Understanding the effects of enamel loss and surface softening caused by acidic soft drinks consumption would help in the clinical treatment of tooth wear and aid in the development of novel dental restorative materials. Hence, this investigation was carried out to examine the effects of "Miswak" on the acid eroded enamel surface at nano-mechanical scale. The first use of a stylus-based inductive gauge is introduced as means of measurement of acid attack on enamel surfaces and the effectiveness of aqueous extracts of Salvadora persica as dissolution inhibitors for acid eroded enamel surfaces. For pre-molar protective, after being exposed to aqueous extracts of Salvadora persica solution, the performance of the enamel surface was improved by R a ≈ 0.82 µm. Whereas, the surface was damaged after immersing in citric acid solution by R a ≈ 0.63 µm. For pre-molar restoring, the enamel surface was degraded by R a ≈ 0.34 µm when exposed to citric acid solution. While, the surface roughness was improved by R a ≈ 0.95 µm when aqueous extracts of Salvadora persica solution was introduced. So, this study concludes that the aqueous extracts of Salvadora persica treatment work effectively on the eroded enamel surface.

A three-component cascade reaction comprising cyclic ketones, arylamines, and benzoylmethylene malonates has been developed to access 4,5,6,7-tetrahydro-1H-indoles. The reaction was achieved through cooperative enamine-Brønsted catalysis in high yields with wide substrate scopes. Mechanistic studies identified the role of the Brønsted acid catalyst and revealed the formation of an imine intermediate, which was confirmed by X-ray crystallography.

Nitride complexes have been invoked as catalysts and intermediates in a wide variety of transformations and are noted for their tunable acid/base properties. A density functional theory study is reported herein that maps the basicity of 3d and 4d transition metals that routinely form nitride complexes: V, Cr, Mn, Nb, Mo, Tc, and Ru. Complexes were gathered from the Cambridge Structural Database, and from the free energy of protonation, the pK b(N) of the nitride group was calculated to quantify the impact of metal identity, oxidation state, coordination number, and supporting ligand type upon metal-nitride basicity. In general, the basicity of transition metal nitrides decreases from left to right across the 3d and 4d rows and increases from 3d metals to their 4d congeners. Metal identity and oxidation state primarily determine basicity trends; however, supporting ligand types have a substantial impact on the basicity range for a given metal. Synergism of these factors in determining the overall pK b(N) values is discussed, as are the implications for the catalytic reactivity of metal nitrides.

Catalyst confinement within microporous media provides the opportunity to site isolate reactive intermediates, enforce intermolecular functionalization chemistry by co-localizing reactive intermediates and substrates in molecular-scale interstices, and harness non-covalent host-guest...