Spin and dielectric transitions promoted by dimerization of anionic radical stacks and volume-conserving motion of cations in an ion-pair compound

Zi Heng Feng, Qin Yu Zhu, Yin Qian, Xu Sheng Gao, Xiao Ming Ren

科研成果: 期刊稿件文章同行评审

摘要

Demonstrating the mechanism of a structural phase transition (SPT) is significantly important for guiding the precise design of new phase transition materials. Herein, an ion-pair compound [DPIm][Ni(mnt)2] (1, DPIm+ = 1,3-dipropylimidazolium and mnt2− = maleonitriledithiolate) has been obtained and thoroughly characterized through microanalysis, spectral, and thermal analysis techniques. The [Ni(mnt)2] anions form columnar stacks, featuring one-dimensional (1D) S = ½ spin chains. 1 undergoes an SPT, associated with thermal, magnetic, and dielectric anomalies. The SPT results from the competition between antiferromagnetic (AFM) coupling interactions within anion stacks and elastic deformation of the lattice. The magnetic anomaly arises from changes in the magnetic coupling constant within an anion stack between two phases, while the dielectric anomaly is due to the volume-conserving motion of the imidazolyl ring in the cation. 1 exhibits high-κ characteristics, attributed to the electron polarization of both anions and cations, ion displacement, and dipole orientation polarization of cations. It is also demonstrated that a longer dialkyl chain inhibits the rotational freedom of the imidazolyl ring, resulting in the absence of a plastic crystal state in 1 compared to others containing [Ni(mnt)2] and dialkylimidazolium.

源语言英语
期刊Dalton Transactions
DOI
出版状态已接受/待刊 - 2024

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