Absorption and ESR spectra of the products of single-electron photooxidation of bacteriochlorophyll

Bobrovskii, A. P.; Kholmogorov, V. E.

doi:10.1007/bf00604515

Cited by 3 publications

(3 citation statements)

References 12 publications

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“…Piperidine can also be used as a donor molecule to aid in the photoassisted reduction of metal phthalocyanine complexes. 29 Both photochemical and electrochemical reduction can, therefore, take place during the in situ reduction. Low-temperature [ZnPc(-4)] 2absorption data were recorded in an Oxford Instruments model 204 optical cryostat from a vitrified DMF/hydrazine hydrate (5:2 v/v) solution.…”

Section: Methodsmentioning

confidence: 99%

“…These cells were previously used to generate the [MgPc(−3)] - and [MgPc(−4)] 2- species for spectroscopic analyses in which isosbestic spectral changes linked the formation of the Pc(−2), Pc(−3), and Pc(−4) species. 18c,e, We have observed that the [MPc(−4)] 2- species is most easily formed by applying a fixed potential of greater than 1.5 V in the presence of excess piperidine as an axial ligand. Piperidine can also be used as a donor molecule to aid in the photoassisted reduction of metal phthalocyanine complexes …”

Section: Methodsmentioning

confidence: 99%

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Assignment of the Optical Spectra of Metal Phthalocyanine Anions

1997

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Specially designed spectroelectrochemical cells were used to record UV−vis absorption and magnetic circular dichroism (MCD) spectral data of the phthalocyanine ring-reduced dianion, [ZnPc(−4)]2-, in situ at room temperature. [ZnPc(−4)]2- was generated at cryogenic temperatures through photoreduction of a vitrified dimethyl formamide/hydrazine hydrate solution using hydrazine as the electron donor. Molecular orbital calculations for [ZnPc(−(2 + n))]- n (n = −1−4) species were performed through the use of the ZINDO program. The approach that was developed previously to assign the major π → π* and π* → π* transitions in the optical spectrum of [ZnPc(−3)]-, which was based on analysis of the relative signs and intensities of close lying Faraday B terms in the MCD spectrum, is used here to assign the major bands seen in the spectrum of [ZnPc(−4)]2-. The spectrum is dominated by a π* → π* transition out of the partially filled lowest unoccupied molecular orbital (LUMO) which gives rise to a pair of oppositely-signed, coupled B terms in the MCD spectrum at 506 and 620 nm. The Q transition of the phthalocyanine ring is assigned to a weak absorption band at 865 nm, while the second π → π* transition is assigned to a band at 370 nm. The band assignment scheme is extended to data that have been reported previously for more highly ring-reduced main group [MPc(−5)]3- and [MPc(−6)]4- species (M = Mg, Zn). The Q band of [MgPc(−5)]3- is assigned to a band at 1125 nm. Bands at 589 and 825 nm are assigned to π* → π* transitions out of the partially occupied Jahn−Teller split eg* LUMO. The second π → π* transition is assigned to a band at 338 nm. As the LUMO is fully occupied, the spectrum of [MgPc(−6)]4- is dominated by π* → π* bands at 625 and 840 nm. An additional band at 305 nm is assigned to the second π → π* transition. A general band assignment scheme is proposed for both main group and transition metal phthalocyanine anion species.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Assignment of the Optical Spectra of Metal Phthalocyanine Anions

1997

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“…Wilson et al were able to form [ZnTPP(À3)] À in DMF using a thin layer spectroelectrochemical cell [69]. A hydrazine reduction method pioneered by Belarussian workers can be used to form stable solutions of anion radicals of porphyrin complexes [70][71][72]. Photoreduction is only successful at low temperature, even in an aprotic solvent such as DMF.…”

Section: Spectral Band Assignments-metalloporphyrinsmentioning

confidence: 99%

Assignment of the optical spectrum of metal porphyrin and phthalocyanine radical anions

Mack

Stillman

2001

J. Porphyrins Phthalocyanines

118

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The approach developed previously to assign the major π → π* and π* → π* bands in the optical spectra of metallophthalocyanine radical species [ MPc (−n)](n−2)− (n = 1–6), which was based on spectral band deconvolution analyses of the UV-vis absorption and magnetic circular dichroism (MCD) spectra and ZINDO calculations, is reviewed in this paper and extended to the major bands observed in the spectrum of the zinc tetraphenylporphyrin radical anion [ ZnTPP (−3)]−. The magnetic circular dichroism spectrum is dominated by an intense pseudo A term associated with the B (or Soret) transition with bands at 445 and 465 nm. Weaker bands associated with the π* → π* transition out of the partially filled LUMO give rise to two widely separated, oppositely signed, coupled B terms in the MCD spectrum at 538 and 910 nm. The Q transition is assigned to a weak absorption band at 750 nm and a shoulder slightly to the blue at 728 nm.

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Excited States of Biomolfecules—iii

Song

Fugate

1975

Photochem & Photobiology

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Absorption and ESR spectra of the products of single-electron photooxidation of bacteriochlorophyll

Cited by 3 publications

References 12 publications

Assignment of the Optical Spectra of Metal Phthalocyanine Anions

Assignment of the Optical Spectra of Metal Phthalocyanine Anions

Assignment of the optical spectrum of metal porphyrin and phthalocyanine radical anions

Excited States of Biomolfecules—iii

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