Novel 3‐hydroxypropyl‐bonded phase by direct hydrosilylation of allyl alcohol on amorphous hydride silica

A novel 3‐hydroxypropyl (propanol)‐bonded silica phase has been prepared by hydrosilylation of allyl alcohol on a hydride silica intermediate, in the presence of platinum (0)‐divinyltetramethyldisiloxane (Karstedt's catalyst). The regio‐selectivity of this synthetic approach had been correctly predicted by previous reports involving octakis(dimethylsiloxy)octasilsesquioxane (Q₈M₈^H) and hydrogen silsesquioxane (T₈H₈), as molecular analogs of hydride amorphous silica. Thus, C‐silylation predominated (～94%) over O‐silylation, and high surface coverages of propanol groups (5 ± 1 μmol/m²) were typically obtained in this work. The propanol‐bonded phase was characterized by spectroscopic (infrared (IR) and solid‐state NMR on silica microparticles), contact angle (on fused‐silica wafers) and CE (on fused‐silica tubes) techniques. CE studies of the migration behavior of pyridine, caffeine, Tris(2,2′‐bipyridine)Ru(II) chloride and lysozyme on propanol‐modified capillaries were carried out. The adsorption properties of these select silanol‐sensitive solutes were compared to those on the unmodified and hydride‐modified tubes. It was found that hydrolysis of the SiH species underlying the immobilized propanol moieties leads mainly to strong ion‐exchange‐based interactions with the basic solutes at pH 4, particularly with lysozyme. Interestingly, and in agreement with water contact angle and electroosmotic mobility figures, the silanol–probe interactions on the buffer‐exposed (hydrolyzed) hydride surface are quite different from those of the original unmodified tube.