EPR spectroscopy study of di-o-quinone bridged by π-extended TTF: redox behavior and binding modes as a ligand

Chalkov, Nikolay O.; Cherkasov, V. K.; Abakumov, G. A.; Starikov, А. G.; Kuropatov, V. A.

doi:10.1039/c5nj02666k

Cited by 7 publications

(6 citation statements)

References 22 publications

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“…The spin-density distribution in the protonated semiquinones (1 · )H and (1 · )H 3 substantially differs from that observed in their analogs with metal ions [3] (see Table 1). Tentatively, this feature could be related to a different bond ionicity of the semiquinone–metal and semiquinone–proton pairs, respectively.…”

Section: Resultsmentioning

confidence: 90%

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Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

Chalkov¹,

Cherkasov²,

Abakumov

et al. 2016

Beilstein J. Org. Chem.

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The chemical oxidation and reduction processes of deprotonated, direduced o-quinone-exTTF-o-quinone in protic solvents were studied by EPR spectroscopy. The formation of relatively stable paramagnetic protonated redox forms of the parent triad was very surprising. The character of spin-density distribution in the semiquinone–quinone and semiquinone–catechol redox forms indicates that the p-phenylene-extended tetrathiafulvalene connector provides a quite effective electronic communication channel between dioxolene coordination sites. It was found that the deprotonated, direduced o-quinone-exTTF-o-quinone is capable to reduction of the metal copper in solution. The radical anion species formed in this reaction exists in solution as a solvent-separated ion pair with a copper cation. A character of spin-density distribution in a radical anion species leads to the conclusion that the ligand corresponds to type III of the Robin–Day classification.

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Section: Resultsmentioning

confidence: 90%

“…Previously we reported paramagnetic derivatives of di- o -quinone ( 1 , Fig. 1) with alkali metals [3]. Using the protonated paramagnetic derivatives of the quinone-exTTF-quinone system we succeeded in organization of a symmetric surrounding for both coordination sites of the molecule.…”

Section: Introductionmentioning

confidence: 99%

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

Chalkov¹,

Cherkasov²,

Abakumov

et al. 2016

Beilstein J. Org. Chem.

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Section: P-phenylene Extended Amphoteric Redox Triadmentioning

confidence: 94%

“…Redox properties of the di-o-quinone 84 were evaluated in reduction reactions with alkali metals. The chemical behavior of the ligand is identical to that of Q-TTF-Q: reduction of 84 proceeds in four one-electron steps: "di-o-quinone"-"o-quinone-o-semiquinone"-"di-o-semiquinone"-" o-semiquinone-catecholate" and "dicatecholate" [54]. Reduction of the diprotonated form 83 with copper in presence of 1,2-bis(diphenylphosphino)ethane leads to formation of solvent-separated radical ion pair 85: Cu(dppe) 2 + and ligand in anion-radical state (Scheme 42) [55].…”

Section: P-phenylene Extended Amphoteric Redox Triadmentioning

confidence: 96%

Functionalized o-Quinones: Concepts, Achievements and Prospects

Martyanov¹,

Kuropatov²

2018

Inorganics

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o-Quinones are both well-studied and promising redox-active chelating ligands. There are plenty of interesting effects to be found on o-quinone-derived metallocomplexes, such as photo-thermo mechanical effect in solid phase and in solution, luminescence, SMM properties and so on. A combination o-quinone function with an additional coordination site or redox active fragment in the same molecule might sufficiently extend an assembling as well as functional capability of such ligand in complexes. In this paper, the authors focus on o-quinones decorated with additional non-dioxolene chelating coordination site or with electron donor redox active annelated fragments.

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“…The spectra are dominated by the π-π* hfac − transition at high energy (33000 cm −1 ) and Intra-Ligand Charge Transfers (ILCTs) at low energy. S → L and H → L (where S = Single Occupied Molecular Orbital, L = Lowest Unoccupied Molecular Orbital and H = Highest Occupied Molecular Orbital) ILCT have been previously identified for the corresponding free H 2 SQ and Q triads with the S and H mainly localized on the extended TTF while L is situated on the semiquinone and quinone acceptors [36,49,50]. Thus for H 2 SQ-Yb and based on DFT calculations for the free H 2 SQtriad [36], the strong absorption band centered at 12500 cm −1 is attributed to the H → L ILCT and the shoulder centered at 20.000 cm −1 is attributed to S → L ILCT.…”

Section: Photophysical Propertiesmentioning

confidence: 99%

Redox-Modulations of Photophysical and Single-molecule Magnet Properties in Ytterbium Complexes Involving Extended-TTF Triads

et al. 2020

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The reaction between the 2,2’-benzene-1,4-diylbis(6-hydroxy-4,7-di-tert-butyl-1,3-benzodithiol-2-ylium-5-olate triad (H2SQ) and the metallo-precursor [Yb(hfac)3]⋅2H2O led to the formation of a dinuclear coordination complex of formula [Yb2(hfac)6(H2SQ)]⋅0.5CH2Cl2 (H2SQ-Yb). After chemical oxidation of H2SQ in 2,2’-cyclohexa-2,5-diene-1,4-diylidenebis(4,7-di-tert-butyl-1,3-benzodithiole-5,6-dione (Q), the latter triad reacted with the [Yb(hfac)3]⋅2H2O precursor to give the dinuclear complex of formula [Yb2(hfac)6(Q)] (Q-Yb). Both dinuclear compounds have been characterized by X-ray diffraction, DFT optimized structure and electronic absorption spectra. They behaved as field-induced Single-Molecule Magnets (SMMs) nevertheless the chemical oxidation of the semiquinone to quinone moieties accelerated by a factor of five the relaxation time of the magnetization of Q-Yb compared to the one for H2SQ-Yb. The H2SQ triad efficiently sensitized the YbIII luminescence while the chemical oxidation of H2SQ into Q induced strong modification of the absorption properties and thus a quenching of the YbIII luminescence for Q-Yb. In other words, both magnetic modulation and luminescence quenching are reached by the oxidation of the protonated semiquinone into quinone.

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EPR spectroscopy study of di-o-quinone bridged by π-extended TTF: redox behavior and binding modes as a ligand

Abstract: Chemical reduction of an acceptor–donor–acceptor bis-chelating system: an EPR and UV-vis study.

Cited by 7 publications

References 22 publications

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

Protonated paramagnetic redox forms of di-o-quinone bridged with p-phenylene-extended TTF: A EPR spectroscopy study

Functionalized o-Quinones: Concepts, Achievements and Prospects

Redox-Modulations of Photophysical and Single-molecule Magnet Properties in Ytterbium Complexes Involving Extended-TTF Triads

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