Facile construction of Zn(II)-porphyrin-cored [5]rotaxane and its controllable aggregation behaviours

Rotaxanes have attracted more and more attentions because of their diverse applications as sensors, catalysts, and functional materials. The construction of highly ordered and discrete multirotaxanes with the well-defined structure remains a challenge. Herein, a symmetric [5]rotaxane with zinc porphyrin as core and the neutral platinum-acetylide as the linkage was synthesized with high yield. The [5]rotaxane was well characterized with NMR spectroscopy and MALDI-TOF mass spectrometry. Interestingly, it was found that the [5]rotaxane showed the controllable aggregation behaviours in different solution compositions. For example, in non-polar solution, the [5]rotaxane could self-assemble into the large-scaled solid nanospheres while the nanofibers were formed in polar solvent. Further investigation revealed that the [5]rotaxane displayed J-type aggregation in solution driven by π-π interaction. Notably, the similar structure without DPP[5]A formed the irregular morphology at the same condition, suggesting that the existence of rotaxanes endowed the complex with a relative rigid structure to facilitate the formation of the ordered aggregates.