Study of Molecular Dimer Morphology Based on Organic Spin Centers: Nitronyl Nitroxide Radicals

Dongdong Wei; Yongliang Qin; Zhipeng Xu; Hui Liu; Ranran Chen; Yang Yu; Di Wang

doi:10.3390/molecules29092042

Study of Molecular Dimer Morphology Based on Organic Spin Centers: Nitronyl Nitroxide Radicals

Molecules. 2024 Apr 28;29(9):2042. doi: 10.3390/molecules29092042.

Authors

Dongdong Wei¹, Yongliang Qin², Zhipeng Xu¹, Hui Liu¹, Ranran Chen¹, Yang Yu³, Di Wang¹

Affiliations

¹ School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China.
² Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China.
³ School of Advanced Manufacturing Engineering, Hefei University, Hefei 230601, China.

Abstract

In this work, in order to investigate the short-range interactions between molecules, the spin-magnetic unit nitronyl nitroxide (NN) was introduced to synthesize self-assembly single radical molecules with hydrogen bond donors and acceptors. The structures and magnetic properties were extensively investigated and characterized by UV-Vis absorption spectroscopy, electron paramagnetic resonance (EPR), and superconducting quantum interference devices (SQUIDs). Interestingly, it was observed that the single molecules can form two different dimers (ring-closed dimer and "L"-type dimer) in different solvents, due to hydrogen bonding, when using EPR to track the molecular spin interactions. Both dimers exhibit ferromagnetic properties (for ring-closed dimer, J/k_B = 0.18 K and ΔE_S-T = 0.0071 kcal/mol; for "L"-type dimer, the values were J/k_B = 9.26 K and ΔE_S-T = 0.037 kcal/mol). In addition, the morphologies of the fibers formed by the two dimers were characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM).

Keywords: dimer; magnetism; nitronyl nitroxide (NN); spin coupling.

Abstract

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