Aggregation in high-spin ferric complexes of tetraarylporphyrins. Structure determination using intermolecular electron-nuclear dipolar relaxation

Snyder, Richard V.; Mar, Gerd N. La

doi:10.1021/ja00464a013

Cited by 29 publications

(14 citation statements)

References 2 publications

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“…26,38 Axial ligation can also occur via dimerization of CuPs, which is strongly affected by the nature of the porphyrin and solvent involved. [39][40][41][42][43][44] Self-aggregation has been reported for tetraphenyl porphyrins, including water-soluble derivatives. 39,40,44 Nevertheless, because very similar polarization patterns are obtained for different porphyrins in different solvents, an influence from aggregation on the electron spin polarization of the copper porphyrins studied here is unlikely, even though such dimers may be formed.…”

Section: Energetics and Possible Relaxation Pathwaysmentioning

confidence: 99%

“…[39][40][41][42][43][44] Self-aggregation has been reported for tetraphenyl porphyrins, including water-soluble derivatives. 39,40,44 Nevertheless, because very similar polarization patterns are obtained for different porphyrins in different solvents, an influence from aggregation on the electron spin polarization of the copper porphyrins studied here is unlikely, even though such dimers may be formed. 45 Moreover, an important consequence of the axial ligation of copper is the strong effect on the excited-state lifetimes.…”

Section: Energetics and Possible Relaxation Pathwaysmentioning

confidence: 99%

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Light‐induced electron spin polarization in the ground state of water‐soluble copper porphyrins

Rozenshtein

Berg

Levanon

et al. 2003

Israel Journal of Chemistry

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Light‐induced spin‐polarized transient EPR spectra are reported for several water‐soluble copper porphyrins. The spectra are assigned to the doublet ground state, with emissive spin polarization resulting from photoexcitation and subsequent electronic relaxation. In contrast to other systems for which polarization of a doublet ground state has been observed, the exchange interactions in the copper porphyrins are strong and the geometry is fixed. It is proposed that intersystem crossing from the photoexcited trip‐doublet to the trip‐quartet state can lead to net polarization of the spin system and that this polarization is maintained during electronic decay, possibly via charge‐transfer and exciplex states. The intensity of the observed spin polarization is essentially independent of the molecular orientation in the external field, but is strongly dependent on the nature of the charged peripheral groups. Possible reasons for this behavior are discussed.

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Section: Energetics and Possible Relaxation Pathwaysmentioning

confidence: 99%

Section: Energetics and Possible Relaxation Pathwaysmentioning

confidence: 99%

Light‐induced electron spin polarization in the ground state of water‐soluble copper porphyrins

Rozenshtein

Berg

Levanon

et al. 2003

Israel Journal of Chemistry

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“…Again, extensive aggregate tetraphenylporphyrin iron(III) halides in solution has been elegantly detected in organic solvents by Snyder and La Mar through NMR relaxation measurements. 26 At intermediate concentrations the (22) Abraham, R. J.; Barnett, G. H.; Bretschneider, E. S.; Smith, K. M.…”

Section: Discussionmentioning

confidence: 99%

Homo- and heterodimer formation in metalloporphyrins

Banci¹

1985

Inorg. Chem.

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The dimer formation constants in chloroform for CuP, AgP, and VOP, where P is mesoporphyrin IX dimethyl ester, have been obtained through EPR measurements at room temperature and spectral simulation. For CuP, measurements have been performed also in 1,1,2,2-tetrachloroethane and dichloromethane, and aggregation was found to be sensibly different in the three solvents. Heterodimer formation constants have been determined between the above metalloporphyrins and FePCl. Invariably the latter constants are larger than expected on the basis of the homodimer formation constants. The frozen-solution EPR spectra of CuP and AgP have provided the spectra of the pure dimeric species through computer manipulation. Evidence of two dimeric species is provided by the frozen-solution EPR spectra of VOP.

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“…This was further subjected to fractional trap-to-trap distillation to give reduced 2 and recovered 1 at an oven temperature of 60 °C (5 mmHg) and the product at higher temperatures (120-200 °C) and more reduced pressure (2 mmHg). Otherwise, solid products (4,7,(12)(13)(14)(15) were recrystallized from methanol after chromatography. Only for 16, purification was achieved by preparative TLC developed with 5/1 (v/v) hexane/ethyl acetate.…”

Section: Methodsmentioning

confidence: 99%

“…It may also be possible that more than one mechanism operates concurrently.2 While, in the past decade, this type of coupling procedure has been considerably broadened by the cooperation of transition metals such as copper, nickel, and palladium,3 the displacement of ferf-alkyl halides with organoalkali metals has not yet been achieved efficiently, due to the intrinsic structure; an Sn2 mechanism is incompatible with the fert-alkyl group and side reactions (e.g., elimination) often dominate. 4 In our continuous interest in the synthesis of adamantane derivatives, the substitution at its bridgehead has been desired using any given organometallics. In the preceding papers, organosilanes have been demonstrated to be useful,5 since the moderately electropositive silicon is rather suited to the mode of this substitution (electrophilic conditions).…”

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confidence: 99%

Cross-coupling reaction of tert-alkyl halides with Grignard reagents in dichloromethane as a non-Lewis basic medium

Ohno¹,

Shimizu²,

Ishizaki³

et al. 1988

J. Org. Chem.

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In dichloromethane as a non-Lewis basic solvent, 1 -haloadamantane 1 underwent a cross-coupling reaction with Grignard reagents to give bridgehead-substituted products 3-16 in moderate yields. In this case the same kind of halogen in both 1 and a Grignard reagent was favored; if not, functional exchange (i.e., la to lc) occurred first. The reaction using 5-hexenylmagnesium bromide as a radical probe afforded uncyclized/cyclized coupling products in a 6/4 ratio. These facts suggested the significant participation of the single-electron-transfer process in these reactions. The present method could be extended to tert-butylation with some Grignard reagents. Interestingly, l,3-dichloro-3-methylbutane coupled with butylmagnesium chloride selectively at the tertiary position. For the above displacement reaction of 1, an organozinc was also found to be effective.

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Aggregation in high-spin ferric complexes of tetraarylporphyrins. Structure determination using intermolecular electron-nuclear dipolar relaxation

Cited by 29 publications

References 2 publications

Light‐induced electron spin polarization in the ground state of water‐soluble copper porphyrins

Light‐induced electron spin polarization in the ground state of water‐soluble copper porphyrins

Homo- and heterodimer formation in metalloporphyrins

Cross-coupling reaction of tert-alkyl halides with Grignard reagents in dichloromethane as a non-Lewis basic medium

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