Fabrication and evaluation of tetraazahexaphenylmacrocycle-bonded stationary phase with multiple retention mechanisms

A 34-membered tetraazahexaphenylmacrocycle (N 4 Ph 6 ) with a rigid π-conjugated moiety was chemically bonded to silica gel with 3-chloropropyltrimethoxysilane as the coupling agent to prepare a novel SiO 2 @N 4 Ph 6 stationary phase. Several common organic analytes, including alkylbenzenes , polycyclic aromatic hydrocarbons , anilines, phenols, phthalates , and folic acid , were selected as probes to investigate its chromatographic performance. The as-developed SiO 2 @N 4 Ph 6 stationary phase showed superiority retention and high selectivity for probe molecules through multiple interactions, including hydrophobic, π–π, hydrogen-bonding, and steric interactions. Density functional theory calculation results using folic acid as model solute provided an intuitive and a quantitative description of the multiple retention mechanisms.