Type III-B rotaxane dendrimers (T3B-RDs) are hyperbranched macromolecules with mechanical bonds on every branching unit. First to third (G1-G3), and up to the fourth (G4) generation (MW>22,000 Da) of pure organic T3B-RDs and dendrons were successfully synthesized through the copper catalyzed alkyne-azide cycloaddition (CuAAC) reaction. By utilizing multiple molecular shuttling of the mechanical bonds within the sphere-like macromolecule, a collective three-dimensional contract-extend molecular motion was demonstrated by diffusion ordered spectroscopy (DOSY). The discrete T3B-RDs were further observed and characterized by atomic force microscopy (AFM), dynamic light scattering (DLS), and mass spectrometry (MS). The binding of chlorambucil and pH-triggered switching of the T3B-RDs were also characterized by 1H NMR spectroscopy.;Type III-C rotaxane dendrimer is a new type of rotaxane dendrimer where in the mechanical bonds are in between and constituing the branchning point to form the macromolecules. First and second (G1-G2) type III-C rotaxane dendrimers were synthesized successfully as a prototypical example. Two different shuttling processes have been deomostrated by the non-methylated and methylated type III-C rotaxane dendrimers, and characterized by 1H NMR spectroscopy.
|Date of Award||30 Jul 2018|
|Supervisor||Ken C F LEUNG (Supervisor)|
- molecular switching