Molecular amplification in a dynamic system by ammonium cations

Using hydrazone chemistry, a simple dynamic system of macrocyclic pseudo-peptides was prepared which contains a cyclic structure that resembles a known receptor for ammonium cations. A series of ammonium salts were tested as templates and the expected receptor was amplified in different degrees according to the template used. Competitive non-covalent interactions with a crown ether were used to demonstrate in situ that the templated system is still dynamic. Formation of host–guest complexes was proven by ESI-MS and 1H ROESY experiments. Relative affinities of the various templates for the isolated receptor correlate well with the effect they produce on the library composition.