Electrochemical and In-situ spectroelectrochemical properties of novel mononuclear 2,4-di-tert-butyl-6-(3,4-dicyanophenoxy)phenolate substituted metallophthalocyanine compounds

In this study, the synthesis and characterization of a series of novel tetra substituted highly soluble metallophthalocyanines [M = CoII, FeIII, MnIII, NiII and ZnII] derivatives bearing 2,4-di-tert-butyl-6-(3,4-dicyanophenoxy)phenolate groups on the peripheral positions are reported. These phthalocyanine (Pc) compounds can be used as new starting materials for the synthesis of dinuclear ball-type Pcs due to the involvement of four phthalonitrile rings as closable end groups in their molecules. The assignment of the redox processes of these compounds indicated that CoII, FeIII, and MnIII centers into the Pc core increased the redox richness of the complexes, with the addition of metal-based electron transfer processes to the ring-based ones while NiPc and ZnPc show only ring-based electron transfer processes. These ball-type Pc precursor compounds exhibited a unique character also as a result of eight redox-active nitrile end groups on the peripheral tails of the Pc core. Thus, electrochemical and spectroelectrochemical properties of metallophthalocyanine complexes were analysed, also in comparison to their previously reported (5-(tert-butyl)-2-((3,4-dicyanophenoxy)methyl)phenyl) methanolate substituted analogues to determine the influence of metal centers and substituents in the periphery. Altering the metal center of the Pc ring as incorporation of a redox active metal center and changing the positions of the substituents slightly affected the potentials for nitrile and Pc ring redox processes. However, the spectral and color responses of the complexes were significantly influenced by the nature of central metal and peripheral substituents. As an important reflection, the electron transfer processes of the complexes and the connection between the electrochemically generated anionic and cationic species originated distinct spectral and color changes, identified with in-situ spectroelectrochemical measurements in solution medium. These measurements pointed out their potential applicability in the fields of the opto electronic technologies.