Laser Induced Temperature Perturbation on Ultramicroelectrodes: Unsupported Solutions in Nonaqueous Methanol

Temperature dependence studies of electrochemical parameters provide insight into electron transfer processes. In cases where adding excess electrolyte experimental causes complications colloidal systems, organic or biological samples it is preferable to deal with the high resistivity of the medium. We validate the use of unsupported and weakly supported solutions in thermoelectrochemical experiments. The temperature dependence of the diffusion coefficient allows calibration of the steady-state current to measure changes when a continuous wave (CW) ultraviolet laser, λ=325 nm, illuminates an ultramicroelectrode (UME) from the front. Calibrating the steady-state current ratios before and after heating with a thermostatic bath allows temperature measurements within an accuracy of 0.6 K. The solutions are without supporting electrolytes in methanol, a volatile solvent, and we use a model that accurately describes the viscosity and temperature dependence of the solvent. We calculated the temperature and derived an equation to estimate the temperature measurement error. A numeric method yields satisfactory results, considering the changes for both diffusion coefficients and viscosity explicitly, and predict the thermostatic temperature bath, agreeing with the theoretical model's error. In unsupported solutions, the ferrocene diffusion coefficient and the iodide apparent diffusion coefficient follow the expected increase with temperature. Under CW laser illumination ΔT=4±1 K.

Earth-Abundant Cobalt based photocatalyst: Visible light induced direct (Het)Arene C-H arylation and CO2 capture

In this work, we have reported a noble metal free heterogeneous photocatalyst to carry out direct (Het)Arene C-H arylation and solvent-free CO2 capture via single-electron transfer processes at room temperature...

In Silico Effects of Steviol on Depression, Inflammation and Cancer Biomarkers

Steviol (ST1), a known natural product, and methylated models (ST2-ST4) were investigated in this in silico work to see their effects were examined on each of depression, inflammation, and cancer biomarkers by participating in interactions with each of monoamine oxidase-A (MAO-A), cyclooxygenase-2 (COX-2), methyltransferase (MTN) enzymes, respectably. The stabilized structures of ST1-ST4 were achieved by performing optimization calculations. Subsequently, formations of interacting ligand-target complexes were examined by molecular docking (MD) simulations. The evaluated molecular orbital features showed a different tendency of ST1-ST4 models for contributing to electron transfer processes. Accordingly, the interacting ligand-target complexes showed differential interactions of each ligand towards each target, making ST1-ST4 as appropriate compounds for the detection of targets. The methylated ST2-ST4 models worked even better than the original ST1 model to affirm the benefit of steviol modification to achieve desired results. Meaningful interactions of ST1-ST4 with the targets also showed the possible application of steviol for the medication of each of depression, inflammation, and cancer cases.

Investigate and Calculation Electron Transfer Rate Constant in the N749 Sensitized Dye Contact to ZnSe Semiconductor

The dye–semiconductor interface between N749 sensitized and zinc semiconductor (ZnSe) has been investigated and studied according to quantum transition theory with focusing on the electron transfer processes from the N749 sensitized (donor) to the ZnSe semiconductor (acceptor). The electron transfer rate constant and the orientation energy were studied and evaluated depended on the polarity of solvents according to refractive index and dielectric constant coefficient of solvents and ZnSe semiconductor. Attention focusing on the influence of orientation energies on the behavior of electron transfer rate constant. Differentdata of rate constant was discussion with orientation energy and effective driving energy for N749-ZnSe system. Furthermore, the electron transfer rate constant is increased with less orientation energy at less effective driving energy while the electron transfer rate constant increased with large orientation energy with large effective driving energy, as seen as the electron transfer rate reach to 1.3109 × 1011 with less orientation energy has 0.188708eV at effective driving energy E=0.22eV comparing the rate reach to 9.7207× 10−96 with driving energy E=1.89eV and same orientation energy. In general, the electron transfer rate constant increases with increases the coupling coefficient of system, its indicate that alignment of energy levels are very good between N749 sensitized metal and ZnSe semiconductor.

