Synthesis of aza-m-xylylene diradicals with large singlet-triplet energy gap and statistical analyses of their EPR spectra

Arnon Olankitwanit, Maren Pink, Suchada Rajca, Andrzej Rajca

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

We describe synthesis and characterization of a derivative of aza-m-xylylene, diradical 2, that is persistent in solution at room temperature with the half-life measured in minutes (∼80-250 s) and in which the triplet ground state is below the lowest singlet state by >10 kcal mol-1. The triplet ground states and δEST of 2 in glassy solvent matrix are determined by a new approach based on statistical analyses of their EPR spectra. Characterization and analysis of the analogous diradical 1 are carried out for comparison. Statistical analyses of their EPR spectra reliably provide improved lower bounds for δEST (from >0.4 to >0.6 kcal mol-1) and are compatible with a wide range of relative contents of diradical vs monoradical, including samples in which the diradical and monoradical are minor and major components, respectively. This demonstrates a new powerful method for the determination of the triplet ground states and δEST applicable to moderately pure diradicals in matrices.

Original languageEnglish (US)
Pages (from-to)14277-14288
Number of pages12
JournalJournal of the American Chemical Society
Volume136
Issue number40
DOIs
StatePublished - Oct 8 2014

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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