Real-Space Evidence of Trimeric, Tetrameric, and Pentameric Uracil Clusters Induced by Alkali Metals

Alkali metal cations are known as the significant participants in biological processes and play the vital role in nucleic acid structures. The interactions between alkali metals and nucleobases have therefore attracted a lot of attention. As a peculiar nucleobase in RNA, uracil with its magic number clusters induced by alkali metals has attracted tremendous interest over the past decades. Here, from the interplay of high-resolution scanning tunneling microscopy imaging and density functional theory calculations, we show the real-space evidence of the formation of trimeric, tetrameric, and pentameric uracil clusters induced by alkali metals (Li, Na, and K) on the Au(111) surface, and further investigate their specific configurations at the atomic-scale, which would be of importance for understanding the formation process of biologically relevant nanostructures involving cations in vivo.