Meso-functionalization of calix[4]arene with 1,3,7-triazapyrene in the design of novel fluorophores with the dual target detection of Al3+ and Fe3+ cations

Abstract

A meso-functionalization strategy has successfully been applied to the synthesis of novel 1,3,7-triazapyrene derivatives of calixarenes. The key synthetic step in these transformations providing the direct C–C bond formation is nucleophilic substitution of hydrogen (S_N^H) in 1,3,7-triazapyrene. General photophysical characteristics for these macrocyclic compounds, as well as features in emission properties upon addition of various metal cations have been elaborated. Studies using NMR spectroscopy have also shown a mutual effect of both calix[4]arene and 1,3,7-triazapyrene moieties on the coordination process. The complex stoichiometry and binding constants for Al³⁺ and Fe³⁺ guests have been explored with titration experiments.