Aggregates of calix[4]arenes based on the 2,6‐diaminotriazine · imide system

The synthesis of several calix[4]arenes functionalized with uracil or diaminotriazine moieties is described. The association between these complementary calix[4]arenes is strongly influenced by processes related to the position and directionality of the hydrogen‐bonding moieties. In the case of bis(uracil)calix[4]arene (4), self‐association is observed (K = 3.4 · 103 M−1 in CDCl3) whereas, in the case of bis(diamidotriazine)calix[4]arene (16), it was concluded from 1H‐NMR studies that intermolecular association is hampered by the formation of intramolecular hydrogen bonds. Due to the divergent orientation of the hydrogen‐bonding groups of bis(diaminotriazine)calix[4]arene (15b), it forms hydrogen‐bonded strands through interaction with 5‐ethyl‐5‐phenylbarbituric acid (17), resulting in the formation of a gel in chloroform.