Mesoporous Metal-Metalloid Amorphous Alloys: The First Synthesis of Open 3D Mesoporous Ni-B Amorphous Alloy Spheres via a Dual Chemical Reduction Method

2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Selective hydrogenation of nitriles is an industrially relevant synthetic route for the preparation of primary amines. Amorphous metal-boron alloys have a tunable, glass-like structure that generates a high concentration of unsaturated metal surface atoms that serve as active sites in hydrogenation reactions. Here, a method to create nanoparticles composed of mesoporous 3D networks of amorphous nickel-boron (Ni-B) alloy is reported. The hydrogenation of benzyl cyanide to β-phenylethylamine is used as a model reaction to assess catalytic performance. The mesoporous Ni-B alloy spheres have a turnover frequency value of 11.6 h−1, which outperforms non-porous Ni-B spheres with the same composition. The bottom-up synthesis of mesoporous transition metal-metalloid alloys expands the possible reactions that these metal architectures can perform while simultaneously incorporating more Earth-abundant catalysts

Macrocyclization in the Design of Organic n‑Type Electronic Materials

Here, we compare analogous cyclic and acyclic π-conjugated molecules as n-type electronic materials and find that the cyclic molecules have numerous benefits in organic photovoltaics. This is the first report of such a direct comparison. We designed two conjugated cycles for this study. Each comprises four subunits: one combines four electron-accepting, redox-active, diphenyl-perylenediimide subunits, and the other alternates two electron-donating bithiophene units with two diphenyl-perylenediimide units. We compare the macrocycles to acyclic versions of these molecules and find that, relative to the acyclic analogs, the conjugated macrocycles have bathochromically shifted UV–vis absorbances and are more easily reduced. In blended films, macrocycle-based devices show higher electron mobility and good morphology. All of these factors contribute to the more than doubling of the power conversion efficiency observed in organic photovoltaic devices with these macrocycles as the n-type, electron transporting material. This study highlights the importance of geometric design in creating new molecular semiconductors. The ease with which we can design and tune the electronic properties of these cyclic structures charts a clear path to creating a new family of cyclic, conjugated molecules as electron transporting materials in optoelectronic and electronic devices