Reversible intercalation of volatile amines into stacks of soluble phthalocyanines

Abstract

Different alkyl amines were intercalated into stacks of tetraalkenylphthalocyaninatozinc by exposing the solids to amine vapor. Since the intercalation is reversible, quantitative and kinetic aspects of the sorption were investigated using quartz crystal microbalances (QCMs) and thermal desorption mass spectrometry (TDS). Two different types of sorption were found and these were interpreted as interaction with aliphatic sidechains and preferential intercalation. At higher vapor concentration most of the interstitial spaces are occupied, suggesting a 1 ∶ 1 host–guest stoichiometry. Structure elucidation of an intercalated n-butylamine was carried out by EXAFS transmission measurements. Intercalation was found to take place while maintaining the columnar arrangement and without significant expansion of the spacing. Additional QCM measurements revealed less favorable sorption of sterically demanding amines which can be explained by morphological discrimination.