Chiral Conducting Me-EDT-TTF and Et-EDT-TTF-Based Radical Cation Salts with the Perchlorate Anion
Chiral Conducting Me-EDT-TTF and Et-EDT-TTF-Based Radical Cation Salts with the Perchlorate Anion
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基于 Me-EDT-TTF 和 Et-EDT-TTF 的自由基阳离子与高氯酸根阴离子的手性传导盐
DOI：
10.3390/cryst10111069
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发表时间：
2020
期刊：
影响因子：
2.7
通讯作者：
N. Avarvari
中科院分区：
文献类型：
--
作者：
Nabil Mroweh;P. Auban;N. Vanthuyne;E. Lopes;M. Almeida;E. Canadell;N. Avarvari
近年来，在分子导体领域中手性的引入在晶体堆积的调制框架中引起了越来越多的兴趣，因此在立体中心的数量和绝对构型（例如外消旋或对映体纯形式）的传导特性方面也受到了越来越多的关注。在这里，我们描述了通过电结晶制备手性自由基阳离子盐，其基于含有一个立构中心的甲基-亚乙基二硫代-四硫富瓦烯 (Me-EDT-TTF) 1 和乙基-亚乙基二硫代-四硫富瓦烯 (Et-EDT-TTF) 2 供体，以及高氯酸根阴离子。供体 1 提供了一系列晶体材料 [(rac)-1]ClO4、[(S)-1]2ClO4 和 [(R)-1]2ClO4，而供体 2 只能制备 1:1 盐 [(rac)-2]ClO4 和 [(R)-2]ClO4 作为适合 X 射线分析的单晶。 1的对映体纯盐在高温状态下表现出β型堆积和金属电导率，室温电导率为5-10 S cm−1，而化合物[(rac)-2]ClO4是一种非常差的半导体。紧束缚扩展休克尔能带结构计算支持 1 的对映纯盐的金属电导率，并表明可能由热收缩或压力引起的微小结构变化可能导致伪椭圆闭合费米面，这是二维金属的典型特征。
Introduction of chirality in the field of molecular conductors has received increasing interest in recent years in the frame of modulation of the crystal packing, and hence conducting properties, with the number of stereogenic centers and absolute configuration, e.g., racemic or enantiopure forms. Here, we describe the preparation by electrocrystallization of chiral radical cation salts, based on the donors methyl-ethylenedithio-tetrathiafulvalene (Me-EDT-TTF) 1 and ethyl-ethylenedithio-tetrathiafulvalene (Et-EDT-TTF) 2 containing one stereogenic center, with the perchlorate anion. Donor 1 provided the series of crystalline materials [(rac)-1]ClO4, [(S)-1]2ClO4 and [(R)-1]2ClO4, while for donor 2 only the 1:1 salts [(rac)-2]ClO4 and [(R)-2]ClO4 could be prepared as suitable single crystals for X-ray analysis. The enantiopure salts of 1 show β-type packing and metallic conductivity in the high temperature regime, with room temperature conductivity values of 5–10 S cm−1, whereas compound [(rac)-2]ClO4 is a very poor semiconductor. Tight-binding extended Hückel band structure calculations support the metallic conductivity of the enantiopure salts of 1 and suggest that small structural changes, possibly induced by thermal contraction or pressure, could lead to a pseudo-elliptic closed Fermi surface, typical for a 2D metal.