Formation of two-dimensional metals by weak intermolecular interactions based on the asymmetric EDO-TTF derivatives
作者:Xiangfeng Shao、Yoshiaki Nakano、Hideki Yamochi、Alexander D. Dubrovskiy、Akihiro Otsuka、Tsuyoshi Murata、Yukihiro Yoshida、Gunzi Saito、Shin-ya Koshihara
DOI:10.1039/b717621j
日期:——
Two mono-substituted EDO-TTF derivatives, 4,5-ethylenedioxy-4′-methyl-TTF (MeEDO-TTF, 2) and 4,5-ethylenedioxy-4′-methylthio-TTF (MeSEDO-TTF, 3), were synthesized in the moderate yields. These two donors showed similar electronic structures of the π-electron systems to that of the parent molecule EDO-TTF, according to the cyclic voltammetry and UV-vis spectroscopy. Despite their different compositions, the radical cation salts of these two donors exhibited similar optical spectra with a low-lying absorption band at around 3.3 × 103 cm−1, which was consistent with their good conductivities at room temperature. The transport properties of these salts ranged from stable metals, metal–insulator transition systems, to semiconductors. Most of the radical cation salts showed Pauli paramagnetic behavior at around room temperature. The crystal structures of the stable metallic salts, (MeEDO-TTF)2X (X = BF4, ClO4), exhibited a novel donor packing pattern, and the calculated band structures showed two-dimensional feature, consistent with their transport properties.
研究人员以中等产率合成了两种单取代的 EDO-TTF 衍生物:4,5-亚乙二氧基-4′-甲基-TTF(MeEDO-TTF,2)和 4,5-亚乙二氧基-4′-甲硫基-TTF(MeSEDO-TTF,3)。根据循环伏安法和紫外-可见光谱法,这两种供体的 π 电子系统与母体分子 EDO-TTF 的电子结构相似。尽管这两种供体的组成不同,但它们的自由基阳离子盐却表现出相似的光学光谱,在 3.3 × 103 cm-1 左右有一个低洼吸收带,这与它们在室温下的良好导电性是一致的。这些盐的传输特性从稳定金属、金属-绝缘体过渡体系到半导体不等。大多数自由基阳离子盐在室温左右表现出保利顺磁性。稳定金属盐 (MeEDO-TTF)2X (X = BF4, ClO4) 的晶体结构呈现出一种新颖的供体堆积模式,计算得到的带状结构呈现出二维特征,这与它们的传输特性相一致。