Silver–Cytosine–Polyoxometalate Assemblies: Assessing the Role of Polyoxometalates in Constructing Ag–DNA Suprastructures

• Published in: Crystal growth & design 2022-04, Vol.22 (4), p.2294-2306
• Main Authors: Smith, Rachelle M, Colliard, Ian, Amiri, Mehran, Galindo, Miguel A, Nyman, May
• Format: Article
• Language: English
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/acs.cgd.1c01385

Engineered DNA–metal complexes and superstructures have been shown to combine superior control of DNA helices and metal–metal interactions to create nanowires with unique luminescence and conductivity properties. Recently, their solid-state characterization reveals polymerization of the metal–DNA helices, leading to a one-dimensional Ag–DNA array. Here, we investigate the potential of polyoxometalates (POMs) to connect and join metal–DNA complexes to disrupt polymerization and control the dimensionality and nuclearity of Ag chains and clusters. We have used [Ag­(mcytosine)2]+ complexes (mcytosine = 1-methyl-cytosine) as inexpensive and well-known models for metal–DNA complexes, to assemble and structurally characterize (via single-crystal X-ray diffraction) five Ag–mcytosine–POM lattices: (1) three featuring the [CrMo6(OH)6O18]3– Anderson POM, (2) one with decavanadate, and (3) one with decaniobate ([M10O28]6–; M = V or Nb). Both covalent and noncovalent interactions drive the crystallization of the observed Ag–mcytosine–POM assemblies, including the targeted Ag–POM bonding. Noncovalent associations include π–π interactions of Ag-bound and unbound mcytosine ligands, Ag–Ag argentophilic interactions, and H-bonding between POMs and mcytosine. These structures reveal that we can influence the [Ag+] n nuclearity by the charge and protonation state of the POM, while the basicity of the POM influences Ag–POM bonding. In addition, we isolate an unprecedented binuclear silver-mediated cytosine pair adopting a Watson–Crick conformation.