Rotaxanes of a macrocyclic ferrocenophane with dialkylammoniumaxle components

摘要

Octaoxa[22]ferrocenophane, 1, was synthesized and employed as the macrocyclic component of[2]rotaxanes. [2]Pseudorotaxanes composed of macrocyclic molecule 1 and dialkylammoniumderivatives with a terminal vinyl group undergo end-capping via cross-metathesis of the terminal groupwith bulky acrylates. The [2]rotaxanes of 1 with axle components having bulky terminal groups, such as3,5-dimethylphenyl, 9-anthryl, and ferrocenyl groups, maintain an interlocked structure in CDCl_3solution, but they are gradually converted into a mixture of the individual components via dethreadingof the end groups in polar solvents such as CD_3CN and dmso-d_6. The reaction rate varies depending onthe end group and solvent. The cationic rotaxane with an anthryl end group of the axle component,[(1){AnCH_2NH_2CH_2C_6H_4-4-OCH_2CH_2CH=CHCOOC_6H_4-4-C(C_6H4-4-tBu)_3}](BAr_F) (An =9-anthryl, BAr_F =B{C_6H_3-3,5-(CF_3)_2}_4) shows weak emission upon excitation of the anthryl group(12b, λ_(em)= 419 nm, quantum yield, Ф=0.012). The quantum yield is lower than that of the neutralrotaxane 13b (Ф = 0.030) formed by N-acetylation of 12b and a physical mixture of the correspondingfree axle molecule, AnCH_2N(Ac)CH_2C_6H_4-4-O_CH_2CH_2CH=CHCOOC_6H_4-4-C(C_6H_4-4-tBu)_3(8), and1 (Ф = 0.34). The efficiency of the quenching caused by the ferrocenylene group caused by energytransfer is affected significantly by the relative positions of the anthryl and ferrocenylene groups in therotaxane. The rotaxane with axles having a secondary ammonium moiety has a redox potential E1/2 =-0.03-0.02 V (vs. Ag+ /Ag), which is lower those of than compound 1(E1/2=-0.10 V) and the neutral[2]rotaxanes with the N-acetylated axle components (E1/2 = -0.11 and -0.22 V).