Magnetic tuning of all-organic binary alloys between two stable radicals

Gonca Seber, Rafael S. Freitas, Joel T. Mague, Armando Paduan-Filho, Xavier Gratens, Valdir Bindilatti, Nei Fernandes Oliveira, Naoki Yoshioka, Paul M. Lahti

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Mixtures of 2-(4,5,6,7-tetrafluorobenzimidazol-2-yl)-4,4,5,5-tetramethyl-4, 5-dihydro-1H-imidazole-3-oxide-1-oxyl (F4BImNN) and 2-(benzimidazol-2-yl)-4,4,5, 5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (BImNN) crystallize as solid solutions (alloys) across a wide range of binary compositions. (F4BImNN) x(BImNN) (1-x) with x < 0.8 gives orthorhombic unit cells, while x ≥ 0.9 gives monoclinic unit cells. In all crystalline samples, the dominant intermolecular packing is controlled by one-dimensional (1D) hydrogen-bonded chains that lead to quasi-1D ferromagnetic behavior. Magnetic analysis over 0.4-300 K indicates ordering with strong 1D ferromagnetic exchange along the chains (J/k = 12-22 K). Interchain exchange is estimated to be 33- to 150-fold weaker, based on antiferromagnetic ordered phase formation below Néel temperatures in the 0.4-1.2 K range for the various compositions. The ordering temperatures of the orthorhombic samples increase linearly as (1 - x) increases from 0.25 to 1.00. The variation is attributed to increased interchain distance corresponding to decreased interchain exchange, when more F4BImNN is added into the orthorhombic lattice. The monoclinic samples are not part of the same trend, due to the different interchain arrangement associated with the phase change.

Original languageEnglish
Pages (from-to)3825-3833
Number of pages9
JournalJournal of the American Chemical Society
Volume134
Issue number8
DOIs
Publication statusPublished - 2012 Feb 29

ASJC Scopus subject areas

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

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    Seber, G., Freitas, R. S., Mague, J. T., Paduan-Filho, A., Gratens, X., Bindilatti, V., Oliveira, N. F., Yoshioka, N., & Lahti, P. M. (2012). Magnetic tuning of all-organic binary alloys between two stable radicals. Journal of the American Chemical Society, 134(8), 3825-3833. https://doi.org/10.1021/ja2104697