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Pure Appl. Chem., 2007, Vol. 79, No. 6, pp. 1087-1096

Synthesis, structure, and complexing properties of macrocyclic receptors for anions

Michał J. Chmielewski1, Tomasz Zieliński1 and Janusz Jurczak2,1

1 Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
2 Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland

Abstract: Understanding of structure-affinity relationships is crucial for rational receptor design, however, such studies for anion receptors are still limited. Therefore, we investigated this issue in the case of amide-based macrocyclic receptors derived from aromatic diacids (i.e., isophthalic and dipicolinic). Using these model compounds, we examined the macrocyclic effect, the influence of intramolecular hydrogen bonds, and the correlation between the ring size and anion affinity. We found that in contrast to what was known for acyclic diamides, macrocyclic isophthalamide receptors bind anions more weakly than their dipicolinic analogs. Comprehensive structural studies revealed that such behavior is due to intramolecular hydrogen bonds present in isophthalamide receptors. Furthermore, we demonstrated how this obstacle can be overcome by the preparation of a hybrid macrocycle based on both building blocks.