Can octupolar molecules be poled by an external electric field?

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

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MixedInsufficient evidencePaper 3560

Study snapshot

PublicationThe journal of physical chemistry. B · 2005

Study typeother

Reported directionMixed

Evidence ratingInsufficient

Abstract

Octupolar molecules are generally believed to be of potential use in developing nonlinear optical materials owing to the fact that they do not easily form molecular aggregates. This is often put against the conjectured drawback that electric fields have no poling, or ordering, effect for this class of molecules because of the lack of a permanent ground state dipole moment. In this paper, we analyze this notion in some detail and present results from molecular dynamics computer simulations of an ensemble of a prototypical octupolar molecule, the 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) molecule, dissolved in chloroform. It is found that TATB molecules indeed show rather significant dipole moments in solutions because of the dual action of the thermal motions of the atoms and the strong intermolecular interactions. Applied electric fields accordingly show significant effects on the orientations of the molecular dipole moments. We also find that TATB molecules can aggregate because of the strong hydrogen-bonding interactions between the molecules, though they lack a static permanent dipole moment. Thus, the simulation results for TATB molecules in solution present us with a totally different notion about the collective properties of octupolar molecules. Taking account of quantum chemistry results, we found that the collective molecular nonlinear optical (NLO) properties are enhanced after the onset of the electric field, showing significant anisotropic characteristics.

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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 typeother

Effect directionmixed

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthInsufficientConfidence: 74% · Peer reviewed: yes

Main findings

Molecular dynamics simulations of TATB in chloroform found that molecules exhibit significant dipole moments in solution due to thermal motion and intermolecular interactions. Applied electric fields significantly affected orientations of molecular dipole moments, and simulations also indicated aggregation via hydrogen bonding; collective NLO properties were enhanced after onset of the electric field with anisotropic characteristics.

Outcomes measured

molecular dipole moments in solution
orientation/poling (ordering) effects under applied electric fields
molecular aggregation (hydrogen bonding)
collective nonlinear optical (NLO) properties and anisotropy

Limitations

Computer simulation (molecular dynamics) rather than experimental study
Study focuses on a specific molecule (TATB) in a specific solvent (chloroform), limiting generalizability
No exposure parameters (field strength, waveform/frequency, duration) reported in the abstract

View raw extracted JSON

{
  "study_type": "other",
  "exposure": {
    "band": null,
    "source": "external electric field (applied)",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "molecular dipole moments in solution",
    "orientation/poling (ordering) effects under applied electric fields",
    "molecular aggregation (hydrogen bonding)",
    "collective nonlinear optical (NLO) properties and anisotropy"
  ],
  "main_findings": "Molecular dynamics simulations of TATB in chloroform found that molecules exhibit significant dipole moments in solution due to thermal motion and intermolecular interactions. Applied electric fields significantly affected orientations of molecular dipole moments, and simulations also indicated aggregation via hydrogen bonding; collective NLO properties were enhanced after onset of the electric field with anisotropic characteristics.",
  "effect_direction": "mixed",
  "limitations": [
    "Computer simulation (molecular dynamics) rather than experimental study",
    "Study focuses on a specific molecule (TATB) in a specific solvent (chloroform), limiting generalizability",
    "No exposure parameters (field strength, waveform/frequency, duration) reported in the abstract"
  ],
  "evidence_strength": "insufficient",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "octupolar molecules",
    "poling",
    "external electric field",
    "molecular dynamics",
    "TATB",
    "chloroform",
    "dipole moment",
    "aggregation",
    "hydrogen bonding",
    "nonlinear optical properties",
    "anisotropy"
  ],
  "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/jp051267t
PubMed: 16853130

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