Modeling the HCOOH/CO2 Electrocatalytic Reaction: When Details Are Key

Our first principles simulations of the electrooxidation of formic acid over nickel identify the reorientation of the formate intermediate and the desorption of CO₂ as the rate‐limiting steps. Although they are not associated with an electron transfer, these barriers are strongly modified when the electrochemical potential is explicitly accounted for and when modeling the influence of the solvent. Hence, such a level of modeling is key to understand the kinetic limitations that penalize the reaction.     

Demokrit und die Quantenmechanik

Democrit and Quantum Mechanics It is shown that the antique atomisms founded a thought principle which has also a fundamental meaning for modern physics, a principle which in its Newtonian version makes it possible to grasp motion and continuum physically.     

2H NMR studies of phase behaviour and molecular motions of doped discotic liquid-crystalline systems

A discotic triphenylene monomer as well as a dimer and a main chain polymer, all substituted with heptyloxy side groups, were doped with an electron acceptor (2,4,7-trinitrofluorenone (TNF)) to give charge transfer complexes. These doped systems were aligned in a magnetic field, thus proving their liquid crystallinity. ²H NMR measurements show that the electron acceptor molecules are incorporated into the columns built of triphenylene cores. In the charge transfer complex with the triphenylene monomer almost all the electron acceptor molecules stack in the columns even close to the clearing temperature T₁, while for the dimer and especially for the polymer a significant fraction of the TNF molecules exhibits isotropic motion, which is attributed to their location in the region between the columns, already way below T₁. This isotropically distributed part increases on approaching T₁. Fast rotation of the discs around their column axes takes place in the monomer and is quenched in the dimer and the polymer, due to the interlinking of the columns by the spacer. The electron acceptor molecules, on the other hand, exhibit free rotation in all samples, even in the charge transfer complexes with the triphenylene dimer and polymer. In the side group labelled triphenylenes increased ²H NMR spectral narrowing is detected in the charge transfer complex samples compared with the corresponding pure triphenylenes. This indicates higher side group mobility in the doped systems, since the incorporation of TNF molecules increases the spacing between the discotic units.     

Zum Problem Camphenilansäure—Camphenansäure und Isocamphenilansäure—Isocamphenansäure

The configuration of camphenilanic acid (1) has been determined by NMR-spectroscopic studies.¹H-,¹³C-NMR and 2D-shift correlation spectroscopy have been used. The socalled camphenanic acid is identical with1, isocamphenanic acid appears to be a mixture of1 and2, the same is true for different camphenilanic acids described in the literature.