Electron paramagnetic resonance identification of a nickel(III) compound produced by electrochemical oxidation of nickel(II) tetraphenylporphyrin

Wolberg, Alexander; Manassen, J.

doi:10.1021/ic50092a035

Cited by 57 publications

(21 citation statements)

References 2 publications

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“…At 77 K the orangered solid showed signals at g, = 2.286 and gll = 2.086, consistent with a low spin d7 (Ni(II1)) electronic configuration and in good agreement with spectra reported by Busch and co-workers (19) and by Wolberg and Manassen (15) for Ni(II1) complexes. The epr signal of the Ni(II1) species slowly decayed with time, being replaced after -24 h by a weak isotropic signal which also decayed with time.…”

Section: Electron Poi-amngnetic Resonancesupporting

confidence: 90%

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Electron transport via metalloporphyrins

Johnson¹,

Niem²,

Doolphin³

1978

Can. J. Chem.

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The controlled potential electrolysis of Ni(II) meso-tetraphenylporphyrin (Ni(II)TPP) gives at room temperature the corresponding metalloporphyrin π-cation radical [Ni(II)TPP]+ •. Upon freezing a solution of the π-cation radical to 77 K an internal electron transfer occurs to give [Ni(III)TPP]+. A discussion of the routes of electron transport in heme proteins is given, and the roles of metalloporphyrin π-cation radicals in electron transport is evaluated.

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Section: Electron Poi-amngnetic Resonancesupporting

confidence: 90%

“…Wolberg and Manassen (15) have reported that the electrochemical oxidation of Ni(I1)TPP in benzonitrile initially givesa Ni(III)TPP+ species which decayed t o a Ni(II)TPP+ ' species. The presence of the two complexes was suggested by epr.…”

Section: Introductionmentioning

confidence: 99%

Electron transport via metalloporphyrins

Johnson¹,

Niem²,

Doolphin³

1978

Can. J. Chem.

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“…[35,39,41] DFT calculations at the RIJCOSX-BP86-D3-ZORA/def2-TZVP level of theory [with and withouts olvent modelling by CPCM(CH 2 Cl 2 )] correctly describe [NiDPP]C + and [NiP 3 P]C + as p radical cationsw ith saddle-shaped macrocycles ( Figure 6). [35,39,41] DFT calculations at the RIJCOSX-BP86-D3-ZORA/def2-TZVP level of theory [with and withouts olvent modelling by CPCM(CH 2 Cl 2 )] correctly describe [NiDPP]C + and [NiP 3 P]C + as p radical cationsw ith saddle-shaped macrocycles ( Figure 6).…”

Section: Resultsmentioning

confidence: 99%

“…DFT calculations with B3LYP,T PSSH and PBE0 functionals converged to weakly distortedn ickel(III) valence isomersa s ground states, which are not observed under our conditions in the EPR spectra.A mbiguities and difficulties in assigning the correct valence isomeric descriptionsh ave been noted before for [NiTPP]C + . [35,39,41] DFT calculations at the RIJCOSX-BP86-D3-ZORA/def2-TZVP level of theory [with and withouts olvent modelling by CPCM(CH 2 Cl 2 )] correctly describe [NiDPP]C + and [NiP 3 P]C + as p radical cationsw ith saddle-shaped macrocycles ( Figure 6). [42] The actuals ymmetry of the spin density in the p radical (a 1u or a 2u in the idealised D 4h symmetry point group) is often ambiguousa sw ell due to static and/ord ynamic pseudo-Jahn-Te ller effects which mixt hese states by appropriate vibrational modes.…”

Section: Mechanistic Aspects Of Ocvd Of Nickel Porphyrinsmentioning

confidence: 99%

Reactivity of Nickel(II) Porphyrins in oCVD Processes—Polymerisation, Intramolecular Cyclisation and Chlorination

