A series of neutral porphyrin-containing catenanes has been synthesised, consisting of a zinc porphyrin strapped by a polyethylene glycol chain containing four or six ethylenoxy-units and incorporating a central naphthoquinol unit, interlinked with a naphthalene diimide macrocycle. The napthalene diimide precursor units exhibit only weak binding with the strapped porphyrins (Ka between 8 and 0.02 Mâ1), but good yields of the catenanes were obtained by Glaser coupling of the alkynyl napthalene diimide precursors in the presence of the porphyrins. Structures and solution conformations were determined by mass spectral and detailed 1H NMR studies. For the longer strapped porphyrins, the diimide macrocycle rotates around the central naphthoquinol unit at 420â450 times per second, while rotation is virtually prevented in the tighter strapped derivatives. A second dynamic process occurring in both sets of catenanes and described as âyawingâ leads to inequivalence in the naphthalene moieties. UV-Visible spectra indicate charge transfer interactions and electronic communication between the two components of the catenane.
一系列中性含
卟啉的链烷已经合成,由
锌卟啉和含有四个或六个乙氧基单元的聚
乙二醇链组成,并包含一个中心
萘醌单元,与
萘二
酰亚胺大环相互连接。
萘二
酰亚胺前体单元与束缚
卟啉的结合力较弱(Ka在8和0.02 M之间),但在
卟啉存在的情况下,通过炔基
萘二
酰亚胺前体的格拉瑟偶联,获得了良好的链烷产量。通过质谱和详细的1H NMR研究确定了结构和溶液构象。对于较长的束缚
卟啉,二
酰亚胺大环以每秒420-450次的频率绕中心
萘醌单元旋转,而在更紧密的束缚衍
生物中,旋转实际上被阻止了。在两组链烷中发生的第二个动态过程被称为“偏航”,导致
萘部分的不等价。紫外可见光谱表明链烷的两个成分之间存在电荷转移相互作用和电子通信。