Interactions of calcium with the external surfaces of fullerenes and endofullerenes doped with radioactive sodium iodide
Autor: | M. Romero, Raúl W. Gómez, Alejandro Valderrama, Vivianne Marquina, Radamés Reynoso |
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Rok vydání: | 2016 |
Předmět: |
Fullerene chemistry
Fullerene Chemistry Organic Chemistry Inorganic chemistry 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Catalysis Computer Science Applications Inorganic Chemistry Electronegativity Molecular dynamics Adsorption Computational Theory and Mathematics Chemical physics 0103 physical sciences Physics::Atomic and Molecular Clusters Endohedral fullerene Molecule Density functional theory Physical and Theoretical Chemistry 010306 general physics 0210 nano-technology |
Zdroj: | Journal of molecular modeling. 23(1) |
ISSN: | 0948-5023 |
Popis: | We report first-principles calculations carried out to analyze the adsorption of calcium on the outer surface of the fullerene C60, yielding [C60 + mCa]. Geometric optimization (GO) and molecular dynamics (MD) simulation were performed using the plane-wave pseudopotential method within the framework of density functional theory (DFT) and time-dependent DFT (TD-DFT) to investigate the configurations, the associated energies in the ground state, and the stabilities of fullerenes and endofullerenes doped with radioactive sodium iodide when they interact with calcium atoms on the outer fullerene surface (i.e., [nNa131I@C60 + mCa]). The reason for investigating these calcium-functionalized (endo)fullerene systems was to gauge their potential stability when used as vectors to deliver radioiodine to cancerous tissue in the human body. In the simulations, we found that the geometric limit on the number of calcium atoms that can be physisorbed on the outer surface of an empty fullerene while maintaining its structural stability is 28 calcium atoms, which also takes into account the proportional expansion of the fullerene as the number of absorbed calcium atoms increases. However, the stability of a fullerene system during calcium adsorption also strongly depends on whether any atoms or molecules are being encapsulated by the fullerene, as these encapsulated atoms/molecules can also interact with the fullerene and influence its stability. A Mulliken electronegativity analysis revealed that, when atoms inside and/or outside the fullerene donate charge (electrons) to the fullerene, the fullerene expands. The excess charge on the carbon atoms of the fullerene weakens some of the carbon–carbon bonds, potentially causing them to break, in which case the fullerene loses its ability to encapsulate molecules and releases them. |
Databáze: | OpenAIRE |
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