X-ray Crystal Structure of a Metalled Double-Helix Generated by Infinite and Consecutive C*-AgI -C* (C*:N1 -Hexylcytosine) Base Pairs through Argentophilic and Hydrogen Bond Interactions.
The synthesis of a metalled double-helix containing exclusively silver-mediated C*-C* base pairs is reported herein (C*=N1 hexylcytosine). Remarkably, it is the first crystal structure containing infinite and consecutive C*-AgI -C* base pairs that form a double helix. The AgI ion occupies the center between two C* residues with N(3)-Ag bond lengths of 2.1 Å and short AgI -AgI distances (3.1 Å) suggesting an interesting argentophilic attraction as a stabilization source of the helical disposition. The solid-state structure is further stabilized by metal-mediated base-pairs, hydrogen bonding and π-stacking interactions. Moreover, the angle N(3)-Ag-N(3) is almost linear in the [Ag(N1 hexylcytosine)2 ]+ motif and the bases are not coplanar, thus generating a double-strand helical aggregate in the solid state. The noncovalent and argentophilic interactions have been rationalized based on DFT calculations.
['Terrón|Angel|A|http://orcid.org/0000-0002-7599-8288', 'Moreno-Vachiano|Blas|B|', 'Bauzá|Antonio|A|http://orcid.org/0000-0002-5793-781X', 'García-Raso|Angel|A|', 'Fiol|Juan Jesús|JJ|http://orcid.org/0000-0003-2480-265X', 'Barceló-Oliver|Miquel|M|http://orcid.org/0000-0003-4309-4118', 'Molins|Elies|E|http://orcid.org/0000-0003-1012-0551', 'Frontera|Antonio|A|http://orcid.org/0000-0001-7840-2139']
solid-state structures X-ray crystallography density functional calculations helical structures silver