Although tautomerization may directly affect the chemical or biological properties of molecules, real-space investigation on the tautomeric behaviors of organic molecules in a larger area of molecular networks has been scarcely reported. In this paper, we choose guanine (G) molecule as a model system. From the interplay of high-resolution scanning tunneling microscopy (STM) imaging and density functional theory (DFT) calculations, we have successfully achieved the tautomeric recognition, separation, and interconversion of G molecular networks (formed by two tautomeric forms G/9H and G/7H) with the aid of NaCl on the Au(111) surface in ultrahigh vacuum (UHV) conditions. Our results may serve as a prototypical system to provide important insights into tautomerization related issues, which should be intriguing to biochemistry, pharmaceutics, and other related fields.

Homocouplings of hydrocarbon groups including alkynyl (sp(1) ), alkyl (sp(3) ), and aryl (sp(2) ) have recently been investigated on surfaces with the interest of fabricating novel carbon nanostructures/nanomaterials and getting fundamental understanding. Investigated herein is the on-surface homocoupling of an alkenyl group which is the last elementary unit of hydrocarbons. Through real-space direct visualization (scanning tunneling microscopy imaging) and density functional theory calculations, the two terminal alkenyl groups were found to couple into a diene moiety on copper surfaces, and is contrary to the common dimerization products of alkenes in solution. Furthermore, detailed DFT-based transition-state searches were performed to unravel this new reaction pathway.

A series of photocatalysts was synthesized by codoping TiO 2 with lanthanum and iodine (La-I-TiO 2 ). The structure and properties of the catalysts were studied by X-ray diffraction (XRD), the Brunauer-Emmett-Teller (BET) method, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis diffuse reflectance spectra. The prepared anatase-phase La-I-TiO 2 (molar ratio 20:20:100) calcined at 400 °C had a BET surface area of 92.9 m 2 g -1 , and the crystallite size calculated from XRD data was ∼3.57 nm, and it had a remarkable absorption in the visible light range of 400-550 nm. The catalytic efficiency was tested by monitoring the photocatalytic degradation of oxalic acid under visible light irradiation. An optimum molar ratio of 20:100 La/TiO 2 was determined for the most efficient inhibition of the recombination of electron-hole pairs and the photocatalytic activity of La-I-TiO 2 calcined at 400 °C was significantly higher than that calcined at 500 or 600 °C in aqueous oxalic acid solution. The probable process of oxalic acid degradation was that it was first adsorbed onto the surface of the catalysts, where it reacted with valence band holes (h vb + ) and the surface-bound or adsorbed • OH radicals ( • OH ads ) as well as reactive oxygen species (ROS) derived from oxygen reduction by photogenerated electrons, and finally converted into CO 2 and H 2 O without any stable intermediate.

Pressure‐induced polymerization (PIP) of aromatics is a novel method for constructing sp3‐carbon frameworks, and nanothreads with diamond‐like structures were synthesized by compressing benzene and its derivatives. Here by compressing a benzene‐hexafluorobenzene cocrystal (CHCF), H‐F‐substituted graphane with a layered structure in the PIP product was identified. Based on the crystal structure determined from the in situ neutron diffraction and the intermediate products identified by gas chromatography‐mass spectrum, we found that at 20 GPa CHCF forms tilted columns with benzene and hexafluorobenzene stacked alternatively, and leads to a [4+2] polymer, which then transforms to short‐range ordered H‐F‐substituted graphane. The reaction process involves [4+2] Diels–Alder, retro‐Diels–Alder, and 1‐1′ coupling reactions, and the former is the key reaction in the PIP. These studies confirm the elemental reactions of PIP of CHCF for the first time, and provide insight into the PIP of aromatics.