@unpublished{pittir9905,
           month = {February},
           title = {Heterogeneous Electron Transfer of Supramolecular Assemblies},
          author = {Jianjun Wei},
            year = {2005},
        keywords = { Cytochrome c; Electron transfer; Porphyrins; Electrochemistry; Self-assembled Monolayers},
             url = {http://d-scholarship-dev.library.pitt.edu/9905/},
        abstract = {Heterogeneous electron transfer of protein, porphyrins through self-assembled monolayer (SAM) at gold electrodes was studied. The SAM was characterized by electrochemistry, thickness measurement, contact angle, scanning tunneling microscopy (STM) and others. The electron transfer rate constants of cytochrome c immobilized on a SAM by directly ??wiring?{$\pm$} its heme through a variety of nitrogen ligands (pyridine, imidazole or nitrilE) were measured by cyclic voltammetry. The electron transfer mechanism was explored by changing the distance between the electrode and protein, the composition of the SAM chains, the type of cytochrome c (horse heart cytochrome, rat cytochrome c and its mutants), and the conditions of electrolyte solutions. The results were compared to those of cytochrome c electrostatically adsorbed at carboxylic acid terminated SAMs, distinguishing the electron transfer mechanism and electron transfer pathways. A unified theoretical model, i.e. a gradual transition of the mechanism from a friction controlled reaction at short distance to tunneling controlled reaction at long distance, was applied to these ??heme-wired?{$\pm$} systems. In a study of photo-induced electron transfer of porphyrins through SAMs with chiral structure, an asymmetrical effect on the efficiency of electron transfer through these chiral chain structures was found. Induced circular dichroism of porphyrin aggregates, orbital angular momentum interaction in electronic coupling, are proposed as possible mechanisms for the asymmetry of electronic tunneling.}
}