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Thermally and Magnetically Robust Triplet Ground State Diradical
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2019-02-28 , DOI: 10.1021/jacs.9b00558
Nolan Gallagher 1 , Hui Zhang 1 , Tobias Junghoefer 2 , Erika Giangrisostomi 3 , Ruslan Ovsyannikov 3 , Maren Pink 4 , Suchada Rajca 1 , Maria Benedetta Casu 2 , Andrzej Rajca 1
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2019-02-28 , DOI: 10.1021/jacs.9b00558
Nolan Gallagher 1 , Hui Zhang 1 , Tobias Junghoefer 2 , Erika Giangrisostomi 3 , Ruslan Ovsyannikov 3 , Maren Pink 4 , Suchada Rajca 1 , Maria Benedetta Casu 2 , Andrzej Rajca 1
Affiliation
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High spin ( S = 1) organic diradicals may offer enhanced properties with respect to several emerging technologies, but typically exhibit low singlet triplet energy gaps and possess limited thermal stability. We report triplet ground state diradical 2 with a large singlet-triplet energy gap, Δ EST ≥ 1.7 kcal mol-1, leading to nearly exclusive population of triplet ground state at room temperature, and good thermal stability with onset of decomposition at ∼160 °C under inert atmosphere. Magnetic properties of 2 and the previously prepared diradical 1 are characterized by SQUID magnetometry of polycrystalline powders, in polystyrene glass, and in other matrices. Polycrystalline diradical 2 forms a novel one-dimensional (1D) spin-1 ( S = 1) chain of organic radicals with intrachain antiferromagnetic coupling of J'/ k = -14 K, which is associated with the N···N and N···O intermolecular contacts. The intrachain antiferromagnetic coupling in 2 is by far strongest among all studied 1D S = 1 chains of organic radicals, which also makes 1D S = 1 chains of 2 most isotropic, and therefore an excellent system for studies of low-dimensional magnetism. In polystyrene glass and in frozen benzene or dibutyl phthalate solution, both 1 and 2 are monomeric. Diradical 2 is thermally robust and is evaporated under ultrahigh vacuum to form thin films of intact diradicals on silicon substrate, as demonstrated by X-ray photoelectron spectroscopy. Based on C-K NEXAFS spectra and AFM images of the ∼1.5 nm thick films, the diradical molecules form islands on the substrate with molecules stacked approximately along the crystallographic a-axis. The films are stable under ultrahigh vacuum for at least 60 h but show signs of decomposition when exposed to ambient conditions for 7 h.
中文翻译:
热和磁鲁棒的三重基态双自由基
高自旋 (S = 1) 有机双自由基可能会提供相对于几种新兴技术的增强特性,但通常表现出低单线态三线态能隙并且具有有限的热稳定性。我们报告了三线态基态双自由基 2 具有较大的单线态-三线态能隙,Δ EST ≥ 1.7 kcal mol-1,导致室温下三线态基态几乎排他性,并且具有良好的热稳定性,在 160° 开始分解C 在惰性气氛下。2 和先前制备的双自由基 1 的磁特性由多晶粉末、聚苯乙烯玻璃和其他基质的 SQUID 磁力测定法表征。多晶双自由基 2 形成一个新的一维 (1D) 自旋 1 (S = 1) 有机自由基链,链内反铁磁耦合 J'/ k = -14 K,这与 N...N 和 N...O 分子间接触有关。2 中的链内反铁磁耦合在所有研究的 1D S = 1 有机自由基链中是迄今为止最强的,这也使得 1D S = 1 链的 2 最具各向同性,因此是研究低维磁性的绝佳系统。在聚苯乙烯玻璃和冷冻苯或邻苯二甲酸二丁酯溶液中,1 和 2 都是单体。如 X 射线光电子能谱所示,双自由基 2 具有耐热性,可在超高真空下蒸发以在硅基板上形成完整双自由基的薄膜。根据 CK NEXAFS 光谱和约 1.5 nm 厚薄膜的 AFM 图像,双自由基分子在基板上形成岛,分子大致沿结晶 a 轴堆叠。
更新日期:2019-02-28
中文翻译:
![](https://scdn.x-mol.com/jcss/images/paperTranslation.png)
热和磁鲁棒的三重基态双自由基
高自旋 (S = 1) 有机双自由基可能会提供相对于几种新兴技术的增强特性,但通常表现出低单线态三线态能隙并且具有有限的热稳定性。我们报告了三线态基态双自由基 2 具有较大的单线态-三线态能隙,Δ EST ≥ 1.7 kcal mol-1,导致室温下三线态基态几乎排他性,并且具有良好的热稳定性,在 160° 开始分解C 在惰性气氛下。2 和先前制备的双自由基 1 的磁特性由多晶粉末、聚苯乙烯玻璃和其他基质的 SQUID 磁力测定法表征。多晶双自由基 2 形成一个新的一维 (1D) 自旋 1 (S = 1) 有机自由基链,链内反铁磁耦合 J'/ k = -14 K,这与 N...N 和 N...O 分子间接触有关。2 中的链内反铁磁耦合在所有研究的 1D S = 1 有机自由基链中是迄今为止最强的,这也使得 1D S = 1 链的 2 最具各向同性,因此是研究低维磁性的绝佳系统。在聚苯乙烯玻璃和冷冻苯或邻苯二甲酸二丁酯溶液中,1 和 2 都是单体。如 X 射线光电子能谱所示,双自由基 2 具有耐热性,可在超高真空下蒸发以在硅基板上形成完整双自由基的薄膜。根据 CK NEXAFS 光谱和约 1.5 nm 厚薄膜的 AFM 图像,双自由基分子在基板上形成岛,分子大致沿结晶 a 轴堆叠。