Electrochemical and spectroelectrochemical characterization of meso-tetra-alkyl porphyrins

Abstract

A series of three meso-tetra-alkyl porphyrins (H 2 TAPs) were synthesised and their electrochemical properties were studied in dichloromethane containing either tetra-butyl ammonium perclorate (TBAP) or tetra-butyl ammonium hexafluorophosphate TBA(PF 6 ) as supporting electrolyte (SE) by cyclic voltammetry and in situ UV/vis spectroelectrochemistry. Values of E 1/2 for the recorded four redox processes of these porphyrins and of the meso-tetra-phenyl porphyrin (H 2 TPP) on glassy carbon and platinum were measured and compared. The redox data collected on the first oxidation and the first reduction processes predict that the value of (LUMO − HOMO) for the H 2 TAPs is lower than for meso-tetra-phenyl porphyrin and, therefore, that the first Q band of the electronic spectra of the H 2 TAPs is red shifted relatively to the same band in the spectrum of H 2 TPP; this shift was indeed found. The second oxidation process of the H 2 TAPs is influenced by the supporting electrolyte used and the dication then formed is consumed by an irreversible chemical reaction. The species produced in this reaction is irreversibly reduced at a considerably lower potential. The electrochemical and spectroelectrochemical data collected are consistent with the occurrence of structural distortion in the macrocycle rings of the H 2 TAPs.

Electronically Tuned Asymmetric meso‐Substituted Porphyrins for p‐Type Solar Cells

“…All relevant data are gathered in Table . Generally, in comparison to the literature reported NiTPP and H 2 TPP, the presence of electron‐withdrawing groups in 3 , 3(Ni) , and 4 , renders reduction easier and oxidation more difficult. In particular, 3 is characterized by two reversible reductions at −1.31 and −1.69 V. Similarly, 3(Ni) displays two reversible reductions at −1.32 and −1.78 V, complemented by one quasi‐reversible at −2.16 V. The subtle cathodic shifts relative to 3 are attributed to the presence of the Ni metal.…”

Electrochemistry of a novel monoruthenated porphyrin and its interaction with DNA

“…As shown in the plot A of Fig. 2, electrochemistry of the ruthenated porphyrin is indeed very rich owing to the presence of many electrochemical active groups such as porphyhin ring, pyridyl, bpy ligands and central ruthenium ion, and so on [28][29][30][31][32]. In order to better analyze the electrochemical responses of [Ru(MPyTPP) (bpy) 2 Cl]Cl, the plot B in Fig.…”

Investigating Electronic Communications in meso–meso Ethene‐Bridged Unsymmetrical Diporphyrins

“…Clear differences corroborate that the dimerization and metallation influence both the reductions and oxidations. Generally, the electrochemical results of 4 – 6 are widely reported in the literature …”

“…In 5 , two reversible reductions at −1.64 and −1.98 eV are observed. The first and the second oxidations at +0.57 and +1.00 eV are assigned to the formation the π‐cation radical and the dication, respectively . Compound 6 shows two well‐defined oxidations at +0.58 and +0.85 eV and one reduction at −1.74 eV.…”