Laser Photocatalysis of the Chlorophyll Dye Using the Cyclic Voltammetry Method

Cyclic voltammetry is a widely used technique in electrochemistry due to its simplicity and large amount of data and information that can be obtained. This study utilises this technique to study chlorophyll a and total chlorophyll (Tchl) alongside a laser light to induce photosynthesis. No oxidative peak was observed, regardless of the solution pH in either a dark or light environment when using a solution with an electrolyte of tetrabutylammonium perchlorate (TBAP) in both dichloromethane (DCM) and acetonitrile (MeCN), whereas in a solution of aqueous HCl a small anodic peak was observed. The concentration of the droplet of Tchl pigment on the surface of macro glassy carbon electrode (GCE) was increased, which resulted in a similar trend and the oxidation peak was observed to be slightly larger when in the presence of light. It was observed that the filtered solution of Tchl pigment produced a weaker signal than the unfiltered solution and there were slightly reduced oxidative peak currents when the concentration of VK1 was increased. were no observed changes in the peak charges or currents over a wide potential range (0.0, 0.2, 0.4, 0.6 and 0.8 V) in the presence or absence of light by using coulometry and amperometry methods, therefore, more information on the 3-D formation is required for the photoreduction processes.

Compressibility Studies of Solvation Behaviour of Lithium and Sodium Ions in Nitromethane + Dimethylsulfoxide Binary Mixtures at 298.15 K

The isentropic compressibilities (Ks) and apparent molal isentropic compressibilities (Ks,φ) of lithium perchlorate (LiClO4), sodium perchlorate (NaClO4), sodium tetraphenylborate (NaBPh4), tetrabutylammonium tetraphenylborate (Bu4NBPh4) and tetrabutylammonium perchlorate (Bu4NClO4), have been calculated from measured ultrasonic velocity (u) and density (ρ) of these salts in the concentration range 0.001 to 0.60 mol Kg-1 in the mixed binary solutions of nitromethane (NM) and dimethyl sulfoxide (DMSO) containing 0, 20, 40, 60, 80 and 100 mol% of DMSO in NM at 298.15 K. Limiting values of apparent molal isentropic compressibilities (K°s,φ) for various salts were evaluated and split into the contributions (K°s,φ)± of the individual ions. Exceptionally large and negative (K°s,φ)± values were obtained whose variation with solvent composition shows strong solvation of both Li+ and Na+ in NM + DMSO mixtures at all compositions of the mixed binary solutions. Solvation of Li+ and Na+ increases as mol% of DMSO in NM increases. Solvation exhibited by Li+, however, is much stronger than Na+ in all compositions of the mixtures. Solvation exhibited by ClO4 – in NM + DMSO mixtures is weak which perchlorate ion shows by having some interactions with DMSO in the DMSO-rich compositions of the mixtures. The large and positive values for Bu4N+ and Ph4B– are indicative of some special type of interactions, mainly solvophobic with the solvent molecules.

Effect of fused indanedione (IND) groups and antipodal β-substituents on electrochemical properties of unsymmetrical metalloporphyrins

The interacting effect of fused indanedione (IND) groups and antipodal Br [Formula: see text]-substituents on the electroreduction of free-base and transition metal tetraphenylporphyrins (TPPs) are elucidated through the use of cyclic voltammetry. A systematic study of the reduction potentials for mono- and di-fused derivatives of MTPP(IND)(R)2 and MTPP(IND)2(R)2 where R = Br or H and M = Cu[Formula: see text], Ni[Formula: see text], Zn[Formula: see text] or H2 is carried out in pyridine containing 0.1 M tetrabutylammonium perchlorate (TBAP) as supporting electrolyte and demonstrates how the overall electrochemical properties of these compounds can be tuned by systematic changes in the number of meso-[Formula: see text]fused IND groups on the molecule and the presence or absence of electron-withdrawing Br [Formula: see text]-substituents. Under these solution conditions, two reversible one-electron reductions are seen for H2TPP, while three reversible reductions are obtained for H2TPP(IND) or H2TPP(IND)Br2 and four for H2TPP(IND)2Br2. Multiple reductions also occur for the other investigated mono- and di-fused metalloporphyrins. Plots of measured [Formula: see text] values for the two ring-centered reductions of compounds in a given series vs. the number of fused IND groups are linear and with slopes varying in magnitude between 15 and 230 mV/IND depending upon the product of the electron transfer (anion radical or dianion), the specific central metal ion and the presence or absence of Br substituents on the pyrrole ring opposite the fused IND group(s). It is anticipated that the information from this study can be used for predicting the reduction potentials for yet to be synthesized compounds where a specific redox reactivity is desired.

