Electrochemical characterization of phthalocyanine derivatives carrying a bulky triester unit on each benzo group

Abstract

The focus of the present work is to gain more insight into the electrochemical behavior of newly synthesized Co II , Zn II , Cu II , and Pd II phthalocyanines with tetra-tricarbethoxyethyl substituents at the peripheral position. A more exhaustive electrochemical study of the complexes was done to determine the desired wisdom for the usage of the complexes as a functional material. A comparative study of the voltammetric measurements of these complexes showed that while Zn II , Cu II , and Pd II phthalocyanines exhibited up to four common phthalocyanine ring reductions, Co II phthalocyanine gave a metal-centered oxidation, a reduction and a ligand-centered reduction process. By contrast observation of the splitting of the second reduction process of Pd II phthalocyanine suggests aggregation of the complex. Diffusion coefficients of all complexes were determined by both the cyclic voltammetry and the potential step chronocoulometry techniques. Diffusion coefficients of the reduced and oxidized forms of the redox couples of the complexes were also calculated by the potential step chronocoulometry technique. Diffusion coefficients of the reduced forms of the electrode products of the complexes were found to be slightly higher than that of the oxidized forms.

Spectroelectrochemical characterization and controlled potential chronocoulometric demetallation of tetra- and octa-substituted lead phthalocyanines

“…The separation between the first and second ring reductions was found to be approximately 0.34 V for all complexes. These peak separations and HOMO-LUMO gap values are in agreement with the reported separation for redox processes in metallophthalocyanine complexes [29][30][31][32][33][34][35][36]. Table 1 The electrochemical data of the lead phthalocyanines…”

Synthesis, electrochemistry and in situ spectroelectrochemistry of water-soluble phthalocyanines

“…In TBAP/DCM electrolyte system, the first oxidation process of 2 recorded at -0.28 could be assigned easily to the Co II /Co I redox couple, respectively, and the remaining processes to the phthalocyanine ring. The separation between the metal center reduction and oxidation processes (*0.85 V) in DMSO and the metal center reduction and ligand-based oxidation processes (*1.25 V) in DCM are comparable with other CoPc papers [36,38,41,[42][43]. Assignments of the redox couple are confirmed by spectroelectrochemical measurements given below.…”

“…The redox potentials of the complexes shift toward negative potentials due to the effect of electron-donating dialkylaminophenoxy groups or trialkylammoniumphenoxy moieties [36][37][38][39]. The separation between the first ring reduction and the first ring oxidation processes is related to the HOMO-LUMO gap, and the peak-to-peak separations are in agreement with the reported electrochemical data of the phthalocyanines [36,[39][40][41][42][43][44][45][46][47].…”

Novel phthalocyanines with naphthalenic substituents

“…The difference between the first and second reduction processes for CuPc is 0.38 V, which compares with the average value for the first and second reduction processes of non-transition metal phthalocyanine complexes. The difference between the second and third reduction processes is 0.48 V, a value that perfectly agrees very well with the literature values of various MPc complexes [30][31][32].…”