New Inorganic-Organic Hybrid Materials for HPLC Separation Obtained by Direct Synthesis in the Presence of a Surfactant

• Published in: Advanced functional materials Vol. 12; no. 2; pp. 134 - 142
• Main Authors: Salesch, T., Bachmann, S., Brugger, S., Rabelo-Schaefer, R., Albert, K., Steinbrecher, S., Plies, E., Mehdi, A., Reyé, C., Corriu, R.J.P., Lindner, E.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag Gmbh 01.02.2002; WILEY‐VCH Verlag Gmbh
• Subjects: High performance liquid chromatogrphy (HPLC) reversed phase; Hybrid materials; Mesoporous materials; Nuclear magnetic resonanze solid-state; Sol-gel processes
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/1616-3028(20020201)12:2<134::AID-ADFM134>3.0.CO;2-A

Nanostructured, mesoporous inorganic–organic hybrid xerogels were reproducibly synthesized by a sol–gel procedure. For the introduction of long alkyl chains into inorganic polymers, trifunctional n‐alkyltrialkoxysilanes of the type CH3(CH2)nSi(OR)3 (n = 7, 11, 17; R = CH3, C2H5) were co‐condensed with Si(OEt)4 (TEOS). The synthetic pathway involves the employment of n‐hexadecylamine as template and catalyst. The xerogels obtained by the present procedure consist of uniform spherical particles with a diameter of about 1 μm. The composition of the new materials was determined by 13C and 29Si cross polarization magic angle spinning (CP/MAS) NMR spectroscopy. In addition, the degree of organization was investigated by small angle X‐ray and electron diffraction. In accordance with 13C CP/MAS NMR spectroscopic measurements, the alkyl chains form a crystalline arrangement within the silica polymer. Brunauer–Emmett–Teller (BET) adsorption measurements confirm specific surface areas of up to 1400 m2/g. The material properties prove the xerogels to be suitable as stationary phases in high‐performance liquid chromatography (HPLC). These novel mesoporous, nanostructured materials have been successfully employed in HPLC for the first time. Different standard reference materials (SRMs) containing polycyclic aromatic hydrocarbons have been separated with the xerogels described in the present work. Nanostructured mesoporous inorganic/organic hybrid xerogels for use as novel HPLC stationary phases have been synthesized by a sol–gel process and successfully tested against hydrocarbon test mixtures. Co‐condensation of an alkyltrialkoxysilane with tetraethoxysilane in the presence of hexadecylamine as both template and catalyst yielded spherical particles about 1 μm in diameter (see Figure for an SEM image) with BET surface areas up to 1400 m2/g.