Interacting networks of purely organic spin–1/2 dimers

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 2; no. 32; pp. 6618 - 6629
• Main Authors: Borozdina, Yulia B., Mostovich, Evgeny, Enkelmann, Volker, Wolf, Bernd, Cong, Pham T., Tutsch, Ulrich, Lang, Michael, Baumgarten, Martin
• Format: Journal Article
• Language: English
• Published: 28.08.2014
• Subjects: Constants; Crystal structure; Diffraction; Exchange; Joining; Mathematical analysis; Radicals; X-rays
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/C4TC00399C

In the present study we report the synthesis of some novel nitronyl nitroxide biradical systems 1–4c with various π-bridges between the radical centres. UV-Vis, IR, EPR and X-ray diffraction studies, along with MS and NMR data where appropriate, are described. Magnetic measurements revealed that the biradicals 1c , 3c and 4c exhibit a moderately strong antiferromagnetic intra -molecular exchange, whereas nitroxide 2c shows a significantly higher exchange coupling, which can only be explained by the presence of strong inter -molecular interactions. From DFT calculations performed on the basis of the X-ray crystal structure of compound 4c , a theoretical value of the intra -dimer coupling constant J intra = −8.6 K is obtained. Direct proof also for inter -molecular arrangement with J inter ∼ −2 K was provided by the low temperature AC studies of biradical 4c . According to the magnetic characterization, the nitronyl biradical 4c is a promising candidate for a purely organic-based low-dimensional quantum magnet.