Construction of unique pseudo[1]rotaxanes and [1]rotaxanes based on mono-functionalized pillar[5]arene Schiff bases.

A series of mono-functionalized pillar[5]arene Schiff bases were successfully synthesized by amidation reaction of pillar[5]arene mono-O-butyrate with various diaminoalkanes and sequential condensation reaction of monoaminoalkyl-functionalized pillar[5]arenes with substituted salicylaldehydes. ¹H NMR and 2D NOESY spectra clearly showed that all monoaminoalkyl-functionalized pillar[5]arenes could form pseudo[1]rotaxanes by self-sorting of aminoalkyl chain into the cavity of pillar[5]arene, while pillars[5]arene Schiff bases with longer than butylene chain (n ≥ 4) could form stable [1]rotaxane. The fluorescence spectrophotometry indicated that pillar[5]arene Schiff bases coordinated with Zn²⁺ ion to form interesting complexes with 2:1 coordination ratio and with significant enhance of the fluorescence intensity. [ABSTRACT FROM AUTHOR]