Selective Binding of D2h-Symmetrical, Acetylene-Linked Pyridine/Pyridone Macrocycles to Maltoside

A macrocyclic host molecule having pyridine-pyridone-pyridine modules for saccharide recognition was prepared by Cu(II)-mediated oxidative homocoupling of a tandem diethynyl precursor. In CH2Cl2, the host molecule associated with dodecyl beta-maltoside much more strongly K-a = 1.4 x 10(6) M-1) than with octyl monohexosides (K-a = ca. 2 x 10(3) to 1 x 10(4) M-1), accompanied with induced CDs. An all-pyridine macrocyclic host was also studied, and its binding strength with saccharides was weaker than that for the pyridine-pyridone-pyridine host.