title: Structures of nucleobases trapped within Au triangles and its effects on hydrogen bonding in base pairs of DNA.
abstract: Nucleobases (adenine (A), thymine (T), cytosine (C), and guanine (G)) trapped within two metal clusters such as Au(3) undergo expansion. Our investigation reveals that this primarily arises due to the concomitant increase in all the bond lengths in molecules. Such expansion of the molecules can be qualitatively understood on the basis of classical harmonic potentials in the bonds and loss of aromaticity in the rings. Specifically, the highly electronegative O and N elements in the base pairs anchor to Au atoms and form X-Au bonds, which leads to charge redistribution within the molecules. As a very important consequence of this, the nature of the hydrogen bonds (in Au(3)-A...T-Au(3) and in Au(3)-G...C-Au(3)) change substantially within these electrodes in comparison to gas-phase structures. These hydrogen bonds have a single-well potential energy profile (of the type N...H...O and N...H...N) instead of double-well potentials (like N-H...O or N-H...N/ N...H-N types). A detailed energy calculation along the proton movement pathway supports our conclusions.
authors.affiliation: Theoretical Sciences Unit, Chemistry and Physics of Materials Unit, and the DST Unit on Nanoscience, Jawaharlal Nehru Center for Advcanced Scientific Research, Jakkur Campus, Bangalore, India.
authors.forename: P J
authors.initials: PJ
authors.lastname: Mohan
authors.forename: Ayan
authors.initials: A
authors.lastname: Datta
authors.forename: Sairam S
authors.initials: SS
authors.lastname: Mallajosyula
authors.forename: Swapan K
authors.initials: SK
authors.lastname: Pati
mesh_terms: D000225:Adenine / Q000737:chemistry; D001482:Base Composition; D002627:Chemistry, Physical / Q000379:methods*; D003596:Cytosine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D010100:Oxygen / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013941:Thymine / Q000737:chemistry
chemical_list: D006147:Guanine; D006046:Gold; D003596:Cytosine; D004247:DNA; D000225:Adenine; D013941:Thymine; D010100:Oxygen