Title

Electrochemistry of hemicarceplexes, hemicarcerands and inclusion complexes

Date of Award

1999

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Angel E. Kaifer, Committee Chair

Abstract

The voltammetric behavior of ferrocene inside two hemicarcerand hosts was investigated in dichloromethane and tetrachloroethane solutions. Substantial changes in the anodic voltammetric behavior of the ferrocene nucleus resulted from encapsulation. Generally, encapsulated ferrocene exhibited a more positive half-wave oxidation potential and a lower apparent standard rate constant of heterogeneous electron transfer than free ferrocene under identical experimental conditions. The anodic shift of the half-wave potential probably results from the hindered solvation of the positively charged, oxidized ferrocene inside the nonpolar hemicarcerand cavities. The observed decrease in electron transfer can be ascribed primarily to the increased molecular mass of the electroactive species and the longer distance of maximum approach between the ferrocene center and the electrode surface which is imposed by the encapsulating host. Generally, electrochemical oxidation did not significantly alter the slow rate of ferrocene guest dissociation or release from the hemicarceplexes surveyed.Two cavitands bearing four peripheral tetrathiafulvalene (TTF) units and one hemicarcerand containing four TTF units as bridges were synthesized. The compounds were characterized by 1H NMR, 13C NMR, and MALDI-TOF mass spectrometry. Their voltammetric behavior was investigated in dichloromethane solutions. The compounds displayed the two redox couples typical of the two consecutive one-electron oxidations of TTF systems demonstrating that all TTF units undergo two single-electron oxidations.Two water soluble dimers bearing ferrocene and cobaltocenium units were synthesized. The compounds were characterized by 1H NMR, 13C NMR, IR and FAB mass spectrometry. Their voltammetric behavior was investigated in the absence and presence of beta-cyclodextrin. Perturbations on the voltammetric waves upon addition of beta-cyclodextrin revealed the formation of inclusion complexes between the redox subunits and the cyclodextrin host.

Keywords

Chemistry, Organic; Chemistry, Physical

Link to Full Text

http://access.library.miami.edu/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9934254