Preparation, Characterization and Analytical Studies of novel Azo dyes and Diazo dyes

The amino {4-hydroxy-3-[(E)-{4-[(5-methylisoxazol-3-yl) sulfamoyl] phenyl} diazenyl] phenyl} acetic acid (1) and the amino {4-hydroxy-3,5-bis[(E)-{4-[(5-methylisoxazol-3-yl) sulfamoyl] phenyl} diazenyl] phenyl} acetic acid (2) were Prepared. The resulting azo and diazo dyes were then characterized using m.p., IR, UV-visible, mass spectrum and 1H-NMR spectrum. Analytical studies were carried on the azo dye (1) and the diazo dye (2). The best solubility of (1) and (2) was in methanol and ethyl acetate respectively, with no deviation from the linear relationship in each dye, which is due to the fact that the effect of the dielectric constant is the main factor that can control the shift of the absorption beaks. Though, the pH effects of (1) and (2) in a range of buffer solution were showed one and two isopiestic points respectively. Calculation of the ionization (pKa) and the protonation (pKp) constants by using the half height method was associated to the nitrogen atom and the OH-groups respectively. The pKp1, pKa1 and pKa2 were also intended. But, the value of the pKp2 was absent in the azo dye (1) and seems to be equal to 2.5 in the diazo dye (2). These results were indicated the suggested ionization scheme in acidic and basic medium of each dye. Furthermore, the dyes with different concentrations have harmless, nontoxic and no haemolysis effects.

Photocatalytic Degradation of Diazo Dye over Suspended and Immobilized TiO2 Catalyst in Swirl Flow Reactor: Kinetic Modeling

The degradation kinetics of Direct Blue 15 (DB15), a diazo dye, were studied over a suspended and immobilized TiO2 catalyst. For all experiments, the kinetics experiments were performed in a swirl flow photoreactor under the influence of UV light. The effect of different parameters: dye concentration, catalyst loading, and light intensity, on the DB15 kinetics was investigated. The kinetic rates were assessed using apparent ka approach, a single value of reaction rate kr and adsorption constant K, and approach of kr as of variable. The DB15 mineralization was discussed as well. Using a dip-coating device, the P25 catalyst was deposited on a Pyrex glass. The thin film surface characterization was examined. The coated catalyst was evaluated by checking the effect of two variables: initial dye concentration and light intensity on the DB15 kinetics. In terms of the ka approach, the results demonstrated that DB15 degradation is described by the pseudo first-order kinetics model. The Langmuir-Hinshelwood (L-H) model was fitted well with the experimental data for the number of process variables. L-H constant kr was determined as a function of three parameters: initial dye concentration, catalyst loading, and light intensity. The ka values were evaluated and compared with experimental results. In terms of three variables, ka can be expressed as ka=0.15 [C]o−0.69 [W]0.73 I0.91 1 + 0.17 Co while the empirical model results in the following expression, ka=0.77 Co−1.65 W0.73 Io0.89. It was observed that 83.64% mineralization was achieved after a period of 16 h. In terms of immobilized catalyst, the DB15 degradation kinetics was described by a pseudo first-order model for different dye concentrations. Meanwhile, a power-law model described the impact of light intensity on dye kinetics. In addition, the coated catalyst was successfully reusable with high efficiency for up to four cycles.

Decolorization and mineralization of diazo dye under artificial and solar light assisted Fenton and photo-Fenton conditions

The aim of this study is to verify the ability of some photochemical processes in the absence of light (Fenton) and in its presence (photolysis/UV, photo-Fenton/UV and photo-Fenton/Solar) to obtain total decolorization and mineralization of an diazo dye in aqueous solution: the Evans Blue (abbreviated as EB). Batch experiments were carried out to evaluate, on the first stage, the influence of different processes on EB decolorization and mineralization. During the second stage the optimal operational conditions like: H2O2 dosage, EB concentration and source of light were investigated. The reaction efficiencies have been compared for the same system in the dark or under the assistance of an artificial or solar light source. The obtained results showed that color removal followed the increasing order: photolysis/UV (18.2%) < Fe(II)/H2O2 (64.12%) < Fe(II)/H2O2/UV365 nm (83.4%) < Fe(II)/H2O2/solar light (86.3%) < Fe(II)/H2O2/UV254 nm (99.9%) with a reaction time of 60 min This improvement could be related to a better production of radicals OH•. In another hand, The efficiency of substrate mineralization in each process has been comparatively discussed by total organic carbon (TOC) and total chemical oxygen demand content of EB solutions.

Molecular Docking Study of Some Nitro Diazo Dye Derivatives as Antiviral Candidates of COVID-19

In this study, the computerized molecular docking method was used to investigate the interactions of five nitro diazo dye derivatives 1-5 with COVID-19, CLpro, RAF and PLpro as very important viral proteins to target the coronavirus SARS-CoV-2. Among the used diazo dyes, compound 5 showed the highest binding free energies and the lowest inhibition constants Ki with all studied proteins, and it exhibits a large effect to inhibit the activities of the RAF and COVID-19. Therefore, compound 5 may be useful as an antiviral candidate that worth more trials for COVID-19 disease. The binding sites of compound 5 with the tested viral proteins were evaluated.