The silver-nucleoside complex [Ag(i)-(N3-cytidine)2]+, 1, self-assembles to form a supramolecular metal-mediated base-pair array highly analogous to those seen in metallo-DNA.

-Cyrene as a bio-alternative solvent: a highly efficient, waste minimizing protocol for the synthesis of ureas from isocyanates and secondary amines in the bio-available solvent Cyrene is reported. This method eliminated the use of toxic solvents, such as DMF, and established a simple work-up procedure for removal of the Cyrene, which led to a 28-fold increase in molar efficiency versus industrial standard protocols.

A change of solvent provides a means to modulate the intermetallic distance of the Ag ion chains in solvated structures of [AgI(cytidine-5′-monophosphate)], a 3D coordination polymer which features the less common O2,N3-binding mode for the nucleobase. Though the shortest Ag···Ag separation is within 5% of that in the metallic element, the coordination polymer is not electrically conducting, as shown by oriented single-crystal I/V measurements. Band structure calculations for the isolated coordination chain ([Ag-(O2,N3-Cyt)]+) n also support this. Additionally, we demonstrate that these AgI ion chains are retained when crystalline MOF samples are processed as dispersions in the liquid phase by ultrasonication, yielding well-defined bilayer nanosheets through cleavage of phosphoester O–Ag bonds.

We have synthesized and structurally characterized examples of the well-known silver-mediated DNA base pair in its simplest possible form, as [AgI-bis-(N3-cytosine)]+. The compounds show differences such as variable coordination geometry, conformation with cisoid and transoid arrangements, and, in one case, intramolecular base pairing. Collectively, these compounds represent three of five permutations of linear/bent coordination geometry and cisoid/transoid arrangement of the cytosine ligands and contain the global minimum conformation as determined by DFT calculations: bent-transoid. Furthermore, these compounds show no argentophilic intercomplex interactions in the solid state, in marked contrast to alkylated and nucleoside analogues, and so do not form the supramolecular 1D “metallo-DNA” duplex observed in those cases but instead form hydrogen-bonded sheets. This marked difference may be attributed, in part, to the additional hydrogen bond donor site at N1 of the nucleobase that ubiquitously participates in intermolecular interactions.