Monolithic capillary columns containing native silica gel were covalently modified with 3,5-disubstituted phenylcarbamate derivatives of cellulose and amylose and applied for enantioseparations in capillary LC. The method previously used for covalent immobilization of polysaccharide phenylcarbamate derivatives onto the surface of microparticulate silica gel was successfully adapted for in situ modification of monolithic fused-silica capillary columns. The effects of the nature of polysaccharide and the substituents, as well as of multiple covalent immobilization of polysaccharide derivative on chromatographic performance of capillary columns were studied. The capillary columns obtained using this technique are stable in all solvents commonly used in LC and exhibit promising enantiomer resolving ability.

The immobilization of cellulose 3,5-dimethylphenylcarbamate derivatives having a polymerizable vinyl group, i.e., 4-vinylphenylcarbamate or 2-methacyloyloxyethylcarbamate, on silica gel was examined under various conditions. The immobilization was basically conducted through the radical copolymerization of the derivatives with a vinyl monomer. Several factors, such as the vinyl monomer content and the type and amount of the vinyl group of cellulose derivatives, were varied. The introduction of a vinyl group onto the silica surface resulted in a more efficient immobilization of the cellulose phenylcarbamate derivatives on the silica gel. As the content of the vinyl group on the cellulose derivatives was reduced, the immobilization became more difficult, although the obtained phase exhibited higher chiral recognition abilities. These immobilized CSPs could be stably used with the eluent containing 10% chloroform, which cannot be used for the phase prepared by coating the derivatives on silica gel. Some racemates were better resolved on the immobilized CSP by using chloroform as a component of the eluent.

Polysaccharide‐immobilized chiral stationary phases (CSPs) were prepared by the polymerization of cellulose 3,5‐dimethylphenylcarbamate, having a polymerizable vinyl group, such as 4‐vinylphenylcarbamate or 2‐methacryloyloxyethylcarbamate, at the 6‐position, with a vinyl monomer, such as styrene, isoprene, t‐butyl acrylate, or t‐butyl methacrylate, on silica gel under various conditions. Their chiral recognition abilities were then evaluated with high‐performance liquid chromatography. The immobilized cellulose 3,5‐dimethylphenylcarbamate remained on the silica gel even if washed with tetrahydrofuran, which could dissolve the cellulose derivative. The chiral recognition abilities of the immobilized CSPs were similar to those of the coated CSPs when the vinyl monomer content was low. The chiral recognition abilities of the obtained immobilized CSPs slightly depended on the vinyl monomers. The immobilization of the cellulose derivatives was more efficiently attained on the silica gel modified with a vinyl compound. The cellulose derivatives, randomly having a vinyl group at the 2‐, 3‐, or 6‐position of the glucose unit, were prepared by a one‐pot reaction. The immobilization efficiency of these derivatives was slightly lower than that of the derivative with the vinyl group at the 6‐position. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3703–3712, 2003

A new cellulose phenylcarbamate derivative having a vinyl group at the 6-position was synthesized and immobilized onto silica gel via radical copolymerization with styrene. The immobilization was efficiently attained using a small amount of styrene. The chiral recognition abilities of the immobilized chiral stationary phase (CSP) were similar to those of the CSP coated on silica gel.

Knotaxane[1] ± so nennen wir die bisher unbekannten Rotaxane mit Knoten als Stopper an den beiden Achsenenden ± sind ein noch unerf¸llter Wunschtraum in der topologischen Chemie.[