UC Santa Barbara

Phthalocyanines are a well-studied class of organic macrocycles with interesting photochemical and electrochemical properties that have applications in chemical sensing, energy storage, and solar energy conversion. We aim to correlate the identity of the metal center with the electronic properties and redox behavior of phthalocyanine complexes. We first describe the synthesis and characterization of a series of soluble first-row transition metal phthalocyanines complexes. This work focused on elucidating how the identity of the metal center shapes the electrochemical behavior of these complexes. Particular attention was paid to the role of axial ligation and its effects the phthalocyanines complexes’ electrochemistry. It was found that axial ligation of the early transitions metal (V, Cr, Mn, and Fe) either through synthetic modification or solvent choice led to an increase in reversibility. While the late transition metals (Co, Ni, and Cu) demonstrated behavior consistent with adsorption onto the electrode surface which we attribute to their planarity. We proceeded to investigate in detail the interaction of a cobalt phthalocyanine complex with electrode surfaces using electrochemical techniques with the intention of forming electrochemically-modified surfaces. We found that the adsorptive behavior of our cobalt complex could be controlled through axial interaction with O2 and full surface modification was possible through repetitive cyclic voltammetry scanning.We then aimed to correlate the solution-state electrochemical behavior of our metal phthalocyanine complex with their ability to function as charge carriers in a redox flow battery. A redox flow battery architecture with a conductive carbon additive was then used to compare the utility of our soluble metal phthalocyanine complexes with commercially available phthalocyanines complexes that demonstrate low solubility in most common solvents. It was found that the use of a conductive carbon additive allowed for the relatively insoluble phthalocyanine complexes to behave as effective charge carriers and we demonstrated that commercially available PcM complexes (PcVO, PcFe, and Pc Ni) could be used in this architecture with good efficiency metrics. Finally, the optical and electronic properties of a manganese nitride phthalocyanine complex in both solution and thin films were investigated to determine its utility in organic electronics. It was found that while the complex displayed favorably red-shifted absorbance and energy levels however the excited-state lifetimes were short.