.
The interface of TiO2 and water has been heavily researched due to the photocatalytical capabilities of this system. Whereas the majority of existing work has targeted the rutile and anatase phases of TiO2, much less is known about the brookite phase. In this work, we use first-principles molecular dynamics simulations to find the hydration structure of the brookite (210) surface. We find both pure water and an aqueous solution of KCl to order laterally at the sites of surface Ti cations due to electrostatic and chemical considerations, qualitatively in agreement with experimental high-resolution atomic force microscopy measurements. A significant fraction of surface oxygens is hydroxylated for all cases, with up to 40% realized for the aqueous solution at bulk coverage, a result originating in orientational constraints placed on water near the solvated K and Cl ions. Proton transfer is nearly equally frequent between the surface and liquid regions and within the liquid region, but the presence of K and Cl ions makes proton transfer less efficient.
Treatment of o-iodobiphenyls with o-bromobenzyl alcohols in the presence of cesium carbonate under palladium catalysis affords a series of highly substituted triphenylenes. The reaction involves two C-C bond formations and C-C and C-H bond cleavages. A combination of palladium and an electron-deficient phosphine ligand proves to be effective for both decarbonylative cross-coupling and intramolecular cyclization.
Recent progress in frequency modulation atomic force microscopy (FM-AFM) has enabled its operation in liquid with true atomic resolution. However, the information contained in a two-dimensional height image obtained by FM-AFM is often insufficient for understanding the structures and phenomena at a solid/liquid interface. In this study, we have developed a method referred to as 3D scanning force microscopy (3D-SFM). Combined with FM-AFM, the method enables to visualize 3D distribution of water and fluctuating surface structures at solid/liquid interfaces. Here we present basic principle and applications of 3D-SFM. The 3D-SFM image obtained at a mica/water interface shows 3D distribution of the hydration layers and adsorbed water molecules with subnanometer-scale resolution. In addition, the 3D-SFM image obtained at a lipid/water interface shows 3D distribution of the fluctuating lipid headgroups.
