Synthesis and characterization of fluorescent receptors based on calix[4]arene with aminopyridine bridges. Ions recognition study

Calixarenes are macrocyclic compounds formed by phenolic units connected by methylene bridges1. Its main characteristics are its conformational mobility and its multiple functionalization. Its applications are present in different areas, like the biological and environmental sciences, since they function as selective receptors to different ions. These receptors may be studied by fluorescent spectroscopy, through the incorporation of different fluorescent moiety2. This is advantageous due to its high sensitivity and selectivity.

The present work aims to obtain new calix[4]arenes as possible fluorescent receivers, modified at the top edge through bridges such as diaminepyridine linked to fluorophores such as naphthalene and pyrene.

Synthetic route: After a di-alkylation of I in the upper rim, II was obtained. A di-formylation is performed generating III. The later reacts with n-bromopropane/K2CO3 in the lower rim yielding IV, which it oxidizes to get V. Amide groups were formed by reacting with the Bridge-Xn fragments, yielding VI.