Time-dependent density functional theory investigation of electric field effects on absorption spectra of meso-meso-linked zinc porphyrin arrays: Role of charge-transfer States.

The journal of physical chemistry. B · 2005 · Unclear · Insufficient evidence

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UnclearInsufficient evidencePaper 3564

Study snapshot

PublicationThe journal of physical chemistry. B · 2005

Study typein_vitro

Reported directionUnclear

Evidence ratingInsufficient

Abstract

By using time-dependent density functional theory, we calculated the transition energies of a zinc porphyrin monomer and its meso-meso-linked arrays. In line with the prediction of the molecular exciton model, the calculated splitting energy of the Soret band increased as the number of linked porphyrins increased. We then examined how the transition energies of the dimer array were shifted by an applied electric field. For reproduction of an electroabsorption spectrum (EA), i.e., the field-induced change in absorption intensity, a model Hamiltonian constructed from five states is proposed. It is concluded for the dimer that the field-induced coupling between the lower-energy Soret band Se and the lower-lying ionic character (charge-transfer) states is responsible for the experimentally observed blue shift of Se as well as the second-derivative profile in the EA spectrum.

Machine Enhanced Logic

AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typein_vitro

Effect directionunclear

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

Time-dependent density functional theory calculations indicated that Soret band splitting increased with the number of meso-meso-linked zinc porphyrins. For the dimer, an applied electric field was modeled to shift transition energies; a five-state Hamiltonian was proposed to reproduce the electroabsorption spectrum. The field-induced coupling between the lower-energy Soret band (Se) and lower-lying charge-transfer states was concluded to explain an experimentally observed blue shift of Se and a second-derivative profile in the electroabsorption spectrum.

Outcomes measured

Transition energies
Absorption spectra / electroabsorption spectrum (field-induced change in absorption intensity)
Soret band splitting and shifts
Charge-transfer (ionic character) state coupling

Limitations

Computational/theoretical study (time-dependent density functional theory) rather than biological/epidemiological evidence
Electric field exposure parameters (magnitude, waveform/frequency, duration) not specified in the abstract
Findings pertain to zinc porphyrin monomer/arrays and spectral properties, not health outcomes

View raw extracted JSON

{
  "study_type": "in_vitro",
  "exposure": {
    "band": null,
    "source": "applied electric field",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Transition energies",
    "Absorption spectra / electroabsorption spectrum (field-induced change in absorption intensity)",
    "Soret band splitting and shifts",
    "Charge-transfer (ionic character) state coupling"
  ],
  "main_findings": "Time-dependent density functional theory calculations indicated that Soret band splitting increased with the number of meso-meso-linked zinc porphyrins. For the dimer, an applied electric field was modeled to shift transition energies; a five-state Hamiltonian was proposed to reproduce the electroabsorption spectrum. The field-induced coupling between the lower-energy Soret band (Se) and lower-lying charge-transfer states was concluded to explain an experimentally observed blue shift of Se and a second-derivative profile in the electroabsorption spectrum.",
  "effect_direction": "unclear",
  "limitations": [
    "Computational/theoretical study (time-dependent density functional theory) rather than biological/epidemiological evidence",
    "Electric field exposure parameters (magnitude, waveform/frequency, duration) not specified in the abstract",
    "Findings pertain to zinc porphyrin monomer/arrays and spectral properties, not health outcomes"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "time-dependent density functional theory",
    "TDDFT",
    "electric field",
    "electroabsorption",
    "zinc porphyrin",
    "meso-meso-linked arrays",
    "Soret band",
    "charge-transfer states",
    "model Hamiltonian"
  ],
  "suggested_hubs": []
}

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AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1021/jp050720y
PubMed: 16852747

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