An electrochemical quartz crystal microbalance study of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin electropolymerization process

The process of 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin electropolymerization has been studied by the quartz crystal microbalance method in different electrodeposition conditions. The films were deposited in two modes: in potentiostatic conditions (at the potential of [Formula: see text]2 V) and in potentiodynamic conditions (CV with the potential scan rate of 20 mV/s). The effect of electrolysis parameters on 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin electropolymerization has been studied by obtaining films in two modes and using two supporting electrolytes: tetrabutylammonium perchlorate or tetrabutylammonium hexafluorophosphate. The biggest film mass gain was observed on a clean electrode surface. At further film deposition on the polyporphyrin-coated electrode, the film mass growth stopped. The electrodeposition effectiveness was somewhat higher in the potentiodynamic conditions, with the formation of a looser film. The nature of the supporting electrolyte did not have a significant effect on the electrodeposition process. A significant contribution to the deposition was made by the electrode material. The film thickness was 25–80 nm. The films possessed [Formula: see text]-type conductivity; and the flat-band potential for poly-H[Formula: see text]T(4-OHPh)P obtained in potentiodynamic conditions was 0.33 V, for poly-H[Formula: see text]T(4-OHPh)P obtained in potentiostatic conditions it was 0.16 V.

Synthesis, characterization and electrochemical properties of isoflavone substituted zinc(II), cobalt(II), and metal-free phthalocyanines

In this study, novel tetrasubstituted metallo- and metal-free phthalocyanines containing 7-hydroxy-4′-methoxyisoflavonoxy moieties at peripheral and non-peripheral positions have been prepared by cyclotetramerization of corresponding phthalonitriles. The most obvious feature of these quaternized complexes is their extensive solubility and non-aggregated species (especially non-peripherally substituted) in organic solvents such as chloroform, tetrahydrofuran, dimethylformamide and dimethylsulfoxide, which makes them candidates for use in many applications in different fields. The new compounds have been characterized by elemental analysis, FT-IR, UV-vis, 1H and [Formula: see text]C NMR and MS (Maldi-TOF MS). Voltammetric and in situ spectroelectrochemical measurements have been performed with the aim of characterizing the electron transfer properties of the compounds on Pt in dimethylsulfoxide/tetrabutylammonium perchlorate, compared to those of previously reported corresponding compounds with tetra 6-hydroxyflavonoxy substituents. The effect of aggregation on the redox character of these complexes was also discussed.

Relationship between Charge Transfer Diffusion Coefficients and Doping Level for electro generated thin PEDOT films on ITO

Thin films of poly-3,4-ethylene dioxythiophene (PEDOT) were electrodeposited on transparent electrodes of indium tin oxide (ITO) using potentiostatic regime. These films had thicknesses ranging from 15 nm to 60 nm and were studied using UV-vis absorption and chronoamperometric techniques in monomer-free tetrabutylammonium perchlorate/acetonitrile solutions. The charge transfer diffusion coefficient (D) of the films were calculated using Cottrell model for a wide range of potential steps from −1.60 to 1.60 V vs. Ag°/AgNO3. For p-doped films, the highest diffusion coefficients were obtained when a potential of 0.70 V was applied. Moreover, a direct relationship between film thickness and their diffusion coefficients was found for thin PEDOT films showing D values up to 1.4 × 10−9 cm2 s−1 for 60 nm thickness films. These values are remarkably higher than the D of 1.8 × 10−11 cm2 s−1 obtained for spin-coated PEDOT: PSS films of similar thickness.

Electropolymerization of poly-5,10,15,20-tetrakis(p-aminophenyl)porphyrin in different deposition modes and solvents

The influence of solvent, supporting electrolyte and electrolysis modes on poly-5,10,15,20-tetrakis([Formula: see text]-aminophenyl)porphyrin film growth were studied by the quartz crystal microbalance method. Electropolymerization was carried out in potentiostatic and potentiodynamic modes from dichloromethane and ethanol solutions. Tetrabutylammonium perchlorate (TBAP) and tetrabutylammonium hexafluorophosphate (TBAHFP) were used as supporting electrolytes. Surface micrographs of films electrodeposited over a different number of cycles of potential variation were obtained. The specific surface area, the pore size, and the thickness of the obtained polyporphyrin films were determined. The number of electrons participating in 5,10,15,20-tetrakis([Formula: see text]-aminophenyl)porphyrin electropolymerization was determined by the quartz crystal microbalance method. Based on the electronic absorption spectroscopy results, it was established that porphyrin macroheterocycles were preserved in an oxidized state in polyporphyrin.