The carbonization of aromatic molecules with three-dimensional structures affords carbon materials with controlled pore sizes at the Ångstrom-level

Carbon materials with controlled pore sizes at the nanometer level have been obtained by template methods, chemical vapor desorption, and extraction of metals from carbides. However, to produce porous carbons with controlled pore sizes at the Ångstrom-level, syntheses that are simple, versatile, and reproducible are desired. Here, we report a synthetic method to prepare porous carbon materials with pore sizes that can be precisely controlled at the Ångstrom-level. Heating first induces thermal polymerization of selected three-dimensional aromatic molecules as the carbon sources, further heating results in extremely high carbonization yields (>86%). The porous carbon obtained from a tetrabiphenylmethane structure has a larger pore size (4.40 Å) than those from a spirobifluorene (4.07 Å) or a tetraphenylmethane precursor (4.05 Å). The porous carbon obtained from tetraphenylmethane is applied as an anode material for sodium-ion battery.

Preparation of Polyimide @ Polypyrrole/Palladium Hollow Composites with Applications in Catalysis

Polyimide based hollow composites were successfully prepared by combining the situ and template methods together. Firstly, the complete words (PPy) shell was covered on the surface of polystyrene nanoparticles, then the polyamide acid and PdCl2 were covered on the surface of the materials after the calcination. Finally, PI@ PPy/Pd hollow composites were obtained by a chemical process. The structure and composition of composites were characterized by scanning electron microscopy X-ray diffraction, thermo gravimetric analyzer and differential scanning calorimeter, respectively. Palladium (Pd) nanoparticles were densely and uniformly anchored on the surface of PPy shell due to the coordination interaction between amino groups on PPy backbone and Pd2+ ions. They are ideal candidates as nanoreactors for heterogeneous catalysis due to their special structure. The catalytic performance of PI@ PPy/Pd hollow composites were studied by the reduction of NaBH4 as a reducing agent. The catalytic performance of composites was characterized by ultraviolet and visible spectrophotometer. The PI@PPy/Pd composites showed excellent catalytic performance in the reduction of methylene blue with sodium borohydride as reducing agent. The dye completely turned colorless as seen within 2.0 minutes.

Active Metal Template Synthesis and Thermal Actuation of a Nanohoop [c2]Daisy Chain Rotaxane

<p>Molecules and materials that demonstrate large amplitude responses to minor changes in their local environment play an important role in the development of new forms of nanotechnology. Molecular daisy chains are a type of a mechanically interlocked molecule that are particularly sensitive to such changes where, in the presence of certain stimuli, the molecular linkage enables muscle-like movement between a reduced-length contracted form and an increased-length expanded form. To date, all reported syntheses of molecular daisy chains are accomplished via passive-template methods, resulting in a majority of structures being switchable only through the addition of an exogenous stimuli such as metal ions or changes in pH. Here, we describe a new approach to these structural motifs that exploits a multi-component active-metal template synthesis to mechanically interlock two pi-rich nanohoop macrocycles into a molecular daisy chain which we show can be actuated through simple thermal changes.</p>

Active Metal Template Synthesis and Thermal Actuation of a Nanohoop [c2]Daisy Chain Rotaxane

<p>Molecules and materials that demonstrate large amplitude responses to minor changes in their local environment play an important role in the development of new forms of nanotechnology. Molecular daisy chains are a type of a mechanically interlocked molecule that are particularly sensitive to such changes where, in the presence of certain stimuli, the molecular linkage enables muscle-like movement between a reduced-length contracted form and an increased-length expanded form. To date, all reported syntheses of molecular daisy chains are accomplished via passive-template methods, resulting in a majority of structures being switchable only through the addition of an exogenous stimuli such as metal ions or changes in pH. Here, we describe a new approach to these structural motifs that exploits a multi-component active-metal template synthesis to mechanically interlock two pi-rich nanohoop macrocycles into a molecular daisy chain which we show can be actuated through simple thermal changes.</p>