Tiara[n]uril: A Glycoluril-Based Macrocyclic Host with Cationic Walls

The synthesis of new cationic macrocyclic host molecules is described. These macrocycles are comprised of glycoluril oligomers linked to two pyrazolium groups, which form part of a cationic wall facing into their cavities. A number of derivatives have been prepared with an objective to increasing the cavity size, and each new product has been fully characterized. Preliminary investigations of pKas of Me10Tu[3]2+ and an interaction of L-glutamine indicate a potential for binding anionic molecules that also carry H-bond donor groups.