Synthesis and Characterization of Mixed Ligand Complexes of Copper(II) with Adenine and Dicarboxylic Acids

Three mixed ligand complexes of copper(II) with adenine and dicarboxylic acids have been synthesized. The resulting complexes were characterized by their melting point, solubility, metal content analysis, FT-IR and UV-visible spectroscopy, magnetic measurement, thermal analysis, cyclic voltammetric measurement and X-ray powder diffraction study. The products are microcrystalline powder, slightly soluble in water and decompose at high temperature. Under experimental condition, the ligands adenine (Ade) behaves as a neutral ligand, whereas oxalic acid (OxH2), succinic acid (SucH2) and tartaric acid (TarH2) are doubly deprotonated to form dianionic ligands that are coordinated to the Cu(II) ion. The Cu(II) content analysis of the complexes confine to their stoichiometry [Cu(Ade)(L)(H2O)] (L = Ox, Suc, or Tar dianion). Electrochemical redox behavior of the complexes in their reaction medium was also examined. They exhibit quasi-reversible one-electron transfer processes. Dhaka Univ. J. Sci. 69(2): 76-81, 2021 (July)

Tropane and Related Alkaloid Skeletons via a Radical [3+3]-Annulation Process

A mild and simple protocol for the synthesis of 8-azabicyclo[3.2.1]octane and 9-azabicyclo[3.3.1]nonane derivatives is described. It provides these valuable bicyclic alkaloid skeletons in good yields and high levels of diastereoselectivity from simple and readily available starting materials using visible-light photoredox catalysis. This unprecedented annulation process takes advantage of the unique reactivity of ethyl 2-(acetoxymethyl)acrylate as a 1,3-bis radical acceptor and of cyclic N,N-dialkylanilines as radical 1,3-bis radical donors. The success of this process relies on efficient electron transfer processes and highly selective deprotonation of aminium radical cations leading to the key α-amino radical intermediates.

Tropane and Related Alkaloid Skeletons via a Radical [3+3]-Annulation Process

A mild and simple protocol for the synthesis of 8-azabicyclo[3.2.1]octane and 9-azabicyclo[3.3.1]nonane derivatives is described. It provides these valuable bicyclic alkaloid skeletons in good yields and high levels of diastereoselectivity from simple and readily available starting materials using visible-light photoredox catalysis. This unprecedented annulation process takes advantage of the unique reactivity of ethyl 2-(acetoxymethyl)acrylate as a 1,3-bis radical acceptor and of cyclic N,N-dialkylanilines as radical 1,3-bis radical donors. The success of this process relies on efficient electron transfer processes and highly selective deprotonation of aminium radical cations leading to the key α-amino radical intermediates.

A Brief History of Photoactive Interlocked Systems Assembled by Transition Metal Template Synthesis

More than three decades of research efforts have yielded powerful methodologies based on transition metal template-directed syntheses for the assembly of a huge number of interlocked systems, molecular knots, machines and synthesizers. Such template techniques have been applied in the preparation of mechanically linked electron donor–acceptor artificial photosynthetic models. Consequently, synthetic challenging photoactive rotaxanes and catenanes have been reported, in which the chromophores are not covalently linked but are still associated with undergoing sequential energy (EnT) and electron transfer (ET) processes upon photoexcitation. Many interlocked photosynthetic models produce highly energetic, but still long-living charge separated states (CSS). The present work describes in a historical perspective some key advances in the field of photoactive interlocked systems assembled by transition metal template techniques, which illustrate the usefulness of rotaxanes and catenanes as molecular scaffolds to organize electron donor–acceptor groups. The effects of molecular dynamics, molecular topology, as well as the role of the transition metal ion used as template species, on the thermodynamic and kinetic parameters of the photoinduced energy and electron transfer processes in the interlocked systems are also discussed.