Binding of calixarene-based Langmuir monolayers to mercury chloride is dependent on the amphiphile structure

Abstract

Two amphiphilic calix[4]arenes bearing four dodecyl chains at the lower rim and two amino functions (vicinal and distal) at the para-phenolic positions have been synthesized. Surface-pressure versus molecular-area isotherms reveal that Langmuir monolayers of the two regioisomers show considerably distinct self-assembly behaviors at the air–water interface. Compression isotherms, Brewster angle microscopy and synchrotron-based X-ray near-total-reflection fluorescence, X-ray reflectivity and grazing incidence X-ray diffraction reveal that the monolayers of the two diamino calix[4]arene derivatives and those of their structural analogues bearing four amino moieties in para positions exhibit significant differences in their binding properties towards HgCl₂ despite the structural and functional similarity among the macrocycles.