Sequence Matters: Precise Synthesis of Hetero[3]rotaxane Isomers with Sequence-dependent Chemical Reactivity and Circularly Polarized Luminescence

Sequence isomerism plays fundamental roles in the encoding of biological information and in tuning material performance, but engineering sequences and elucidating their effects remain a major and largely unmet challenge in synthetic chemistry. Herein, We develop a novel wheel assembling approach aiming at the precise sequence control of hetero[3]rotaxanes, a typical family of mechanically interlocked molecules. Based on a key [2]rotaxane precursor with exchangeable pentafluorophenyl ester stoppers, We successfully synthesized both sequence isomers of diverse hetero[3]rotaxanes. Moreover, taking advantage of the chirality retention along with the wheel assembling process, corresponding sequence isomers of chiral functionalized hetero[3]rotaxanes were further precisely synthesized. Impressively, these hetero[3]rotaxanes revealed remarkable sequence-dependent chemical reactivity and circularly polarized luminescence, highlighting fantastic sequence effects. This proof-of-concept study lays the foundation for the investigations on the structure-property relationships of heterorotaxanes, which would further direct the rational design and precise synthesis of sequence-defined heterorotaxanes with desired properties for practical use.