Syntheses and electro(co)polymerization of novel thiophene- and 2,2′:5′,2″-terthiophene-functionalized metal–tetraazamacrocycle complexes, and electrochemical and spectroelectrochemical characterization of the resulting polythiophenes
作者:Simon J. Higgins、Thomas J. Pounds、Paul A. Christensen
DOI:10.1039/b103284b
日期:——
We have prepared novel tetraazacyclotetradecane derivatives, functionalised at nitrogen with a pendant thiophene or oligothiophene group, for electropolymerisation. Square planar Ni(II) complexes of these ligands, [Ni(L)](ClO4)2, have been prepared, and their electropolymerisation has been examined. The terthiophene-bearing complex was electrooxidised in CH3CNâ0.2Â M Et4NBF4 to give soluble oligomers, which are likely to be the products of dimerisation (sexithiophenes). However, by employing a more positive potential limit, they are electropolymerised, to afford polythiophene films on indium-doped tin oxide (ITO)-coated glass or platinum electrodes, and the Ni(II)/Ni(III) wave is superimposed upon the polythiophene redox process. Attempts to isolate films of the dimerised terthiophene by the oxidation
of neutral [NiCl2(L)] complexes in less polar media were unsuccessful. A polymer film could not be generated from the thiophene-bearing complex alone, even though a âspacerâ of five carbon atoms was incorporated between the thiophene and the bulky metal centre. However, copolymerisation with 3-methylthiophene successfully gave polythiophene copolymers incorporating the nickel(II) complex. In situ FTIR reflectance spectroelectrochemistry shows that in the early stages of film oxidation, the film behaves as a conventional polythiophene, but at higher potentials, the electronic band attributable to the transition from the valence band to the first intergap state undergoes some very unusual changes. Possible explanations for these are suggested.
我们已经制备了新型的四氮环十四烷衍生物,在氮原子上用悬挂的噻吩或寡噻吩基团进行功能化,以便进行电聚合。已经制备了这些配体的方形平面镍(II)络合物 [Ni(L)](ClO4)2,并对其电聚合进行了研究。含有三噻吩的络合物在 CH3CN–0.2 M Et4NBF4 中被电氧化,生成可溶的寡聚物,这些聚物可能是二聚化的产物(六噻吩)。然而,通过采用更正的电位极限,它们被电聚合,形成了在掺铟锡氧化物(ITO)涂层玻璃或铂电极上的聚噻吩薄膜,并且镍(II)/镍(III)波与聚噻吩的氧还原过程重叠。通过在非极性介质中氧化中性 [NiCl2(L)] 络合物来分离二聚的三噻吩薄膜的尝试未能成功。即使在噻吩和大分子金属中心之间加入了五个碳原子的“间隔”基团,仍无法单独从含噻吩的络合物生成聚合物薄膜。然而,与 3-甲基噻吩的共聚合成功生成了含有镍(II)络合物的聚噻吩共聚物。原位 FTIR 反射光谱电化学显示,在薄膜氧化的早期阶段,该薄膜表现得像传统的聚噻吩,但在更高的电位下,归因于从价带到第一个禁带态的跃迁的电子带经历了一些非常不寻常的变化。对此可能的解释被提出。