Synthesis of O6-Corona[3]arene[3]pyridazines and Their Molecular Recognition Property in Organic and Aqueous Media

O-6-Corona[3]arene[3]pyridazines were synthesized from the one-pot macrocyclic condensation reaction of 3,6-dichlorotetrazine with 1,4-dihydroquinone derivatives followed by the inverse electron demand Diels-Alder reaction of the tetrazine rings with a cyclopentanone-derived enamine. Conversion of six ester groups within macrocycle into all sodium acetate moieties afforded a water soluble O-6-corona[3]arene[3]pyridazine. The coronary macrocycle host formed complexes selectively with organic ammoniums and dinitrile guests in a 1: 1 stoichiometric ratio in organic solvents with association constants ranging from (2.96 +/- 0.10)x10(1) to (2.53 +/- 0.33)x10(5)Lmol(-1). Water soluble O-6-corona[3]arene[3]pyridazine was also able to complex strongly with organic ammoniums in water to give an association constant up to (2.67 +/- 0.21)x10(4)Lmol(-1). The pseudo-rotaxane and inclusion structures of the host-guest complexes were revealed by the X-ray crystallography.