Triplet ESR spectrum of the copper porphyrin cation radical

Konishi, Shiro; Hoshino, Mikio; Imamura, Masashi

doi:10.1021/ja00371a060

Cited by 23 publications

(14 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…36, 40 In this complex, a metal-based unpaired electron formally resides in the d x2−y2 orbital of the Cu(II) center, which is orthogonal to the π orbitals of the tripyrrindione scaffold hosting the ligand-based electronic spin. This results in a ferromagnetic interaction between the unpaired electrons and in stabilization of the triplet state, as previously observed in Cu(II) complexes featuring planar radical ligands, 40–44 including porphyrin cation radicals, 36, 45 in which the magnetic orbitals are orthogonal.…”

Section: Resultssupporting

confidence: 66%

Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers

et al. 2017

View full text Add to dashboard Cite

The ability of tetrapyrrolic macrocycles to stabilize unpaired electrons and engage in π–π interactions is essential for many electron-transfer processes in biology and materials engineering. Herein, we demonstrate that the formation of π dimers is recapitulated in complexes of a linear tripyrrolic analog of naturally occurring pigments derived from heme decomposition. Hexaethyltripyrrindione (H3TD1) coordinates divalent transition metals (i.e., Pd, Cu, Ni) as a stable dianionic radical and was recently described as a robust redox-active ligand. The resulting planar complexes, which feature a delocalized ligand-based electronic spin, are stable at room temperature in air and support ligand-based one-electron processes. We detail the dimerization of neutral tripyrrindione complexes in solution through electron paramagnetic resonance (EPR) and visible absorption spectroscopic methods. Variable-temperature measurements using both EPR and absorption techniques allowed determination of the thermodynamic parameters of π dimerization, which resemble those previously reported for porphyrin radical cations. The inferred electronic structure, featuring coupling of ligand-based electronic spins in the π dimers, is supported by density functional theory (DFT) calculations.

show abstract

Section: Resultssupporting

confidence: 66%

Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The absence of clear fundamental transitions (Δ m s =±1) in the present spectrum does not permit a precise determination of the triplet‐state zero‐field splitting parameter ( D ) but through the use of second‐order perturbation theory20 we estimate D ≈0.5 cm −1 (14 GHz), substantially larger than the D parameter seen in the corresponding copper–porphyrin systems (0.116 cm −1 ) 21, 22…”

supporting

confidence: 86%

OC025: Diagnosis and prognosis of ischemic and hemorrhagic lesions of the fetal brain

Elchalal

Porat

Beni‐Adani³

et al. 2003

Ultrasound Obstet Gynecol

View full text Add to dashboard Cite

One ring, two oxidations: The first doubly ring‐oxidized metal phthalocyanine complex has been synthesized by galvanostatic electrocrystallization. Copper phthalocyanine was oxidized in the presence of perrhenate anions to form the new molecular compounds [Cu(pc)(ReO4)] and [Cu(pc)(ReO4)2] (structure shown). Single‐crystal EPR results show that the oxidation of [Cu(pc)(ReO4)2] is entirely ring‐based.

show abstract

“…The first oxidation potentials of the porphyrin and porphycene complexes are listed in Table 1 and correspond to the tetrapyrrole ligand centred oxidation reaction of complexes, giving p-cation radicals. [30][31][32][33][34][35][36][37] The oxidation potential of the porphycene complexes is comparable to those of the corresponding porphyrin complexes. On the other hand, the first oxidation potentials of distorted OETPP complexes are significantly lower than those for the planar porphyrin complexes.…”

Section: Redox Potentialsmentioning

confidence: 83%

Electron transfer reaction of porphyrin and porphycene complexes of Cu(ii) and Zn(ii) in acetonitrile

Aoki

Goshima

et al. 2009

Dalton Trans.

View full text Add to dashboard Cite

The outer-sphere one-electron oxidation reaction of the Cu(II) and Zn(II) complexes of nonplanar 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin and planar porphycenes as well as those of 2,3,7,8,12,13,17,18-octaethylporphyrin and 5,10,15,20-tetraphenylporphyrin by Cu(2+) giving corresponding pi-cation radicals was investigated spectrophotometrically in acetonitrile. The electron self-exchange rate constants between the parent porphyrin and porphycene complexes and their pi-cation radicals were determined using the Marcus cross relation for the electron transfer reaction. The obtained rate constants are in the order of 10(9) to 10(11) M(-1) s(-1) for the planar porphyrin and porphycene complexes and 10(4) to 10(6) M(-1) s(-1) for the nonplanar OETPP complexes at T = 25.0 degrees C. The relatively slow self-exchange reaction of the distorted porphyrin complexes, as compared with those for the planar porphyrin and porphycene complexes, was ascribed to the significant deformation of the complex associated with the oxidation reaction from the parent complex to the corresponding pi-cation radical.

show abstract

Triplet ESR spectrum of the copper porphyrin cation radical

Cited by 23 publications

References 2 publications

Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers

Interactions of Metal-Based and Ligand-Based Electronic Spins in Neutral Tripyrrindione π Dimers

OC025: Diagnosis and prognosis of ischemic and hemorrhagic lesions of the fetal brain

Electron transfer reaction of porphyrin and porphycene complexes of Cu(ii) and Zn(ii) in acetonitrile

Contact Info

Product

Resources

About