Immobilized cobalt(II) phthalocyanine–cobalt(II) porphyrin pentamer at a glassy carbon electrode: Applications to efficient amperometric sensing of hydrogen peroxide in neutral and basic media

Corrosion resistance of aluminum against acid activation in 1.0 M HCl by symmetrical ball - type zinc phthalocyanine

The inhibition effect of symmetrical Ball - type Zinc Phthalocyanine on Aluminum in 1mol/L hydrochloric acid was analyzed by electrochemical techniques. A novel ball-type zinc phthalocyanine (Zn-Pc) inhibitor has been synthesized and verified utilizing FTIR, nuclear magnetic resonance (1H NMR and 13C NMR), MALDI-TOF MS, and absorption spectroscopy (UV-Vis). In addition, laser-induced breakdown and photoluminescence spectroscopy were employed for additional study. Weight loss technique was employed to investigate the corrosion inhibition effectiveness of the synthesized Zn-Pc on Aluminum in 1mol/L hydrochloric acid at the range of variation temperatures (293-333 K). The inhibition efficiency of Zn-Pc increased with higher concentrations of Zn-Pc and decreased as the temperature increased. Furthermore, Zn-Pc demonstrated outstanding outcomes, achieving 72.9% at a very low inhibitor concentration (0.4 mmol/L) at 298 K. The experimental data for Zn-Pc Aluminum in 1mol/L hydrochloric acid obeys the Langmuir adsorption isotherm. Moreover, the corrosion system's thermodynamic parameters and activation energy were determined. Quantum chemical calculations applying the (DFT) Density Functional Theory method was conducted and applied in this study. These calculations played a pivotal role in elucidating molecular structures and reactivity patterns. Through DFT, numerous reactivity indicators were computed, providing valuable insights into the chemical behavior of the studied compounds. These indicators, such as frontier molecular orbitals, electron density, and molecular electrostatic potential, were subsequently correlated with experimental data.

Bienzymatic biosensor for rapid detection of aspartame by flow injection analysis

A rapid, simple and stable biosensor for aspartame detection was developed. Alcohol oxidase (AOX), carboxyl esterase (CaE) and bovine serum albumin (BSA) were immobilised with glutaraldehyde (GA) onto screen-printed electrodes modified with cobalt-phthalocyanine (CoPC). The biosensor response was fast. The sample throughput using a flow injection analysis (FIA) system was 40 h⁻¹ with an RSD of 2.7%. The detection limits for both batch and FIA measurements were 0.1 µM for methanol and 0.2 µM for aspartame, respectively. The enzymatic biosensor was successfully applied for aspartame determination in different sample matrices/commercial products (liquid and solid samples) without any pre-treatment step prior to measurement.

Metallophthalocyanines and metalloporphyrins as electrocatalysts: a case of hydrogen peroxide and glucose detection

This review summarizes the applications of metallophthalocyanine (MPc) and metallo-porphyrin (MP) complexes as electrocatalysts immobilized onto various electrodes for the detection of hydrogen peroxide and glucose. The uses of MPc and MP complexes as electron mediators for the detection of glucose at glucose oxidase modified surfaces are discussed.

Electrochemical hydrogen peroxide sensor based on cobalt phthalocyanine captured in polyaniline film on a glassy carbon electrode

This work demonstrated preparation, characterization, and application of a cobalt phthalocyanine based enzymeless/mediatorless hydrogen peroxide sensor. The cobalt phthalocyanine (CoPc) was retained in polyaniline (PANI) film on a glassy carbon electrode during electrochemical polymerization of aniline and consequently a novel composite electrode (GCE/PANI/ CoPc ) for the electrochemical sensor application was constructed. The CoPc functionalized composite electrode, GCE/PANI/ CoPc , was evaluated by voltammetry, electrochemical impedance spectroscopy, and UV-vis spectroscopy. The results displayed retaining of the CoPc molecules in the PANI film on the GCE electrode. Presence of CoPc in PANI increased conductivity of the composite on the electrode. Sensing performance of the GCE/PANI/ CoPc composite electrode to H2O2 were evaluated in detail with respect to the selectivity, reproducibility, repeatability, stability, linear concentration range, and sensitivity with voltammetric and double potential step chronoamperometric techniques. The GCE/PANI/ CoPc composite electrode gives a linear range for H2O2 between 2 and 18 μM H2O2 with sensitivities of 1.55 A.M-1 during the cathodic SWV scan and with sensitivities of 4.01 A.M-1 during the anodic SWV scan. A direct application of the sensor was performed in a real working condition, for the detection of hydrogen peroxide produced from the reaction between the glucose and glucose oxidase enzyme.

Surface electrochemistry of N,N',N″,N‴-tetramethyl-tetra-3,4-pyridinoporphyrazinocobalt(II)

The complex N,N',N″,N‴ -tetramethyl-tetra-3,4-pyridinoporphyrazinocobalt(II) ([ Co II TMPz [4+])4+ adsorbed on a graphite electrode undergoes spontaneous reduction, forming a surface containing Co I. Five reversible surface peaks are observed at low pH, two of which are two-electron concerted processes. At high pH, one of these two-electron processes splits into two one-electron waves. Both oxidation and reduction of the central metal can be observed, along with successive reduction steps involving the porphyrazine ligand. Notable is the marked shift to positive potentials of these processes, relative to unsubstituted cobalt phthalocyanine, due to the positive charge localized on the porphyrazine. The electrocatalytic activity of this complex modified electrode toward the reduction of hydrogen peroxide is also reported. We demonstrate that a series of different surfaces exist which are obtained by variation of pH and polarization potential and that these surfaces possess differing electrocatalytic activity. Surfaces inactive to hydrogen peroxide can exist at potentials more negative than active surfaces even though the driving force for peroxide reduction will be greater for the former.

Electrocatalytic and photosensitizing behavior of metallophthalocyanine complexes

Electrocatalytic or photosensitizing (photocatalytic) properties of metallophthalocyanine (MPc) complexes are dependent on the central metal. Electrocatalytic behavior is observed for electroactive central metals such as Co , Mn and Fe , whereas photosensitizing behavior is observed for diamagnetic metals such as Al , Zn and Si . In the presence of nanoparticles such as quantum dots, the photosensitizing behavior of MPc complexes is improved. Carbon nanotubes enhance the electrocatalytic behavior of MPc complexes.