A1 Journal article (refereed)
Polymorphism in a π stacked Blatter radical : structures and magnetic properties of 3-(phenyl)-1-(pyrid-2-yl)-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl (2020)

Constantinides, C. P., Lawson, D. B., Zissimou, G. A., Berezin, A. A., Mailman, A., Manoli, M., Kourtellaris, A., Leitus, G. M., Clérac, R., Tuononen, H. M., & Koutentis, P. A. (2020). Polymorphism in a π stacked Blatter radical : structures and magnetic properties of 3-(phenyl)-1-(pyrid-2-yl)-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl. CrystEngComm, 22(33), 5453-5463. https://doi.org/10.1039/d0ce00789g

JYU authors or editors

Mailman, Aaron
Tuononen, Heikki

Publication details

All authors or editors: Constantinides, Christos P.; Lawson, Daniel B.; Zissimou, Georgia A.; Berezin, Andrey A.; Mailman, Aaron; Manoli, Maria; Kourtellaris, Andreas; Leitus, Gregory M.; Clérac, Rodolphe; Tuononen, Heikki M.; et al.

Journal or series: CrystEngComm

eISSN: 1466-8033

Publication year: 2020

Volume: 22

Issue number: 33

Pages range: 5453-5463

Publisher: Royal Society of Chemistry

Publication country: United Kingdom

Publication language: English

DOI: https://doi.org/10.1039/d0ce00789g

Publication open access: Not open

Publication channel open access:

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/73205

Abstract

3-(Phenyl)-1-(pyrid-2-yl)-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl (2) demonstrates the first example of polymorphism in the family of Blatter radicals. Two polymorphs, 2α and 2β, have been identified and characterized by single crystal X-ray diffractometry and magnetic susceptibility measurements to investigate their magnetism–structure correlations. Both polymorphs form one-dimensional (1D) π stacks of evenly spaced radicals with distinctly different π–π overlap modes. Within the 1D π stacks, radicals are located at evenly interplanar distances, 3.461 Å for 2α and 3.430 Å for 2β. Magnetic susceptibility studies indicate that both polymorphs exhibit antiferromagnetic interactions inside their 1D π stacks. The magnetic susceptibility data are best interpreted in terms of a regular chain model of antiferromagnetically coupled quantum spins Image ID:d0ce00789g-t1.gif with exchange-interactions of J/kB = −36.7(3) K (−25.5(2) cm−1) for 2α and J/kB = −72(3) K (−50(2) cm−1) for 2β. For polymorph 2β, a crossover on the magnetic susceptibility around 20 K suggests the presence of a phase transition, which might be related to dimerization of the radicals along the chain. DFT calculations support the experimental structure–magnetism results and the antiferromagnetic nature of the local interactions between radicals within the 1D π stacks.

Keywords: organic compounds; free radicals; crystals; magnetic properties

Fields of science: