Merging Photocatalysis with Electrochemistry: The Dawn of a new Alliance in Organic Synthesis

The merging of a homogeneous photocatalytic system with an electrochemical cell, having exchanged electrons as the only common point, has been recently demonstrated. This combination opens unexplored pathways in synthesis and allowed net‐oxidative photocatalytic processes to be realized in the absence of a chemical oxidant, including: 1) the C?H alkylation of heteroarenes and 2) the coupling of azoles with arenes in the presence of an electrogenerated photocatalyst.     

Fitting continuum wavefunctions with complex Gaussians: Computation of ionization cross sections

We implement a full nonlinear optimization method to fit continuum states with complex Gaussians. The application to a set of regular scattering Coulomb functions allows us to validate the numerical feasibility, to explore the range of convergence of the approach, and to demonstrate the relative superiority of complex over real Gaussian expansions. We then consider the photoionization of atomic hydrogen, and ionization by electron impact in the first Born approximation, for which the closed form cross sections serve as a solid benchmark. Using the proposed complex Gaussian representation of the continuum combined with a real Gaussian expansion for the initial bound state, all necessary matrix elements within a partial wave approach become analytical. The successful numerical comparison illustrates that the proposed all-Gaussian approach works efficiently for ionization processes of one-center targets.     

Probing Molybdenum Active Sites during In Situ Photoreduction of the Mo6+/SiO2 Catalyst

The photoreduction of the Mo⁶⁺/SiO₂ system with CO was investigated in situ, employing a recently developed experimental setup allowing for the acquisition of transmission FT-IR spectra under simultaneous UV irradiation. Carbon monoxide, besides acting as a reducing agent in such processes, is also a useful probe molecule able to detect coordinatively unsaturated sites exposed on the surface. The unprecedented quality of the spectroscopic data, obtained as a function of the reduction time, allowed us to better rationalize the different mechanisms previously proposed for the photoreduction process. These results, coupled with UV-Vis spectroscopic data, shed light on the oxidation state and surface structure of supported molybdenum species, which are key active sites for several important reactions, such as selective oxidation, polymerization, hydrodesulfurization, epoxidation and olefin metathesis.     

A broadbanded pressure differential wave energy converter based on dielectric elastomer generators

Nonlinear Dynamics - Dielectric elastomer generators (DEGs) are a promising option for the implementation of affordable and reliable sea wave energy converters (WECs), as they show considerable...     

Insight of the Metal–Ligand Interaction in f-Element Complexes by Paramagnetic NMR Spectroscopy

The magnetic properties of Ln^III and An^III complexes formed with dipicolinate ligands have been studied by NMR spectroscopy. To know precisely the geometries of these complexes, a crystallographic study by single-crystal X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) in solution was performed. Several methods to separate the paramagnetic shifts observed in the NMR spectra were applied to these complexes. Methods using a number of nuclei of the dipicolinate ligands revealed an abrupt change in the geometries of the complexes and a metal–ligand interaction in the middle of the lanthanide series. A study of the variation of the paramagnetic shifts with temperature demonstrated that higher-order terms of the dipolar and contact contributions are required, especially for the lightest Ln^III and almost all the studied An^III. Bleaney's parameters <S_z>_a and relating to the contact and dipolar terms, respectively, were deduced from experimental data and compared with the results of ab initio calculations. Quite a good agreement was found for the temperature dependencies of <S_z>_a and . However, the values obtained from cation magnetic anisotropy calculations showed some discrepancies with the values derived from Bleaney's equation defined for Ln^III. Other parameters, such as the crystal field parameter and the hyperfine constants F_i obtained from the experimental data of the [An(ethyl-dpa)₃]³⁻ complexes (ethyl-dpa=4-ethyl-2,6-dipicolinic acid), are at odds with the assumptions underlying Bleaney's theory.