Reciprocal principle of molecular recognition in supramolecular chromatography-highly selective analytical separation of cyclodextrin congeners on a silica-bonded [60]fullerene stationary phase

The supramolecular pair fullerene/cyclodextrin represents a new example for the concept of reciprocal molecular recognition in liquid chromatography. Through inverting their roles as selectand and selector, small-to-large-ring cyclodextrins were chromatographed on silica-bonded [60] fullerene, whereas [60]- and [70] fullerenes were previously separated on a silica-bonded beta-cyclodextrin. The recognition of cyclodextrins of intermediate ring size on silica-bonded [60] fullerene is highly selective. Thus, CD8, CD9 and CD10 are separated both from lower (CD6 and CD7) and higher (CD11-CD25) congeners with a remarkable and unprecedented retention window. By using the retention-increment method, employing a reactor column (with selector) and a reference column (without selector), apparent relative complexation constants K(rel) of CD6-CD12 and [60]fullerene were determined by supramolecular liquid chromatography. The historical development of the reciprocal principle of molecular recognition in chromatography is reported in the introduction.