Master of Science (MS)
Semester of Degree Completion
Radu F. Semeniuc
The self-sorting ability of certain crown ethers make them important players in the field of supramolecular chemistry, especially those studying mechanically interlocked molecules (MIMs). Of these MIMs, rotaxanes and catenanes are the most common. Our approach in the synthesis of poly-rotaxane systems involves the preparation of axles containing multiple recognition motifs to determine the self-sorting principles that each motif shows. These principles include narcissistic self-sorting, and also type I and type II social self-sorting principles. Using these techniques, poly-rotaxane formation can be made readily available.
A hetero-poly-rotaxane equipped with a naphthalene diimide (NDI) site and two ammonium salt sites has been developed and expanded on by its structure to determine the different effects that certain crown ethers have on the formation of poly-rotaxanes. Using UV-Vis and solid-state structure studies, the association constants of the poly-rotaxanes were determined to study how the formation of poly-rotaxanes were effected. Our studies determined that the socially self-sorting principles of the crown ethers to the different recognition motifs were favorable for type I social self-sorting principles. This means that the DB24C8 had an affinity for only the ammonium salt, and the 15DN38C10 had an affinity for the NDI.
Determined from UV-Vis titration studies, it was found that the DB24C8 had minimal effect on the formation of the NDI central piece with the 15DN38C10. The same was determined in the solid-state studies. When adding 3+ equivalents of the DB24C8 to the axles with three recognition motifs, it was determined that the DB24C8 had no affinity for the NDI central piece. This lack of affinity that the Dibenzo crown showed for the NDI reinforced our conclusion that the type I socially self-sorting principles were displayed in the system. What this means, is that poly-rotaxane formation can be simplified by the fact that certain crown ethers have an affinity for special recognition sites through social self-sorting principles.
Welti, Austin P., "Synthesis and Characterization of Molecular Components for the Preparation of Poly-Rotaxanes" (2014). Masters Theses. 1365.