High-Spin (S = 1) Blatter-Based Diradical with Robust Stability and Electrical Conductivity

Shuyang Zhang, Maren Pink, Tobias Junghoefer, Wenchao Zhao, Sheng Ning Hsu, Suchada Rajca, Arrigo Calzolari, Bryan W. Boudouris, Maria Benedetta Casu, Andrzej Rajca

Research output: Contribution to journalArticlepeer-review

Abstract

Triplet ground-state organic molecules are of interest with respect to several emerging technologies but usually show limited stability, especially as thin films. We report an organic diradical, consisting of two Blatter radicals, that possesses a triplet ground state with a singlet-triplet energy gap, ΔEST≈ 0.4-0.5 kcal mol-1(2J/k ≈ 220-275 K). The diradical possesses robust thermal stability, with an onset of decomposition above 264 °C (TGA). In toluene/chloroform, glassy matrix, and fluid solution, an equilibrium between two conformations with ΔEST≈ 0.4 kcal mol-1and ΔEST≈ -0.7 kcal mol-1is observed, favoring the triplet ground state over the singlet ground-state conformation in the 110-330 K temperature range. The diradical with the triplet ground-state conformation is found exclusively in crystals and in a polystyrene matrix. The crystalline neutral diradical is a good electrical conductor with conductivity comparable to the thoroughly optimized bis(thiazolyl)-related monoradicals. This is surprising because the triplet ground state implies that the underlying π-system is cross-conjugated and thus is not compatible with either good conductance or electron delocalization. The diradical is evaporated under ultra-high vacuum to form thin films, which are stable in air for at least 18 h, as demonstrated by X-ray photoelectron and electron paramagnetic resonance (EPR) spectroscopies.

Original languageEnglish (US)
Pages (from-to)6059-6070
Number of pages12
JournalJournal of the American Chemical Society
Volume144
Issue number13
DOIs
StatePublished - Apr 6 2022

ASJC Scopus subject areas

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

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