Preparation of a cyclophane-bonded stationary phase and its application to separation of naphthalene derivatives

Abstract

A cyclophane (CP44)-bonded silica gel stationary phase was prepared and elution behaviour of hydrophobic solutes was investigated in the reversed-phase mode. Aromatic compounds were retained on the stationary phases more strongly than the corresponding alicyclic compounds, as was expected by the complex-forming ability of the cyclophane. The stationary phases also showed isomer-selective separation for monomethyl- and dimethylnaphthalenes. The isomers having methyl groups at the α-position were eluted prior to those having methyl groups at the β-position, i.e., the retention order for methylnaphthalene was, α<β and that for dimethylnaphthalene, α,α<α,β<β,β. Moreover, some dimethylnaphthalene isomers which cannot be separated on ordinary reversed-phase stationary phases were separated finely on this stationary phase. The separation mechanism is discussed on the basis of the structure of the cyclophane-involved complex.