Electrochemical Investigation of Porphyrin and Its Derivatives at Various Interfaces

Abstract

This chapter describes the electrochemistry of the porphyrins at solid-liquid and liquidliquid interfaces. The fundamental electrochemical approach toward the porphyrin molecules in estimating their HOMO and LUMO energy levels is given. Various factors such as the effect of central metal ion, the periphery of the aromatic ring and axial ligands on the redox potentials of porphyrins have been discussed. Electrochemical sensing application of porphyrin molecules is described with few examples in brief. Much focus has been given on the electrochemistry of the self-assembled monolayer (SAM) of thiol-porphyrins on the gold electrode. Structural characterization and charge transfer across the SAM using cyclic voltammetry and electrochemical impedance spectroscopy are discussed. Theory and methodologies developed to study photoinduced charge transfer kinetics of porphyrin molecules using scanning electrochemical microscope at the solid-liquid and liquid-liquid interface have been described. Use of porphyrin molecules as luminophores in electrochemiluminescence sensing applications and the mechanisms involved are described through representative examples.

Water soluble porphyrin‐Schiff base ligands and their metal complexes: Synthesis, photophysical, electrochemical, and chemosensor properties

“…As can be observed from the anodic and cathodic peak values in Table S2, the metal free ligands have two anodic peak potential values in the range of −0.55 to 0.77 V. Two oxidation peak potentials are assigned to π‐cation radicals and π‐dications, while the reduction potentials are π‐anion radicals and π‐dianions. [ 40a,b ] On the other hand, the ligands Na 6 (H 5 L 1 ) and Na 6 (H 5 L 2 ) have two cathodic peak potentials in the range of −0.77 to 0.82 V, while ligand Na 6 (H 5 L 3 ) has three cathodic peak potentials in the range of −0.63 to 0.79 V. Depending on the increase in scanning rates, the cathodic and anodic peak values shift towards more positive regions. Another observed difference is that the groups on the formyl ring of the ligands donated more electrons to the ring and the cathodic peak values shifted to more positive regions.…”

“…Na 6 [Zn 4 (L 3 )Cl 3 ]·4H 2 O (9) complex also shows similar electrochemical processes to other porphyrin Zn +2 complexes. [ 40a,b ] At scan rates of 750 and 1,000 mV/s, complex Na 6 [Zn 4 (L 3 )Cl 3 ]·4H 2 O (9) has quasi‐reversible redox pairs, while at other scan rates, the redox processes are irreversible.…”

Versatile Metalloporphyrin‐Based Electrochemical Sensing Applications: From Small Gasotransmitters to Macromolecules

“…[32] Transducers commonly reported for the construction of electrochemical sensors are conducting organic polymers, [33] carbon-based materials, [34] metal nanoparticles, [35,36] and gold electrodes modified with selfassembled monolayers (SAMs). [13,37] The resulting electrical signal is related to the recognition process and is proportional to the analyte concentration. [4,38] Different approaches to achieve chemically modified electrodes could be described, depending on the molecular binding of metalloporphyrins to several types of electrodes (Figure 4): [31,[38][39][40] 1.…”

Electrochemical Sensing and Photoelectrodegradation of Pentachlorophenol using Co‐, Mn‐ and Zn‐Porphyrins

“…Through modification of the structure of porphyrin, its electronic properties such as light absorption, redox processes, energy and electron transfer can be altered. [15,16] The rich redox chemistry of metal porphyrins make them ideal for electrocatalysis [16,17] hence the use of metal porphyrins in this study. We employ a glassy carbon electrode (GCE) and indium tin oxide (ITO) electrode modified with manganese ([Mn III (TMtPP)Cl]), cobalt ([Co II (TMtPP]), and zinc ([Zn(TMtPP)]) metalated meso-tetra-[4-(methylthio) phenyl] porphyrins for electrochemical sensing and photoelectrocatalytic degradation of pentachlorophenol (PCP).…”