ABSORPTION SPECTRA OF THE BACKBONE TAILORED GA AND CT NUCLEIC ACID STRANDS

Abstract

The excitation properties of peptidic chain tailored single strand nucleic acids such as GA (purine strand) and CT (pyrimidine strand) was studied using Time Dependent Density Functional Theory (TDDFT). The existence of ground state geometries of the GA and CT were confirmed by the optimization at B3LYP/6–31G* level of theory from DFT method. The singlet excitation calculations were also made for considered systems at the same level of theory used for optimization. In order to understand the effect of tailoring the peptidic chain as a backbone instead of phosphate group in natural nucleic acid constructs, the various excited electronic properties such as HOMO-LUMO energy gap (Egap), vertical excitation energy (VE), oscillator strength (OS) and UV-vis gap and DOS spectrum were calculated. The results revealed that the absorption properties of both strands significantly enhanced when compared to the natural nucleic acid strands, which suggested that the replacement of the DNA backbone had great potential towards improved excitation properties for electronic and optical related applications.