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Dimer of the DPPH Stable Radical.

Adela F Dobre1, Cecilia Lete2, Victor E Kuncser3

  • 1Faculty of Chemistry, University of Bucharest, Panduri 90, Bucharest 050663, Romania.

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|August 25, 2025
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Summary
This summary is machine-generated.

Researchers synthesized a stable DPPH-dimer and oxidized it to a DPPH-diradical, which mimics the properties of the original DPPH radical. This discovery opens new avenues for stable radical research.

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Area of Science:

  • Organic Chemistry
  • Radical Chemistry
  • Materials Science

Background:

  • The 2,2-diphenyl-1-(2,4,6-trinitrophenyl)-hydrazyl (DPPH) radical is known for its exceptional stability.
  • Dimerization of DPPH is typically not observed due to its inherent stability.

Purpose of the Study:

  • To synthesize a stable DPPH-dimer through an alternative method.
  • To investigate the properties of a novel DPPH-diradical derived from the dimer.
  • To explore the electrochemical and magnetic characteristics of the DPPH-diradical.

Main Methods:

  • Alternative synthesis of DPPH-dimer.
  • Oxidation of DPPH-dimer to DPPH-diradical.
  • Structural confirmation using NMR, IR, UV-vis, and HR-MS.
  • Electron spin resonance (ESR) spectroscopy for diradical characterization.
  • Cyclic voltammetry and SQUID measurements for electrochemical and magnetic properties.
  • Density Functional Theory (DFT) calculations.

Main Results:

  • Successful synthesis of a DPPH-dimer.
  • Generation of a DPPH-diradical exhibiting properties similar to the DPPH radical.
  • Characterization of the diradical's structure and properties using various spectroscopic and analytical techniques.
  • DFT calculations indicated an open-shell singlet ground state with a diradical character (y) of 0.279 and a vertical S-T gap of -5.81 kcal mol⁻¹.

Conclusions:

  • The DPPH-diradical represents a stable radical species with potential applications.
  • The study provides insights into the synthesis and properties of stable organic diradicals.
  • The findings challenge previous assumptions about DPPH dimerization and stability.