ABSTRACT We demonstrate that Ullman fragment-coupling can be used to synthesise an oxacalix[4]arene monocarboxylic acid, which provides easy access to its water-soluble carboxylato derivatives. Crystallographic and computational data suggest that the new carboxyl-substituted oxacalix[4]arene adopts a 1,3-alternate conformation both in the solid-state and in methanol solution. Its water-soluble tetrabutylammonium derivate can detect the herbicide paraquat at neutral pH in aqueous media (K a = 111 ± 3 M–1) and in methanol (K a = 2020 ± 70 M–1). Graphical Abstract

中文翻译：

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新的oxacalix[4]芳烃羧酸盐检测质子介质中的紫精

摘要 我们证明了 Ullman 片段偶联可用于合成氧杂杯 [4] 芳烃单羧酸，这为获得其水溶性羧基衍生物提供了便利。晶体学和计算数据表明，新的羧基取代的氧杂杯[4]芳烃在固态和甲醇溶液中均采用 1,3-交替构象。其水溶性四丁基铵衍生物可在中性 pH 值下检测水性介质 (K a = 111 ± 3 M–1) 和甲醇 (K a = 2020 ± 70 M–1) 中的除草剂百草枯。图形概要