Electrochemical Rectification of Redox Mediators Using Porphyrin-Based Molecular Multilayered Films on ITO Electrodes

Abstract

Electrochemical charge transfer through multilayer thin films of zinc and nickel 5,10,15,20-tetra(4-ethynylphenyl) porphyrin constructed via copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) "click" chemistry was examined. Current rectification toward various outer-sphere redox probes is revealed with increasing numbers of layers, as these films possess insulating properties over the neutral potential range of the porphyrin, then become conductive upon reaching its oxidation potential. Interfacial electron transfer rates of mediator-dye interactions toward [Co(bpy)3](2+), [Co(dmb)3](2+), [Co(NO2-phen)3](2+), [Fe(bpy)3](2+), and ferrocene (Fc), all outer-sphere redox species, were measured by hydrodynamic methods. The ability to modify electroactive films' interfacial electron transfer rates, as well as current rectification toward redox species, has broad applicability in a number of devices, particularly photovoltaics and photogalvanics.

Electrocatalytic Properties of Binuclear Cu(II) Fused Porphyrins for Hydrogen Evolution

“…In this context, tetrapyrrolic macrocycles, including metalloporphyrins, have garnered significant attention − as they are essential to the function of biological systems and serve as molecular components in existing and emerging technologies. As electrocatalysts, metalloporphyrins are capable of chemically transforming protons into hydrogen as well as converting carbon dioxide into carbon monoxide and other reduced forms of carbon. − …”

Azides and Porphyrinoids: Synthetic Approaches and Applications. Part 1—Azides, Porphyrins and Corroles

“…In fact, this strategy is very convenient to generate multichromogenic (donor-acceptor) energy transfer assemblies to develop full spectral light harvesting materials for DSSC devices [49]. The same research group, by following the LbL process and through a click approach, prepared other porphyrin-based molecular multilayer films (ITO-MP1-Zn) on indium tin oxide (ITO) electrodes for photovoltaic and photogalvanic devices [50]. Zhang and co-workers described the preparation of organic-inorganic hybrid porphyrin derivatives with a polyhedral oligomeric silsesquioxane (POSS) [51,52].…”

Enhanced Signal Amplification in a Toll-like Receptor-4 Biosensor Utilizing Ferrocene-Terminated Mixed Monolayers

“…0.25 V vs Ag/AgCl). This results in much larger anodic currents than seen for either a comparable ferrocene SAM or for the oxidation of ferrocyanide at a similar nonferrocenyl-terminated SAM, and quite small cathodic currents, often referred to as rectification. − This strategy for the generation of signals in an electrochemical biosensor has been previously explored, e.g., in the design of DNA-based biosensors. − …”