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Topical Application Bioassay to Quantify Insecticide Toxicity for Mosquitoes and Fruit Flies
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DDT Polymorphism and the Lethality of Crystal Forms.

Jingxiang Yang1,2, C T Hu1, Xiaolong Zhu1

  • 1Department of Chemistry and Molecular Design Institute, New York University, 100 Washington Square East, Room 1001, New York City, NY, 10009, USA.

Angewandte Chemie (International Ed. in English)
|June 14, 2017
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Summary

Researchers discovered a new crystal form (Form II) of the insecticide DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane). This new form is more potent, offering potential for reduced environmental impact through improved formulations.

Keywords:
DDTcrystallographyinsecticidespolymorphism

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Area of Science:

  • Crystallography
  • Insecticide Chemistry
  • Environmental Science

Background:

  • DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) has been historically considered a monomorphic compound.
  • Its insecticidal properties were discovered in 1939, leading to widespread use and subsequent environmental concerns.

Purpose of the Study:

  • To report the discovery and characterization of a new polymorphic form of DDT.
  • To investigate the relative insecticidal activity of the newly discovered form.

Main Methods:

  • Crystal structure prediction using an evolutionary algorithm.
  • Isolation and characterization of single crystals of the new DDT polymorph.
  • Preliminary contact insecticidal activity assays using Drosophila melanogaster.

Main Results:

  • A second polymorph of DDT, designated Form II, was discovered and characterized.
  • Form II slowly converts to the previously known Form I at room temperature.
  • Computational analysis identified Forms I and II among the four lowest energy crystal structures.
  • Form II demonstrated higher insecticidal activity against fruit flies compared to Form I.

Conclusions:

  • DDT exists in at least two polymorphic forms, challenging previous assumptions of monomorphism.
  • The enhanced insecticidal activity of Form II suggests potential for developing more effective and environmentally conscious DDT formulations.
  • Further research into solid-state formulations could lead to reduced DDT usage and minimized environmental impact.