Abstract

Avat Arman Taherpour* and Ahmad-Reza Shafaati

The primary structure of both DNA and RNA consists of a polymeric chain of nucleotides. Nucleotides are the basic monomer building block units in the nucleic acids. A nucleotide is composed of a nucleobase (nitrogenous base) and a five-carbon sugar (either ribose or 2'-deoxyribose), and one to three phosphate groups. Together, the nucleobase and sugar comprise a nucleoside. The DNA nucleotide bases are guanine (G) and adenine (A), and the pyrimidine bases are thymine (T) and cytosine (C). The voltammetric oxidation of all deoxyribonucleic acid (DNA) monophosphate nucleotides was investigated before. Since the discovery of fullerenes (Cn ), one of the main classes of carbon compounds, the unusual structures and physiochemical properties of these molecules have been discovered, and many potential applications and physicochemical properties have been introduced. Up to now, various empty carbon fullerenes with different numbers “n,” such as C60, C70, C76, C82 and C86, have been obtained. Topological indices are digital values that are assigned based on chemical composition. These values are purported to correlate chemical structures with various chemical and physical properties. They have been successfully used to construct effective and useful mathematical methods to establish clear relationships between structural data and the physical properties of these materials. In this study, the number of carbon atoms in the fullerenes was used as an index to establish a relationship between the structures of guanine (G), adenine (A), thymine (T) and cytosine (C), 1-4 and fullerenes Cn (n=60, 70, 76, 82 and 86), which create [DNA-Nucleotide bases]@Cn , A-1 to A-5 ([Guanine]@Cn), B-1 to B-5 ([Adenine]@Cn), C-1 to C-5 ([Thymine]@Cn) and D-1 to D-5 ([Cytosine]@Cn ). The relationship between the number of carbon atoms and the free energies of electron transfer (ΔGet(1) to ΔGet(4)) are assessed using the Rehm-Weller equation for A-1 to A-5, B1 to B-5, C- 1 to C-5 and D-1 to D-5 supramolecular [DNA-Nucleotide bases]@Cn complexes 5-24. Calculations are presented for the four reduction potentials (Red.E1 to Red.E4 ) of fullerenes Cn . The results were used to calculate the four free-energies of electron transfer (ΔGet(1) to ΔGet(4)) of supramolecular complexes A-1 to A-18 to B-1 to B-18, C-1 to C-18 and D-1 to D-18 (5-76) for fullerenes C60 to C300.

Fullerenes; DNA; Nucleotide bases; Rehm-Weller equation; Free energy of electron transfer; Electrochemical properties; Reduction potential

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