Katayev Evgeny A, Boev Nikolay V, Khrustalev Victor N, Ustynyuk Yuri A, Tananaev I G, Sessler Jonathan L
Department of Chemistry, M. V. Lomonosov Moscow State University, Leninskie Gory, 119899 Moscow, Russian Federation.
J Org Chem. 2007 Apr 13;72(8):2886-96. doi: 10.1021/jo0624849. Epub 2007 Mar 16.
Three new amido-imine-type hybrid macrocycles based on substituted pyrrole units have been synthesized and shown to act as effective receptors for oxoanions in the solid state and in acetonitrile solution. One of the macrocycles in question, compound 15, was characterized by X-ray diffraction analysis as the free macrocycle and as a complex with sulfuric acid. A comparison of the resulting structures reveals that this receptor is capable of undergoing a conformational change and, as a consequence, varying the number of donor sites that can interact with a bound substrate. This system and the other two new receptors described in this work (macrocycles 14 and 16, respectively) display a high affinity toward oxoanions (studied as their tetrabutylammonium (TBA) salts), with association constants on the order of 10(7) M-1 being determined in acetonitrile solution using standard UV-vis spectroscopic titration methods. A competitive titration method was used to determine affinity constants in excess of ca. 10(6) M-1. Two of the receptors (14 and 15) were found to bind acetate, hydrogen sulfate, and dihydrogen phosphate anion well, and the bipyrrole-based receptor (14) was also found to bind the perrhenate anion. In contrast, the bis-dipyrromethane-derived receptor (16) was found to bind chloride anion preferentially. The unusual selectivity displayed by 16 for this spherical anion was rationalized on the basis of single-crystal X-ray diffraction data and DFT modeling calculations, which revealed a rigid structure appropriately suited for chloride anion recognition.
基于取代吡咯单元的三种新型酰胺-亚胺型杂化大环化合物已被合成，并显示在固态和乙腈溶液中可作为氧阴离子的有效受体。其中一种大环化合物，即化合物15，通过X射线衍射分析对游离大环化合物及其与硫酸形成的配合物进行了表征。对所得结构的比较表明，该受体能够发生构象变化，因此能够改变与结合底物相互作用的供体位点数量。该体系以及本文描述的其他两种新型受体（分别为大环化合物14和16）对氧阴离子（以其四丁基铵（TBA）盐形式研究）表现出高亲和力，使用标准紫外-可见光谱滴定法在乙腈溶液中测定的缔合常数约为10⁷ M⁻¹。采用竞争滴定法测定亲和力常数超过约10⁶ M⁻¹。发现其中两种受体（14和15）能很好地结合醋酸根、硫酸氢根和磷酸二氢根阴离子，并且发现基于联吡咯的受体（14）也能结合高铼酸根阴离子。相比之下，发现双二吡咯甲烷衍生的受体（16）优先结合氯离子。基于单晶X射线衍射数据和DFT建模计算对16对这种球形阴离子表现出的异常选择性进行了合理化解释，结果表明其刚性结构适合氯离子识别。
