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

Abstract

The reaction of N(3)(CH(2))(3)Si(OTMS)(3) (TMS = SiMe(3)) with a dialkylammonium having hexynyl group 1, [FcCH(2)NH(2)CH(2)C(6)H(4)-4-O(CH(2))(4)C≡CH]PF(6) (Fc = Fe(C(5)H(4))(C(5)H(5))), in the presence of dibenzo[24]crown-8-ether (DB24C8) and [Cu{Fe(CN)(4)}]PF(6) 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{(CH(2))(3)N(3)}-](n)[-O-SiMe(2)-](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 PdCl(2)(MeCN)(2) to a solution of the side-chain polyrotaxane forms gel which regenerates the sol upon addition of PPh(3).