Dinuclear complexes of a pseudocalixarene macrocycle: structural consequences of intramolecular hydrogen bonding

Abstract

A series of dinuclear complexes of a pseudocalixarene macrocycle H₆L containing two 2,2′-methylenediphenol groups have been synthesised and structurally characterised. Using divalent metal ions, complexes containing a common hyperbolic paraboloid (saddle) M₂(H₄L)²⁺ core are formed. The structure is controlled by two strong O–H–O interactions resulting from metal ion-promoted monodeprotonation of the methylenediphenol units. The metal ions are located in a cleft within which neutral or anionic guests can bind. Use of trivalent metal ions leads to complete deprotonation of the phenol groups and loss of the saddle conformation.