A DFT study on the adsorption of nucleobases with Au₂₀

The interactions of nucleobase with Au₂₀ cluster were studied utilizing density functional theory (DFT). We find that the nucleobases were attached with Au₂₀ through Au-N or Au-O bonds. The orders of calculated adsorption energy are cytosine > adenine > guanine > thymine. The maximum adsorption energy is - 0.787 eV which belongs to the adsorption of cytosine on Au₂₀ cluster. Our calculations show that the HOMO-LUMO gaps of Au₂₀ are significantly decreased by the nucleobase adsorption, suggesting the potential detection for nucleobases. The interactions between Au₂₀ and nucleobases are revealed through the QTAIM analysis. The NBO analysis was investigated for the electron transfer of donor-acceptor of all types of complexes. The IR and UV-vis spectra were simulated for the further identification in the experiment.