionally, bis(heptafulvene) was synthesized by dehydrogenating suitably substituted cycloheptatriene. final system contains two quinomethane units, protonated yield stable tropylium‐like dication.

Язык: Английский

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Heptannulated Perylene Diimides: Formation and Reactivity of Electron‐Deficient Tropylium Cations and Heptafulvenes

Angewandte Chemie International Edition, Год журнала: 2024, Номер unknown

Опубликована: Ноя. 15, 2024

Abstract The development of new π‐conjugated motifs opens pathways to previously unexplored classes organic semiconductors and functional dyes. In this study, five‐ seven‐membered carbocycles were fused at the ortho bay regions electron‐deficient perylenes, starting from a common dialdehyde precursor. Structural analysis resulting perylene tetraesters, dianhydrides, diimides (PDIs) revealed three distinct ring‐fusion patterns defined stereochemistry. PDI cycloheptatrienes demonstrated susceptibility acid‐catalyzed transarylation, involving tropylium cation intermediates, which can be used preparatively. Under superacidic conditions, cations directly observed shown undergo hydride‐transfer reductions. Additionally, bis(heptafulvene) was synthesized by dehydrogenating suitably substituted cycloheptatriene. final system contains two quinomethane units, protonated yield stable tropylium‐like dication.

Язык: Английский

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