The molecular recognition of catecholamines by hydrindacene-basedreceptors 1 and 2, as well as the durene-based receptor 3, and the guest-induced conformational changes are reported. These receptors selectively bind adrenaline and dopamine salts through the guests' ammonium group and 3-hydroxyl group on the aromatic ring. In the case of adrenaline, an additional hydrogen bond with a benzylic hydroxyl
The macrocyclization of 2,6‐diethynyl hydrindacenes (1) with functional groups at mutually perpendicular positions results in the formation of novel macrocycles which, as a result of the hindered rotation of the hydrindacene units, possess directionally persistent peripheral functionalities. The two hydrindacene units in the dimer macrocycle (2) have been shown to interact electronically through their
3-hydroxybenzyl alcohol with K2/K1 = 3-33. Both the entropy and the enthalpy terms are important in this allosteric system; the crystallographic studies provide the first clear evidence that the cooperativity in amidehydrogenbonding by polarization contributes to the positive homotropic allosteric binding property.