Synthesis and characterization of amino-derived T-butylcalix [4]arene bonded phases for HPLC /

Abstract

The cone conformation of a calixarene has the perfect shape to receive molecules for host-guest complexation, which makes these molecules desirable in chromatography. Host/guest complexation is the ability of a host molecule (calixarene) to interact with a guest molecule (PAH's) or a guest ion (Na+). The objective of this research was the development of a reliable method for covalent attachment, with high surface coverage, of p-tert-butylcalix[4]arenes to the surface of silica particles to utilize their host/guest abilities. A new synthetic method has been developed based on imine formation between an amino-derived calixarene and amino-derived silica with a glutaraldehyde linker. Specific types of solute probes (homologous series of PAH's, alkyl benzenes, and aromatic amines) were used to test the effectiveness of the calixarene stationary phases to separate in the reversed-phased mode of chromatography. Chromatograms were compared before and after endcapping the stationary phase, and it was concluded that the tailing of the peaks and the non-linearity of the log k' vs. number of atoms in a homologue was indicative of host/guest complexation due to the tethered calixarenes.