Efficient calculations of a large number of highly excited states for multiconfigurational wavefunctions

Electronically excited states play important roles in many chemical reactions and spectroscopic techniques. In quantum chemistry, a common technique to solve excited states is the multiroot Davidson algorithm, but it is not designed for processes like X-ray spectroscopy that involves hundreds of highly excited states. We show how the use of a restricted active space wavefunction together with a projection operator to remove low-lying electronic states offers an efficient way to reach single and double-core-hole states. Additionally, several improvements to the stability and efficiency of the configuration interaction (CI) algorithm for a large number of states are suggested. When applied to a series of transition metal complexes the new CI algorithm does not only resolve divergence issues but also leads to typical reduction in computational time by 70%, with the largest savings for small molecules and large active spaces. Together, the projection operator and the improved CI algorithm now make it possible to simulate a wide range of single- and two-photon spectroscopies. © 2019 Wiley Periodicals, Inc.     

Development of a Submerged Thermal Plasma Process for Combustion of Organic Liquid Waste

Plasma Chemistry and Plasma Processing - A process for the destruction of organic liquid waste has been developed in which a nontransferred arc plasma torch is operated with oxygen as the plasma...     

An Artificial Lithium Protective Layer that Enables the Use of Acetonitrile‐Based Electrolytes in Lithium Metal Batteries

The resurgence of the lithium metal battery requires innovations in technology, including the use of non‐conventional liquid electrolytes. The inherent electrochemical potential of lithium metal (?3.04 V vs. SHE) inevitably limits its use in many solvents, such as acetonitrile, which could provide electrolytes with increased conductivity. The aim of this work is to produce an artificial passivation layer at the lithium metal/electrolyte interface that is electrochemically stable in acetonitrile‐based electrolytes. To produce such a stable interface, the lithium metal was immersed in fluoroethylene carbonate (FEC) to generate a passivation layer via the spontaneous decomposition of the solvent. With this passivation layer, the chemical stability of lithium metal is shown for the first time in 1 m LiPF₆ in acetonitrile.     

Solid-phase synthesis of serine-based glycosphingolipid analogues for preparation of glycoconjugate arrays

Synthetic glycolipids with defined structures are important tools in the study of glycolipid biology. In this paper we describe a solid-phase synthesis of three galactosylated serine-based glycosphingolipid analogues using the novel linker 2-fluoro-4-(hydroxymethyl)-phenoxyacetic acid. Gel-phase (19)F-NMR spectroscopy was used to measure the yield and stereochemical outcome of the solid-phase glycosylations. Under NIS-TfOH promotion, alpha- and beta-selective glycosylations were performed at room temperature with thioglycoside donors carrying fluorine labelled protective groups. Finally, the glycolipids were covalently linked to microtiter plates and labelled lectins with different selectivity for alpha- and beta-galactosides could bind to the glycolipid arrays.     

A rapid and convenient synthesis of β-proline

A short, reliable, and cheap synthesis of both enantiomers of β-proline, an efficient organocatalyst and an important building block in medicinal chemistry, has been developed in four steps (overall yield: 72%) from the diasteromeric adducts of methyl itaconate and (R)-α-methylbenzylamine. The key step involves the chemoselective reduction of a lactam group in the presence of a benzyl ester.     

Sound focusing in rooms: the time-reversal approach

New perspectives in audible range acoustics, such as virtual sound space creation and active noise control, rely on the ability of the rendering system to recreate precisely a desired sound field. This ability to control sound in a given volume of a room is directly linked to the capacity to focus acoustical energy both in space and time. However, sound focusing in rooms remains a complicated problem, essentially because of the multiple reflections on obstacles and walls occurring during propagation. In this paper, the technique of time-reversal focusing, well known in ultrasound, is experimentally applied to audible range acoustics. Compared to classical focusing techniques such as delay law focusing, time reversal appears to considerably improve quality of both temporal and spatial focusing. This so-called super-resolution phenomenon is due to the ability of time reversal to take into account all of the different sound paths between the emitting antenna and the focal point, thus creating an adaptive spatial and temporal matched filter for the considered propagation medium. Experiments emphasize the strong robustness of time-reversal focusing towards small modifications in the medium, such as people in motion or temperature variations. Sound focusing through walls using the time-reversal approach is also experimentally demonstrated.     

Chiral-at-metal ruthenium complex as a metalloligand for asymmetric catalysis

The mononuclear [Ru(bpy)(2)(bpym)][PF(6)](2) complex (bpy = 2,2'-bipyridine; bpym = 2,2'-bipyrimidine) has been prepared in its enantiopure Lambda form. Because of the chelating property of the bipyrimidine moiety, it is possible to use this chiral-at-metal complex as a chiral inorganic ligand for a second metal cation acting as a catalytic center. Here we report the synthesis and the structural characterization of a novel dinuclear Lambda-[(bpy)(2)Ru(bpym)RuCl(p-cymene)](3+) compound (1). The asymmetric-inducing properties of the enantiopure chiral-at-metal metalloligand have been probed during asymmetric transfer hydrogenation to ketones catalyzed by 1. This provides one of the very few illustrations of the potential of this original class of chiral inorganic ligands.     

Nanopowders of ferroic oxides for magnetoelectric composites

Piezoelectric oxides are currently being considered in combination with magnetic materials for the development of magnetoelectric composites, in which stress transfer across the interface is a key issue. In this context, we report here a detailed study of the mechanochemical activation processes of the ferroelectric perovskite BiScO₃–PbTiO₃ and of the ferrimagnetic spinel NiFe₂O₄. Highly sinterable, single-phase nanopowders of both ferroic oxides are synthesised, and used for the preparation of high-density materials and two-phase composites by hot pressing. Emphasis is put on studying chemical reactions at and interdiffusion across the interface between the two phases using high spatial resolution techniques such as micro X-ray diffraction and piezoresponse force microscopy. The feasibility of preparing magnetoelectric composites by this approach is demonstrated, for which the necessity of controlling physicochemical processes at the interface is key to obtain functionality.