NMR Studies On The Interaction Of Host-Guest Complexes Of Disubstituted Cucurbit[6]uril

In this thesis, evidence for inclusion complexation in solution between the synthetic receptor symmetrical tetramethylcucurbit[6]uril (TMeQ[6]) , and a series of alkyl-and aryl-substituted ammonium ion ligands is elaborated by NMR. The thesis consists of two parts.In part one, complexation between symmetrical tetramethylcucurbit[6]uril (TMeQ[6]) and 2-(Aminomethyl) pyridine (ampy), 5, 5'-bimethy-2, 2'-bipyridine (bmbpy) and 2, 2'-bipyridine (bpy) was studied by two dimensional nuclear magnetic resonance (2D NMR) as a host-guest interaction. Intermolecular NOEs appeared in 2D ROESY spectrum reveal a well-defined complex structure between them.~1H exchange spectroscopy (2D EXSY) showed that the 1:1 complex between TMeQ[6] and bmbpy is undergoing slow exchange at high temperature with two pyridine rings of bmbpy alternatively entering the cavity of TMeQ[6] and changing the combinative sites between the two portals of TMeQ[6]. The temperature dependence of the rate constants calculated from the EXSY spectra yielded an activation energy of 104. 2 kJ /mol for the exchange process.In part two, a TMeQ[6]-based intramolecular switch is designed. Dissociation constants (Kd) for a series of alkyl-and aryl-substituted ammonium ion ligands is measured by quantitative ~1H NMR integration. While the stabilities of TMeQ[6] and many ammonium ion ligands complexes strongly depend on pH, and the Kd values have a large difference, bpy, C7H15NH3+ and TMeQ[6] is choiced to compose a three compounds system in which TMeQ[6] exhibits a bimodal binding pattern contingent upon pH.