A hexahomotrioxacalix[3]arene-based ditopic receptor for alkylammonium ions controlled by Ag+ Ions

Abstract

A receptor cone-1 based on a hexahomotrioxacalix[3]arene bearing three pyridyl groups was successfully synthesized, which has a C3-symmetric conformation and is capable of binding alkylammonium and metal ions simultaneously in a cooperative fashion. It can bind alkylammonium ions through the π-cavity formed by three aryl rings. This behaviour is consistent with the cone-in/cone-out conformational rearrangement needed to reorganize the cavity for endo-complexation. As a C3-symmetrical pyridyl-substituted calixarene, receptor cone-1 can also bind an Ag+ ion, and the nitrogen atoms are turned towards the inside of the cavity and interact with Ag+. After complexation of tris(2-pyridylamide) derivative receptor cone-1 with Ag+, the original C3-symmetry was retained and higher complexation selectivity for n-BuNH3+ versus t-BuNH3+ was observed. Thus, it is believed that this receptor will have a role to play in the sensing, detection, and recognition of Ag+ and n-BuNH3+ ions.