A series of new squaraine rotaxanes have been synthesised with a tetralactam macrocycle and stopper groups of varying sizes and functionalities. In chloroform, the relative size of the stopper group appears to have little influence on the high mechanical stability of the rotaxane structure. There is no evidence of unthreading (sometimes referred to as deslipping), even in the presence of competing chloride salts or elevated temperatures. A difference in rotaxane stability emerges as the polarity of the organic solvent is increased. Squaraine rotaxanes with small stopper groups undergo unthreading in the polar aprotic solvent DMSO. However, a water-soluble tetracarboxylic acid derivative was found to be highly stable in aqueous solvents containing serum.

中文翻译：

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塞子尺寸对方酸菁轮烷稳定性的影响

一系列新的方酸轮烷已由四内酰胺大环和不同大小和功能的终止基团合成。在氯仿中，终止基团的相对大小似乎对轮烷结构的高机械稳定性影响不大。即使存在竞争性氯化物盐或升高的温度，也没有证据表明存在松脱（有时称为脱滑）。随着有机溶剂极性的增加，轮烷稳定性出现差异。具有小终止基团的方酸轮烷在极性非质子溶剂 DMSO 中进行脱线。然而，发现水溶性四羧酸衍生物在含有血清的水性溶剂中高度稳定。