الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 366 |  |  |
| | | from | 366 | | |
Abstract
Part 1: Novel triphenylamine-based porphyrins: Synthesis, structural characterization, and theoretical investigation for dye-sensitized solar cell applications. A series of new triphenylamine-bases porphyrin structures (8, 12, and 16) were synthesized as the dye sensitizers of the solar cells and have been investigated. The structural establishment, preparation, and characterization of three new organic metal-free photosensitizers: (DTPA-π-DPorph-A(DE1), DTPA(π-DPorph-A)2(DE2) and DTPA(π-DPorph-A)3(DE3)) based on triphenylamine (TPA) as the core donor (DTPA), connected to one, two, or three porphyrins are described here. Dye anchoring in DSCs is essential for maximizing performance, and phosphonate and carboxylate anchoring units are often used. However, little research has been conducted to investigate how the number of anchoring subunits present in dye structures affects DSC performance. So, our work aims to synthesize novel porphyrin sensitizers composed of different numbers of anchoring groups for dye-sensitized solar cells and obtain some insight into their structure-property relationships. Also, the study examined how changing the number of DPorph and the number of anchoring groups (AGs) affected the photovoltaic performance of dye-sensitized solar cells. The structural, electronic, and spectroscopic properties and the photovoltaic performance of the DSSCs by using the DFT and TD-DFT calculations have been obtained and analyzed. The results showed that the studied porphyrins (8, 12, and 16) containing mono, di, and tri anchoring groups are proper to be applied in DSSCs because the LUMO level of the dyes lies over the CB of TiO2 while the HOMO levels are under the reduction potential energy of the electrolyte. These electronic properties make effective electron transfer and dye regeneration processes. Among all structures, porphyrin 16 showed the best results due to containing more anchoring groups, which translated to the best performance. Figure 4. Calculated isodensity of frontier occupied molecular orbitals for porphyrins 8, 12, and 16. It is indeed worth noting that all the Greg readings for the created compounds are negative, indicating that their regeneration capability is thermodynamically beneficial. As a result, the excited state of the dye has a potential that is less than that of the redox pair. Research results indicate that extremely efficient dye-sensitized solar cells may be made by fabricating the recently designed Porphyrins 8, 12, and 16 (DSSCs). The efficiency of DSSC solar cells is determined by the number of photons converted to power. The suggested substances (porphyrins 8, 12, and 16) operate for dye-sensitized solar cells. Part 2: A New Strategy for the Synthesis of Porphyrin and Expanded Porphyrin Derivatives from Di- and Tripyrromethanes: Antioxidant, Cytotoxic Activity, and Molecular Docking Evaluation. We have improved a method for synthesizing of 5-aryldipyrromethanes in the absence of solvent that requires little or no work-up (simple crystallization from the reaction mixture). The condensation reaction of aromatic aldehydes with excess pyrrole grinded and catalyzed by p-TsOH is used to form porphyrins. This approach appears to be quite general, and the dipyrromethanes might be obtained in a very selective manner by carefully controlling the reaction time, which is highly dependent on the type of the aldehydes. This ’green’ synthetic route to dipyrromethanes by grinding, which we believe is currently undervalued, has been (and will continue to be) an impulse for oligopyrrolic macromolecule research. New A2B2 porphyrins and hexaphyrins were discovered, and yields were improved. The acid catalyst of choice was p-TsOH (at a very low concentration), which produced the greatest yields. Evaluations of the antioxidant and cytotoxic activity of new compounds were presented. When compared to vitamin C as a standard, the porphyrin derivatives 21g and 21h demonstrated high antioxidant potential. The cytotoxic activity of compounds 21h, 21b, and 21c against the human cell lines HePG-2 and MCF-7 was encouraging. The binding modes of the synthesized compounds were analyzed by docking studies that showed good binding scores against the diverse amino acids of the selected proteins (Bcl-2). The conducted docking studies were found to be consistent with cytotoxic results. Thus, the results indicate that the designed structures can be a potential lead as anticancer agents. Part 3: Novel Synthesized Porphyrin Derivatives as Corrosion Inhibitors for Stainless Steel 304 in Acidic Environment: Electrochemical and DFT Studies. The corrosion problem is a great problem, which faced the world from the last years until now, we cannot hide this problem from our life but we can reduce “inhibit” it in the metals and alloys by several methods as the environment need. This part discusses the corrosion of Stainless steel 304 (SS304) in 2 M HCl. The aim of this work contains four main sections. Section 1: Evaluation of the inhibitor efficiency by weight loss method in the presence and absence of the used organic compounds in 2 M HCl. This revealed that the inhibitor efficiency increases with increasing concentration. These investigated compounds follow Langmuir’s isotherm showing that the inhibition is by adsorption. The degree of surface coverage (θ) for the inhibitors on the metal surface increases with increasing the concentration in the corrosive medium. Section 2: Potentiodynamic polarization measurements were carried out for SS304 in 2 M HCl in the absence and presence of different concentrations of the investigated organic compounds. The polarization curves indicated that these inhibitors influence both cathodic and anodic processes (mixed type). AC impedance spectroscopy measurements were carried out for SS304 in 2 M HCl in the absence and presence of different concentrations of the investigated organic compounds under charge transfer control. The value of charge transfers resistance (Rct) increases with increase in the concentration of the inhibitors and this indicates that the inhibition is due to adsorption of these compounds on SS304 surface. The order of decreasing the inhibition efficiency of the investigated compounds in 2M HCl solution by all methods were: A > B. Section 3: Some quantum–chemical quantities were calculated for protonated organic compounds. The inhibition efficiency was found to increase with increasing the energy of HOMO, the smaller is the value of ΔE indicate the more is the probable inhibition efficiency.