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We fabricated an NMR cell equipped with 10−100 nm scale spaces on a glass substrate (called extended nanospaces), and investigated molecular structure and dynamics of water confined in the extended nanospaces by 1H NMR chemical shift (δH) and 1H and 2H NMR spin−lattice relaxation rate (1H- and 2H-1/T1), 1H NMR spin−spin relaxation rate (1H-1/T2), and 1H NMR rotating-frame spin−lattice relaxation rate (1H-1/T1ρ) measurements of H2O and 2H2O. The δHand 1H- and 2H-1/T1results showed that size-confinement produces slower translational motions and higher proton mobility of water, but does not affect the hydrogen-bonding structure and rotational motions. Such unique phenomena appeared in the space size of 40 to 800 nm. However, the 1H-1/T1value at 40 nm was still different from that in 4 nm porous nanomaterial, because translational and rotational motions were inhibited for H2O molecules in the nanomaterial. By examining temperature- and deuterium-dependence of the 1H-1/T1values, the molecular translational motions of the confined water were found to be controlled by protonic diffusion invoking a proton hopping pathway between adjacent water rather than hydrodynamic translational diffusion. Furthermore, we clarified that proton exchange between adjacent water molecules in extended nanospaces could be enhanced by the chemical exchange of protons between water and SiOH groups on glass surfaces, (SiO−···H+···H2O) + H2O → SiO−+ (H3O++ H2O) → SiO−+ (H2O + H3O+), based on 1H-1/T2measurements. An enhancement of proton exchange rate of water due to the reduction of space sizes was verified from the results of 1H-1/T1ρvalues, and the rate of water in the 100 nm sized spaces is larger by a factor of more than ten from that of bulk water. Such size-confinement effects were distinctly observed for hydrogen-bond solvents with strong proton-donating ability, while they did not appear for aprotic and nonpolar solvent cases. Based on these NMR results, we suggested that an intermediate phase, in which protons migrate through a hydrogen-bonding network and the water molecules are loosely coupled within 50 nm from the surface, exists mainly in extended nanospaces. This model could be supported by a three-phase theory based on the weight average of three phases invoking the bulk, adsorbed, and intermediate phases. [ABSTRACT FROM AUTHOR]

Surface potential switching on gold(111) surfaces is induced by complexation/decomplexation reactions of a bipyridine (BP) derivative and palladium(II) chloride, as observed by Kelvin probe force microscopy (KFM). On the basis of the theoretical predictions, a 4-(5-phenylethynyl-2,2‘-bipyridine-5‘-yl-ethynyl)benzenethiol (PhBP) derivative was synthesized and used as an active monolayer to catch transition metal ions. By using the microcontact printing (CP) technique, micron-size patterned PhBP monolayers, which act as effective hosts to coordinate palladium(II) chloride, were prepared on gold(111) surfaces. The KFM signal decreases by complexation of the Pd(II) chloride in PhBP monolayers and is recovered by removal of Pd ions using an ethylenediamine solution, as confirmed by X-ray photoelectron spectroscopy. This process is reversible, indicating that the surface potential switching is realized by complexation/decomplexation of Pd(II). A CP PhBP monolayer, when it detects the target palladium ion, shows sensitivity for the picomolar level detection judged from surface potential changes in KFM measurements. The dipole moment estimated by the surface potentials is much smaller than the calculated value, indicating that mechanisms for the reduction of the surface dipole moment exist in real monolayers prepared by the CP method. [ABSTRACT FROM AUTHOR]