Towards Allosteric Receptors – Synthesis of Resorcinarene‐Functionalized 2,2′‐Bipyridines and Their Metal Complexes

Based on a first example of an allosteric hemicarcerand ( 1 ) we prepared four new 2,2′‐bipyridines that carry resorcinarene moieties in a highly convergent manner. Upon coordination to suitable transition metal ions or their complexes these compounds undergo conformational changes in a way that they switch between “ open ” and “ closed ” forms ( 2 , 3 , and 4 ) or vice versa ( 5 ), thus, bringing together or separating the two functional moieties on the central bipyridine. Among the transition metal complexes that act as effectors for the conformational switching, [Re(CO) 5 Cl] and monomeric copper(I) complexes of sterically hindered 2,9‐arylated 1,10‐phenanthrolines proved to be very effective. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)