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

A 34-membered tetraazahexaphenylmacrocycle (N4Ph6) with a rigid π-conjugated moiety was chemically bonded to silica gel with 3-chloropropyltrimethoxysilane as the coupling agent to prepare a novel SiO2@N4Ph6 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 SiO2@N4Ph6 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.