Self-assembly of a silylated steroid-based organogelator and its use as template for the in situ sol–gel polymerization of tetraethyl orthosilicate

VALERIA C. EDELSZTEIN; GERARDO BURTON; PABLO H. DI CHENNA

TETRAHEDRON

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2010 vol. 66 p. 2162 - 2167

0040-4020

In this paper we report the synthesis of a new steroid-based low-molecular weight organogelator, the analysis of the self-assembled fibrilar network (SAFIN) and its use as template for the preparation of SiO2 nanotubes. This novel steroidal organogelator has a unique structure among the well known family of steroid-based organogelators, the most important characteristic of this molecule is the presence of a silylether group at C-3 together with a 6b,19-oxo bridge. It was capable to gelate hydrocarbons and tetraethyl orthosilicate at very low concentrations (<1 wt %). An insight into the aggregation mechanism is provided revealing that complementary interaction between an a-oriented bond donor and a b-oriented acceptor on the steroid is the driving force for the primary 1D self-assembly. The SAFIN was successfully used as template to grow silica nanotubes (external diameter: 40–60 nm, internal diameter: 7 nm and several micrometers length) through a catalyst-free in situ co-assembly polymerization process. Hydrogen bond or electrostatic interactions between the anionic silicate intermediate species and the SAFIN are proposed to be the driving force for templating.