Bengasi

Baba

Back

et al. 2019

Chemistry A European J

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Oxidative chemical vapour deposition of (5,15‐diphenylporphyrinato)nickel(II) (NiDPP) with iron(III) chloride as oxidant yielded a conjugated poly(metalloporphyrin) as a highly coloured thin film, which is potentially useful for optoelectronic applications. This study clarified the reactive sites of the porphyrin monomer NiDPP by HRMS, UV/Vis/NIR spectroscopy, cyclic voltammetry and EPR spectroscopy in combination with quantum chemical calculations. Unsubstituted meso positions are essential for successful polymerisation, as demonstrated by varying the porphyrin meso substituent pattern from di‐ to tri‐ and tetraphenyl substitution. DFT calculations support the proposed radical oxidative coupling mechanism and explain the regioselectivity of the C−C coupling processes. Depositing the conjugated polymer on glass slides and on thermoplastic transparent polyethylene naphthalate demonstrated the suitability of the porphyrin material for flexible optoelectronic devices.

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“…Complex Ni II -4 exhibits two oxidations at 0.43 and 0.86 V that correlate to the formation of [Ni II P]C + and [Ni II P] 2 + accordingly. When the reductive scans are considered, the C 60 reductions evolve at À0.87, À1.33, and À1.84 V, whereas [Ni II P]C À [18] formation takes place at À1.68 V. The voltamogram of Mn III -4 reveals a single oxidation at 0.88 V that gives [Mn III P]C + . [19] Of the four reductive processes detected, the ones at À1.25 and À1.97 V are assigned to C 60 -based reductions, whereas those at À0.77 and À1.82 V are thought to represent the reductions of [Mn III P] to [Mn II P] and to [Mn I P].…”

Section: Resultsmentioning

confidence: 99%

A Charge‐Transfer Challenge: Combining Fullerenes and Metalloporphyrins in Aqueous Environments

Krokos

Spänig

Ruppert

et al. 2011

Chemistry A European J

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A series of truly water-soluble C(60)/porphyrin electron donor-acceptor conjugates has been synthesized to serve as powerful mimics of photosynthetic reaction centers. To this end, the overall water-solubility of the conjugates was achieved by adding hydrophilic dendrimers of different generations to the porphyrin moiety. An important variable is the metal center of the porphyrin; we examined zinc(II), copper(II), cobalt(II), nickel(II), iron(III), and manganese(III). The first insights into electronic communication between the electron donors and the electron acceptors came from electrochemical assays, which clearly indicate that the redox processes centered either on C(60) or the porphyrins are mutually affected. Absorption measurements, however, revealed that the electronic communication in terms of, for example, charge-transfer features, remains spectroscopically invisible. The polar environment that water provides is likely to be a cause of the lack of detection. Despite this, transient absorption measurements confirm that intramolecular charge separation processes in the excited state lead to rapid deactivation of the excited states and, in turn, afford the formation of radical ion pair states in all of the investigated cases. Most importantly, the lifetimes of the radical ion pairs were found to depend strongly on several aspects. The nature of the coordinated metal center and the type of dendrimer have a profound impact on the lifetime. It has been revealed that the nature/electronic configuration of the metal centers is decisive in powering a charge recombination that either reinstates the ground state or any given multiplet excited state. Conversely, the equilibrium of two opposing forces in the dendrimers, that is, the interactions between their hydrophilic regions and the solvent and the electronic communication between their hydrophobic regions and the porphyrin and/or fullerene, is the key to tuning the lifetimes.

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Electron paramagnetic resonance identification of a nickel(III) compound produced by electrochemical oxidation of nickel(II) tetraphenylporphyrin

Cited by 57 publications

References 2 publications

Electron transport via metalloporphyrins

Electron transport via metalloporphyrins

Reactivity of Nickel(II) Porphyrins in oCVD Processes—Polymerisation, Intramolecular Cyclisation and Chlorination

A Charge‐Transfer Challenge: Combining Fullerenes and Metalloporphyrins in Aqueous Environments

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