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Herein we present the synthesis and association analysis of a new family of "pincer" receptors containing units of stable 26-membered tetraamidic macrocyclic scaffolds in their structures. These units, linked by aliphatic or aromatic chains, are capable of binding an anionic guest due to the presence of amide functions playing the role of hydrogen bond donating systems. Such neutral receptors show strong binding properties with respect to dicarboxylate anions. Despite the discovery that we observed a complexed, mixed binding model in all the systems tested, we can infer that the receptor region to which the guest chain is associated depends on the latter's length. [ABSTRACT FROM AUTHOR]

Herein, we present the synthesis and anion binding studies of a family of homologous molecular receptors 4–7 based on a DITIPIRAM (8-propyldithieno-[3,2-b:2′,3′-e]-pyridine-3,5-di-amine) platform decorated with various urea para-phenyl substituents (NO2, F, CF3, and Me). Solution, X-ray, and DFT studies reveal that the presented host–guest system offers a convergent array of four urea NH hydrogen bond donors to anions allowing the formation of remarkably stable complexes with carboxylates (acetate, benzoate) and chloride anions in solution, even in competitive solvent mixtures such as DMSO-d6/H2O 99.5/0.5 (v/v) and DMSO-d3/MeOH-d3 9:1 (v/v). The most effective derivatives among the series turned out to be receptors 5 and 6 containing electron-withdrawing F- and -CF3para-substituents, respectively. [ABSTRACT FROM AUTHOR]