Host-guest complexation studies in aqueous solution and at the electrode-solution interface
Date of Award
Doctor of Philosophy (Ph.D.)
First Committee Member
Angel E. Kaifer, Committee Chair
The electrochemical behavior of cobaltocenium (Cob +) and carboxycobaltocenium (Cob+-COO- ) in aqueous solution was investigated by cyclic voltammetry in the presence of beta-cyclodextrin (beta-CD). While Cob+ and Cob+-COO- do not interact significantly with beta-CD, their reduced partners (Cob and Cob-COO-) do form stable inclusion complexes with beta-CD host.The complexation of Cob+ by sulfonated calixarene host was investigated in buffered aqueous solution using cyclic voltammetry and 1H NMR spectroscopy. The results indicate that the sulfonated calixarene forms a 1:2 complex with Cob+, but does not bind the reduced form Cob significantly. In the presence of beta-CD, reduction of the strong 2:1 complex between Cob+ and sulfonated calixarene leads to the formation of 1:1 complexes between Cob and beta-CD.A series of poly(propyleneimine) dendrimers functionalized with 4, 8, 16 and 32 peripheral Cob+ subunits were investigated, placing especial emphasis on their electrochemical properties and binding interactions with beta-CD. These dendrimers in combination with beta-CD constitute novel supramolecular assemblies whose formation is driven by the electrochemical reduction of these dendrimers.The interfacial binding properties of electrodes prepared by the electrostatic immobilization of positively charged beta-aminocyclodextrin (beta-ACD) hosts onto a self-assembled monolayer of thioctic acid on gold were investigated using Osteryoung square wave voltammetry. The results indicate that the water-soluble ferrocenecarboxylate (Fc-COO-) guest was effectively bound by the interfacial beta-ACD hosts, with binding constants in the range 2--5 x 104 M-1. The measured binding constants were found to increase slightly with the surface density of immobilized hosts.The electrochemical behavior on cystamine-modified gold electrodes of three novel dendrimers containing a single, unsymmetrically positioned ferrocene unit and 3, 9 and 27 carboxylic acid groups in their periphery was investigated as a function of solution pH in the range of 3--7. The results constitute the first example of orientation effects on the heterogeneous electron transfer rates of synthetic compounds whose electron transfer behavior is similar to redox proteins.
Wang, Yun, "Host-guest complexation studies in aqueous solution and at the electrode-solution interface" (2000). Dissertations from ProQuest. 3878.