A one-pot approach to coaxial hybrid nanotubes of calixarene/silica via self-assembly and sol-gel transition

In this one-pot approach, amphiphilic terminal amino calix[6]-biscrowns (TAC) self-assembled quickly into nanotubes, on the surface of which, tetraethoxysilane (TEOS) was absorbed and hydrolyzed under the catalysis by the amino groups of TAC leading to the formation of the outer layer of silica. The thickness of the silica coating layer in the resultant coaxial nanotubes is tunable by changing either the reaction time or the dosage of TEOS. The hybrid nanotubes exhibit the capability of selective complexation with metal ions as evidenced by the substitution of K(+) by Cs(+).