Synthesis of Diazenido-Ligated Vanadium Nanoparticles

Metallic vanadium nanoparticles stabilized with 4-octylphenyldiazenido groups (particle size: 1.7 ± 0.2 nm) were synthesized via the reduction of VCl₄ with superhydride (LiBHEt₃) in the presence of 4-octylphenyldiazonium salt in an Ar-filled glovebox. The resulting particles were characterized using TEM, elemental analysis, and XPS measurements. The unusual reaction on the surface resulted in the passivation of V–NN–Ar covalent bonds

Effective Method for Micro-Patterning Arene-Terminated Monolayers on a Si(111) Electrode

Microstructured electrodes are significant to modern electrochemistry. A representative aromatic group, 4-ferrocenylphenyl one, was covalently bound to a micropatterned silicon electrode via the arylation of a hydrogen-terminated silicon(111) surface formed selectively on a Si wafer. Starting from a silicon(100)-on-insulator (SOI) wafer, the aromatic monolayer was attached sequentially by spin-coating a resist, electron beam lithography, Cr/Au deposition, lift-off, anisotropic etching with aqueous KOH solution, and Pd-catalyzed arylation. Cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) are used to characterize the coupling reaction between 4-ferrocenyl group and silicon substrate, and to confirm performance of the final modified microsized electrode. These data show that this synthetic protocol gives chemically well-defined and robust functionalized monolayers on a silicon semiconducting surface with a small electrode

A New Method To Generate Arene-Terminated Si(111) and Ge(111) Surfaces via a Palladium-Catalyzed Arylation Reaction

Formation of silicon–aryl and germanium–aryl direct bonds on the semiconductor surface is a key issue to realize molecular electronic devices, but the conventional methods based on radical intermediates have problems to accompany the side reactions. We developed the first example of versatile and efficient methods to form clean organic monolayers with Si–aryl and Ge–aryl bonds on hydrogen-terminated silicon and germanium surfaces by applying our original catalytic arylation reactions of hydrosilanes and hydrogermanes using Pd catalyst and base in homogeneous systems. We could immobilize aromatic groups with redox-active and photoluminescent properties, and further applied in the field of rigid π-conjugated redox molecular wire composites, as confirmed by the successive coordination of terpyridine molecules with transition metal ions. The surfaces were characterized using cyclic voltammetry (CV), water contact angle measurements, X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, and atomic force microscopy (AFM). Especially, the AFM analysis of 17 nm-long metal complex molecular wires confirmed their vertical connection to the plane surface

Photocurrent Generation of Reconstituted Photosystem II on a Self-Assembled Gold Film

Photosystem II (PSII)-modified gold electrodes were prepared by the deposition of PSII reconstituted with platinum nanoparticles (PtNPs) on Au electrodes. PtNPs modified with 1-[15-(3,5,6-trimethyl-1,4-benzoquinone-2-yl)]­pentadecyl disulfide ((TMQ­(CH₂)₁₅S)₂) were incorporated into the Q_B site of PSII isolated from thermophilic cyanobacterium <i>Thermosynechococcus elongatus</i>. The reconstitution was confirmed by Q_A-reoxidation measurements. PSII reconstituted with PtNPs was deposited and integrated on a Au(111) surface modified with 4,4′-biphenyldithiol. The cross section of the reconstituted PSII film on the Au electrode was investigated by SEM. Absorption spectra showed that the surface coverage of the electrode was about 18 pmol PSII cm^–2. A photocurrent density of 15 nAcm^–2 at <i>E</i> = +0.10 V (vs Ag/AgCl) was observed under 680 nm irradiation. The photoresponse showed good reversibility under alternating light and dark conditions. Clear photoresponses were not observed in the absence of PSII and molecular wire. These results supported the photocurrent originated from PSII and moved to a gold electrode by light irradiation, which also confirmed conjugation with orientation through the molecular wire

Anionic Iron Complexes with a Bond between an Ate-Type Pentacoordinated Germanium and an Iron Atom

The first stable anionic iron(0) complexes bearing an ate-type pentacoordinated germanium­(IV) ligand were synthesized. The X-ray crystallographic analysis shows trigonal-bipyramidal and piano-stool geometries of germanium and iron, respectively. The complexes have moderately electron-rich iron centers and polar Ge–Fe bonds which can be cleaved by oxidation

Anionic Iron Complexes with a Bond between an Ate-Type Pentacoordinated Germanium and an Iron Atom

The first stable anionic iron(0) complexes bearing an ate-type pentacoordinated germanium­(IV) ligand were synthesized. The X-ray crystallographic analysis shows trigonal-bipyramidal and piano-stool geometries of germanium and iron, respectively. The complexes have moderately electron-rich iron centers and polar Ge–Fe bonds which can be cleaved by oxidation

π‑Conjugated Nickel Bis(dithiolene) Complex Nanosheet

A π-conjugated nanosheet comprising planar nickel bis­(dithiolene) complexes was synthesized by a bottom-up method. A liquid–liquid interfacial reaction using benzenehexathiol in the organic phase and nickel­(II) acetate in the aqueous phase produced a semiconducting bulk material with a thickness of several micrometers. Powder X-ray diffraction analysis revealed that the crystalline portion of the bulk material comprised a staggered stack of nanosheets. A single-layer nanosheet was successfully realized using a gas–liquid interfacial reaction. Atomic force microscopy and scanning tunneling microscopy confirmed that the π-conjugated nanosheet was single-layered. Modulation of the oxidation state of the nanosheet was possible using chemical redox reactions