Superhydrophilicity of $\alpha$-Alumina Surfaces Results from Tight Binding of Interfacial Waters to Specific Aluminols

Understanding the microscopic driving force of water wetting is challenging and important for design of materials. In this work, we investigate, using classical molecular dynamics simulations, the water/$\alpha$-alumina (0001) and ($11\overline{2}0$) interfaces chosen for their chemical and physical differences. There is only one type of aluminol group on the nominally flat (0001) surface but three types on the microscopically rougher ($11\overline{2}0$) surface. We find that both surfaces are completely wet, consistent with contact angles of zero. Moreover, the work required to remove water from a nanoscale volume at the interface is larger for the (0001) surface than the ($11\overline{2}0$) surface, suggesting that the (0001) surface is more hydrophilic. In addition, translational and rotational dynamics of interfacial water molecules are slower than that in bulk water, suggesting tight binding to the surface. Interfacial waters show two major polar orientations, either pointing to or away from the solid surface. In the former case, waters donate strong hydrogen bonds to the surface, while in the latter they accept relatively weak ones from aluminol groups. The strength of hydrogen bonds is estimated using their lifetime and geometry. We found that for all aluminols, water-to-aluminol hydrogen bonds are stronger and have longer lifetimes than the aluminol-to-water ones. One exception is the long lifetime of the \ce{Al3OH}-water hydrogen bonds on the ($11\overline{2}0$) surface, due to geometric constraints. Interactions between surfaces and interfacial waters promote a templating effect whereby the latter are aligned in a pattern that follows the underlying lattice of the mineral surface.

Peptide Gelators to Template Inorganic Nanoparticle Formation

The use of peptides to template inorganic nanoparticle formation has attracted great interest as a green route to advance structures with innovative physicochemical properties for a variety of applications that range from biomedicine and sensing, to catalysis. In particular, short-peptide gelators offer the advantage of providing dynamic supramolecular environments for the templating effect on the formation of inorganic nanoparticles directly in the resulting gels, and ideally without using further reductants or chemical reagents. This mini-review describes the recent progress in the field to outline future research directions towards dynamic functional materials that exploit the synergy between supramolecular chemistry, nanoscience, and the interface between organic and inorganic components for advanced performance.

From Starphenes to Non-Benzenoid Linear Conjugated Polymers by Substrate Templating

Combining on-surface synthetic methods with the power of scanning tunneling microscopy to characterize novel materials at the single molecule level, we show how to steer the reactivity of one anthracene-based precursor towards different product nanostructures. Whereas using a two-dimensional Au(111) surface results in the dominant formation of a starphene derivative, the templating effect of a reconstructed Au(110) surface allows the selective growth of non-benzenoid linear conjugated polymers. We further assess the electronic properties of each of the observed product structures via tunneling spectroscopy and DFT calculations, altogether advancing in the synthesis and characterization of molecular structures of notable scientific interest that have been only scarcely investigated to date, as applied to both starphenes and to non-benzenoid conjugated polymers. <br>

From Starphenes to Non-Benzenoid Linear Conjugated Polymers by Substrate Templating

Combining on-surface synthetic methods with the power of scanning tunneling microscopy to characterize novel materials at the single molecule level, we show how to steer the reactivity of one anthracene-based precursor towards different product nanostructures. Whereas using a two-dimensional Au(111) surface results in the dominant formation of a starphene derivative, the templating effect of a reconstructed Au(110) surface allows the selective growth of non-benzenoid linear conjugated polymers. We further assess the electronic properties of each of the observed product structures via tunneling spectroscopy and DFT calculations, altogether advancing in the synthesis and characterization of molecular structures of notable scientific interest that have been only scarcely investigated to date, as applied to both starphenes and to non-benzenoid conjugated polymers. <br>

Recent Advances in the Application of Metal–Organic Frameworks for Polymerization and Oligomerization Reactions

Polymers have become one of the major types of materials that are essential in our daily life. The controlled synthesis of value-added polymers with unique mechanical and chemical properties have attracted broad research interest. Metal–organic framework (MOF) is a class of porous material with immense structural diversity which offers unique advantages for catalyzing polymerization and oligomerization reactions including the uniformity of the catalytic active site, and the templating effect of the nano-sized channels. We summarized in this review the important recent progress in the field of MOF-catalyzed and MOF-templated polymerizations, to reveal the chemical principle and structural aspects of these systems and hope to inspire the future design of novel polymerization systems with improved activity and specificity.

In Situ Monitoring of Mechanochemical Covalent Organic Framework Formation Reveals Templating Effect of Liquid Additive

Covalent organic frameworks (COFs) have emerged as a new class of molecularly precise, porous functional materials characterized by a broad structural and chemical versatility, leading to a diverse range of applications. Despite the increasing popularity of COFs, fundamental aspects of their formation are poorly understood and profound experimental insights into their formation processes are still lacking. Here we use a combination of in situ X-ray powder diffraction and Raman spectroscopy to elucidate the reaction mechanism of mechanochemically synthesized imine COFs, leading to the observation of key reaction intermediates. Real-time monitoring provides experimental evidence of templating effects by the liquid additive for the subsequent pore formation and layer assembly. Moreover, the solid-state catalyst scandium triflate Sc(OTf)₃ is revealed to be instrumental in directing the reaction kinetics and mechanism, resulting in products with crystallinity and porosity en par with solvothermally synthesized COFs. This work highlights the potential of mechanochemistry as a green synthetic route towards COF synthesis, and emphasizes the subtle interplay between choice of liquid additives, catalysts, and activation procedure.<br>

In Situ Monitoring of Mechanochemical Covalent Organic Framework Formation Reveals Templating Effect of Liquid Additive

Covalent organic frameworks (COFs) have emerged as a new class of molecularly precise, porous functional materials characterized by a broad structural and chemical versatility, leading to a diverse range of applications. Despite the increasing popularity of COFs, fundamental aspects of their formation are poorly understood and profound experimental insights into their formation processes are still lacking. Here we use a combination of in situ X-ray powder diffraction and Raman spectroscopy to elucidate the reaction mechanism of mechanochemically synthesized imine COFs, leading to the observation of key reaction intermediates. Real-time monitoring provides experimental evidence of templating effects by the liquid additive for the subsequent pore formation and layer assembly. Moreover, the solid-state catalyst scandium triflate Sc(OTf)₃ is revealed to be instrumental in directing the reaction kinetics and mechanism, resulting in products with crystallinity and porosity en par with solvothermally synthesized COFs. This work highlights the potential of mechanochemistry as a green synthetic route towards COF synthesis, and emphasizes the subtle interplay between choice of liquid additives, catalysts, and activation procedure.<br>