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The formation process and structure of a self-assembled monolayer (SAM) of lipoic-acid-terminated polyproline on a gold surface in aqueous solution were investigated by several techniques. The amount of polyproline molecules on the gold surface was determined from the area of the reductive desorption peak, and orientation and thickness of the polyproline SAM were determined in situ by attenuated total reflection infrared (ATR-IR) spectroscopy and ellipsometry. The kinetics of the polyproline SAM formation process were discussed on the basis of these results. The in situ IR study confirmed that the conformation of the polyproline SAM was changed by changing the solvent from water to methanol and methanol to water, as is the case for polyproline dissolved in solution., (© 2011 American Chemical Society)

The potential dependence of the interfacial water structure at Pt and Au thin film electrodes was investigated by sum frequency generation (SFG) spectroscopy in internal reflection mode. In the case of the Pt electrode, two broad peaks were observed in the OH stretching region at ca. 3200 cm(-1) and ca. 3400 cm(-1), which are known to be due to the symmetric OH stretching (upsilon1) of tetrahedrally coordinated, i.e., strongly hydrogen bonded "ice-like" water, and the asymmetric OH stretching (upsilon3) of water molecules in a more random arrangement, i.e., weakly hydrogen bonded "liquid-like" water, respectively. In the case of the Au electrode, however, a 3400 cm(-1) band was dominant in the SFG spectrum, suggesting that the interaction between water molecules and Au and Pt are different, i.e., water molecules are more disordered at the Au surface. The potential dependence of interfacial water during the methanol oxidation reaction on a Pt electrode was also investigated. SFG intensity strongly depended on electrode potential. Several possibilities are suggested for the potential dependence of the SFG intensity.

Biphenyl-2,2′-diylbis(10-methyl-9-methyleneacridan)-type electron donor 1, which has two tethered cyclic disulfide units at the 6,6′-positions, was designed and synthesized as the first member of a dynamic redox (dyrex) system that can form molecular layers on a Au(111) electrode. Upon the two-electron (2 e) oxidation of 1, the persistent dicationic dye 22+ was generated with the formation of a new C−C bond, which is reversibly cleaved upon 2 e reduction to regenerate 1 (dyrex behavior). Similar dyrex interconversion occurs in the molecular layer of 1 on gold. The chemical identities of 1/Au and electrochemically generated 22+/Au were unambiguously determined by in situ IR spectroscopy in the attenuated total reflection mode. In situ scanning tunneling microscopy (STM) was conducted under electrochemical conditions to examine the surface structure of 1 adsorbed on a Au(111) electrode. Although no long-range-ordered morphology was found in the STM image of 1, an in situ STM study of the potential-induced dyrex reaction of 1 to 22+ showed that the grained spots in the image became slightly brighter. [ABSTRACT FROM AUTHOR]

The cover picture shows the first member of a dynamic redox system attached to a gold surface that can undergo electrochemical switching on the surface. Reversible C−C bond formation/cleavage upon two‐electron transfer endows the system with high electrochemical stability. This study demonstrates a prototype toward the realization of molecular‐based data storage devices using electrochemical input by a scanning tunneling microscopy tip. Details are given in the Communication by Takanori Suzuki and co‐workers on page 1043 in Issue 7, 2017 (DOI: 10.1002/cplu.201600649). [ABSTRACT FROM AUTHOR]

The molecular orientation in self-assembled monolayer (SAM) of octadecanethiol (ODT) on platinum surface prepared in ethanol solution was examined by broad-bandwidth sum frequency generation (BB-SFG) spectroscopy. The bands attributed to the CH3 symmetric and asymmetric stretching vibrational modes were observed in the SFG spectra. From the analysis of SFG intensity ratio of these two modes, the alkyl chain on platinum was found to be more perpendicular to the substrate than those on gold surface. [ABSTRACT FROM AUTHOR]

Electrochemical deposition (electrodeposition) and dissolution processes of Pd on a polycrystalline Au electrode surface in HClO4 solution containing PdCl42− were investigated by second harmonic generation (SHG) measurements. Both 1064 nm (near-IR) and 600 nm (visible) excitations were employed to monitor the SHG behavior in situ. Under the near-IR excitation, the resulting SHG signal contained contributions from both the Pd deposit and the adsorbed PdCl42−. On the other hand, the adsorption of the PdCl42− did not affect the SHG signal under the visible excitation. The SHG signal under the visible excitation was resonantly enhanced with the first and second monolayer depositions of Pd but declined with higher Pd coverage. These results confirm the unique structure and property of an ultra-thin Pd overlayer on gold, suggested by scanning tunneling microscopy (STM), surface X-ray scattering (SXS) and electrochemical measurements at electrodeposited Pd thin layers on single crystalline gold surfaces. [Copyright &y& Elsevier]