Solution-Processed Formation of DNA-Origami-Supported Polyoxometalate Multi-Level Switches with Countercation-Controlled Conductance Tunability

Abstract

We report a chemically programmed design and the switching characteristics of a functional metal–DNA-origami–polyoxometalate (POM) material obtained from the solution-processed assembling of biocompatible molecular precursors. The DNA origami is immobilized on the gold surface via thiolate groups and acts as a carrier (ad-layer) structure, ensuring the spatially controlled hybridization of the pre-defined six-helix bundle (6HB) positions with DNA-augmented, tris­(alkoxo)-ligated Lindqvist-type polyoxovanadate (POV6) units. The DNA-confined POV6 units accept electrons in a stepwise fashion, allowing for a multi-logic function, which we directly probe using scanning tunneling electron microscopy and spectroscopy. Electron acceptance and injection into the originally non-conducting DNA structure and the subsequent release to the gold substrate depend upon the potential at the nanoscale tip and the oxidation state of POV6, as well as on the mechanism of action of POV6 countercations. By combining experiment and theory, we show that the bio-hybrid heterojunction has far-reaching potential to create a chemically controlled POM-based nano-environment with synaptic behavior.

Capacitor or Memristor: Janus Behavior of Polyoxometalates

“…(D) Conceptual sketch of an STM experiment containing a single DNA-functionalized POM with the (E) corresponding I – V hysteresis curve. Reprinted in part with permission from ref . Copyright 2023 American Chemical Society.…”

“…Typically, POMs are anionic species, which entail stabilization by additional countercations. The number and chemical nature of the latter also have a strong influence on the electronic and adsorptive properties of POMs. − …”

“…However, the concomitant capacitive properties of POMs in resistive switching setups have a significant disadvantage, namely, the rather low lifetime of the resistance state in unmodified POMs on conducting or semiconducting electrode surfaces, because additional charge will be quickly transferred to the substrate. Electronic decoupling by modification with large electronically insulating DNA ligands have already demonstrated an increase in the excited states’ lifetimes from a few milliseconds (unmodified) to approximately 200–300 ms (Figures D and E) . This is, of course, still a long way toward a real-world nonvolatile memory, but it clearly shows the way.…”

Influence of Polyoxovanadate and Phthalocyanine on 4f Electron Transfer in Gold-Confined Monolayers Probed with EGaIn Top Contacts

“…Polyoxometalate (POM) compounds designed to form robust SAMs , offer a unique molecular platform for pursuing these goals. The relative ease of systematically augmenting POMs toward inorganic–organic hybrid structures of interest is beneficial for tailoring the POM reactivity on substrate surfaces via the ligand functionality and of the corresponding charge-transfer properties. − The self-assembly of molecules on surfaces is governed by the specific interactions between molecules and the chemistry at their interface and POMs are no exception; their organization, orientation, stability, reactivity, and redox activity depend strongly on the properties of the substrate (e.g., hydrophobic vs hydrophilic) and its passivation/functionalization. − It can also be influenced by methods of molecular deposition , and the adsorption of POM itself can exert electronic effects on, e.g., biomolecular nanostructures such as DNA origami confined to the surface . The utility of POMs as redox-active building blocks includes the investigation of electron transport in the context of polarizability, spintronics, , organic neuromorphics, − , thermoelectrics, molecular magnetism, , molecular sensors, and plasmonics. , Thus, POMs are a natural extension of molecular electronics ,, into the phenomenology of f-shell lanthanides ,− and their interactions with transition metals, metal–ligand charge transfer effects, shielding effects, and other potentially useful, yet-to-be-discovered electron charge and spin phenomena at the nanoscale …”

Multistate switching of scanning tunnelling microscopy machined polyoxovanadate–dysprosium–phthalocyanine nanopatterns on graphite

“…Indeed, to specifically determine the POV12 redox states and the physical mechanisms that occur in the PcDy-POV12 layer, it is necessary to carry out additional, time-consuming theoretical studies, which will be published elsewhere. It is noteworthy that such complex electronic interactions of POM anions with their counter cations and the resulting effects on the redox-controlled electron transport characteristics of the POM get more and more attention 37 of the experimental 38,39 and theoretical 40,41 POM communities.…”