Korendovych Ivan V, Cho Mimi, Makhlynets Olga V, Butler Phillip L, Staples Richard J, Rybak-Akimova Elena V
Department of Chemistry, Tufts University, 62 Talbot Avenue, Medford, Massachusetts 02155, USA.
J Org Chem. 2008 Jul 4;73(13):4771-82. doi: 10.1021/jo800128r. Epub 2008 Apr 9.
Binding of inorganic anions, carboxylic acids, and tetraalkylammonium carboxylates by macrocyclic compounds of different size was studied by NMR in DMSO-d6. It has been shown that at least a 15-membered ring is necessary for successful recognition of fluoride. Larger macrocycles were shown to bind HSO4(-), H2PO4(-), Cl(-), and carboxylic acid salts. Effects of binding topicity are discussed. The 30-membered macrocycles 4 and 4m selectively bind substrates that are size- and shape-complementary: maximum binding is observed for dicarboxylic acids and dicarboxylates with four-carbon chains, and the binding constant for association of fumaric acid and 4 is ca. 5 orders of magnitude higher than that of maleic acid. The 30-membered macrocycle 4m showed selectivity toward alpha-ketocarboxylic acids. Secondary amino groups were not crucial for binding of fluoride to the macrocycles; however, they proved to be very important for selectivity and strength of carboxylic acid binding. The X-ray structure of the adduct of 4 and nitrobenzoic acid confirmed the guest H-bonding with both the amide and the secondary amino groups of the 30-membered macrocyclic host.
在氘代二甲亚砜（DMSO-d6）中，通过核磁共振（NMR）研究了不同大小的大环化合物对无机阴离子、羧酸和四烷基铵羧酸盐的结合作用。结果表明，要成功识别氟离子，至少需要一个15元环。研究发现，较大的大环能结合硫酸氢根离子（HSO4(-)）、磷酸二氢根离子（H2PO4(-)）、氯离子（Cl(-)）和羧酸盐。文中讨论了结合拓扑性的影响。30元大环化合物4和4m能选择性地结合尺寸和形状互补的底物：对于具有四碳链的二元羧酸和二元羧酸盐，观察到最大结合效果，富马酸与4缔合的结合常数比马来酸高约5个数量级。30元大环化合物4m对α-酮羧酸表现出选择性。仲氨基对于氟离子与大环的结合并非至关重要；然而，它们对于羧酸结合的选择性和强度非常重要。4与硝基苯甲酸加合物的X射线结构证实了客体与30元大环主体的酰胺基和仲氨基之间存在氢键作用。
