New electron donors: BEDT-TTF derivatives bearing a pyridine group; synthesis, crystal structure, electrochemical studies and the formation of charge transfer complexes
作者:Wei Xu、Deqing Zhang、Hongxiang Li、Daoben Zhu
DOI:10.1039/a900063a
日期:——
Bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) derivatives 1a,b and 2a,b containing a pyridine group have been synthesized and their redox potentials have been studied by cyclic voltammetry in dichloromethane solution, which indicate that they are weaker electron donors than BEDT-TTF. Compound 2b has been studied by X-ray crystallography, which revealed a column-packing pattern in its crystal lattice. The charge transfer (CT) complexes formed between these new donors and tetracyanoquinodimethane (TCNQ), 2,3-dichloro-5,6-dicyanobenzo-1,4-quinone (DDQ) as well as cupric chloride (CuCl
2
) have been investigated. Among them the CT complexes 1b
1.1
·TCNQ and 1a·CuCl
2
show conductivity in the semiconducting range at room temperature (σ
rt
=1.6×10
–3
S cm
–1
for 1b
1.1
·TCNQ, 4.3×10
–3
S cm
–1
for 1a·CuCl
2
measured on a compressed pellet). From the results of X-ray photoelectron spectroscopy (XPS) and conductivity measurements, we suggest that charge transfer and coordination contact coexist in the complex 1a·CuCl
2
.
合成了含有吡啶基的双(乙烯硫醚)四硫富瓦烯(BEDT-TTF)衍生物1a、b和2a、b,并通过循环伏安法研究了它们在二氯甲烷溶液中的氧化还原电位,结果表明它们的电子给体能力弱于BEDT-TTF。化合物2b通过X射线晶体学研究,揭示了其晶体格子的柱状包装模式。探讨了这些新给体与四氰基喹啉(TCNQ)、2,3-二氯-5,6-二氰基苯-1,4-醌(DDQ)及氯化铜(CuCl₂)形成的电荷转移(CT)复合物。其中,CT复合物1b•1.1·TCNQ和1a·CuCl₂在室温下显示出半导体范围内的导电性(1b•1.1·TCNQ的σ_rt = 1.6×10⁻³ S cm⁻¹,1a·CuCl₂的σ_rt = 4.3×10⁻³ S cm⁻¹,测量是在压缩后球粒上进行的)。根据X射线光电子能谱(XPS)和导电性测量的结果,我们建议复合物1a·CuCl₂中电荷转移和配位接触共存。