Institute of Organic Chemistry, Polish Academy of Sciences, Warsaw, Poland.
Chemistry. 2012 Oct 22;18(43):13686-701. doi: 10.1002/chem.201201909. Epub 2012 Sep 13.
The easy-to-make 7,7'-diamino-2,2'-diindolylmethane was used as a building block for the construction of anion receptors operating by hydrogen bonds. Its various bisamide and bisurea derivatives were designed and synthesised as acyclic as well as macrocyclic molecules, then their structural and anion binding properties were studied in solution and in the solid state. The bisamide receptors demonstrate high affinity towards oxoanions in highly polar and partially aqueous solutions (DMSO with up to 25 % H(2)O) with significant selectivity for dihydrogen phosphate. Remarkably, the bisurea-based molecules are able to bind anionic guests even in pure methanol and show selectivity toward tetrahedral oxoanions, that is, hydrogen sulphate and dihydrogen phosphate. X-ray analysis revealed that both classes of molecules adopt a similar conformation in the solid state: a bent sheet shape with a binding pocket equipped with hydrogen-bond donors (four for the amides and six for the bisureas), whose orientation is particularly tailored for oxoanions. The results of ROESY NMR experiments are in agreement with the findings for the solid state and confirmed that both bisamides and bisureas can easily adapt the conformation with convergent hydrogen-bond donors, which is highly suitable for anion binding.
易于制备的 7,7'-二氨基-2,2'-二吲哚甲烷可用作通过氢键作用操作的阴离子受体的构建块。设计并合成了其各种双酰胺和双脲衍生物作为非环状和大环分子，然后在溶液中和固态中研究了它们的结构和阴离子结合性质。双酰胺受体在高极性和部分水性溶液（DMSO 中高达 25%的 H2O）中对氧阴离子表现出高亲和力，对二氢磷酸盐具有显著的选择性。值得注意的是，基于双脲的分子即使在纯甲醇中也能够结合阴离子客体，并对四面体氧阴离子（即硫酸氢盐和二氢磷酸盐）表现出选择性。X 射线分析表明，这两类分子在固态中采用相似的构象：带有氢键供体的弯曲片形（酰胺为四个，双脲为六个），其取向特别适合氧阴离子。ROESY NMR 实验的结果与固态的结果一致，并证实双酰胺和双脲都可以很容易地适应具有收敛氢键供体的构象，这非常适合阴离子结合。
