New macrocyclic compounds with naphthyridine units for molecular recognition studies of biotin and urea derivatives

Two macrocyclic hosts containing benzenedicarboxamide or pyridinedicarboxamide moieties and two 1,8-naphthyridine units linked by a crown ether like chain, have been synthesized and fully characterized by multinuclear NMR spectroscopy. X-ray diffraction analysis is provided for one of the macrocycles including a DMSO guest molecule. Binding constant determination of both hosts with four ureido derivatives, amongst them (+)-biotin methyl ester, was achieved by means of 1 H NMR titrations.