Synthesis And Characterization Of Several Pseudorotaxanes Based On Dibenzo-24-Crown-8-Ether

With the development and improvement of supramolecular chemistry, pseudorotaxanes and rotaxanes based on crown ethers were paid more and more attention. In this thesis, the general situation of supramolecular chemistry was introduced as well as the concepts of molecular recognition, self-assembly, non-bonded interactions and so on. Then the studies on pseudorotaxanes and rotaxanes based on the recognition modes of dibenzo-24-crown-8 (DB24C8) and secondary ammonium cation, 1, 2-bis(pyridinium)- ethane, paraquat were reviewed respectively. Several molecular machines which had the similar recognition fashion were described. On this condition, a series of guests are synthesized and assembled with DB24C8. To further understand the molecular recognition, varying analytical means were adopted and the crystal structure was dissected. The major contents of this thesis as follows:1. Three guests 1, 2-bis(4-(propionamido)pyridinium)-ethane, 1, 2- bis(4-(benzamido)pyridinium)-ethane, 1, 2-bis(4-(pyridin-4-ylformamide)pyridinium)- ethane were synthesized, and formed three pseudorotaxanes with DB24C8 respectively. ~1H NMR was used to investigate the solution behaviors of the three pseudorotaxanes, and the association constant of [1, 2-bis(4-(benzamido)pyridinium)-ethane(?)DB24C8] was determined; The crystal structures of the other two pseudorotaxanes were studied by X-ray diffraction as well as the assembly behavior of [1, 2- bis(4-(pyridin-4-ylformamide)pyridinium)-ethane(?)DB24C8].2. Mono- and di-protonated 4, 4′-bipyridine were synthesized and mixed with DB24C8 respectively to give two pseudorotaxanes. The ~1H NMR, ESI-MS, UV Job's method were used to investigate the recognition mode, gaseity behavior and stoichiometry of the guest and host in the inclusion compound; The two association constants (Ka) were determined by ~1H NMR and UV titration method respectively. The solid crystal structure and self-assembly behavior of [2]pseudorotaxane formed by mono-protonated 4, 4′-bipyridine and DB24C8 was studied by X-ray diffraction.3. Several secondary ammonium cations were designed; a synthetic route was established to gain the precursors. P-TsCl and o-NsCl were used to protect the amidogen of dibenzylamine. The products N-dibenzyl-4-methylbenzenesulfonamide and N- dibenzyl-2-nitrobenzenesulfonamide reacted with 2-,3- and 4-(chloromethyl)pyridine to give six N-alkylated compounds which then suffered a failed de-protection. However, N,N-dibenzylammonium were successful obtained by the similar method.