الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The propensity of tow-dimensional nanomaterials, specifically GN and borophene nanosheets, to adsorb a variety of toxic molecules involving VOCs, carbon dichalcogenides, and tetrahalomethanes was investigated. Furthermore, the adaptability of the GN nanosheet for monitoring Favipiravir (FPV) anti-COVID and Cisplatin (cisPtCl2) anticancer drugs was discussed in-depth. All computations in this thesis were performed using Quantum Espresso code via density functional theory (DFT).
The potentiality of striped borophene (sB), β12 borophene (β12), and pristine graphene (GN) to detect electron-rich and electron-deficient π-systems was investigated utilizing benzene (BNZ) and hexafluorobenzene (HFB), respectively. The results showed that the adsorption process of the π systems on the studied 2D sheets was more favourable in the parallel configuration than in the vertical one. Based on the Bader charge findings, the π-system∙∙∙sB complexes generally had the largest charge transfer differences values. Band structures and the density of state results affirmed that the adsorption process of the BNZ and HFB on the surface of the investigated 2D sheets changed their electronic properties. The sB and β12 sheets showed greater affinity to adsorb the BNZ and HFB than the GN analogue.
Adsorption of toxic carbon dichalcogenides (CX2; X = O, S, or Se) on the β12 and GN sheets was studied in both vertical and parallel configurations of CX2∙∙∙β12/GN complexes. The parallel configuration exhibited adsorption energies up to –10.96 kcal/mol more than the vertical analogue. The adsorption energies of the CX2∙∙∙β12/GN complexes decreased in the order CSe2 > CS2 > CO2. Electron-donating property was observed for the CO2 molecule, whereas the CS2 and CSe2 molecules had dual behaviour as electron donors and acceptors in vertical and parallel configurations, respectively. Band structure and DOS plots revealed that the electronic properties of β12 and GN sheets were strongly affected after the adsorption process in the parallel configuration further than the vertical one.
The potentiality of the β12 and GN nanosheets for adsorbing the toxic tetrahalomethanes (CX4; X = F, Cl, or Br) was revealed with a series of DFT calculations. Accordingly, tetrel (XC-X3)- and halogen (X3C-X)-oriented configurations were designed within the CX4∙∙∙β12/GN complexes at different adsorption sites. The adsorption process in the CX4∙∙∙β12/GN complexes within the XC-X3 resulted in more desirable negative adsorption energy values than that within the X3C-X analogues. Bader charge analysis demonstrated an electron-donating character for the CX4 molecules after the adsorption process on the β12 and GN nanosheets in both configurations, except for the adsorbed CBr4 molecule on the GN sheet in XC-X3. New bands and peaks were observed in the band structure and DOS plots, respectively, with a larger number in the case of the tetrel-oriented configuration than that of the halogen-oriented one. Additionally, after performing the adsorption process in the presence of a water medium, the adsorption energies of the CX4∙∙∙β12/GN complexes enhanced.
Hence, the ability of the GN nanosheet to be a Favipiravir (FPV) anti-COVID-19 drug delivery was investigated in perpendicular and parallel configurations DFT method. The parallel configuration of FPV∙∙∙GN complexes showed higher desirability than in the perpendicular analogue. The desirability of the parallel configuration could be attributed to the participation of the π-π stacking in the overall strength of the adsorption process. According to Bader charge affirmations, the FPV showed an electron-donating character within the adsorption process, indicated by the negative sign of the computed charge transfer (Qt) values. In this regard, the adsorption of the FPV drug in the parallel configuration within the FPV∙∙∙T@GN complex demonstrated the most considerable Qt value of –0.0377 e. Based on the band structure and DOS observations, the adsorption of the FPV drug on the GN sheet affected its electronic characteristics in the perpendicular and parallel configurations, revealing the occurrence of the adsorption process. Recovery time results confirmed the ability to use the GN sheet as a FPV drug delivery system.
Moreover, the adsorption behaviour of the Cisplatin (cisPtCl2) drug and its analogues on the GN nanosheet was investigated in perpendicular and parallel configurations using the DFT method. Based on the findings, the parallel configuration demonstrated the most significant negative adsorption energies (Eads) within the cisPtX2∙∙∙GN complexes (where X = Cl, Br, or I) with values up to –25.67 kcal/mol at the H@GN site. Three orientations were intended for the adsorption process of the cisPtX2∙∙∙GN complexes in the perpendicular configuration, namely, X/X, X/NH3, and NH3/NH3. The negative Eads values of the cisPtX2∙∙∙GN complexes increased by increasing the atomic weight of the halogen atoms in the following order cisPtCl2∙∙∙ < cisPtBr2∙∙∙ < cisPtI2∙∙∙GN. Bader charge transfer outcomes demonstrated the electron-accepting property for the cisPtI2 within the cisPtI2∙∙∙GN complexes in both configurations. The electron-donating character of the GN nanosheet increased as the electronegativity of the halogen atom increased. Further, band structure and density of state plots revealed the occurrence of the adsorption of the cisPtX2 on the GN nanosheet, remarked by the appearance of new bands and peaks. Based on the solvent effect outlines, the negative Eads values generally decreased after the adsorption process in a water medium. The recovery time results were in line with the Eads findings, at which the cisPtI2 in the parallel configuration had the longest time to be desorbed from the GN nanosheet with values of 61.63 × 108 ms at 298.15 K.
All calculations were executed using High-Performance Computer (HPC) located at CompChem Lab, Minia University, and supported by the Science and Technology Development Fund, STDF, Egypt, Grants No. 5480 & 7972.