meta-Substituted benzamide oligomers that complex mono-, di- and tricarboxylates: folding-induced selectivity and chirality
作者:Zhu-Ming Shi、Shi-Gui Chen、Xin Zhao、Xi-Kui Jiang、Zhan-Ting Li
DOI:10.1039/c1ob06026k
日期:——
meta-Substituted arylamide trimer, pentamer and heptamer have been prepared from simple benzene-1,3-diamine, benzene-1,3-dicarboxylic acid, and 3-aminobenzoic acid units. 2D NOESY 1H NMR experiments reveal that these flexible oligomers form folded conformations to complex di- and tricarboxylate anions of varying sizes and shapes in DMSO of high polarity, which is driven by multiple intermolecular N–H⋯OC and C–H⋯OC hydrogen-bonds between the amide and aromatic hydrogens of the oligomers and the carboxylate oxygens of the anions. Generally, tricarboxylate anions display an increased binding affinity compared with the dicarboxylate anions and the complexes formed by 1,3-benzenedicarboxylate anion are more stable than those formed by 1,2- or 1,4-benzenedicarboxylate anions. Circular dichroism experiments show that chiral glutamic acid dianion can induce the oligomers to produce chiral bias, leading to the formation of chiral supramolecular complexes.
元--从简单的苯-1,3-二胺、苯-1,3-二甲酸和 3-氨基苯甲酸单元制备出了取代芳酰胺三聚体、五聚体和七聚体。二维 NOESY 1H NMR 实验显示,在高极性二甲基亚砜中,这些柔性低聚物会与大小和形状各异的复杂二羧酸根和三羧酸根阴离子形成折叠构象,这是由低聚物的酰胺和芳香烃氢根与阴离子的羧酸根氧根之间的多个分子间 N-H⋯OC 和 C-H⋯OC 氢键驱动的。一般来说,与二羧酸阴离子相比,三羧酸阴离子显示出更强的结合亲和力,而且 1,3-苯二羧酸阴离子形成的复合物比 1,2- 或 1,4- 苯二羧酸阴离子形成的复合物更稳定。环二色性实验表明,手性谷氨酸二阴离子可诱导低聚物产生手性偏向,从而形成手性超分子复合物。