Coordination-Controlled One-Dimensional Molecular Chains in Hexapodal Adenine–Silver Ultrathin Films

Abstract

Growth of a silver coordination polymer of a C-symmetric hexaadenine ligand is studied on highly oriented pyrolytic graphite (HOPG), using high-resolution atomic force microscopy (AFM). This unusual ligand offers 6-fold multidentate coordination sites, and consequently, a multidimensional growth of coordination polymer is expected. Notably, each discrete hexapodal unit is bridged by two silver ions along one of the crystallographic directions, resulting in high interaction energy along this direction. When the polymer was deposited on an HOPG surface from a dilute solution, we observed abundant one-dimensional (1D) coordination polymer chains, with a minimum width of approximately 4.5 nm. The single-crystal structure using X-ray analysis is compared with the surface patterns to reconcile and understand the structure of the 1D polymer on an HOPG surface. The energy levels of Ag-L1 within the proposed model were calculated, on the basis of the X-ray crystal structure, and compared to the ligand states to gain information about the electronic structure of ligand upon Ag coordination. On the basis of the wave functions of a few molecular orbitals (MOs) near the Fermi energy, it is surmised that unfilled MOs may play a crucial role in the transport properties of the Ag-L1 adlayer.

Self‐Assembly of Nucleobase, Nucleoside and Nucleotide Coordination Polymers: From Synthesis to Applications

“…This is quite different from the anionic products of Au. Extensive work has been performed with modified adenine and Ag + by Verma and co‐workers . As an example, fluorescent Ag + /9‐allyl adenine (9‐AA) CPs were investigated by X‐ray crystallography .…”

“…Most of the coordination within this framework occurred through the N1, N3, N7 and carboxyl groups on 9‐carboxyadenine (9‐CA). More recent work from this group has focused on the interaction of Ag + and other metals with thiol, imine and carboxyl modified adenine …”

“…Extensive work hasb een performed with modified adenine and Ag + by Vermaa nd co-workers. [65][66][67][68][69][70][71] As an example, fluorescent Ag + /9-allyl adenine (9-AA) CPs were investigated by Xray crystallography. [65] The main structural unit was aq uartet, where each Ag + binds to 3sites on 9-AA.…”

Exfoliating a CdII–Purine Framework: Conversion of Nanosheets‐to‐Nanofibers and Studies of Elastic and Capacitive Properties

“…Atomic force microscopy (AFM) is a powerful microscopic technique to meticulously examine various types of molecules on surfaces. We have carried out many such studies revealing interesting characteristics of purines, peptides, and their conjugates/derivatives on different surfaces . With the various existent modes in AFM, it is possible to analyze properties of 2D and 1D nanostructures, such as determination of capacitive properties by scanning Kelvin probe force microscopy (SKPFM) and Young's modulus by amplitude modulation–frequency modulation (AM–FM) AFM .…”

Surface modification and pattern formation by nucleobases and their coordination complexes

“…116 For example, adenine interacts efficiently with metal ions to create a vast number of coordination polymers in the solid state, with a distinct possibility of surface patterning, [117][118][119][120] in addition to such custom surfaces being amenable to further processing. In one example, 9-allyladenine afforded silver-mediated metallamacrocyclic quartet 1, where all the imino nitrogens of adenine coordinated to silver ions.…”