Recognition and detection of orthophosphate

人工受体对阴离子的选择性识别一直是化学领域的一个挑战。虽然已经开发了大量的受体，选择性地结合某种阴离子，但几乎所有的受体都在有机溶剂中起作用。真实的应用需要在水溶液中结合，类似于天然蛋白质所做的。在水中结合阴离子比阳离子困难得多，因为阴离子具有各种几何形状，以不同的质子化状态存在，并且与等电子阳离子相比具有低得多的表面电荷密度。在我们的项目中，我们专注于识别和检测正磷酸盐，主要是因为磷酸盐是自然界和生物体的重要组成部分。近年来的研究表明，我国含磷矿产资源在下一个世纪将急剧减少甚至枯竭。40年因此，了解水中正磷酸根的结合和检测原理具有重要的理论和技术意义。为了面对这一挑战，我们正在开发一种策略，如何设计高度选择性的受体，结合水中的正磷酸盐。该策略涉及1）同时提供与客体的不同非共价相互作用的结合位点的组合，和2）这些结合位点在分子中的排列以提供主体和客体之间的最佳配合。去年，我们设计了一个人工受体的正磷酸盐，显示出前所未有的选择性，正磷酸盐在水缓冲液-甲醇混合物。从这项初步工作开始，我们计划1）通过引入水增溶基团合成在水中具有100%溶解度的受体，2）生产环状衍生物，以提高受体的整体结合性能。在项目的另一部分，我们提出了一种方法，如何功能化受体的基本结构，以获得正磷酸盐的开启荧光探针。

Selective recognition of anions by artificial receptors is still a great challenge in chemistry. Although there have been a large number of receptors developed that bind a certain anion selectively, almost all of them operate in organic solvents. Real applications require binding in an aqueous solution, similar to what natural proteins do. To bind anions in water is much more difficult than cations because anions have various geometries, exist in different protonation states, and possess much lower surface-charge densities as compared to isoelectronic cations. In our project, we focus on recognition and sensing of orthophosphate primarily because phosphates are an essential part of nature and living organisms. Recent prognoses predict dramatic decrease and even exhausting of phosphor-containing mineral resources during the next ca. 40 years. Thus, understanding the principles how to bind and detect orthophosphate in water is of great fundamental and technological significance. To face this challenge we are developing a strategy how to design highly selective receptors that bind orthophosphate in water. The strategy involves 1) combination of binding sites that provide simultaneously different non-covalent interactions with a guest, and 2) arrangement of these binding sites in a molecule to provide best fit between a host and a guest. Last year we have designed an artificial receptor for orthophosphate that shows unprecedented selectivity for orthophosphate in aqueous buffer - methanol mixtures. Starting from this preliminary work we plan 1) to synthesize the receptor with 100% solubility in water by introduction of water-solubilizing groups and 2) produce cyclic derivatives in order to improve overall binding properties of the receptors. In the other part of the project, we suggest a method how to functionalize basic structure of receptors to obtain turn-on fluorescent probes for orthophosphate.