Title

Non-covalent encapsulation of redox active compounds by resorcin[4]arenes

Date of Award

2005

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Chemistry

First Committee Member

Angel E. Kaifer, Committee Chair

Abstract

This dissertation describes the effective encapsulation of the electroactive compounds, cobaltocenium (Cob+), ferrocenium (Fc+), and tetrathiafulvalene (TTF·+) inside self assembling capsules of resorcinarenes and pyrogallolarenes in non-polar solvents. Both 1H NMR spectroscopic and voltammetric experiments clearly reveal that these Cob+ experience encapsulation. Diffusion coefficient measurements obtained from PGSE NMR experiments indicate that these molecular capsules exist in dichloromethane solution in the absence of any cations. However, bound and free Cob+ ions undergo slow exchange in the NMR time scale, but the bound Cob+ ions rotate and/or tumble freely inside the molecular capsules. Under electrochemical conditions the encapsulation of all three positively charged guests depends on the nature of the supporting electrolyte. Tetraalkylammonium hexafIuorophosphate, tetrafIuoroborate and perchlorate supporting electrolytes prevent the encapsulation of Cob+, while tetraalkylammonium chloride and bromide salts allow it. The nature of the tetraalkylammonium cation also plays a smaller role in the encapsulation. More efficient encapsulation occurs in the presence of supporting electrolytes with longer alkyl chains. Finally, the structure of the host (whether resorcinarene or pyrogallolarene) also factors in the overall stability of the molecular assembly. Resorcinarenes, which are less stable in the presence of polar solvents such as dimethylsulfoxide, are more efficient at encapsulating these guests than pyrogallolarenes.

Keywords

Chemistry, Analytical; Chemistry, Organic

Link to Full Text

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