Vibrational spectra of ammonium ions in crown-ether–NH +4-montmorillonite complexes

Abstract

Intercalation of crown ethers (15-crown-5 and 18-crown-6) in NH⁺₄-montmorillonite produces strong modifications in the infrared spectrum of the ammonium ions located in the interlamellar space of the phyllosilicate. These modifications are explained as a result of the lowering of the T_d symmetry, characteristic of free NH⁺₄ cations as a consequence of their interaction with oxygen atoms of the intercalated macrocyclic molecules.