Introduction of ferrocene-containing [2]rotaxanes onto siloxane, silsesquioxane and polysiloxanes via click chemistry

The reaction of N-3(CH2)(3)Si(OTMS)(3) (TMS = SiMe3) with a dialkylammonium having hexynyl group 1, [FcCH(2)NH(2)CH(2)C(6)H(4)-4-O(CH2)(4)C CH]PF6 (Fc = Fe(C5H4)(C5H5)), in the presence of dibenzo[24] crown-8-ether (DB24C8) and [Cu{Fe(CN)(4)}]PF6 catalyst yielded the [2]rotaxane containing the dialkylammonium unit terminated by a bulky silyl group. Azides with a silsesquioxane group react similarly to form the corresponding [2]rotaxanes having a bulky silsesquioxane end group. The azide-functionalized polysiloxane, [-O-SiMe{(CH2)(3)N-3}-](n)[-O-SiMe2-](m) also undergoes a click reaction with 1 to produce the side chain polyrotaxane. Cyclic voltammograms of these rotaxanes and 1 [(DB24C8) 1] show the Fe(II)/Fe(III) redox at the same potential, but with different current depending on their molecular weights. Addition of PdCl2(MeCN)(2) to a solution of the side-chain polyrotaxane forms gel which regenerates the sol upon addition of PPh3.