Comparison of octadecyl bonded titania phases

Summary The structure of a C₁₈ phase based on titania (C₁₈-A), synthesized by the method of solution polymerization, is investigated by diffuse reflectance infrared Fourier transform (DRIFT) and solid-state nuclear magnetic resonance (NMR) spectroscopy. The findings are compared with the results of a second C₁₈ phase based on titania (C₁₈-B) which was synthesized by the method of surface hydrosilation. The dynamic behavior of both phases is examined by¹H MAS NMR detection of spinlattice relaxation times in the rotating frame (T_1pH) and conventional spin-lattice relaxation times (T₁). Due to a smaller ligand density, phase C₁₈-A appears to be a somewhat more mobile than phase C₁₈-B. The chromatographic capability of the phase C₁₈-A is demonstrated by the separation of samples containing benzene derivates or anilines. The elution order is analogous to the phase C₁₈-B, but for both test mixtures the polarity of the mobile phase has to be increased. Phase C₁₈-A is classified as being polymeric by the Sander and Wise test, whereas phase C₁₈-B shows intermediate retention behavior.