Fabrication of DNA Nanowires by Orthogonal Self-Assembly and DNA Intercalation on a Au Patterned Si/SiO₂ Surface

Abstract

A novel Ru complex bearing both an acridine group and anchoring phosphonate groups was immobilized on a surface in order to capture double-stranded DNAs (dsDNAs) from solution. At low surface coverage, the atomic force microscopy (AFM) image revealed the "molecular dot" morphology with the height of the Ru complex ( approximately 2.5 nm) on a mica surface, indicating that four phosphonate anchor groups keep the Ru complex in an upright orientation on the surface. Using a dynamic molecular combing method, the DNA capture efficiency of the Ru complex on a mica surface was examined in terms of the effects of the number of molecular dots and surface hydrophobicity. The immobilized surface could capture DNAs; however, the optimal number of molecular dots on the surface as well as the optimal pull-up speed exist to obtain the extended dsDNAs on the surface. Applying this optimal condition to a Au-patterned Si/SiO 2 (Au/SiO 2) surface, the Au electrode was selectively covered with the Ru complex by orthogonal self-assembly of 4-mercaptbutylphosphonic acid (MBPA), followed by the formation of a Zr (4+)-phosphonate layer and the Ru complex. At the same time, the remaining SiO 2 surface was covered with octylphosphonic acid (OPA) by self-assembly. The selective immobilization of the Ru complex only on the Au electrode was identified by time-of-flight secondary-ion mass spectrometry (TOF-SIMS) imaging on the chemically modified Au/SiO 2 surface. The construction of DNA nanowires on the Au/SiO 2 patterned surface was accomplished by the molecular combing method of the selective immobilized Ru complex on Au electrodes. These interconnected nanowires between Au electrodes were used as a scaffold for the modification of Pd nanoparticles on the DNA. Furthermore, Cu metallization was achieved by electroless plating of Cu metal on a priming of Pd nanoparticles on the Pd-covered DNA nanowires. The resulting Cu nanowires showed a metallic behavior with relatively high resistance.

Photoresponsive Molecular Memory Films Composed of Sequentially Assembled Heterolayers Containing Ruthenium Complexes

“…Preparation and immobilizationofR u-NP and Ru-CP The targeted Ru-NP and Ru-CP complexes were obtainedf rom microwave-assisted heatingo fr eaction mixtures containing [Ru(EtL)(CH 3 CN)Cl 2 ]( EtL = 2,6-bis(N-(2,4,6-methyl-3,5-diethylphosphonatomethyl-benzyl)-benzimidazole-2-yl)-pyridine) [54,55] and tetra(pyridyl)-pyrazine or -benzene, followed by deprotecChem. Eur.J.2016, 22,1658 -1667 www.chemeurj.org tion of the ethyl group with trimethylsilylbromide.T he UV/Vis/ NIR spectralf eatures and redox potentials of Ru-NP and Ru-CP are almost identicalt ot hose of the reported Ru-N and Ru-C complexes.…”

“…[52] The judiciousd esign of the anchoring ligand in these redox-activec omplexes has allowed us to control the molecular inclusion by redox reactions [54] and to achieve DNA trapping on these immobilized Ru complexes. [55] When phosphonate anchor groups were incorporated at both ends of the rod-shaped Ru complexes,s table-layer structures were obtained on as olid surface via zirconium(IV)-phosphonate bonds. [47] The resulting multilayer films, containing Ru complexes, displayed stable redox responses on ITO electrodes, as well as long-distanceE Tp roperties when incorporated between two electrodes.…”

Electron hopping rate measurements in ITO junctions: Charge diffusion in a layer-by-layer deposited ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate–TiO2 film

“…35% w/w Titania sol (TKS-202) was obtained from Tayca Corporation. The dinuclear ruthenium(II)-bis(benzimidazolyl)pyridine-phosphonate metal complex was prepared following a literature procedure [19,20]. Demineralised and filtered water was taken from a Thermo Scientific water purification system (Barnstead Nanopure) with 18.2 MX cm resistivity.…”

Synthesis, Electrochemistry, and Single-Molecule Conductance of Bimetallic 2,3,5,6-Tetra(pyridine-2-yl)pyrazine-Based Complexes

“…The tpp ligand, used in conjugation with tpy coligands, provides a convenient entry point to linear, multimetallic assemblies in which the metal centers can be strongly coupled, 27−31 and it is well-suited to use in the construction of molecular arrays both in solution and from "on-surface" coordination chemistry approaches. 20,21 We now report the synthesis, electrochemical properties, and single-molecule conductance behavior of mono and bimetallic ruthenium complexes based on [Ru(tpy) 2 ] 2+ and [{(tpy)Ru}-(μ-tpp){Ru(tpy)}] 4+ structural motifs. The multimetallic complexes are shown to be capable of serving as wirelike assemblies of up to 3 nm long.…”